The relationship between preoperative needle electromyography findings and muscle power restoration after surgery in severe carpal tunnel syndrome patients.
OBJECTIVE
Needle electromyography provides essential information about the functional aspects of the muscle. But little attention has been given in the literature to needle electromyography examinations in carpal tunnel syndrome. We examined the relationship between preoperative needle electromyography findings and functional recovery of the abductor pollicis brevis (APB) muscle in severe carpal tunnel syndrome patients.


METHODS
The subjects of this study were 49 patients, 58 hands, who fit the following 5 criteria: (1) idiopathic carpal tunnel syndrome; (2) pre-op MMT grade of the APB muscle was M0 or M1; (3) APB-CMAP (compound muscle action potential) was not evoked in a median nerve conduction study; (4) needle electromyography of the APB muscle had been done; (5) underwent carpal tunnel release only. The patients were divided into two groups according to the results of pre-op needle electromyography: voluntary motor unit potential of the APB muscle was evoked [MUP(+) group]or not [MUP(-) group]. We evaluated APB muscle strength at one year after surgery, and patient satisfaction and functional evaluations (CTSI-FS) at more than one year after.


RESULTS
The APB muscle recovery rate to M3 or higher was 100% in the MUP(+) group, and 57% in the MUP(-) group. Patient satisfaction was also high and functional recovery was sufficient in the MUP(+) group. No patients requested a second opponensplasty.


CONCLUSIONS
Our findings suggest that post-op restoration of thumb function relates to whether or not the MUP ofthe APB muscle is evoked. Single-stage opponensplasty may be unnecessary if the MUP of the APB muscle is; evoked. Needle electromyography is therefore useful in consideration for opponensplasty.


METHODS
Level Ⅲ, case-control study.
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1Tennoudai, Tsukuba, Ibaraki, Japan. Electronic address: yukihara@md.tsukuba.ac.jp.
Yuki
Y
Hara
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1Tennoudai, Tsukuba, Ibaraki, Japan.
Yasumasa
Y
Nishiura
Department of Orthopaedic Surgery, Kikkoman General Hospital, 100 Miyazaki, Noda, Chiba, Japan.
Naoyuki
N
Ochiai
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1Tennoudai, Tsukuba, Ibaraki, Japan.
Shinji
S
Murai
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1Tennoudai, Tsukuba, Ibaraki, Japan.
Masashi
M
Yamazaki
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D004576:Electromyography / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009339:Needles; D009431:Neural Conduction / Q000502:physiology*; D019635:Neurosurgical Procedures / Q000379:methods*; D017060:Patient Satisfaction; D011184:Postoperative Period; D057234:Preoperative Period; D020127:Recovery of Function; D012189:Retrospective Studies; D012720:Severity of Illness Index