The Effect of Carpal Tunnel Syndrome Phenotyping on Response to Treatment

Patients rate the current pain intensity from 0 ("no pain") to 10 ("worst possible pain").

Boston Carpal Tunnel Questionnaire - Symptom Severity Scale is an 11-item questionnaire used to assess symptom severity in individuals with CTS. Each item is scored from 1 to 5. Scores range from 1 (no symptoms) to 5 (worst symptoms). The patient's symptom severity score is the average score of 11 items.

Boston Carpal Tunnel Questionnaire - Functional Status Scale is an 8-item questionnaire used to assess the functional status of patients with CTS. Each item is scored from 1 to 5. Scores range from 1 (no functional deficit) to 5 (worst possible function). The patient's functional status score is the average of all 8 items.

The Michigan Hand Questionnaire (MHQ) is a hand-specific questionnaire that measures the health status of patients with acute and chronic hand disorders. The MHQ is an outcome tool consisting of 37 questions and 6 domains: (1) overall hand function, (2) activities of daily living, (3) pain, (4) work performance, (5) aesthetics, and (6) patient satisfaction with function. Each domain is scored using an unweighted method by summing the responses on each scale (1 to 5) and normalising the scores to a scale from 0 to 100. A lower score indicates more severe disability, other than pain. The final score is obtained by averaging the six scores after inverting the pain score.

For cold pain threshold, ice cubes (-5°C) placed in a plastic bag will be placed on the patients' skin for 10 seconds. Increased sensory perception will be considered as gain of function. The intensity of pain will also be recorded on an NRS scale ranging from 0 (no pain) to 10 (worst pain imaginable).

Thermal pain perception will be tested using a metal piece equal to (lab-QST thermode size). The metal parts will be heated to 45˚C for hot pain threshold. The metal pieces will be applied to the skin for 3 seconds. It will be determined whether the stimulus is painful (yes/no), and if painful, the intensity of the pain on a numerical rating scale (NRS) (0: no pain, 10: imaginably worse pain).

A digital algometer will be used to measure Pressure Pain Threshold levels. Pressure will be applied at a rate of approximately 30 kPa/s with the algometer placed perpendicular to the point of application. Participants will be instructed to report when the sensation changes from pressure to pain. The intensity of pain will also be recorded on an NRS scale ranging from 0 (no pain at all) to 10 (worst pain imaginable).

Mechanical pain threshold: to be assessed with a toothpick and a von Frey filament (256 mN). Increased sensory perception will be considered to reflect gain of function. The intensity of pain will also be recorded on an NRS scale ranging from 0 (no pain at all) to 10 (worst pain imaginable).

Patients will be touched on the affected area and the control area with a brush, an ear stick and a piece of cotton wool. The assessment tools will be applied 4 times by drawing a cross of 2 strokes (length 5 cm) at an angle of 90˚C in each direction. For each stimulus (brush/ear swab/cotton swab), they will indicate (1) whether the stimulus was perceived as painful (yes/no) and (2) the pain intensity on the NRS-11 (0 no pain, 10 imaginably worse pain).