Evaluation of Clemastine's Effects on Clinical and Electrodiagnostic Parameters in Individuals With CTS: A Preliminary Placebo-Controlled Double-Blind RCT.

Only 24 people completed the trial and no power analysis was done, so the study could not have detected small differences and the positive findings may not hold up. The authors themselves warn that the many comparisons raise the risk that some 'significant' results are false positives. Drowsiness occurred only in the clemastine group, so some patients may have guessed they were on the real drug, which can bias a patient-reported outcome like the questionnaire. Three of 27 participants dropped out, including one whose symptoms worsened enough to need a procedure, so the completers may be the milder cases. Follow-up stopped at 3 months, and the authors say that is likely too short to see remyelination changes on nerve testing. Both groups received a night wrist splint, so the trial cannot tell you anything about clemastine used on its own.

The investigators declare no financial or nonfinancial disclosures for this project. Clemastine is an off-patent antihistamine, so no commercial sponsor is named.

Do not read the questionnaire improvement as proof that clemastine repairs the median nerve. The objective nerve conduction and ultrasound measures showed no significant difference between the groups, the sample was 24, and the authors state the study is underpowered and may contain false positives.