Incidence and natural history of touch allodynia after open carpal tunnel release.

Open surgical decompression is believed to be a safe treatment with few complications. However, it was our subjective impression that its morbidity had been underestimated. Fifty one consecutive patients with carpal tunnel syndrome were evaluated prospectively for three years after operation. Twenty one patients (41%) experienced allodynia of the operated hand at one month after surgery, 13 (25%) at three months, and three (6%) at 12 months. These were confirmed by significantly lowered pressure-pain thresholds over both the thenar and hypothenar eminences (p < 0.005). During the first month after operation all patients were relieved of nocturnal pain, and all clinical signs had disappeared at three months in all 51 patients. Our results confirm that open carpal tunnel decompression has a high success rate, but highlights a previously underestimated morbidity of postoperative allodynia.