Touch allodynia following endoscopic (single portal) or open decompression for carpal tunnel syndrome.

We investigated if single-portal endoscopic carpal tunnel decompression equipment (Agee, 3M, USA) would cause increased carpal tunnel pressure during the release and if endoscopic release would reduce postoperative touch allodynia. Measurements on cadavers of the pressure produced during endoscopic release showed similar pressures to those produced during maximal range of motion. One hundred patients underwent either open or endoscopic decompressions. Twenty normal individuals served as controls. At 1 month after surgery both groups had significant allodynia compared with the controls, but at 3 months the endoscopic group had returned to normal though the open group was still significantly abnormal. The reported endoscopic release may therefore be of particular advantage to patients who would seriously be disadvantaged if postoperative touch allodynia should develop. The Agee endoscope is unlikely to cause disturbance of the nerve function due to increased carpal pressure during the release.