Vascular malformations of the central nervous system
4 types:
- Developmental venous anomalies (2%), benign
- Capillary telangiectasias (0.7%), benign
- Cavernous malformations (0.4%), neurologic sequelae tendency
- Arteriovenous malformations(1%), neurologic sequelae tendency
DEVELOPMENTAL VENOUS ANOMALIES (venous angiomas)
1. Introduction
-DVAs most often are solitary, although multiple lesions have been described in association with other clinical syndromes (eg, the blue rubber bleb nevus syndrome: multiple cutaneous venous malformations in association with visceral lesions, most commonly affecting the GI tract.).
-DVAs also may occur concurrently with cavernous malformations in 13 to 40 %.
-Microscopically, the venous structures appear largely normal with rare degenerative changes consisting of thickening and hyalinization.
2. Location
supratentorial with a frontal lobe predominance, not occur in the diencephalon, brainstem, or spinal cord.
3. Clinical presentation
Headache is the most common presenting complaint, may followed by seizures and sensory-motor phenomena.
The hemorrhage rates were usually minor
4. Diagnosis
gold standard: Cerebral angiography
-venous phase: "caput medusae" appearance, arterial phase: normal
enhanced CT, MRA: dilated venous
enhanced T1 MRI: "sunburst" pattern, White matter abnormalities and/or calcifications may be observed in the parenchyma surrounding the DVA.
5. treatment
DVAs should be treated conservatively in the vast majority of cases, with associated symptoms such as headaches and seizures managed medically.
Surgery may be required in the rare patient with hemorrhage associated with a DVA or with uncontrolled seizures.
CAPILLARY TELANGIECTASIAS
1. introduction
The lesions are composed of small, dilated capillaries devoid of smooth muscle or elastic fibers. The intervening brain is often normal; it may also demonstrate areas of microhemorrhage or gliosis.
Most telangiectasias represent an angiodysplastic phenomenon resulting from faulty embryogenesis of the vascular wall and have been associated with angiomatous phacomatoses such as Osler-Weber-Rendu (hereditary hemorrhagic telangiectasia), Louis-Bar (ataxia-telangiectasia), and Wyburn-Mason (unilateral retinocephalic vascular malformation) syndromes.
2. location
small and multiple lesions, most commonly found in the pons, middle cerebellar peduncles, and dentate nuclei.
3. Clinical presentation
Most: clinically silent, found incidentally on neuroimaging studies or at postmortem examination.
Rare symptomatic cases occur: headache, nausea, and seizures.
4. Diagnosis
MRI: "black dots" on T1 and T2-weighted imaging.
Telangiectasias can be identified in the late arterial/early capillary phase of angiography as a faint blush with an associated venous channel. Thus, these lesions can be distinguished from DVAs that are visualized during the venous phase of the study.
5. Treatment
Capillary telangiectasias are nonoperable lesions.
CAVERNOUS MALFORMATIONS
Introduction
also referred to as cavernous angiomas, cavernous hemangiomas, or cavernomas.
Developmental venous anomalies (DVAs) may be associated with CMs.
prevalence 0.1 - 0.5%, mean age of 30 to 40
women more commonly present with hemorrhage and neurologic deficits.
1. Location
(1). supratentorial : Most cavernomas are found in the brain hemispheres
(2). infratentorial: 1/4~1/5 are found in the hindbrain, especially in the pons region of the brainstem.
(3). spinal cord: rare, family history
2. Etiology
(1). Sporadically: majority
(2). Familial: more common in Hispanic, CCM1, CCM2 (On chromosome 7), and CCM3 (On chromosome 3), more commonly multiple
3.
gross →mulberry, vary from 2 mm to several centimeters in diameter.
Microscopic → dilated, thin walled capillaries with a simple endothelial lining and a thin, fibrous adventitia. Elastic fibers and smooth muscle are not present in the vessel walls.
4. Symptoms
Most: asymptom
(1). Supratentorial: hemorrhage, seizures, and progressive neurologic deficits
-Annual bleeding rates of 0.25 ~ 1.1 %
(2). Infratentorial: hemorrhage and progressive neurologic deficits
-annual bleeding rate for brainstem lesions is 2 ~ 3% per year
-recurrent hemorrhage rates approaching 17 ~ 21 %
(3). Brainstem: cranial neuropathies
5. Diagnosis
T2 MRI: "popcorn" pattern, A dark hemosiderin ring
CMs may not be seen on angiography and often are referred to as "angiographically occult."
6. Treatment
(1). Asymptomatic CMs are observed, irrespective of location.
(2). Indications for surgical resection: progressive neurologic deficit, intractable epilepsy, and recurrent hemorrhage.
(3). Surgically inaccessible lesions: eloquent tissue (eg, rolandic cortex, brainstem, thalamus/basal ganglia) are usually observed despite the poor natural history associated with untreated brainstem and thalamic lesions.
(4). Stereotactic radiosurgery is a potential alternative to conservative therapy in patients with such surgically inaccessible lesions, and the available evidence suggests that it does lead to a reduction in hemorrhage, especially two years or more after radiosurgery, but high complication rates.
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