Neurovascular Anatomy of CNS

Table of Contents

Feeding Arteries

Anterior Circulation (Internal Carotid Artery)

Internal Carotid Artery               

Internal carotid artery (ICA) is the main artery for feeding the supra-tentorial brain structure. There are several systems for identifying the anatomical segments of ICA such as traditional numbering and Fischer system.Read more

Anatomy of Circle of Willis

Circle of Willis is a symmetrical communicating arterial pathway formed by an arterial polygon as the internal carotid and vertebral systems anastomose around the optic chiasm and infundibulum of the pituitary stalk. This communicating pathway allows equalization of blood-flow between two sides of the brain through the connection between the middle cerebral artery with the posterior cerebral artery and basilar system.Read more

Variant Anatomy of Circle of Willis

A complete circle of Willis, in which no component is absent or hypoplastic is only seen in 20-25% of anatomical specimens, whereas posterior circle anomalies are seen in nearly 50% of individuals.Read more

Anterior Cerebral Artery (ACA)

Read more

Middle Cerebral Artery (MCA)


Read more

Posterior Cerebral Artery (PCA)

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Posterior Fossa Circulation   

Vertebral arteries and basilar artery are the main feeding arteries of posterior fossa. The basilar artery is built from the joining of 2 vertebral arteries.

The vertebral arteries arise from subclavian arteries and extend to the junction of vertebrobasilar.Read more

Basilar Artery (BA)

Basilar artery is built from joining of two vertebral arteries and located at the anterior surface of pons. It gives several perforating branches usually in three groups such as caudal, middle, and the rostral.

The caudal perforators vary in number from 2-5, and occasionally branched off in ponto-medullary, pyramidal and the hypoglossal branches.Read more

Superior Cerebellum Artery (SCA)

It arises from basilar artery and supplies the upper brainstem colliculi and deep cerebellar nuclei.

It divides itself into four main segments shown in below table.Read more

Anterior Inferior Cerebellar Artery (AICA)

AICA originates from the caudal third of the basilar artery at the level of the junction between the medulla oblongata and the pons in the brainstem. It sweeps backward to anastomosing with the PICA. It is principal vessel of the cerebellopontine angle. It divides into two branches; rostro-lateral and caudo-medial arteries and supplies the ponto-medullar junction laterally, the anterior inferior quarter of the cerebellar cortex.Read more

Posterior Inferior Cerebellar Artery (PICA)

The vertebral artery gives off the branch PICA for supplying the medulla, inferior part of cerebellar hemisphere as well as vermis and IV ventricle. It divides into two main lateral and medial branches and additionally into 5 segments shown in below table.Read more

Drainage System of CNS             

Generally there are two superficial and deep venous systems of brain.

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Basal vein (Vein of Rosenthal)

The important deep vein of basal surface of brain is Basal vein “Vein of Rosenthal”, which drains into the “Vein of Galen”.  The Vein of Rosenthal is truly not a deep vein, but it is located basal and far and plays a significant role in connection between the superficial and deep venous systems, in particular in present of an AVM.Read more

Internal Cerebral Vein

This is a truly the deep vein belongs to the deep venous system and is located right above the third ventricle. It collects a very large amount of bunches including basal ganglia, thalamus, and lots of deep white matter. Its tributaries are divided into smaller medial group that drains septum pellucidum and fornices and a much more impressive lateral group.Read more

Vein of Galen (The great Cerebral Vein)

The vein of Galen (AKA the great cerebral vein), is named for its discoverer, the Greek physician “Galen”. It is one of the largest vein of brain draining the cerebral blood. It is a deep/internal vein and formed by the union of the two internal cerebral veins, thalamostriate vein and choroid vein at the interventricular foramen.Read more

Drainage System of Medulla Oblongata

Veins of the medulla oblongata drain into the veins of the spinal cord, the adjacent Dural venous sinuses, or into variable radicular veins which accompany the last four cranial nerves to either the inferior petrosal or occipital sinuses, or to the superior bulb of the jugular vein.Read more

Cerebrovascular Disease

Intracranial Occlusion Disease

Cerebral Artery Occlusion

Ischemic Stroke


Acute occlusion of cerebral arteries results in a stroke with sequel neurological deficits, depending on the location of the lesion. This basically occurs in two forms such as ischemic (Brain infarction) in about 80% of patients and hemorrhagic infarct in 20% of cases. An ischemic stroke occurs when a region of cerebral blood flow is suddenly stopped or limited. This may occur by vessel occlusion or by low blood flow.Read more


Acute cerebral artery occlusion by an embolus or thrombosis is the most common causes. Due to the interruption of blood flow to a brain area, neuron metabolism is disturbed caused by lock of oxygen and glucose delivering through the involved artery. Cell death may occur after approximately 6 minutes of halted blood circulation.Read more


These may vary from lethargic to comatose, but some patients may present agitation associated with sensory Motor dysfunction. Occasionally, the cranial nerves also are involved with resultant in CN paresis.Read more


CCT-scan is the initial study of choice which may show a hypodense area (Ischemic infarct) in the area of the brain related to the involved feeding artery.Read more


The immediate thrombolytic therapy after onset is the best intervention of choice to reopen and to reestablish the blood flow to brain parenchyma. Read more

Prognosis and Conclusion

Approximately, 30-70/ of young stroke patients may return to work, with the higher fraction being men and those educated beyond high school. Recovery of visual field deficits may be limited; resulting in major limitations in their quality of life, despite normal motor function.Read more

Hemorrhagic transformation of ischemic stroke into hemorrhagic infarct

Hemorrhagic transformation (reperfusion injury of blant stroke) represents the conversion of an ischemic stroke (bland infarction) into a hemorrhagic infarct. This may occur as a petechial hemorrhage (Extravasation of red cells from weakened capillaries) or as a real intra-parenchymal hematoma.Read more

Hemorrhagic Stroke


In hemorrhagic stroke, bleeding occurs directly into the brain parenchyma. The usual mechanism is thought to be leakage from small intracerebral arteries damaged by chronic hypertension (Atherosclerosis).Read more


Hemorrhagic stroke is less common than ischemic stroke. It accounts about 8-18% of all strokes occurred to the brain 4). According to the (WHO), yearly about 15 million people suffer from stroke worldwide. Of these, usually 5 million die and another 5 million has a permanent disability over their life. 27)Read more


The etiologies of stroke are varied, but the common mechanism of hemorrhagic infarct is thought to be leakage of small intracerebral arteries damaged by chronic hypertension (Atherosclerosis). Intracerebral hemorrhage has a predilection for some sites of brain such as thalamus, putamen, brain stem and cerebellum. In 20-40% of patients with ischemic infarction, hemorrhagic transformation may occur within 1 week after ictus.12,13).Read more

Signs and symptoms

Symptoms in Patients with hemorrhagic infarct are worse than those with ischemic stroke. These are such as headache, nausea and vomiting, and/or marked hypertension signs of elevated ICP, as well as seizures and focal neurologic deficits. None of these deficits and symptoms reliably distinguishes between hemorrhagic and ischemic stroke 6).Read more


CCT- scan is the first modality of choice and a crucial step in the evaluation of suspected hemorrhagic stroke and must be obtained on an emergent basis. It also aids in excluding an ischemic stroke. CCT-scan is the first and initial modality of choice to show the intracranial- and intra-ventricular hemorrhage, brain edema, as well as hydrocephalus. Read more


Differentiating between the two types of stroke (ischemic and hemorrhagic) is an essential part of therapy, as the subsequent management of each disorder will be vastly different. Treatment and management of patients with acute intracerebral hemorrhage depends on the cause and severity of the bleeding. Basic life support such as control of bleeding, seizures, BP as well as intracranial pressure are crucial measurements.Read more

Outcome and prognosisPrevious

Next Section: Background

The prognosis of hemorrhagic stroke varies depending on the severity, the location and the size of the hemorrhage. Growth of the hematoma volume is associated with a poorer functional outcome and increased mortality rate.Read more

Moyamoya Disease


It is a Japanese word and means “Puff of smoke” called for the first time by Suzuki and Takaku. This is an angiopathetic disease with vascular changes associated with poor intracranial perfusion. Etiology and pathogenesis of the disease has still not been clearly understood, however it usually occurs in patients with known disease such as arteriosclerosis.Read more


The first report was in 1957 by Takeuchi and Shimizu.Read more


Approximately, 100 new cases occur worldwide each year. It tends to be higher in females than males. Familial version has been identified.Read more


Basic pathological mechanism of the disease is a disposition of smooth muscles of cerebral vessels associated with a chronic inflammatory response. This phenomenon may lead slowly and long-term to the proliferation of smooth muscles and progressive occlusion of vessels.Read more


The disease may lead to cerebral ischemic events such as TIAs or stroke with various clinical symptoms. The most common symptoms in children younger than 10 years are seizure, headache, visual disturbances, and also retardation.Read more


The diagnosis is usually based on pan-angiography. In the case of high risk of angiography in some patients, MRI / MRA are the second alternative option. Additional investigations are CT, EEG and CBF measurement.Read more


It depends on the clinical conditions and stages of disease. There are various options of treatment such as medical, surgery, or a combination of both.Read more

Medical Treatment

There is no definite treatment for the disease, but also a variety of medical treatments such as vasodilators, anticoagulants, anticonvulsants and steroid therapy.Read more


The main goal of surgery is maintenance of blood circulation due to the revascularization to prevent brain ischemia. This can partially be achieved by direct and indirect methods of surgical intervention. Read more


Moyamoya disease is characterized by chronic, but progressive occlusion of the intracranial vessels with unknown etiology. This leads to secondary fragile collateral circulation. This may cause TIA, stroke or cerebral hemorrhage. It may occur in children and adults and has a propensity to the Asian populations.​Read more

Cerebral Venous- and Sinus Thrombosis


Cerebral venous thrombosis (CVT) is usually a rare pathological process, which may involve the cortical and deep cerebral veins and also dural sinus with non- typical signs.Read more


The first report of a superior sinus thrombosis was at the beginning of the 19th century by Ribs at an autopsy.Read more


It is very rare and an exact incidence is not known. CVT occurs in all ages and sexes, but it is more common in women between 20-40 years, maybe due to contraceptives.  Cerebellar vein thrombosis is extremely rare and fatal.Read more


There are numerous factors that may play a significant role in the development of venous thrombosis such as alterations in the chemical and hemodynamic properties of blood flow and also physical and anatomical changes of the vasculature.Read more


These are based on raised ICP. The most common, earliest sign is headache in about 80% of cases, but also vomiting, visual disturbance and papilledema are further symptoms in about 50% of patients.Read more


CT is the initial imaging study of choice in suspected patients with symptoms. The common earlier signs are the triangle sign (delta sign) and cord sign. CT-contrast shows enhancement of peripheral Dural leaf in about 30% of patients with superior sagittal sinus thrombosis.Read more


This is based on the treatment of any underlying cause that should be treated if it is present in patients suspected to CVT. This ranges from conservative therapy of the raised ICP to surgical intervention.   Read more

Thrombolytic Agents

These can be administrated systematically or through the neuro-radiological intervention. Systematic therapy of thrombolytic agents such as streptokinase, urokinase may lead to massive intracerebral and gastrointestinal hemorrhage. Therefore, the local delivery of them directly to the involved venous canal through endovascular technique is recommended.Read more


This is based on various complications of CVT, such as rapid increase of ICP, intracranial hemorrhage, or progressive neurological signs. The main goal of surgery should be to reduce the ICP due to the ventriculostomy, and direct thrombectomy through a craniotomy, however the outcome is usually not particularly promising.Read more

Outcome and Prognosis

Thrombolytic and antithrombotic treatment has contributed to a better outcome and prognosis in patients with CVT in recent years.  However elderly patients, in particular with initial coma and thrombosis of deep venous system or cerebellar, have a bad outcome and prognosis. Generally, prognosis in patients with CVT is better than arterial thrombosis. The recurrence rate of CVT is estimated in about 10% to 15% of cases.Read more


An earlier diagnosis may play a significant role in the therapy of CVT. This could be possible through the MRI and MRV as standard diagnostic studies. Thrombolytic agent therapy, particularly local and selective delivery of agents in the venous sinus through the endovascular technique minimize the hemorrhagic complications, and thus provides a better outcome and prognosis in patients with CVT.Read more

Intracranial Hemorrhagic Disease  

Subarachnoid Hemorrhage (SAH)

Traumatic Cerebral Hemorrhage (see chapter of head trauma)

Spontaneous Cerebral Hemorrhage caused by Aneurysms (SAH)

Spontaneous Cerebral Hemorrhage caused by AVM

Spontaneous Cerebral Hemorrhage (Non-aneurysm, Non-AVM)


SAH is a pathologic condition and is based on the existence of blood in the subarachnoid space. The most common cause of SAH is head injury in about 33% to 39 % of patients with GCSS of 8 to 14.The most common spontaneous SAH is aneurysm rupture. Cocaine use and sickle cell anemia may be associated with aneurysmal SAH. Read more


This accounts for about 6% to 8% of all stroke cases, approximately 11 cases in 100,000 populations per year. SAH usually occurs in 43% of cases during stressful time, in 34% during non-stressful time, in 12% during rest and sleeping time, and in 11% of cases with unknown circumstances. Read more


The SAH may occur traumatically or non-traumatically such as rupture of an aneurysm or even no known cause (idiopathically). However the clinical signs and symptoms will be depended upon the volume and location of bleeding. This varies from a negligible amount to massive bleeding which may even be fatal. There is a general correlation between the volume of SAB and risk of mortality or complications such as vasospasm and clinical grade according to the GCSS.Read more


These are sudden severe headache before the initial event, nausea, vomiting, stiff-necked, dizziness and changes in level of consciousness, and eventually neurological deficits. Un-ruptured aneurysms may also cause some symptoms such as localized headache, visual loss and field defect, hemiparesis or brachio-facial paresis depending on size and site of the lesions.Read more


CT is the initial imaging modality of choice in patients with suspected SAH. This may show on the first day of the event SAH in 92% of patients, intracerebral or intra-ventricular hemorrhage in 20%, and subdural hemorrhage in 19%.Read more

Lumbar Puncture

In the case of a small amount of SAH, CT-Scans may be normal. LP can be useful for diagnosis such cases. If there are high-level available signs for an infectious meningitis or limited access to a CT, then LP can be helpful as an initial diagnostic test. Any erythrocyte in the CSF means hemorrhage (SAH), unless this is caused by local LP.Read more


It is the best imaging study of choice for definitive diagnosis of the SAH. Four-vessel angiography is generally performed for diagnosis of not only multiple aneurysms, but also cerebral AVM.Read more


This is based on multiple factors, including neurologic grade, medical status, and age of patients, also location and size of aneurysms. Read more

The Initial Management of a SAH

Admission of worse-grade patients to an ICU,- but the good-grade cases can be admitted to a normal station,- keeping the patient in a dark room with minimal stimulation in bed rest. Monitoring includes obtaining hourly the vital signs, and assessment of neurologic signs.Read more

Control of BP

Achieving an optimal BP in patients after SAH is not easy, because of many factors that play a role after occurrence of the SAH. The main goal should be to establish an optimal perfusion to the brain while minimizing the pressure gradient across the aneurysm. 

Hypertension should be avoided in the early phase after SAH, particularly during transport and angiography.Read more

Management of Complications of the SAH

Re-bleeding: is a disaster associated with a mortality rate of about 75% according to numerous studies. The risk factors of re-bleeding are decreased clinical conditions, high grade pre-existing hypertension, large size of aneurysm, age and female sex.Read more

Intracranial Hemorrhage

These are more likely to occur in frontal and temporal lobes in about 40% of all cases. Aneurysms arising from the distal ACA usually produce such intracerebral hemorrhage.

Diagnosis is possible through the CT or MRI imaging, and angiography can be indicated based on clinical suspicion.Read more

Intra-ventricular Hemorrhage

This is a most common complication of aneurysm rupture and accounts for about 13% to 28% of various clinical series. It is much higher in autopsy series. There is a definitive correlation between the IVH and mortality in about 64% of cases.Read more


Acute clinical hydrocephalus after SAH is very common and accounts for about 20% of cases. This is more likely to be associated with intra-ventricular hemorrhage, diffuse or focal thick SAH, use of antifibrinolytic agents, posterior circulation aneurysms, and increasing age of patients.Read more

Increased ICP

Therapy of increased ICP includes removal of intracerebral and intra-ventricular blood due to the surgery and ventricular drainage, intravenous mannitol with or without furosemide, deep sedation, and hyper-ventilation. The ICP should be kept to less than 25 mm Hg to minimize the risk of re-bleeding.Read more


Acute seizure may occur at or around the first week after SAH in about 20% patients. There are also late seizures reported in literature. About 72% of these occur within 1 year and 94% within 2 years (34).    

The causes of seizures are very complex and controversial, but in most cases seizures are the result of SAH not the cause of aneurysm rupture. This may increase cerebral O² consumption and so produce hypoxyemia, acidosis, and eventually aspiration and also pneumonia.Read more

Outcome of SAH

Approximately 12% of cases die even before medical treatment, and 40% of patients with SAH die before and after the treatment 60% can recover. Factors that affect outcome of SAH are various and may be associated with prior- or postoperative hypertension, intra-ventricular or intracerebral hemorrhage, developing vasospasm or cortical infarction, existence of diffuse or focal thick SAH, and age of patients. The aneurysms of posterior circulation usually have poor clinical grade.


Surgery is nowadays an effective treatment in patients with aneurysmal SAH. This prevents re-bleeding and provides the possibility of continuing further effective therapy. Monitoring of patients and its alteration should also be continued for controlling the postoperative clinical and neurological complications and performing early appropriate treatment.Read more

Cerebral Vasospasm


This is a cerebral arterial narrowing after SHA demonstrated on angiography. This may lead to the cerebral ischemia with corresponding symptoms. It is a prolonged and even severe complication of SAH, that commonly occurs one day after SAH, but it is certainly a reversible process.Read more


The first angiographic report was in 1951 by Ecker and Schneider. The first clinical report about the usefulness of hypertension in association with vasospasm was in 1976 by Kosnik & Hunt and Giannotta & colleagues. Miller Fisher and colleagues described in 1980 the relationship between SAH clots and the increased risk of vasospasm.Read more

Time Course and Incidence of Vasospasm

Generally, the development of vasospasm may occur during the first week of initial SAH and last about 3 to 4 weeks. The peaks of severity can be in the 2nd week.Read more


There are several causes for developing vasospasm, but the most common causes for vasospasm are the local or diffuse thick layers of blood clots. However there are also some non-aneurysmal causes and risk factors such as Trauma, AVM, incomplete circle of Villis, pre-existing hypertension, poor clinical condition, age younger than 35 years, and excessive smoking for developing of vasospasm.Read more


One of the common clinical deteriorations in patients with SAH could be vasospasm. The symptoms of vasospasm usually have a gradual onset, but some patients may have a sudden deterioration. That is sudden severe headache, and depressed alertness. The signs may depend on the localization of vasospasm such as mono- or hemiparesis in patients with vasospasm of MCA.Read more


After ruling out the other causes of delayed clinical deterioration in patients with SAH, vasospasm may remain the next cause to diagnose with appropriate examination such as transcranial Doppler and imaging studies.Read more

Transcranial Doppler (TCD)

This is a non-invasive method, which can be performed at the bedside for diagnosis and daily control of developing vasospasm. It is based on monitoring the narrowing cranial arteries and blood flow velocities.Read more

Therapy of Vasospasm

Preventive Treatment

It is used for preventing early brain ischemia and includes avoiding hypo-volumia, hypotension and red cell anemia. Patients can receive about 3000 CC of isotonic fluid daily and BP should be between 120 to 160 mm Hg. A more important parameter is cerebral perfusion pressure (CPP), which should be maintained greater than 70 mm Hg in the case of increased ICP.Read more

Calcium Chanel Blockers

Nimodipine may block the calcium chanel (L-type) and prevent the increase of intracellular calcium resulting in vasospasm. Daily oral dosage is about 240 mg divided every 4 hours.Read more

Reversal Treatment

Endovascular treatment of vasospasm is recommended in the case of failed hyper-volumic and hypertensive therapy, and also in patients with heart failure, or possessing additional un-ruptured aneurysms.  

The percutaneous transluminal balloon angiography used mostly by trained interventional radiologists is now more accepted in selected patients around the world.Read more


Mortality rate of vasospasm after SAH accounts for about 10% -15%. This could be improved due to modern preventive and reversal therapies.Read more


Surgical clipping is usually the first modality of choice for continuing the further preventive and reversal treatments in patients with SAH caused by ruptured aneurysms.Read more

Carotid Artery Aneurysms (ECAAs)

Extra-cranial Carotid Artery Aneurysms (ECAAs)

Cavernous Segment Aneurysms (CavSeg. Aneurysm)

Anatomical Consideration

Cavernous segment is one of the four segments of ICA such as Cervical, Petrous, Cavernous and Supra-clinoid segment. It begins from the carotid canal (CC) of the petrous bone at the foramen lacerum and runs through the cavernous sinus to the carotid-oculomotor membrane (COM).Read more


Approximately up to 15% of all angiographic identified intracranial aneurysms arising from ICA. Cavernous Segment aneurysms account for about 3% to 5% of all IC-aneurysms. These mostly originate from horizontal segment followed by anterior and posterior genu. It is much more common in females with a female-to-male ratio of 9:1. High peak of age is V. and VI. decade of life.Read more


There are several causes and risk factors that may contribute to the formation of aneurysms. They are pre-existence of arteriosclerosis with permanent hemodynamic stress at the arterial branch sites, but also spontaneous and traumatic dissection.Read more


Onset can be mild and insidious or explosive, isolated or a combination of signs. Most common symptoms are adjacent cranial nerve deficits caused by mass effect of aneurysms such as occulomotor, trochlear, abducens, and trigeminus nerve paresis, in the form of ophthalmoplegia and facial pain. A secondary extension of aneurysms in SAS may cause the SAH in some cases. Read more


CT is the best imaging modality of choice for demonstrating SAH. It may also show the aneurysm, particularly large and giant aneurysm with mostly intraluminal thrombosis and wall calcification as a round extradural parasellar mass.Read more

Four–Vessel Trans-femoral Angiography:

This is the gold standard study of choice. A definitive diagnosis of aneurysms may be established only by angiography, before the planning of any therapeutically intervention. Read more


Cavernous Segment aneurysms: CavSeg aneurysms without extension into the SAS and with mild symptoms such as slight oculomotor or trigeminal nerve deficits don’t need to be operated.Read more

Clinoidal Segment Aneurysms (ClinSeg Aneurysm)

The clinoidal segment of ICA is the anterior vertical segment after anterior genu of cavernous segment. It is located neither within venous canal nor within SAS, but it is an intradural segment.Read more

Anterolateral Type: It arises from anterolateral surface of the ClinSeg underneath the anterior clinoidal process (ACP) and may expand laterally and anteriorly to the ascending ICA.Read more

Medial Type: It arises from the medial surface of the CliSeg and extends beneath the diaphragma sella into the pituitary fossa. Its enlargement and eventually rupture may cause hypopituitarism or pituitary apoplexy.Read more


These are visual disturbance, diplopia, headache / facial pain limited to the V1 branch of fifth nerve (V. CN) and occasionally facial numbness. A full-blown cavernous sinus syndrome is very rare.Read more


CT- scans show the erosion of adjacent bony structures and thrombosis or wall calcification. MRI may define the surrounding soft tissues, particularly the association of the medial type with the pituitary gland.Read more

DD: Between medial type aneurysms of ClinSeg and superior hypophyseal artery (SHA) is not easy, because both lesions project medially. And also DD between the anterolateral type and ophthalmic artery (OPH) aneurysms can often be a big challenge.Read more


It depends on the size and symptoms of the aneurysms. The small aneurysms are mostly without the severe neurological deficits, but large lesions usually extend through the overlying Dura into the SAS and cause intracranial or /and SAH.Read more

Ophthalmic Segment Aneurysms (OphSeg Aneurysms)

Ophthalmic segment is the sub-division of supra-clinoidal segment of ICA and extends from COM to the origin of posterior communicated artery (PCA). It lies entirely within the SAS. There are some arterial branches arising from the OphSeg as follow:

– Ophthalmic artery: It is the most significant branch and arises from posteromedial surface of ICA below the optic nerve. It accompanies the optic nerve through the optic canal and supplies the retina and orbit.Read more

Sup. Hypophyseal Artery aneurysms: It arises from the inferior and inferomedial surface of the ICA and project towards and below diaphragma sella and carotid cave, therefore is called also carotid cave or parasellar variat aneurysm. Another variety of Sup. Hpo. Art. projects medially above the carotid cave and expands into the medial suprasellar space and is called suprasellar variant.  Read more   

– Dorsal carotid wall aneurysms: It arises from dorsal surface of the ICA, distal to the Oph. Art. and called dorsal variant of OphSeg. – These usually project laterally to the visual system and uncommonly cause visual disturbances.Read more


Most common symptoms are visual disturbances caused by mass effect of giant aneurysms > 2.5 cm, particularly visual field deficits based on laterally situated projection of aneurysm to the visual system and affected portion of optic nerve by extension of Oph. Art. Aneurysms and also SAH.   Read more


As these aneurysms arise from the distal to the dural ring along the ICA, therefore cause no bony erosions. The MRI is the best imaging modality of choice defining the relationship between aneurysm and visual system. Angiography is usually the final choice of imaging study before the planning of surgical or endovascular intervention.Read more


There are several alternative therapeutic modalities for different types of aneurysms with variant sites and shapes. Un-ruptured small aneurysms with low risk of rupture can be treated conservatively, particularly in older patients and in patients with pre-morbidities.Read more

Intracranial Carotid Artery Aneurysms (ICAAs)

These are aneurysms mostly arising from ICA trunk, intracranial carotid artery bifurcation, anterior cerebral artery (ACA), MCA, ACoA, PCoA, and also form anterior choroidal artery. They are mostly saccular form aneurysms.Read more

ICA Trunk Aneurysms

They usually arise from the ventral wall of ICA and are very rare. These may project anteromedially, displacing the pituitary stalk or anterior perforators. They are mostly seen in patients with pre-existing arthero-sclerotic changes. Therefore, clipping of these aneurysms should be performed very carefully under proximal control of ICA preventing the intraoperative hemorrhage. Read more

Bifurcation Aneurysms

This is the dividing point of ICA to the ACA and MCA. It gives lenticulo-striate perforators. These usually supply the basal ganglia and hypothalamus, mesial temporal lobe and optic apparatus. Aneurysms of ICA bifurcation usually project towards the anterior perforated substance.Read more

Incidence: These account for about 5% to 15% of all intracranial aneurysms.Read more

Symptoms: These are based on the behavior of aneurysms to enlarge the size and cause compression on the optic apparatus. They also present symptoms due to the SAH or ntracerebral hemorrhage, particularly into the basal ganglia.Read more

Diagnosis: As mentioned previously the CT-scans are the first modality of choice, but also CT-Angio and MRA may be useful for identifying the aneurysms.Read more

Surgical Treatment

Standard patient positioning and petrional cranio-tomy are performed as described previously. 

For obtaining proximal control splitting of Sylvain fissure is here also necessary. After exposing the inferior surface of both ACA and MCA, the arachnoid membrane over the bifurcation can be rolled up.Read more

Posterior Communicating Artery (PCoA)

PCoA is one of the two arteries, which arises from communicating segment of ICA and builds left and right sides of Circle of Vilisi. PCoA arises from posteromedial surface of the ICA, distal to the takeoff of the artery and extends through the membrane of liliquest medial to the occulumotor nerve.Read more

Incidence: These account for about 50% of ICA aneurysms and are common in females.Read more

Symptoms and clinical findings

These depend on the size of aneurysms causing the mass effect as well as producing SAH into the different cistern. They may also cause an intra- parenchymal or intra-ventricular hemorrhage.Read more


CT is the first imaging study of choice in patients with SAH. It is also helpful in detecting multiple aneurysms and non-aneurysmal SAH. CT-angiography and MRA are reliable in detecting small aneurysms less than 5 mm and are used to delineate aneurysm location and anatomy (12).Read more


For surgical obliteration of the PCoA aneurysms, the Sylvain fissure should be split from lateral to medial. This is advantageous for any anterior circulation aneurysms. After opening the optic and carotid cistern and separating the optic nerve from the undersurface of frontal lobe, gentle retraction of frontal lobe may allow proper visualization of proximal optic nerve and ICA.Read more

Anterior Choroidal Artery Aneurysms

This artery arises from the posterior communicating segment according to the new classification system. It usually follows the optic tract and supplies a branch to the mesial temporal structures. Read more


Because of the high location of aneurysms above the tentorium, cranial nerve deficits are very rare. SAH usually occurs in the ambient cistern and supra-sellar region. Read more


CT-Scans are usually the first modality of choice. It can be completed by MRA and other radiological studies such as Pan-angiography.Read more

Surgical Treatment

Following standard positioning and a pterionic craniotomy as described previously, the Sylvain fissure should also be split to minimize the frontal and temporal lobe retraction.Read more

Anterior Cerebral Artery Aneurysms (ACA)

Anterior Communicating Artery (AcoA) Aneurysms

Proximal ACA and ACoA are the most common sites for intracranial aneurysms. The ACA is divided into 5 segments by Perlmutte and Rhoton as follows:

A1 segment: starts at the division of ICA into ACA and MCA and ends at the ACoA. Its average diameter is about 2.6 mm (0.9 to 4.0 mm). Hypoplasia of the A1 segment occurs in about 10% of cases. Paired A1 Segments have an equal diameter in about 50% of cases.Read more

 A2 segment (pericallusal Artery): starts at the ACoA junction and ends at the junction of rosterum and genu of corpus callosum. There is an important perforator artery called medial striate artery or recurrent artery of Heubner.

It arises in 78% of cases from A2-segment and 14% of cases from A1-Segement. Its length is about 23.4 mm (range 12 to 38 mm), whereas the length of A1 is about 12.7 mm.Read more

A3 segment: extends over the curve of the genu and ends where the ACA turns above the genu.Read more

A4 and A5 segments: Extend over the body of corpus callosum. Transition from A4 to A5 occurs at the level of coronal suture.Read more


It accounts for about 30.3% of all intracranial aneurysms (13). Recent studies show the total incidence of A1-ACoA and A2 of the ACA aneurysms 34.6% and of total ACoA /ACA in about 39.0% of cases.Read more


The symptoms of aneurysmal SAH of the ACoA are the same as that of aneurysms in other locations.Read more


CT-scan is the first modality of choice as described previously in other chapters. It may show the thicker clot in the inter-hemispheric fissure as well as intracerebral hemorrahge commonly in the region of gyrus rectus.Read more

Surgical Treatment of A1-ACoA

In contrast to the other aneurysms, the ACoA aneurysms have two A1 parent arteries. Both A1arteries should be exposed operatively to obtain earlier proximal control. Besides, the specific anatomic features such as deep middle location; intimate relationship to the several perforator arteries; and also their bilateral ante-grade arterial supply through the paired A1, makes ACoA aneurysms surgically a challenging lesion. There is no other intracranial aneurysm intimately associated with so many arteries and perforators. This all makes the ACoA aneurysms more particular.Read more

Surgical Outcome and Complications of ACoA Aneurysms

Before the 1970s, the outcome of ruptured ACoA was very low. In 1975 the first report of a series of 203 patients with ACoA aneurysms was reported by Yasargil and colleagues. The second report of ACoA aneurysm operated in 371 patients was in 1984 with a total surgical mortality of 5.9%.Read more


The recent encouraging results of aneurysmal surgery indicate that an advanced surgical technique and a complex treatment strategy including the pre-intra-and postoperative management, may contribute to a better outcome.Read more

Distal Anterior Cerebral Artery Aneurysms (Median Artery of the Corpus Callosum)

Aneurysms that arise beyond the ACoA junction are called distal ACA aneurysms. These include the A2-segment to A5-segment of the ACA, and arise from ACA as well as from its branches distal to the ACoA. Read more


They are rare and account for about 2.8% to 5% of all intracranial aneurysms. Approximately 41% of them have one or more additional IC-aneurysms. The most common site of them is the MCA aneurysms in 43% of cases.Read more


The majority of patients with ACA aneurysms present poor clinical grades (Hunt & Hess grade 4 or 5).Read more


CT-scan is the first modality of choice to demonstrate the SAH, intra-parenchymal hemorrhage (into epsilateral frontal lobe), and also convexity subdural hematoma.Read more

Surgical Treatment

Distal ACA aneurysm surgery is specific and has special difficulties which have been reported by Yasargil. For the very proximal aneurysms of ACA, a standard petrional approach is appropriate exposing and clipping the aneurysms. Yoshimoto and colleagues have recommended a proximal inter-hemispheric approach through very low bi-frontal craniotomy for exposing and clipping of distal ASA aneurysms.Read more

Surgical Outcome and complications

These usually are the same like other proximal ICA aneurysms and mostly depend on the clinical grade at the time of surgery. Patients with Hunt & Hess grade 1 and 2 have the best outcome. They are usually operated earlier, within 24-72 hours.Read more


General management of the distal ACA aneurysms is like other locations, a complex procedure requiring the pre- intra- and post-operative management. The clinical grade at the time of surgery, surgical timing and also a meticulous microsurgical technique may contribute to the optimal management of these aneurysms.Read more

Middle Cerebral Artery Aneurysms (MCAA)

MCA starts from the ICA bifurcation and is divided into 4 segments shown in below table.Read more


It accounts for about 20% of all intracranial aneurysms. However it varies among genetically different populations. According to several studies, incidence of a single MCA and also mirror aneurysm of the contralateral MCA is about 11%.  An association with other multiple IC- aneurysms has been reported in Yasargil’s series of 184 patients with MCA aneurysms in about 32% of cases (3).Read more

Symptoms and clinical findings

Approximately, 90% of MCA aneurysms present with rupture and SAH. IC-hematoma is also the most common clinical presentation in 40%-50% of patients with ruptured MCA aneurysms. Mass effect of the un-ruptured giant aneurysms may cause focal neurological deficits such as hemiparesis as well as seizure.Read more


CT-scan is the first imaging modality of choice, completed with routine four-vessel Pan-angiography before the surgical intervention. CT-Angio with D3 reconstruction, MRI & MRA may be helpful in some cases.Read more

Surgical Treatment

Despite the modern microsurgical technique, surgical management of MCA aneurysms is one of the most difficult challenges for neurosurgeons.

A better outcome of the surgical intervention is usually associated with an exact and appropriate timing of surgery.   

-Timing of surgery: in patients with SAH depends on the clinical grade, and also presence of hematomas with mass effect. In patients with low grade Hunt & Hess (1-2 Grade ) without complexity early operation is advocated.Read more

– Lateral Trans-Sylvain approach

It is appropriate for un-ruptured and uncomplicated aneurysms located at the MCA bifurcation.Read more

– Medial Trans-Sylvain approach

It is appropriate for aneurysms that arise from a short M1 trunk. It is also an approach for complicated aneurysms with a high risk of re-rupture at the time of exposure.Read more

– Superior Temporal Gyrus approach

It is useful for patients with intracerebral hematomas, because the evacuation of hematoma may lead to brain relaxation and better access to the ICA bifurcation, therefore it is the preferred approach for patients with MCA bifurcation aneurysms.Read more


The outcome of the MCA aneurysms is also relatively worse, due to the large volume of cortex supplied by the MCA with limited collateral arteries. However, the Hunt & Hess grade is the most important predictor of good or poor outcome in operated patients.Read more

General Consideration of Aneurysmal Surgery of Anterior Circulation

Preoperative Management:

Generally, there are four important issues which should be considered as preoperative management in the aneurysmal surgery. These are: Managing and Preventing the vasospasm, hydrocephalus, electrolyte abnormalities, as well as the risk of re-bleeding.Read more

Timing of Aneurysmal Surgery

This either occurs on an early surgery, or a delayed surgery.

-Early Surgery: The early surgical intervention usually occurs on an urgent basis after admitting the patient to the ICU. After completing the radiographic examination and placing the patient as a candidate for surgery.Read more

-Delayed surgery within 4-14 days: has been the rule in patients with poor clinical grade 3-4, unless there is a life-threatening lesion requir-ing prompt evacuation of intracerebral hematomas.Read more

Disadvantage of delayed surgery: is re-bleeding of aneurysms, and particularly limitation of aggressive hypertension and perfusion therapy.Read more

For obliterating the Oph. Art. aneurysms, the falciform ligament should be cut along the lateral aspect of the optic nerve for exposing the proximal neck of aneurysm. Distal neck is usually free of perforators.Read more

For obliterating the Sup. Hyp. Art, a circumferential sectioning of the dural ring is necessary for identifying the perforators supplying the optic system and pituitary structure. Read more

Intraoperative Complications:

Intraoperative aneurysm rupture is one of the terrible complications of aneurysm operation. It should be prepared to be dealt with before the procedure. Generally, there are intra-operatively 4 phases of aneurysm rupture as follows: Read more

Postoperative complications:

These are based on the neurovascular structures present around the Circle of Willis. These may be the cranial nerve deficits, arterial injuries and even delayed thrombosis or stenosis. Excessive manipulation of optic nerve or arterial perforators may lead to the postoperative visual disturbances.Read more


A good understanding and preoperative evaluation of the angiographic features of the parent vessel, perforators, as well as atherosclerosis may play a significant role in aneurysmal surgery to prevent the intraoperative complication and to achieve good results.Read more

Posterior Circulation Aneurysms

General Consideration

Posterior circulation aneurysms are anatomically and surgically much more complicated than anterior circulation. These are very close to the lower cranial nerves and brain stem, therefore their surgical intervention may carry much higher morbidity and mortality.Read more


Posterior circulation aneurysms are relatively uncommon and account for about 8%-9% of all intracranial aneurysms. 25% of these arise from vertebral artery, PICA and vertebra-basilar junction and account for about 2% of all intracranial aneurysms.Read more

Anatomy of Vertebral Trunk

Vertebral arteries arise from subclavian arteries and ascend through the transverse processes of the upper six vertebrae. They pass posteriorly to the lateral mass of the atlas and anteriorly to the atlanto-occipital membrane into subdural space.Read more


The most common clinical symptoms and Findings of vertebral arteries, PICA and vertebra-basilar junction aneurysms are caused by SAH in about 80% of patients. In a series of 27 patients with vertebral artery and PICA complex aneurysms reported by Bertalanffy and colleagues, 81.5% presented with SAH. Other symptoms are ataxia, hemiparesis and posterior fossa syndrome.Read more


CCT is the first study of choice. In the case of negative SAH on the CT-scans, it can be followed by LP (if it is not contra-indicated). Conventional four-vessel angiography is necessary and essential in the diagnostic and preoperative planning to show details in regard to the size, shape, site and multiple aneurysms even smaller than 3 mm.Read more


Preoperative Assessment and Planning: For planning a surgical intervention, appropriate patient selection is crucial. This includes the assessment of medical grade, surgical outcome, postoperative prognosis, as well as considering the other endovascular interventions. In addition, it should include careful attention to the imaging details such as size and morphology of aneurysms, projection of the dome and neck, which plays a significant role in planning the appropriate approach for vertebral / PICA and vertebra-basilar aneurysms.Read more

Surgical Therapy

There are several approaches to the above aneurysms with their advantages and disadvantages.Read more


Outcome of surgical clipping of the vertebral-PICA and vertebra-basilar aneurysms has been advancing with improving in microsurgical technique. Nevertheless, they have still not equaled with that of the anterior circulation aneurysms.Read more


The most common complications of surgical treatment are the lower cranial nerves injury (IX through XII) due to the retracting and stretching of the nerve rootlets. In addition, in the case of occlusion of the PICA, this may cause lateral medullary syndrome (Wallenberg syndrome).Read more


Management of the vertebral artery, PICA and vertebra-basilar junction aneurysms is still associated with a high rate of morbidity and mortality due to the difficult approaches and propensity of aneurysms to re-bleeding in the acute period.Read more

Basilar Trunk Aneurysms

Aneurysms of the basilar trunk are rare, but they are the most difficult challenges in neurovascular surgery. Aneurysms of basilar trunk are those arising between the vertebra-basilar junction and superior cerebellar arteries (SCA).Read more


The basilar trunk artery begins from the vertebra-basilar junction at the level of ponto-medullary sulcus and extends superiorly in the basilar sulcus of the pons and ends at the origin of superior cerebellar artery (SCA).Read more


Posterior circulation aneurysms are rare in comparison with the anterior circulation aneurysms. In a series of 1200 patients reported by Peerles and Drake, 16% of cases were located at the upper basilar trunk (between SCA and AICA), 8% in lower basilar trunk (between AICA and vertebra-basilar junction) and 7% at the vertebra-basilar junction. Read more


These are usually caused by SAH like other locations of aneurysms. These are usually headache, nausea, vomiting (signs of increase of ICP) as well as nuchal neck pain and rigidity.Read more


CCT is the initial imaging study of choice in patients with suspected SAH. In the case of strong patient’s history suggested SAH, with negative CT finding, a LP may be useful (if there is no reason of contra-indication). CT-angiography and MRA may be useful for giant aneurysms with partial calcification to assess internal dimensions of the lumen as described in previous chapters.Read more


After preoperative evaluation and assessment of clinical status and also attention to the imaging details, surgical intervention of the basilar trunk aneurysms can be planned. There are several approaches with their advantages and dis-advantages. The main obstacle of a lateral surgical approach to the basilar trunk aneurysms is the petrous bone which should be drilled through the temporal bone.Read more


The most devastating complication is the intraoperative rupture, because of the very high morbidity and mortality rate. Other major complications are the brain stem ischemia, cranial nerves injury, and intracranial hematomas.Read more

Basilar Apex Aneurysms

These are the aneurysms arising from the top of the basilar bifurcation.  Deep midline location of the basilar apex and bony enclosure of the clivus, posterior clinoid process and also the anatomic complexity of the inter-peduncular cistern make basilar apex aneurysm surgery one of the technically challenging procedures for neurosurgeons.Read more

Microsurgical Anatomy

Basilar apex is the terminal station of the basilar trunk, where it is divided into the PCA and SCA arteries. It is located in the inter-peduncular cistern within the posterior portion of the anterior incisural space between the posterior perforated substance and clivus.Read more


These account for more than 50% of all posterior circulation aneurysms. Aneurysms of the posterior circulation account for about 15% of all intracranial aneurysms.Read more


The most common symptom of basilar apex aneurysms is SAH, like other locations of anterior and posterior circulation. It institutes in approximately 80% of patients.Read more

 Diagnosis: CT is the first modality of choice as described previously. Four-vessel angiography is necessary for planning surgical procedures. CT-angiography and MRA is useful in demonstrating the giant aneurysms, in particular with partial calcification and thrombosis. (see previous chapters).Read more     

Surgical Treatment: There are several approaches to the basilar apex aneurysms such as other location in this region.Read more

Transsylvain approach: is used for many vascular and tumoral lesions in the middle fossa, because a wide exposure is feasible through the opening of the membrane of liliequist. Besides, neurosurgeons are familiar with this approach.Read more

The sub-temporal approach: It also has several assets; the lateral view makes it easy to dissect the posterior perforators as well as better proximal control on parent artery. Exposure and clipping of the anteriorly and posteriorly projected aneurysms is also uncomplicated.Read more

The petrional approach: This is the extended tailored and modified approach from both above approaches described by B. R. Bendok and colleagues. This approach has the following advantages: real dissection of the Sylvain fissure from the dominate side of surgeon.Read more

Endovascular management: It is an alternative method for treating some of the giant and fusiform aneurysms, or when the surgery is not safe in an acute situation (e. g., high clinical grade). According to literature, its morbidity and mortality rate may be competitive with surgery. Multiple studies have demonstrated a good short-term result, but long-term data is lacking in the literature.Read more

Complications: Each approach has its own special complications, but the intraoperative rupture is generally the most devastated onset in aneurysm surgery. Injury to the perforators is also one of the common complications.Read more

PCA Aneurysms

PCAs arise at the basilar bifurcation supplying the deep structures of the midbrain such as thalamus, plexus choroid of third and lateral ventricles as well as some portions of the brain hemispheres. Read more


The incidence of PCA aneurysms range from (0.7% to 2.2%), is published in literature. In a series of 115 PCA aneurysms identified in literature by Zeal and Rhoton, 15% arose from P1, 16% from P1-P2 junction, 20% from proximal P2A, 36% from P2B, and 13% from distal of the artery.Read more


These are the same as the other location of posterior circulation aneurysms described in previous chapters.Read more


CT- D3-angiography and MRA are very useful to demonstrate the aneurysms and appropriate access to the lesions, because a large number of aneurysms are giant aneurysms mostly with partial thrombosis or calcification.Read more

Surgical Treatment

All discussed approaches for basilar apex aneurysms can be used for P1Seg. of the PCA. P2 Seg. aneurysms can be reached better via sub-temporal approach. Aneurysms of the supratentorial part of P2 Seg. can be reached via temporal horn of the lateral ventricle.Read more

Endovascular Management

Surgery is the most suitable option for a large number of the PCA aneurysms, nevertheless there are some factors, as mentioned in previous chapters, which may necessitate the endovascular management of PCA aneurysms.Read more


The surgical outcome in patients with PCA aneurysms is much better than other locations in the posterior circulation.Read more


There are enough factors which make microsurgery the first modality of choice for treatment of the basilar apex and PCA aneurysms. Early timing of surgery within 48 to 72 hours may avoid mortality and morbidity caused by re-bleeding and vasospasm. However, early surgery may harm the high grade patients (i.e. Hunt & Hess grade 4 and 5), particularly through the sub-temporal approach. Read more      

Giant Aneurysms


Cerebral aneurysms with a dimension of 25 mm or more are considered as giant aneurysms. They are sometimes mistaken for brain tumors. Their anatomic complexity and poor natural history make these aneurysms to the most challenging lesion for neurosurgeons.  Read more


The first description of a giant aneurysm was in 1875 by Hutchinson. At the beginning of the 20th century the only treatment procedure of aneurysms was hunterian ligation of ICA. Dandy was the first, who exposed a cerebral aneurysm and clipped its neck.Read more


Approximately 2% -5% of all IC aneurysms are giant aneurysms. There is an equal distribution related with gender and age (fourth through sixth). According to different studies, about 34% – 67% of giant aneurysms are associated with ICA, 11% – 40% with anterior circulation and 13% to 56% with posterior circulation.Read more


There are several factors which play a role in developing and rupturing of a giant aneurysm such as systemic atherosclerosis, congenital vessel defects, direct trauma, as well as homodynamic factors. They can be sacular or fusiform and also dolicholectatic lesions.Read more


SAH is the most common symptom in about 40% – 80% of patients. Approximately 50% to 60% of patients present neuropathy caused by mass effect, particularly in fusiform aneurysms.Read more


CCT is the first modality of choice to demonstrate the SAH. It also shows the relationship between the aneurysms and skull base and also existent calcification. It may show the dimensions of the aneurysms.Read more


Management of giant aneurysms is the same as those with small aneurysms. There are several options depending on the patient’s medical grade, and ruptured or un-ruptured aneurysms. In the case of SAH, the complications of aneurismal rupture should be managed.Read more


Recently, a combination of endovascular interventions and technically improved surgical approaches has allowed impressive outcome is managing the IC giant aneurysms.Read more


“Exposure is everything” this statement is composed of the essence of a successful aneurysm surgery. There are enough factors which make the surgery the first choice of therapy for all types of aneurysms.Read more

Vascular Malformations

These can be sporadic as well as congenital malformation shown in below table.Read more

Capillary Telangiectasia (Capillary Malformations)


These are vascular malformations composed of enlarged capillaries with normal capillary structures and without increasing the number of capillaries.Read more


There is not much information about the incidence of Capillary Telangiectasia (Cap. T.). It accounts for about 0.06-0.4%, of all CNS vascular lesions based on large autopsy series.Read more


Microscopically, they consist of enlarged normal capillary with thin walls without adjacent gliosis or hemosiderin deposition. There is no histological difference between enlarged cerebral Capillary T. and normal capillary.Read more


Cap. T. usually is asymptomatic and angiographically occult lesion. The most common symptoms are headache, focal neurological deficits. Hemorrhage and seizure are rare.Read more


Cap.Ts are not identified in the conventional angiography or CT studies. MRI may demonstrate them as a hypo- or isointense mass on T1-weighted images, and iso-or hyper intense on T2-weighted images.Read more


Asymptomatic lesions don’t need to be treated. In the case of hemorrhage and suspected cause of a capillary telangiectasia, surgical intervention is similar to that of any other ICH.Read more

Cavernous Malformation ( Cavernomas (CMs))

(Cavernoma (CMs) = Cavernous Angioma = or Cavernous Hemangioma)


CMs are comprised of a large proportion of vascular components which may occur sporadic (non-hereditary) or congenital and familiarly.Read more


These account for about 0.5% of all IC- vascular lesions based on clinical series. They usually occur at any age and equally in men and women, however they are diagnosed more in adults in their 20s to 30s.Read more


Etiology of CMs is still uncertain, but some authors have advocated the same pathogenetic process for CMs as for capillary telangiectasia, or developmental venous anomalies (DVA). They are usually small and the average size tends to be between1-2 cm, but lesions measuring 8 cm have also been reported.Read more


These are like other lesions: headache, seizure, and focal neurological deficits resulting from hemorrhage. In contrast to other AVMs, the CMs are mostly presented by seizure.Read more


CMs are angiographically an occult lesions such as Cap. T. lesions. CCT-scans may show them as hyper-dense or heterogeneous lesions that may enhance partially. MRI is the most sensitive and specific imaging study for demonstrating the CMs. They usually appear on T1-weighted images as low-intensity lesion with a centrally heterogeneous signal.Read more


Total surgical resection of symptomatic lesions is the best choice of therapy. The asymptomatic lesions may need further evaluation and control however some authors still recommend surgery for accessible asymptomatic lesions. Surgical intervention may depend on the presenting of the different symptoms such as hemorrhage, seizure, or focal neurologic deficits.Read more


These are failure of surgery due to the small lesions, intracranial hemorrhage, postoperative persistence of the neurological deficits or /and seizure.

Venous Anomalies (Venous Malformations = Venous Angiomas)


They are congenital cerebral anomalies that occur in any age and sex. However there is no evidence of a familiar role in developing the venous anomalies.Read more


According to the retrospective imaging study, they account for about 0.5- 0.7% of all intracranial malformations, which rises to 2.6% in autopsy series.Read more


The etiology of VAs is still not clear, but it is usually formed in the late stage of fetal maturation probably due to an intrauterine accident resulting from an ischemia. This is anatomically an abnormal lesion with thickened and hyalinized veins, with physiologically normal low venous outflow.Read more


These are usually the same symptoms like other intracranial vascular abnormalities such as headache, vomiting, seizure, and neuropathy. Patients with frontal lobe lesions present mostly headache in about 67%, whereas those with posterior fossa lesions mostly show ataxia, dizziness and lower cranial nerve deficits.Read more


The conventional Pan-angiography is the best imaging study of choice. The classic angiographic finding is caput medusa. This is usually presented as the lesion like a spider, umbrella, or a sunburst. Delineation of the medullary vein may be presented by CT-contrast. Read more


It depends on the presented symptoms. Patients with a single symptom of epilepsy don’t need a surgical intervention, but they are treated successfully by anticonvulsant medication. The first onset of hemorrhage is very rare. Many authors advocate surgical treatment for the patients with symptomatic hemorrhage.Read more


The most common postoperative complications are the venous infarction and /or brain edema, in particular if the normal venous drainage is interfered intra-operatively.Read more


Generally, no surgical intervention should be directed at non-symptomatic venous anomalies (VAs). In the case of symptomatic hemorrhage, firstly other causes must be searched, secondly that should be treated like an ICH, without further manipulation of lesions avoiding venous infarction.Read more

True Arteriovenous Malformations (AVMs)


These are an abnormal intracranial connection between the arterial and venous system without the normal intervening capillary bed. These are congenital and may be caused by some genetical and familial disorders. Read more


Approximately, 0.1% of population may harbor an AVM, about 2% of these are multiple lesions.Read more


They are lesions with congenital origin. Pathogenesis of AVMs is very complex and based on several predisposing factors such as angiogenic humoral immune factors, abnormal venous drainage, as well as hormonal influence. The familial and genetic factors also may play a role as predisposing factors.Read more


Approximately 12% of the lesions present symptoms during their life. Learning disorders has been reported in about 66% of patients with symptomatic AVM. This can be a sign of functional brain deficits and may present before any other symptoms.Read more


CCT-scans are usually the first study of choice to detect the hemorrhage or mass effect. MRI may present the size, location, mass effect and the symptomatic hemorrhage as well as secondary changes such as edema, and ischemia around the lesions.Read more


Surgical risk of permanent morbidity and mortality in patients with AVMs depends on several factors such as size, location, and venous draining pattern. However, clinical status and grade play also a significant role in the surgical risk, e. g. surgical risk for grade 1 to grade 3 is always almost very low about 0%, whereas grade 4 patients incurred a 21.9% risk, and grade 5 patients incurred a 16.7% risk.Read more

Mixed Vascular Malformations  

It is not usual to see the lesions composed of the true AVMs and other vascular abnormalities. But there are some reports in literature describing such mixed lesions, particularly the coexistence of AVMs and DVAs.

Awad and colleagues reported 3 cases of AVMs in association with DVA.Read more

AVMs and Aneurysms

There are several studies that attempt to classify the relationship between both lesions based on distance and flow relationship of aneurysms to the AVMs. These are three forms of them shown in below table.Read more

Syndromic Vascular Malformations (Congenital Malformation)

There is evidence in literature about a genetic predisposition for developing vascular malformations in association with the two following syndromes.Read more

Rendu-Oslar-Weber Syndrome


It is presented by collection of extra-and intracranial features based on autosomal dominant disorders. Microscopically, lesions consist of dilatation venules into telangiectasia without elastic fibers. The accompanied AVMs are rarely identified.Read more


The most common extra-cranial manifestations are epistaxis, cutaneous telangiectasia as well as pulmonary arteriovenous fistulas. This may lead to cerebral ischemia (stroke) or cerebral infection (brain abscess).Read more


Approximately; AVMs occur in about 5% of patients with Rendu-Oslar-Weber syndrome. About 1/3 of these patients may present clinical symptoms such as seizure, or symptomatic hemorrhage associated with AVMs. A high rate of patients with multiple AVMs (about 5 in seven patients) and family history of vascular disease are associated with the above syndrome.Read more

Weyburn-Mason Syndrome (Encephalo-retino-facial Angiomatosis)


It is a very rare syndrome involving unilateral AVMs of the diencephalon or mesencephalon brain and ipsilateral retina and face. The role of a genetic defect is still unknown.Read more

Acquired Vascular Malformations (Arteriovenous Fistulas)

Read more

Dural Arteriovenous Fistulas (DAVFs)

Sinus Dural Arteriovenous Malformation (SDAVFs)

In this chapter we discuss the both DAVFs & SDAVFs


It is a direct shunt between dural arterial supply and dural draining venous system. Occipital and meningeal arteries are the most involved feeding arteries.Read more


The exact prevalence of DAVFs, is not well known, because of the number of the asymptomatic DAVFs, that have not been reported. However, they account for about 10% to 15% of all intracranial vascular malformations.Read more


Etiology of DAVFs is very variable, but they are mostly caused by trauma, cranial surgery, in particular meningiomas, cranial infection as well as sinus infection or sinus thrombosis.Read more


DAVFs may present either mild and benign or progressive and catastrophic symptoms. These depend on the location, blood flow rate, as well as reversal of flow and hypertension in the venous draining system.

The most common symptom of a non-hemorrhagic lesion is pulsatile tinnitus. This usually occurs due to the high-flow fistulas in the transverse or sigmoid sinus. The compression of the carotid artery and jugular vein may reduce the auscultated bruit over the cranium.Read more


CCT may be useful for demonstrating the SAH, SDH or ICH and also enhanced dilated cortical veins in contrasted CT.

MRI is more sensitive and may show the parenchymal changes such as edema, ischemia, and chronic hemorrhages.Read more


Generally only DAVFs with a high-risk of hemorrhage, venous infarction or progressive neurological deficits such as visual loss can urgently be considered as a therapy candidate. Surgical treatment of the intracranial vascular malformations should be completed like aneurysm surgery. Partial surgery doesn’t guarantee prevention of further recurrent hemorrhage. Read more

Transverse/ Sigmoid-Dural AFMs 

Compression Therapy

It is a simple manual self-compression therapy that may be useful, if the DAVF is supplied only by the occipital meningeal artery. Patients may be advised by the physician to compress the pulsatile occipital artery 3 times a day for about 30 minutes. Approximately, 25% of such cases can be thrombosed completely.Read more

Trans-arterial Therapy

It is a selective preoperative adjunct method to embolize the lesions through the trans-arterial route, in the case when the venous access is not obtainable. It may cause thrombosis of some venous access channels, but rate of cure is very low.Read more

 Trans-venous Therapy

It is a very effective method to accomplish the occlusion of the fistulas, because occlusion of the fistula or its immediate recipient vein is the only way to save and cure a DAVM. Read more

Surgical Therapy

Surgery is the first choice of therapy for treating the transverse-sigmoid sinus. However, due to the strong blood loss during the operation (about 300 ml/ minute, estimated by Sundt and Piepgras), prophylactic preoperative blood transfusion is necessary.Read more

Superior Sagittal Sinus Dural ( AVM)

Arteriovenous Malformation

The management of the superior sagittal DAVM is always almost the same as the transverse/sigmoid described previously.

A simple fistula may be occluded by accessing the feeding arteries through the fistulous site into the venous recipient vein.Read more

Outcome and Complications

In general, a high percentage of patients with symptomatic hemorrhage are treated by surgery with or without the preoperative embolization. In a series of 67 patients reported by Sundt and Piepgras, 7% of them have a poor outcome. Most common complications associated with the surgery are excessive blood loss, venous hypertension or infarction, cerebral edema and also rarely hydrocephalus.Read more


A better understanding of the nature of DAVMs is crucial to achieve a successful therapy of DAVMs with lesser complications. Currently, advancing the endovascular technique has resulted in an evolution of treatment for these lesions.Read more

Cavernous Carotid Fistulas (CCFs) = (Pulsatile Exophthalmos)


The CCF is either a direct shunt between the ICA and cavernous sinus or an indirect shunt via DAVMs.

The original name of pulsatile exophthalmos drives from the orbital symptoms caused by these lesions.Read more


The first term of pulsatile exophthalmos was used in 1809 by Travers based on orbital finding.

Around 1823 Baron in France found an abnormal communication between the ICA and cavernous and assumed this as the etiology of the pulsatile exophthalmos.Read more


There are several causes for developing a carotid cavernous fistula. It may occur spontaneously in an areal shunt such as types B-D, or can be caused by a blunt or penetrating cranial trauma, as well as due to a surgical manipulation in cavernous sinus region such as type A.Read more


The most common signs of carotid cavernous fistulas are orbital findings such as exophthalmos, chemosis, proptosis in about 90% of patients, but also bruit, diplopia and double vision due to the abdusence palsy.Read more


It depends on the patient’s symptoms, whether there is a high risk of intracranial hemorrhage based on angiographic features. There are several manual, endovascular and surgical therapy such as following:

Digital Compression

It is an ipsilateral manual carotid artery and jugular vein compression as a conservative treatment for some indirect carotid cavernous fistulas. This may yield curative outcome in about 25% to 30% of cases, achieved within 4 to 6 weeks.Read more

Endovascular Management

Definitive assessment of benefits and risks of intervention must be considered before choosing endovascular intervention for treating of CCVFs. There are several methods of endovascular intervention as follows:

Balloon Embolization: This method is usually performed for direct carotid cavernous fistulas due to the trans-arterial deployment of detachable balloon or detachable silicone balloon mounted. Debrun and colleagues reported a successful therapy in 97% of cases.Read more

Coil Embolization

The Guglielmi Detachable Coil is the appropriate method for trans-arterial embolization of carotid cavernous fistulas. It allows a more precise and targeted embolization than non-targeted pushable coils. However indirect carotid cavernous Fs (CCFs) often have complex arterial supply and it is not easy to occlude them with trans-arterially procedure alone. Additionally, the lesions are mostly supplied by residual small arteries which are not easy to catheterize.Read more


Some centers have been using radiosurgery through the Leksell gamma knife or stereotactic frame and external cobalt source to treat CCFs. Radiosurgery can be effective in treating some indirect CCFs, however this has some disadvantages and also limitation shown in below table.Read more


According to literature endovascular management, particularly trans-arterial balloon occlusion can be useful for direct fistulas type A, as well as for many cases of type B to D. The remaining cases should be treated by open microsurgery. Using the modern techniques of skull base microsurgery provides a much better outcome of surgical management of these lesions.Read more


These are epistaxis or ICH and SAH in about 3% of patients with carotid cavernous fistulas. ICH or SAH may be caused due to the arterialization of the dilated, tortuous cerebral veins in patients with carotid cavernous fistulas.Read more


Endovascular intervention has become increasingly the initial treatment modality of choice for CCFs with direct and indirect shunt fistula. In the case that it is not feasible or fails in some cases, open microsurgery to expose the carotid/cavernous (CC) region, using modern skull base microsurgery should be seriously considered.Read more

Spinal Vascular Disease

Spinal Vascular Anatomy

Blood Supply to the Spinal Column

The blood supplying of vertebral column are variable. It is depended on 3 vessels of the segmental arteries that arise from aorta. Segmental Arteries of the vertebral column supply radicular arteries which arise from posterior aspect of aorta and are known as intercostal and lumbar arteries in thoracic and lumbar regions. These segmental arteries proceed to intervertebral foramina appropriate to their level, where they divide into terminal branches.Read more

Blood supply to the Spinal Cord

Spinal cord blood supply occurs through two longitudinal pathways include the anterior spinal artery (ASA) and posterolateral arteries (PSA). Medullary perforating arteries from the ASA supply the anterior 2/3 of spinal cord as well as the central portions of SC (grey matter score) consisting the corticospinal and spinothalamic tracts.Read more

Drainage System of Spinal Column and Spinal Cord (SC)

Basically, the spinal venous system is complex and variable. Generally, the venous drainage system of the spine and spinal cord is accomplished through a complex network of venous structures including the intrinsic, extrinsic, and intra-osseous systems.Read more

Intrinsic Venous System  

The intramedullary veins are known as radial veins. However there are two anterior and posterior longitudinal spinal veins named “anterior and posterior coronal veins” that run along the SC in an interconnecting fashion with the radial veins and collected blood from radial- and other veins to build the intradural plexus.Read more

Extrinsic Venous System (Epidural veins) 

The extrinsic network consists of anterior epidural plexus and a generally smaller posterior epidural plexus.  The medullary veins drain into a venous network within and around the nerve sheath which is called “emissary veins”. These dorsal and ventral emissary veins connect the dorsal and ventral epidural plexuses (Batson’s Plexus) which run cranial and caudal along the vertebral body.Read more

Intra-osseous Venous System (para-spinal veins)

This network drains outside of the spinal column via emissary veins which surround the nerve root. The emissary veins drain into longitudinal efferent veins and located on the side of the vertebral body as the extrinsic venous plexus. Read more


Knowledge of the different pattern of origin and course of the proximal portion of the anterior spinal artery is important when planning and executing endovascular and surgical procedures involving the distal vertebral artery, vertebro-basilar junction and the ventral medulla.Read more

Spinal Vascular Diseases

They are a heterogeneous group of abnormal vascular lesions that occur as congenital or acquired malformations. Therefore their nature, treatment and outcome usually depend on the type of lesion.

The modern classification system of spinal cord vascular lesions is based more on radiographic features of the nidus concept, obtained by selective angiography.Read more

Spinal Arteriovenous Lesions

These are divided into two main groups as follow

1) Spinal Cord Arteriovenous Malformations (SC-AVMs)

2) Dural Arteriovenous Fistulas (DAVFs)

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Spinal Cord Arteriovenous Malformations (SC-AVMs)


These are a direct or an indirect connection between spinal feeding arteries and spinal venous system with the presence of a nidus like the cerebral AVMs. These can be located extradural or intra-dural as well extra-medullary or intramedullary.Read more

History: The first successful operation of a spinal cord AVM was in 1914 by Elsberg.Read more


Spinal Cord AVMs are either congenital due to an autosomal-dominant trait mapped on the chromosome 7q or acquired and usually occur sporadically. They may occur in association with cerebral AVMs.Read more

Extradural /Intradural (SC- AVMs)


They are uncommon spinal lesions and are known as juvenile, metameric, or Type III AVMs in the older nomenclature. They respect no tissue boundaries and involve the skin, vertebrae and the spinal cord with both extra- and intra-dural components.Read more

Symptoms: These are mostly pain, progressive radiculo-myelopathy as well as hemorrhage.Read more


The imaging evaluation of spinal cord AVMs has two components: Imaging studies for diagnostic and screening studies for the evaluation of patients with suspected progressive radiculo-myelopathy.  MRI is the first diagnostic study of choice. It is a non-invasive method and has meanwhile replaced the myelography.Read more


It is an imperative to use a multidisciplinary treatment, combining the endovascular and surgical approaches. Embolization of multiple feeding arteries with delivery of PVA, NBCA, coils, or a combination of these is crucial to undertake the next step by staged surgical resection.Read more

Intradural (DAVMs)


They are either intramedullary (within spinal cord) or partially intra- and extra-medullary. They are usually more uniformly distributed than cerebral AVFs and are mostly associated with other vascular abnormalities. This suggests that they may be congenital lesions.Read more

Juvenile Type: These have a voluminous arteriovenous nidus fed by several enlarged medullary arteries. They may involve the vertebral body and para-spinal soft tissue.Read more

Glomus Type: These usually have a compact nidus confined to a segment of spinal cord. They are usually located anteriorly to the SC, and are fed by one or two medullary arteries.Read more


These usually are sudden onset of back pain, sub-occipital pain associated with meningismus and loss of consciousness. SAH or intramedullary hemorrhage may occur in about 35% to 50% of patients with intra-dural AVMs, particularly in children younger than 15 years.Read more


MRI is the best study of choice to show the hematomyelia, thrombosis, venous drainage and eventually edema. MRI may also demonstrate the postoperative results in patients with AVMs. The selective spinal angiography is the gold standard modality of imaging study.Read more


The main goal of therapy is the complete obliteration of abnormal vessels within the AVMs. That may be achieved by planning a multidisciplinary treatment combined of a) endovascular embolization, b) surgical approach.Read more

 Embolization of spinal cord AVMs

It has been developed due to the improvement and refinement of selective arteriography. This is usually performed by delivery of different agents such as PVA, variety of coils or combination of these in general anesthesia.Read more


It is planned after carefully studying the angiogram and considering the outcomes as well as  risks and benefit of the operation. In the case of SAH or intramedullary hemorrhage, delayed surgery is the best option to allow time for clot lysis and absorption. Intraoperative ultrasonography and angiography may be helpful in identifying the intramedullary nidus and also to distinguish the afferent from efferent vessels.Read more

Complications of SC-AVMs

The most common complications of AVMs occur 24 to 48 hours after the embolization. These are neurological deficits probably caused by thrombosis in the large venous plexus. To avoid this, patients should be heparinized 48 to 60 hours after the procedure.Read more

Spinal Dural Arteriovenous Fistulas (DAVFs)


Dural AVFs are a direct connection between dural feeding arteries and venous system (mostly a solely medullary vein). These have mostly no marked nidus and are distributed more diffused than AVMs. They are divided into two main types such as extradural arteriovenous fistulas and intra-dural DAVFs.Read more

Extradural (DAVFs)

They are represented by a direct connection between an extradural artery and vein which leads to developing of a high flow fistula and enlargement of the epidural venous complex. The epidural venous engorgement is the result of an exclusive drainage to the extradural venous system, but drainage into both extradural and intradural veins has also been reported in some cases.Read more


The exact pathogenesis and mechanism of dural AVFs is still unclear. However, lack of association with other vascular abnormalities, and occasional development of lesions after spinal operation or trauma, let suggest these as being acquired lesions.Read more


These are progressive myelopathy due to the mass effect and also venous congestion and arterial steal resulting in ischemia, SAH as well as EDH.Read more


MRI and particularly D3 contrast-enhanced MRA is the initial study of choice. This shows exact location of the DAVM, spinal level of fistula and also the medullary vein, into which the fistula drains.Read more


Endovascular management of spinal DAVFs such as embolization is almost always the best modality of choice. They rarely need an open surgery.Read more

Intradural (DAVFs)


They are the most controversial lesions regarding to their origin, pathophysiology and also therapy. These are subdivided into two types as follows:

1) Intradural dorsal DAVFs (Type I, according to the Spetzler’s classification of AVMs)

2) Intradural Ventral DAVFs (Type IV of SC-AVMs,- see also chapter of SC-AVMs)

Read more

Type I (Intradural Dorsal AVFs)

It is the most common type of spinal dural AVFs, and mostly occurs in males in about 85% of cases.Read more


These are progressive myelopathy like other types of AVMs and AVFs associated with back pain, and rarely bowel and bladder dysfunction.Read more


It is based on the dilatation, elongation and tortuosity of the vessels of the venous plexus which produces venous congestion, hypertension. This may lead to reduction of the arterial pressure-perfusion, which may result in ischemia and myelopathy. (see also pathogenesis of extradural DAVFs)Read more


Therapy of DAVFs may be embolization, surgery or a combination of both.Read more

Embolization: is the first initial treatment of choice. But there is a 39% failure rate reported. Techniques and equipment for endovascular catheterization and embolization are the same as other spinal vascular anomalies.Read more

Surgery: may be reserved for patients in whom endovascular treatment failed or in whom the initial  evaluation of imaging features indicates surgery alone. A low morbidity rate and a relatively high success rate have been reported in a surgical series by Eskandar & colleagues from Massechusetts General Hospital).Read more

Intradural Ventral AVFs (Type IV of SC-AVMs)

Type IV for ventral DAVFs was termed in 1986 by Gueguen and colleagues. Recently, Spetzler and colleagues subdivided Type IV into three subtypes such as (IVa), (IVb), and (IVc).Read more


These are the same as other spinal AVFs such as mass effect on spinal cord, vascular arterial steal and also progressive myelopathy.Read more


The sensitivity, specificity, accuracy and ability of the MRI and D3 MRA to predict the AVFs and their vertebral level have been proved by several studies, as mentioned in previous chapters. Selective normal angiography or digital subtraction angiography are the best modality of choice, demonstrating the angio-architectures of spinal AVFs.Read more


Therapy of DAVFs may be embolization, surgery or combination of both. The details have been discussed previously (see also dorsal AVFs in above text.). The most popular treatment modality for the majority of cases is microsurgery.Read more

Conus AVMs

Their location and angiographic features composing of AVFs (multiple direct shunts) and AVMs make these lesions as a distinguished malformation. These may be comprised of both extra- and intramedullary AVMs. They usually have multiple feeding arteries, more than one nidus and also have a complex venous drainage system (Spetzler & colleague). Read more

Symptoms: These are usually pain and progressive radiculo-myelopathey and also hemorrhage. Read more


MRI is the best first study of choice followed by spinal angiography. This may demonstrate location, feeding arteries, and complex venous patterns of lesions.Read more


A multidisciplinary therapy combined of endovascular and microsurgical intervention may lead to the successful obliteration of such complex lesions. Intraoperative angiography can sometimes be helpful.Read more


For a successful surgical treatment of spinal AVMs you need to get exact information about their localization, vascular structure, and hemodynamics. This information will help you to choose optimum procedures of microsurgical and endovascular interventions according to the type of malformation.Read more

Spinal Cord Aneurysms

They are usually associated with spinal cord AVMs. Pathogenesis of the lesion is based on high flow rate and dissection of the arteries. (see also cranial aneurysms and AVMs). These may involve Adamkiewicz, anterior spinal artery and further radicular arteries.Read more

Symptoms: These are sudden-onset of pain and also SAH.Read more

Diagnosis: MRI followed by selective spinal angiography is the best modality of choice.Read more


This consists of treatment of both lesions AVM and aneurysm. The strategy is the same as described previously for spinal AVMs. This is the endovascular embolization of the feeding arteries combined with surgical procedure.Read more


Significant advances of the modern MRI technique (rapid- sequence imaging) and selective intraoperative arteriography permit a defined diagnosis of various subtypes as well as details of anatomy and patho-physiology of the lesions. When selective angiography has established the diagnosis of an AVM or AVF, all therapy options should be considered. Read more

Spinal Neoplastic Vascular Lesions

These occur either sporadically in a familial pattern or spontaneously. The most common lesions of this group are cavernous angiomas or hemangiomas.Read more

Spinal Cavernous Malformations (Cavernous Angiomas)

They are comprised of sinusoidal vascular channels surrounded by a hemosiderin-stained gliotic rim of tissue. They are angiographically an occult lesion and may be seen in any location of the neuro-axis from cerebrum to the spine. They usually occur intramedullary, but they may be presented as an epidural lesion and involve more than one level of the spine.Read more


They occur sporadically as well as spontaneously in association with familial multiple cavernous angiomas related to an autosomal-dominant trial mapped to the chromosome 7q. They usually are low-flow lesions and pathogenesis of myelopathy mostly is hematomyelia.Read more


Myelopathy is the most common symptom, particularly in young patients through to middle age. Progressive neuropathy is usually associated with repeated small hemorrhages. Small lesions may remain asymptomatic throughout the life.Read more


MRI is the first study of choice followed by selective angiography like other vascular abnormalities.Read more


Surgery is the initial modality of choice. Complete excision and carefully inspection of the bed of the lesion is mandatory, because of the residual portion that tends to hemorrhage and cause myelopathy. Read more

Outcome and Complications

Postoperative results depend on the preoperative clinical conditions of the patients and angio-character of lesions. These are the same as other spinal vascular malformations associated with increased neurological deficits after surgery which will be resolved with time. That is reported in about 15% to 25% of cases.Read more


These are usually associated as a familial lesion with von Hippel-Lidau disease. Hemangioblastomas usually occur in cerebellum, but they have also been seen in spinal cord mostly intramedullary, or along the nerve root.  Despite the various locations of the lesions histopathology of the intra-spinal and intra-cranial tumors are similar. Intramedullary lesions as a cyst may mimic a syrinx. Surgical procedure is the same as in other spinal AVMs. Read more