Boston Carpal Tunnel Syndrome Questionnaire (BCTQ)
BCTQ, the most commonly used measurement of CTS symptoms, contains two multi-item scales with a summary score of 0 to 5 for each item; a higher score indicates greater severity. A total of 11 items in the Symptom Severity Scale (SSS) and the 8 questions in the Functional Status Scale (FSS) were used to evaluate the severity of symptoms and functional status, respectively.23The minimal clinically important difference (MCID) for SSS and FSS were 8.8 and 4 points, respectively, and the proportion of participants meeting the MCID value was recorded.24
Secondary outcome
Cross-sectional area of nerve: The same physician used an electronic caliper to evaluate the cross-sectional area (CSA) of the MN. For reliable results, the patients held their wrists in a neutral position with the palm facing upwards and the fingers in a semi-extended position. The examinations were performed at the proximal inlet of carpal tunnel with the short-axis scan (scaphoid-pisiform level) and where the largest swelling of the MN was identified, as described previously.6; 19 The ultrasonographic evaluation of the CSA of the MN performed at this level has high sensitivity (89%) and specificity (83%) for the diagnosis of CTS.25; 26 Measurements were repeated three times and averaged for further analysis.
Electrophysiological study: The same physician performed the examinations to compare the antidromic SNCV and DML of the MN.6; 7; 27 To survey the SNCV, a stimulator was placed 14 cm proximal to the active electrode where the 2nd interphalangeal joint was recorded. To assess the DML, the active electrode was placed on the abductor pollicis brevis with a stimulator at 8 cm proximal to the active electrode. The cutoff values for MN’s SNCV and DML for the diagnosis of CTS using electrophysiological assessment were <3.6 ms and <4.3 ms, respectively.20-22 We performed each measurement three times overall and averaged these values for a mean SNCV and DML for statistical analysis.28