Coexistence of muscle anomalies and rheumatoid arthritis in patients with carpal tunnel syndrome.

During a five-year period, surgical release of the carpal tunnel was performed on 150 patients with median nerve compression. Seventeen (11%) had rheumatoid arthritis. Among this subgroup, six patients had anomalous muscles in the wrist and proximal palm. An additional patient with psoriatic arthritis demonstrated a comparable abnormality. No other patients in this series had similar findings. This statistically highly significant occurrence is probably related to additive effects of the two disorders in producing median nerve compression.