Time-dependent changes in median nerve sensory amplitude after local anesthetic administration and tourniquet application

Indirect visualization, as used in several newer mini-open and endoscopic carpal tunnel release (CTR) procedures, may increase the possibility of nerve injury in some cases. Intraoperative neural monitoring may be used to evaluate nerve location and integrity. In the study reported here, we assessed...

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Bibliographic Details
Published inThe American journal of orthopedics (Belle Mead, N.J.) Vol. 35; no. 11; p. 515
Main Authors Timpson, Wendy L, Kong, Xuan, Hamlet, Ward P, Gross, Patrick, Gozani, Shai N
Format Journal Article
LanguageEnglish
Published United States 01.11.2006
Subjects
Action Potentials - drug effects
Action Potentials - physiology
Adult
Anesthetics, Local - pharmacology
Feasibility Studies
Female
Humans
Lidocaine - pharmacology
Male
Median Nerve - drug effects
Median Nerve - physiopathology
Middle Aged
Monitoring, Intraoperative
Range of Motion, Articular
Time Factors
Tourniquets - adverse effects
Wrist - physiopathology
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Summary:Indirect visualization, as used in several newer mini-open and endoscopic carpal tunnel release (CTR) procedures, may increase the possibility of nerve injury in some cases. Intraoperative neural monitoring may be used to evaluate nerve location and integrity. In the study reported here, we assessed the feasibility of intraoperative neural monitoring by systematically exploring the effect of local anesthetic and tourniquet on median sensory amplitude. Results for 30 median nerves (7 symptomatic) showed that sensory amplitude decreased, on average, 54% with lidocaine injection, 15% with tourniquet application, and 47% with the combination. Sensory amplitudes of 9 of 10 nerves were still above 1.0 microV 15 minutes after anesthetic administration and tourniquet application. Study results demonstrate that intraoperative monitoring, using the amplitude of the median sensory nerve response, is viable under CTR conditions.
ISSN:1078-4519