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2009.08.17 Quz: Anoxic–ischemic encephalopathy

About the prognosis of patients with anoxic–ischemic encephalopathy, which of the following is incorrect?
A. The absence of a pupillary reaction to light suggests a poor prognosis but has unclear specificity when assessed early after a cardiac arrest, but if pupillary reactions are still absent at day 3 after cardiac arrest, the outcomes are poor. 
B. Motor response to noxious stimuli that was no better than extensor posturing (i.e., a decerebrate response or no response) at 72 hours was associated with no false positives for a poor outcome, even if hypothermia is used. 

C. The brain stem is more resistant to anoxic–ischemic damage than the cerebral cortex. 

D. The measurement of somatosensory evoked potentials (SSEPs), especially the N20 response from the primary somatosensory cortex (assessed 20
msec after electrical stimulation of the median nerve at the wrist), has emerged as the most accurate predictor of a poor outcome in patients with anoxic–ischemic encephalopathy.


Answer: B
 

A small study of 37 initially comatose patients who underwent hypothermia showed recovery of awareness (on day 6) in 2 of 14 patients who had a motor response that was no better than extensor posturing on day 3. Therefore, caution is warranted in relying on the motor response alone before day 6 or possibly even later for patients who have received hypothermia therapy.

Reference
Young GB.; N Engl J Med. 2009 Aug 6;361(6):605-11. Neurologic prognosis after cardiac arrest [Review]