Diagnosis of motor fascicle compression in carpal tunnel syndrome

Median nerve motor fascicle compression in patients with carpal tunnel syndrome is usually characterised by reduced finger grip and pinch strength, loss of thumb abduction and opposition strength and thenar atrophy. The functional outcome in patients with advanced changes may be poor due to irreversible intraneural changes.

The aim of this study was to investigate patient-reported symptoms, which may enable a clinical diagnosis of median nerve motor fascicle compression to be made irrespective of the presence of advanced signs.

One hundred and twelve patients (166 hands) with a clinical diagnosis of carpal tunnel syndrome were referred to the neurophysiology department and completed symptom severity questionnaires with subsequent neurophysiological testing.

An increasing frequency of pain experienced by patients was significantly associated with an increased severity of median nerve motor fascicle compression with prolonged motor latencies measured in patients that described pain as a predominant symptom. An increasing frequency of paraesthesia and numbness and weakness associated with dropping objects was significantly associated with both motor and sensory involvement but not able to distinguish between them.

This study suggests that patients presenting with a clinical diagnosis of carpal tunnel syndrome with pain as a frequently experienced and predominant symptom require consideration for urgent investigation and surgical treatment to prevent chronic motor fascicle compression with permanent functional deficits.