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 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.
Timpson
Wendy L
WL
NeuroMetrix, Inc., Waltham, Massachusetts 02451, USA.
Kong
Xuan
X
Hamlet
Ward P
WP
Gross
Patrick
P
Gozani
Shai N
SN
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000328:Adult; D000779:Anesthetics, Local / Q000494:pharmacology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D008475:Median Nerve / Q000187:drug effects* / Q000503:physiopathology; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D016059:Range of Motion, Articular; D013997:Time Factors; D014111:Tourniquets / Q000009:adverse effects*; D014953:Wrist / Q000503:physiopathology
D000779:Anesthetics, Local; D008012:Lidocaine