3. DEFINITION
• It is a clinical & radiographic syndrome of
heterogeneous etiologies that are grouped
together because of similar findings on
neuroimaging studies.
• Reversible subcortical brain edema.
6. Autoregulatory failure
• Normal autoregulation maintains constant CBF
over a range BP , by means of arteriolar
constriction and dilatation . If it is exceeded,
arterioles dilate and CBF increases resulting in
brain hyperperfusion, may lead to breakdown of
the BBB allowing extravasation of fluid and
blood products.
7. Cerebral ischemia
• Disordered autoregulation may lead to
reactive focal vasoconstriction, thereby
resulting in local hypoperfusion, cytotoxic
edema, and cerebral infarction
8. Endothelial dysfunction
• Especially in cases - preeclampsia or cytotoxic
therapies.
direct toxicity on vascular endothelium, leading to
-Capillary leakage
-BBB disruption
-Axonal swelling
which may then trigger vasogenic edema
9. Why posterior mainly
• Heterogeneity in the sympathetic distribution
of the intracranial arterioles,
• Postulated that greater concentration of
adrenergic nerves around pial and
intracerebral vessels in the anterior circulation
than posteriorly.
13. CLINICAL FEATURES
• Any age group .
• Females are slightly more affected .
SEIZURES HEADACHE
VISUAL
DISTURBANCES
ALTERED
SENSORIUM
14. EXAMINATION
• Focal neurologic deficits are rare.
• Fundoscopic examination is often normal,
might –papilledema.
• The deep tendon reflexes are frequently brisk
with Babinski signs often present.