DETECTION OF STROKE DURING CARDIAC OPERATIONS WITH SOMATOSENSORY-EVOKED RESPONSES

Objectives: The objectives of this study were to determine if monitori ng of intraoperative somatosensory evoked potentials could be used to detect stroke during cardiac operations and to establish indicators of cerebral ischemia based an changes in these potentials. Methods: Twen ty-five patients undergoing cardiac operations underwent preoperative and post-operative neurologic examinations as well as intraoperative r ecording of somatosensory evoked potentials, Detailed analysis of the waveforms of these potentials was performed. Results: Two of the lj pa tients had intraoperative strokes, These patients and only these patie nts had changes : in their somatosensory evoked potentials during the operation suggesting cerebral ischemia. The unilateral disappearance o f the cortical somatosensory evoked potential waves correlated signifi cantly with the clinical outcome of stroke (p < 0.004). Ischemic chang es were detected in real time and were related to the removal of the a ortic crossclamp in one patient and to the initiation of cardiopulmona ry bypass in the other. Conclusions: Somatosensory evoked potentials c an detect intraoperative stroke during cardiac operations. Acute, unil ateral decreases in amplitude of the cortical potential are more usefu l than changes in latency in detecting intraoperative stroke.