Nerve Conduction Study Evidenced Carpal Tunnel Syndrome among Females: An Altrasonic Assessment

Carpal tunnel syndrome (CTS) is the most commonly diagnosed entrapment neuropathy of the upper extremity. Current American Academy of Orthopaedic Surgeons recommendations are to obtain a confirmatory electrodiagnostic test in patients for whom surgery is being considered. Ultrasound has emerged as an alternative confirmatory test for CTS; however, its potential role is limited by lack of adequate data for sensitivity and specificity relative to electrodiagnostic testing.

The aim of the study is to assess the usefulness of sonographic measurement of the median nerve (MN) cross-sectional area (CSA) in the diagnosis of carpal tunnel syndrome (CTS) and grading of its severity using clinical examination and nerve conduction study (NCS) as the diagnostic standard in female patients with idiopathic CTS.

A prospective cross-sectional study at Al-Sadir Medical city in Al-Najaf, in which ultrasonographic study of 63 wrists with clinical and electrophysiological confirmed CTS of different severity, graded by NCS, and wrists of 40 healthy volunteers were performed. Age, height, weight, body mass index were recorded, and CSA of the MN were obtained at the carpal tunnel inlet using direct tracing method.

A significant difference is found between the mean CSA ± SD of the MN at the tunnel inlet (13.11 ± 3)mm² in CTS patients and the mean control group's CSA, which was (6.87 ± 1.04)mm² (p < 0.001). The mean CSA ± SD of the MN was (10.26 ± 0.83)mm² in patients with mild CTS, (13.81 ± 1.89)mm² in patients with moderate CTS, and (17.86 ± 1.89)mm² in patients with severe CTS, each of these subgroups 'CSA shows significant difference from the median nerve CSA of the control group (p< 0.001). Furthermore, a significant difference is also noted between each of these three patients subgroups with each other (p< 0.001).

The mean CSA of the MN of healthy volunteers ± 2SD was considered as the cut-off value, this yielded a sensitivity of (96.8%), a specificity of (100%), p value < 0.001, a positive predictive value (PPV) of (100%), a negative predictive value (NPV) of (97.6%) and an accuracy of (95.3%) for the ultrasound to diagnose CTS.

Ultrasonographic examination of the median nerve seems to be a promising method in the diagnosis and grading of carpal tunnel syndrome. Further studies with larger samples are recommended to confirm our preliminary results.