Ann Rehabil Med.  2011 Dec;35(6):816-825. 10.5535/arm.2011.35.6.816.

Motor Unit Number Estimation and Motor Unit Action Potential Analysis in Carpal Tunnel Syndrome

• Sohn MK
• Jee SJ
• Hwang SL
• Kim YJ
• Shin HD

• KMID: 2266807
• DOI: http://doi.org/10.5535/arm.2011.35.6.816

Abstract

OBJECTIVE
To evaluate the clinical significance of motor unit number estimation (MUNE) and quantitative analysis of motor unit action potential (MUAP) in carpal tunnel syndrome (CTS) according to electrophysiologic severity, ultrasonographic measurement and clinical symptoms. METHOD: We evaluated 78 wrists of 45 patients, who had been diagnosed with CTS and 42 wrists of 21 healthy controls. Median nerve conduction studies, amplitude and duration of MUAP, and the MUNE of the abductor pollicis brevis were measured. The cross sectional area (CSA) of the median nerve at the pisiform and distal radioulnar joint level was determined by high resolution ultrasonography. Clinical symptom of CTS was assessed using the Boston Carpal Tunnel Questionnaire (BCTQ).
RESULTS
The MUNE, the amplitude and the duration of MUAP of the CTS group were significantly different from those found in the control group. The area under the ROC curve was 0.944 for MUNE, 0.923 for MUAP amplitude and 0.953 for MUAP duration. MUNE had a negative correlation with electrophysiologic stage of CTS, amplitude and duration of MUAP, CSA at pisiform level, and the score of BCTQ. The amplitude and duration of MUAP had a positive correlation with the score of BCTQ. The electrophysiologic stage was correlated with amplitude but not with the duration of MUAP.
CONCLUSION
MUNE, amplitude and duration of MUAP are useful tests for diagnosis of CTS. In addition, the MUNE serves as a good indicator of CTS severity.

Keyword

Carpal tunnel syndrome; Electrodiagnosis; Electromyography; Ultrasonography

MeSH Terms

Action Potentials
Boston
Carpal Tunnel Syndrome
Electrodiagnosis
Electromyography
Humans
Joints
Median Nerve
ROC Curve
Wrist
Surveys and Questionnaires

Figure

• 

  Fig. 1 The MUNE (A), MUAP amplitude (B) and duration (C) of APB and cross-sectional area of median nerve at pisiform (D) and radio-ulnar joint level (E) showed statistically significant differences between the CTS and control group (*p<0.05 by independent t-test).

• 

  Fig. 2 Receiver operating characteristic (ROC) curves of MUNE (A), MUAP amplitude and duration (B) of APB. The area under the curve of MUNE is 0.944, MUAP amplitude is 0.923, MUAP duration is 0.953 (p<0.05).

• 

  Fig. 3 The MUNE and median motor distal amplitude (MMDA) of APB were compared in a patient with CTS according to the electrophysiologic severity and control groups. The abnormal cutoff values were 112.55 for MUNE and 6.35 mV for MMDA.

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