Vascular neurology board type minutiae

1. AF increases the risk of stroke 6 fold, 18 fold if cardiac valve disorder is also present.
2. Diabetes doubles risk fo stroke compared to age matched controls
3. Flow factors studies in macaques and gerbils show functional impairment with flow below 23 mL/100g/min (normal is 55) but this is reversible for a time. Flow below 10-12 is irreversible and causes infarction. The EEG is slowed at rates 12-23, and is isolelectric below 12.
4. Low K causes stroke although the mechanism is obscure.
5. In penumbra, K increases (efflux from injured depolarized cells), ATP and creatine phosphate are depleted. Disturbance of calcium homeostasis and accumulation of free fatty acids impairs recovery. FFA's appearing as phospholipases are activated and destroy phospholipids of neuronal membranes. leading to accumulation of prostaglandins, leukotrienes, and free radicals.
6. Autoregulation operates from BP of 50-150 mm Hg and affects small pial vessels.
7. Irreversible inury is caused by excitatory transmitters affecting NMDA receptors and causing an influx of Ca and Na. Damage is accentuated also by an inflammatory response that activates endothelial cells to express cell adhesion molecules that attract more inflammatory cells, upregulate inflammatory proteins (metalloproteinases) and cytokines (interleukins and chemokines) as reviewed by Lo et al.
8. Ames and nesbitt studying rabbit retina showed cells can withstand complete anoxia for 20 minutes but irreversibly infarct after 30 minutes. Tolerance is less with HYPOglycemia and is prolonged with magnesium that reduces energy requirements in the cells.
9.