Factor analysis of Carpal Tunnel Syndrome Questionnaire in relation to nerve conduction studies

ObjectiveThis study aims to assess the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) structure and its relation to nerve conduction studies (NCS).MethodsA 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.ResultsFactor 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.ConclusionsBCTQ 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.SignificanceFactor-2 sensory-related questions of BCTQ may be more useful in diagnosis, follow-up and assessing therapeutic outcome in CTS.

► Based on factor analysis, the variance of Boston Carpal Tunnel Syndrome Questionnaire can be represented by three separate factors: functional status (factor one), sensory symptoms (factor two) and pain (factor three). ► Questions relating to numbness and tingling (factor two) had a strong and direct statistical correlation with sensory and motor distal latencies of the median nerve. ► Questions related to sensory symptoms are most useful to determine the severity of disease of Carpal Tunnel Syndrome and to evaluate outcomes.