Factor analysis of carpal tunnel syndrome questionnaire in relation to nerve conduction studies.

OBJECTIVE: This study aims to assess the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) structure and its relation to nerve conduction studies (NCS). METHODS: A total of 403 patients with clinical and/or electrophysiological definition of CTS were evaluated with the instrument. The structure of the questionnaire was assessed by means of factor analysis. Factors obtained were compared with NCS. RESULTS: Factor analysis showed that three factors represented nearly 60% of the variance of the instrument. Factor one is related to all the function domain questions and to the weakness and difficulty in grasping questions of the symptom domain; factor two to questions that assess numbness and tingling, and to the pain-awakening question of the symptom domain; and factor three, to pain questions of the symptom domain. Factor two had a stronger correlation with latencies of NCS and with the neurophysiological scale than the other two factors. CONCLUSIONS: BCTQ assesses function and symptoms in patients with CTS by means of questions related to numbness and tingling sensation, pain and functional status. Questions related to numbness and tingling (factor two) better reflected the pathophysiology of the median nerve. SIGNIFICANCE: Factor-2 sensory-related questions of BCTQ may be more useful in diagnosis, follow-up and assessing therapeutic outcome in CTS.