Experimental evidence of ischemic thresholds and functional recovery.

BACKGROUND Impaired blood flow below certain critical levels and an insufficient supply of energy-rich substrates cause failure of neuronal function, triggering biochemical disturbances that eventually lead to ischemic cell damage. SUMMARY OF REVIEW This article reviews experimental studies that attempted to define those ischemic thresholds using functional and histological markers and, more recently, chemical markers of ischemic damage. CONCLUSIONS The duration of ischemia causing irreversible cell damage still is ill defined. Reestablishment of sufficient perfusion must be induced very early after an ischemic attack to ameliorate the potentially harmful biochemical sequelae of transient ischemia.