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.