Comparison of carpal canal pressure in paraplegic and nonparaplegic subjects: clinical implications

The purpose of this study was to evaluate the pressure within the carpal tunnel that was generated with certain tasks in paraplegic versus nonparaplegic subjects. Four groups of subjects were evaluated: 10 wrists in six paraplegic subjects with carpal tunnel syndrome, 11 wrists in six paraplegics without the syndrome, 12 wrists in nine nonparaplegics with the syndrome, and 17 wrists in 11 nonparaplegics without the syndrome. Carpal canal pressures were measured in the wrists in three positions (neutral, 45-degree flexion, 45-degree extension) and during two dynamic tasks [wheelchair propulsion and RAISE (relief of anatomic ischial skin embarrassment) maneuver]. External force resistors were placed over the carpal canal and correlated with internal tunnel pressures. At each wrist position, paraplegics with carpal tunnel syndrome consistently had higher carpal canal pressure than did the other groups at the corresponding wrist position; statistical significance was evident with regard to the neutral wrist position (p < 0.05). Within each group of subjects, wrist extension and wrist flexion produced a statistically significant increase in carpal canal pressure (p < 0.05), compared with the neutral wrist position. Dynamic tasks (wheelchair propulsion and the RAISE maneuver) significantly elevated the carpal canal pressure in paraplegics with carpal tunnel syndrome, compared with the other groups (p < 0.05). Lastly, there is a linear positive correlation between carpal canal pressure and external force resistance.