ABSTRACT
The presence and extent of the ischemic penumbra is time-dependent, but especially patient-dependent. Indeed, from patient to patient, survival of the penumbra can vary from less than 3 hours to well beyond 48 hours. From 90 to 100% of patients with supratentorial arterial occlusion show ischemic penumbra in the first 3 hours of a stroke, but, interestingly enough, 75-80% of patients still have penumbral tissue at 6 hours after stroke onset.11-13
The relatively negative results to date of thrombolysis trials between 3 and 6 hours,3,4,13 in spite of the high percentage of patients with penumbra within this time window, relates to the fact that these trials did not use any method of penumbral imaging to select patients for therapy, despite the penumbra being the target for treatment.
