Pain and motor function in carpal tunnel syndrome: a clinical, neurophysiological and psychophysical study

Patients with carpal tunnel syndrome (CTS) complain of motor symptoms. The study is aimed to understand which features are associated with the presence of motor symptoms in CTS.

We recruited 282 consecutive CTS patients. After selection, 129 patients (203 hands) were included. Patients were asked about the presence and severity of hand weakness (HW) and hand clumsiness (HC). They underwent a self-administered questionnaire on symptoms, clinical evaluation and neurographic study. Quantitative sensory testing (QST) was performed on the patients with unilateral right CTS.

HW and HC may be found in 56 % and 48 % of CTS hands, respectively. HW was related to the severity of sensory symptoms (pain, numbness and tingling) but not to clinical-neurographic measures of median nerve involvement. HC was related to the severity of sensory symptoms and to the clinical-neurographic signs of motor but not sensory nerve damage. Motor symptoms were significantly more frequent in right hands. QST showed a relationship between the presence and severity of HW and HC and the warm threshold.

Motor symptoms may be found in approximately half of CTS hands. Clinical and neurographic signs of median nerve motor damage appear to be poorly correlated to motor symptoms. The factor that can help reconcile the discrepancy between motor symptoms and motor signs is pain. Pain modulation on motor function may take place at various anatomical levels in CTS. Nociceptive C-fibers may be involved in pain-motor interactions finally leading to motor symptoms.