title: Somatosensory evoked potential monitoring in carotid surgery. I. Relationships between qualitative SEP alterations and intraoperative events.
abstract: This paper presents the results of intraoperative median nerve SEP monitoring in 205 successive patients undergoing isolated carotid endarterectomy (CE) (N = 172) or CE followed by coronary bypass (CBP) and/or vascular replacement (VR) (N = 33). The left and right median nerves were alternately stimulated and recordings performed on 4 channels: cervical, ipsi- and contralateral parietal, and frontal. SEPs were qualitatively rated in terms of mild, moderate, or severe ipsilateral, contralateral, or bilateral abnormalities. The SEP abnormalities were subdivided into 5 categories as a function of their relationships with intraoperative events: no alterations (67.3%), early or late SEP alterations after carotid cross-clamping (15.6%), SEP alterations after a drop in blood pressure (occurring outside of or within the cross-clamping period) (15.1%), SEP alterations of a most likely embolic origin (2.4%), SEP changes after head positioning (1%), and SEP changes after a modification of the anesthetic regimen (1.5%). Only moderate to severe SEP alterations occurring soon after carotid cross-clamping justified shunt installation in 16% of the cases. SEP alterations after a drop in blood pressure were reversed merely by restoring blood pressure. The neurological outcome was uneventful in 94.2% of cases. Of the 12 patients who developed neurological sequellae, only one case presented transient sequellae after isolated CE without SEP changes while most cases either had undergone combined CE and CBP and/or VR (6 cases) or had presented SEP alterations of embolic origin (3 cases). We conclude that our system of qualitative rating of SEPs proved very sensitive to intraoperative hemodynamic disturbances or macroembolisms.
authors.affiliation: Clinical Neurophysiology Unit, Cliniques Universitaires Saint-Luc, University of Louvain Medical School, Brussels, Belgium.
authors.forename: J M
authors.initials: JM
authors.lastname: Guérit
authors.forename: C
authors.initials: C
authors.lastname: Witdoeckt
authors.forename: M
authors.initials: M
authors.lastname: de Tourtchaninoff
authors.forename: S
authors.initials: S
authors.lastname: Ghariani
authors.forename: A
authors.initials: A
authors.lastname: Matta
authors.forename: R
authors.initials: R
authors.lastname: Dion
authors.forename: R
authors.initials: R
authors.lastname: Verhelst
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000777:Anesthetics; D001794:Blood Pressure; D016893:Carotid Stenosis / Q000503:physiopathology / Q000601:surgery*; D002561:Cerebrovascular Disorders / Q000517:prevention & control; D016894:Endarterectomy, Carotid / Q000379:methods*; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000175:diagnosis; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009431:Neural Conduction; D013525:Surgical Instruments; D016896:Treatment Outcome
chemical_list: D000777:Anesthetics