(Image #1 and Image #2)
(Image #3 and Image #4)
(Image #1 and Image #2)
(Image #3 and Image #4)
Click on Images for Enlarged View
Findings: Image #1 is a noncontrast enhanced axial CT image through the head demonstrating extensive calcifications just superior to the left Sylvian fissure in the region of the distribution of the MCA.
Image #2 is a post contrast enhanced axial CT image demonstrating large feeding and draining vessels.
Image #3 is a selective injection of the left internal carotid artery from an angiogram demonstrating an arteriovenous malformation in the distribution of the left MCA. Note is made of an early draining vein just superior to this AVM.
Image #4 again demonstrates the AVM with extensive tortuous venous drainage.
Diagnosis: Arteriovenous malformations.
Discussion: Intracranial vascular malformations represent a spectrum of entities which generally are classified into four major groups. These include capillary telangectasia, cavernous angioma, venous angioma, and arteriovenous malformation (AVM). These are histologically considered hamartomas. Arteriovenous malformations are the most common type of intracranial vascular malformation to produce symptoms with approximately 80% presenting by the fourth decade. Most common presenting symptoms include seizures with an over-all hemorrhagic risk approaching approximately 3% annually. Symptoms may also be secondary to local mass effect or secondary to steel phenomenon due to the high flow state of the AVM. AVMs are felt to most likely occur secondary to underdevelopment or maldevelopment of a normal capillary bed. Histologically, the abnormal vessels demonstrate features characteristic of both arteries and veins. Approximately 10% of AVMs are associated with aneurysm formation. Arteriovenous malformations are most commonly found in the distribution of the middle cerebral artery.
Radiologically, the arteriovenous malformation is characterized by extensive tortuous, dilated vessels on contrast enhanced computed tomography. In addition, approximately 25% of intracranial arteriovenous malformations demonstrate calcification. Imaging with MRI demonstrates a serpiginous tangle of flow void consistent with the high flow state of most AVMs. Angiography is the definitive examination to define the local vascular anatomy as well as for treatment planning. In addition, angiography is the best means available for the detection of associated aneurysms. Although most larger AVMs will most likely be treated surgically, smaller AVMs may be managed successfully with embolization.
References:
Wagner BJ. Intracranial Vascular Malformation. Seminars in Ultrasound,
CT, and MRI. 1995;16(3):253-268.
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