Motor unit number estimate (MUNE) testing in male patients with mild to moderate carpal tunnel syndrome

Carpal tunnel syndrome is a frequent clinical entity with an excellent prognosis if adequately treated. However, in rare cases of treatment failure, patients may suffer significant impairment of hand function with various degrees of disability. Loss of motor units in the hand muscles is the pathophysiological basis for this functional impairment. In our study we utilized motor unit number estimate (MUNE) testing in patients with mild to moderate carpal tunnel syndrome in an attempt to identify a patient population with a "silent" loss of motor units in the affected hand. As a result of the study we identified two groups of such patients; first, the group with an associated cervical radiculopathy, and second, the group with an increased amount of polyphasic motor units in the abductor pollicis brevis muscle on electromyographic (EMG) evaluation. Potentially, these patient populations are predisposed for functional impairment of the hand and, therefore, require a more active diagnostic and therapeutic evaluation. Our study also indicates that morphology of motor unit potentials is a good indicator of the motor unit reserve and correlates well with our MUNE results. MUNE testing proved to be a well tolerated, reliable and practical technique in the diagnosis, treatment and research of neuromuscular disorders.