Intraoperative dynamic pressure measurements in carpal tunnel syndrome: Correlations with clinical signs

Objective This study was designed to evaluate the correlations between dynamic carpal tunnel pressure and clinical signs. Methods From December 2008 to May 2010, open carpal tunnel release (OCTR) was performed on a total of 90 hands (83 patients). All patients completed neurological and provocation tests (two-point discrimination, Tinel test, Phalen test, reverse-Phalen test and assessment of thenar muscle atrophy). Carpal tunnel pressure (CTP) was measured in two parts of carpal tunnel (proximal and distal carpal tunnel) and in three different postures (neutral, wrist flexion and wrist extension). Results There were 74 females and nine males aged 36 to 86 years (mean age 54). CTP values were more elevated in the wrist extension than wrist flexion in the proximal carpal tunnel but not at the distal carpal tunnel. There was no statistically significant correlation among CTP, provocation testing, and clinical signs. However, two-point discrimination (2-PD) showed a statistically significant correlation with CTP, especially in the proximal area in the wrist extension posture (P < 0.01). Duration of symptoms (SD) statistically correlated with CTP in the distal carpal tunnel in the neutral posture (P < 0.01). Conclusions 2-PD and duration of symptoms are correlated with the CTP value in specific areas and with hand postures. This emphasizes the importance of releasing the entire carpal tunnel lesion since CTP values appear to vary within the carpal tunnel space and according to hand posture.