There are mour major categories of vascular anomalies: arteriovenous
malformations (most common), cavernous angiomas, capillary telangiectasias,
and venous antiomas. These lesions are found in about 5% of patients at
autopsy. They are generally asymptomatic. Clinical manifestations occur
most often in young people. In fact, a vascular malformation would be the
most likely cause of intracerebral hemorrhage in a child. The arteriovenous
angioma is most often clinically significant.
A.Arteriovenous Malformations (AVM)
1. Characteristics
a. Tangles of abnormal vessels or channels of various sizes with
thin walls; vessels are separated by gliotic neural parenchyma
b. Developmental origin
c. Bleeding most common in 10-30 year age group
d. Most often located in cerebral hemispheres
2.Clinical Signs
a. Seizures--the initial sign in 25-50% of cases
b. Headache--the initial sign in 15% of patients
c. Focal neurologic signs--specific signs related to location
of lesion
3.Consequences
a. Hemorrhage--subarachnoid or intracerebral
b. Ischemic necrosis of tissue surrounding the malformation
(1) "steal" phenomenon--blood shunted directly
from arteries to veins
(2) atherosclerosis and thrombosis of vessels
The microscopic appearance
of an AVM is shown; large vessels are separated by gliotic tissue.
B.Sturge-Weber Syndrome (Encephalofacial angiomatosis)
This syndrome is associated with intracranial venous malformation and hemangioma
of the face in the distribution of one or more divisions of the fifth cranial
nerve ("port wine stain"). The venous angioma (malformation) usually
occurs at the cortical surface. Common symptoms include mental retardation,
seizures, contralateral hemiparesis.
