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CARDIOVASCULAR ANESTHESIA

Somatosensory Evoked Potential Monitoring During Carotid Endarterectomy in Patients with a Stroke

Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada

Address correspondence and reprint requests to Dr. Pirjo H. Manninen, Department of Anesthesia, Toronto Western Hospital, 399 Bathurst St., Toronto, Ontario, Canada, M5T 2S8. Address e-mail to Pirjo.Manninen{at}uhn.on.ca

The aim of our study was to assess the characteristics and feasibility of somatosensory evoked potential (SSEP) monitoring in patients who have had a stroke undergoing carotid endarterectomy. We retrospectively reviewed the medical and SSEP records of 204 patients. The patients were divided into two groups: Stroke (n = 65) and No-Stroke (n = 139). The amplitude and latency of the N20-P25 cortical complex on the ipsilateral side (surgical) were compared with the contralateral side in each group and between groups. Stroke patients showed asymmetry of their cortical waveforms; the ipsilateral N20-P25 baseline amplitude was 1.5 ± 1.0 µv versus 1.9 ± 1.2 µv for the contralateral (P = 0.001), for No-Stroke patients 2.0 ± 1.1 µv versus 2.1 ± 1.1 µv (P = 0.2). Forty-eight percent of Stroke patients had a ratio (ipsilateral/contralateral amplitude) of <1.0 ± 0.2 compared with 26% for No-Stroke patients (P = 0.01). There were no differences in latency measurements, in the incidences of significant SSEP changes (four Stroke, six No-Stroke) and immediate postoperative neurological deficits (two Stroke, six No-Stroke) between the two groups. Nine patients (three Stroke, six No-Stroke) had a decrease in ipsilateral N20-P25 amplitude >50% after cross-clamping, and had a shunt inserted. In conclusion, patients with a history of a stroke before surgery had a decrease in the amplitude of the ipsilateral cortical peak. There were no differences in the incidences of SSEP changes or neurological deficits.

Implications: Patients who have had a preoperative stroke may show asymmetry of theircortical baseline somatosensory evoked potential waveforms; however, this doesnot interfere with the ability to use somatosensory evoked potential as amonitor during surgery.

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				S. J. Howell Carotid endarterectomy Br. J. Anaesth., July 1, 2007; 99(1): 119 - 131. [Abstract] [Full Text] [PDF]