Time course and predictors of median nerve conduction after carpal tunnel release.
OBJECTIVE
To identify predictors of outcome and of electrophysiologic recovery in patients with carpal tunnel syndrome (CTS) treated by endoscopic carpal tunnel release using a nerve conduction testing system (NC-Stat; NEUROMetrix, Inc, Waltham, MA).


METHODS
Validity of the automated nerve conduction testing system was shown by comparing presurgical distal motor latencies (DMLs) against a reference obtained by referral to an electromyography laboratory. The DML was evaluated in 48 patients with CTS. Measurements were obtained within 1 hour of surgery and at 2 weeks, 6 weeks, 3 months, and 6 months after carpal tunnel release. Presurgical and postsurgical DMLs were then compared and correlated with variables and possible predictors of outcome including age, body mass index, gender, and presurgical DMLs.


RESULTS
The automated nerve conduction testing system DMLs matched those of reference electromyography/nerve conduction study values with high correlation. Sensitivity of the automated nerve conduction testing system when compared with a standardized CTS case definition was 89%, with a specificity of 95%. A significant correlation was found between the DML before release and the DML 1 hour after release. Moreover, maximal postsurgical DML improvement was highly dependent on the presurgical DML, with no improvement shown for the <4-ms group, mild improvement for the 4-to-6-ms group, and maximal improvement in the >6-ms group. Among the clinical variables of age, gender, and body mass index only age was mildly predictive of postrelease DML changes at 6 months. No other correlations between clinical variables and postsurgical DMLs were significant. In addition the predictive value of age was lost when combined with the presurgical DML in a multivariate analysis.


CONCLUSIONS
Postsurgical changes in the median nerve DML were highly dependent on the prerelease latency. The sensitivity and specificity of a nerve conduction monitoring system in detecting and aiding in the diagnosis of CTS is useful in the long-term management of patients with CTS and can aid in determining the level of improvement in median nerve function after endoscopic carpal tunnel release.
Rotman
Mitchell B
MB
Orthopedic Center of St Louis, St Louis, MO, USA.
Enkvetchakul
Bobby V
BV
Megerian
J Thomas
JT
Gozani
Shai N
SN
D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology / Q000601:surgery*; D004594:Electrophysiology; D004724:Endoscopy; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D015999:Multivariate Analysis; D009431:Neural Conduction / Q000502:physiology*; D017063:Outcome Assessment, Health Care; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D012680:Sensitivity and Specificity; D013997:Time Factors