COMPARISON OF MEDIAN NERVE CROSS-SECTIONAL AREA AT THE PISIFORM AND HOOK OF HAMATE LEVELS USING ULTRASONOGRAPHY IN CARPAL TUNNEL SYNDROME

Abstract

Introduction: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and results from compression of the median nerve at the wrist. High-resolution ultrasonography is a non-invasive, low-cost tool for assessing nerve swelling, yet the best measurement level and cutoff values remain debated.

Objective: To compare median nerve cross-sectional area (CSA) at the pisiform and hook of hamate levels, with a pronator quadratus forearm reference, in patients with CTS.

Methodology: This cross-sectional analytical study was conducted at Gulberg Medical Center, Islamabad, over nine months. A total of 118 participants were recruited by non-probability purposive sampling. Median nerve CSA was measured with a Toshiba Xario-Prime system using a 7–14 MHz linear transducer at the pisiform, hook of hamate and pronator quadratus levels. Intraneural vascularity was assessed with power Doppler. Paired t-tests, repeated-measures ANOVA, chi-square tests and receiver operating characteristic (ROC) analysis were applied.

Results: Mean age was 53.6 ± 9.0 years and 76.3% were female. Mean CSA was 16.82 ± 3.32 mm² at the pisiform, 12.60 ± 2.32 mm² at the hook of hamate and 7.11 ± 0.89 mm² at the pronator quadratus (p < 0.001). Hypervascularity was present in 68.6%, and surgery was recommended in 80.5%. A pisiform CSA of at least 13.0 mm² identified surgical candidates with 97.9% sensitivity, 100% specificity and an area under the curve of 0.998.

Conclusion: Median nerve CSA is greatest at the pisiform level and falls progressively distally. Pisiform CSA combined with power Doppler is a practical basis for sonographic assessment and surgical triage in CTS, although validation against electrodiagnostic testing and healthy controls is still needed.