Nerve Ultrasound Findings in Carpal Tunnel Syndrome and its Correlation with Clinical and Electrophysiological Data

Abstract

Background: Sonologic evaluation of the median nerve has been shown to be a useful tool in carpal tunnel syndrome diagnosis. Neurosonology supplants clinical and electrodiagnostic work up. Objectives: To determine the median nerve ultrasound parameters in carpal tunnel syndrome (CTS) patients and find their correlation with patient reported clinical data and electrophysiology findings,to assess diagnostic accuracy of nerve ultrasound in CTS in comparison to clinical evaluation combined with electrodiagnosis as reference standard. Methods: 23 consecutive patients with carpal tunnel syndrome symptoms (46 wrists-35 with nerve conduction study confirmed CTS, 11 without CTS) underwent neurosonologic evaluation with high resolution ultrasound including median nerve cross sectional area(CSA) at carpal tunnel inlet, flattening ratio, Wrist/forearm CSA ratio measurements. Patient reported measures were recorded using Boston carpal tunnel syndrome questionnaire (BCTQ). Results: Statistically significant correlation was found between median nerve CSA at carpal tunnel inlet and disease severity assessed by electrodiagnosis (r=0.545, p value-0.002), hand function status had significant correlation with electrodiagnostic severity class (r=0.422, p value 0.012). Flattening ratio, Wrist/forearm CSA ratio did not show significant correlation with clinical and electrophysiology measures. Sensitivity and specificity for a cross sectional area cut off of 9 cm2 for diagnosis of CTS was found to be 85.7 percent and 64 percent respectively. Conclusion: Median nerve cross sectional area CSA measurement is the most useful neurosonologic parameter and correlates with electrodiagnostic severity. Ultrasound is a useful complementary tool for CTS diagnosis, assessment alongside electrodiagnosis. Keywords: Carpal Tunnel Syndrome, Neurosonology, Compression neuropathy