The carpal tunnel syndrome. A study of carpal canal pressures.

We measured intracarpal canal pressures with the wick catheter in fifteen patients with carpal tunnel syndrome and in twelve control subjects. The mean pressure in the carpal canal was elevated significantly in the patients. When the wrist was in neutral position, the mean pressure was thirty-two millimeters of mercury. With 90 degrees of wrist flexion the pressure increased to ninety-four millimeters of mercury, while with 90 degrees of wrist extension the mean pressure was 110 millimeters of mercury. The pressure in the control subjects with the wrist in neutral position was 2.5 millimeters of mercury; with wrist flexion the pressure rose to thirty-one millimeters of mercury, and with wrist extension it increased to thirty millimeters of mercury. Carpal tunnel release brought about an immediate and sustained reduction in pressure.