OBJECTIVES:To determine if a window of time could be defined during which angioplasty would be most effective in reversing neurological decline and ultimately improving outcome.METHODS:Of a group of 466 patients, 93 underwent endovascular management of clinical vasospasm that was medically refractory. Eighty-four of the 93 patients were available for follow-up for at least 6 months. All patients underwent mechanical angioplasty using compliant microballoon system and, if distal spasm was present, the administration of papaverine.RESULTS:Fifty-one patients underwent endovascular management within a 2-hour window, and 33 patients underwent treatment more than 2 hours after the development of their symptoms. Compared with the group treated more than 2 hours after neurological decline (P< 0.01; χ2= 8.02), the group that underwent endovascular management within a 2-hour window after the development of symptoms demonstrated sustained clinical improvement.CONCLUSION:When a patient develops symptomatic vasospasm and is unresponsive to traditional measures of critical care management, angioplasty may be effective in improving the patient's neurological status if this procedure is performed as early as possible. The results indicate that a 2-hour window may exist for restoration of blood flow to ultimately improve the patient's outcome.