CNS

Question 1

Global Cerebral Ischemia

Answer 1

• causes: low perfusion (ie: atherosclerosis), cardiogenic shock, chronic hypoxia (ie: anemia), repeated episodes of hypoglycemia

damage to vulnerable areas

• infarcts in watershed areas – area between MCA and ACA
• laminar necrosis (pyrimdal neurons of cerebral cortex layers 3,5 and 6)
• damage to hippocampus – impaired long term memory
• damage to purkinjie layer of cerebellum

Question 2

Ischemic Stroke

Answer 2

• regional ischemia –> focal neurologic defecits (unlike GLOBAL cerebral ischemia)
• Thrombotic: rupture of atherosclerotic plaque at bifurcation of internal carotid a. and MCA in circle of Willis) –> pale infarct
• Embolic: thromboemboli from L heart to MCA usually –> hemorrhagic infarct
• Lacunar: secondary to hyaline arteriolosclerosis (HTN) –> lenticulostriate vessels –> small, cystic areas of infarction (internal capsule involvement = pure motor stroke)
• liquefactive necrosis: red neurons –> inflamm infiltration –> fluid-filled cystic space surrounded by gliosis

Question 3

Intracerebral Hemorrhage

Answer 3

• bleeding into brain parenchyma
• rupture of Charcot-Bouchard aneurysm of lenticulostriate arteries (complication of HTN) –> Basal ganglia is most common site
• severe HA, N+V –> coma

**note: thromboemboli do not usually cause intracerebral hemorrhage – they are confined to the cortex mostly

Question 4

Subarachnoid Hemorrhage

Answer 4

• “worst HA of my life!”
• rupture of Berry Aneurysm (thick-walled saccular outpouchings at branch pts in circle of Willis)
• associated with Marfan, Ehler’s Danlos, ADPKD (lack media layer)

Question 5

Epidural Hematoma

Answer 5

• fracture of temporal bone with rupture of middle meningeal artery
• lens-shaped lesion on CT (blood does NOT cross suture lines)
• “talk and die”: lucid interval before abrupt loss of consciousness

Question 6

Subdural Hematoma

Answer 6

• tearing of bridging veins that lie between dura and arachnoid
• secondary to trauma
• symptoms may not present until weeks later bc bridging veins are under venous pressure and blood accumulates a lot more slowly (ie: CT scans are initially negative)