Injection with methylprednisolone proximal to the carpal tunnel: randomised double blind trial

Objective To assess the effect of a 40 mg methylprednisolone injection prox imal to the carpal tunnel in patients with the carpal tunnel syndrome. Design Randomised double blind placebo controlled trial. Setting Outpatient neurology clinic in a district general hospital. Participants Patients with symptoms of the carpal tunnel syndrome for more than 3 months, confirmed by electrophysiological tests and aged over 18 yea rs. Intervention Injection with 10 mg lignocaine (lidocaine) or 10 mg lignocain e and 10 mg methylprednisolone. Non-responders who had received lignocaine received 40 mg methylprednisolone and 10 mg lignocaine and were followed in an open study. Main outcome measures Participants were scored as having improved or not im proved. Improved was defined as no symptoms or minor symptoms requiring no further treatment. Results At 1 month 6 (20%) of 30 patients in the control group had improved compared with 23 (77%) of 30 patients the intervention group (difference 5 7% (95% confidence interval 36% to 77%)). After 1 year, 2 of 6 improved pat ients in the control group did not need a second treatment, compared with 1 5 of 23 improved patients in the intervention group (difference 43% (23% to 63%), Of the 28 non-responders in the control group, 24 (86%) improved aft er methylprednisolone. Of these 24 patients, 12 needed surgical treatment w ithin one year. Conclusion A single injection with steroids close to the carpal tunnel may result in long term improvement and should be considered before surgical de compression.