CNS 2 Flashcards
Reduction or cessation of blood flow to a localized area of brain due to partial or complete arterial occlusion
clinical manifestations depend on the anatomic location of the lesion
Causes: thrombosis, embolism, inflammatory lesions
Focal Cerebral Ischemia
- evident at 48 hours as pale, soft regions of edematous brain, with neutrophilic infiltration; tissue then liquefies, and a fluid-filled cavity containing macrophages is lined by reactive glia
- Acute: red neuron, cerebral edema, neutrophilic infiltration
- Subacute: liquefactive necrosis, influx of macrophages, reactive gliosis with neovascularization
- Healed: tissue loss surrounded by residual gliosis
Nonhemorrhagic infarcts (bland or anemic infarcts)
exhibit blood extravasation and resorption
Hemorrhagic infarcts
- ## occurs with generalized reduction of cerebral perfusion or decreased oxygen carrying capacity of the bloodclinical outcome varies with the severity and length of the insult
- Neurons are most sensitive to ischemia
+ Pyramidal layer of hippocampus (CA1: Sommer sector)
+ Cerebellar Purkinje cells
+
Pyramidal cells of cerebral cortex
Global Cerebral Ischemia
- occur in the regions of the brain or spinal cord that lie at the most distal reaches of the arterial blood supply
- usually develop after severe hypotensive episodes and are most commonly seen in patients resuscitated after cardiac arrest
Border zone (“watershed”) infarcts
Gross
- Edematous and swollen brain: widening of the gyri and narrowing of the sulci
Microscopic
- Early changes: dead red neurons
Subacute changes: tissue necrosis, influx of macrophages, vascular proliferation, and reactive gliosis
- Repair: removal of necrotic tissue, loss of normal CNS architecture, and gliosis
- Laminar necrosis in cerebral neocortex
Global Cerebral Ischemia
- involves spontaneous rupture of a small intraparenchymal vessel
- “ganglionic hemorrhages” occurs in basal ganglia and thalamus
- “lobar hemorrhages” occurs in cerebral hemispheres
- Hypertension is the risk factor most commonly associated with deep brain parenchymal hemorrhages; occur in the putamen, thalamus, pons, and rarely the cerebellar hemispheres
- Cerebral amyloid angiopathy (CAA) is the risk factor most commonly associated with lobar hemorrhages
INTRAPARENCHYMAL HEMORRHAGE
- Most common cause: ruptured saccular “berry” aneurysm
- Saccular aneurysm: most common intracranial aneurysm
+ Most common location: anterior circulation (90%) - Associated with ADPKD, Ehlers-Danlos syndrome type IV, NF Type 1, Marfan syndrome, fibromuscular dysplasia, CoA
- Clinical manifestation: “worst headache of my life” and syncope
- Lesions are a few millimeters to 2 to 3 cm in diameter with a red, shiny, translucent wall. At the aneurysm neck, the muscular wall and intimal elastic lamina are absent or fragmentary; the sac wall is composed of only thickened hyalinized intima
SUBARACHNOID HEMORRHAGE
Classification of Vascular Malformations that is enlarged tangled vessels with intervening brain tissue
as its common location is in the vessels of the subarachnoid space and brain
AV Malformation
Classification of Vascular Malformations that is Enlarged vessels without intervening brain tissue
as its common location are in Cerebellum, pons, and subcortical regions
Cavernous malformation
Classification of Vascular Malformations that is Small, thin-walled vessels with intervening brain tissue
as its common location are in the pons
Capillary telangiectasia
Classification of Vascular Malformations that is Ectatic venous channels
as its common location are variable
Developmental venous anomalies (venous angiomas)
is caused by multi-focal vascular disease of several types, including
(1) cerebral atherosclerosis,
(2) vessel thrombosis or embolization from carotid vessels or from the heart, and
(3) cerebral arteriolosclerosis from chronic hypertension.
vascular dementia
When the pattern of injury preferentially involves large areas of the subcortical
white matter with myelin and axon loss, the disorder is referred to as
Binswanger disease (subcortical white matter dementia)
