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Needle electromyography in carpal tunnel syndrome
1Electromyography Laboratory, Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
Electromyography and Clinical Neurophysiology
|June 12, 2002
Summary
Routine needle electromyography (EMG) for carpal tunnel syndrome (CTS) offers no additional diagnostic value beyond nerve conduction (NC) studies. Therefore, needle EMG of thenar muscles is not recommended for routine CTS evaluation.
Area of Science:
- Neurology
- Clinical Electrophysiology
Background:
- The diagnostic utility of needle electromyography (EMG) in routine carpal tunnel syndrome (CTS) evaluations remains uncertain.
- Nerve conduction (NC) studies are standard for CTS diagnosis.
Purpose of the Study:
- To assess if needle EMG of thenar muscles provides additional information beyond NC studies in CTS patients.
- To determine the role of needle EMG in the routine evaluation of carpal tunnel syndrome.
Main Methods:
- Retrospective review of electrophysiologic procedures in 84 patients (103 hands) diagnosed with CTS.
- Correlation of median thenar motor NC data with needle EMG findings in the abductor pollicis brevis (APB) muscle.
Main Results:
- Needle EMG findings in the APB muscle strongly correlated with the severity of motor NC data.
- Decreased compound muscle action potential amplitude and increased nerve conduction slowing/block corresponded with EMG changes like enlarged motor units and reduced recruitment.
Conclusions:
- Needle EMG examination of thenar muscles does not offer supplementary information when NC data confirms a CTS diagnosis.
- Routine needle EMG of thenar muscles is not recommended for carpal tunnel syndrome evaluation.