Correlation of Ultrasonography and MRI with Electrodiagnostic Studies in Carpal Tunnel Syndrome

Background: One controversial question in Carpal Tunnel Syndrome (CTS) diagnosis is whether magnetic resonance imaging (MRI) and Ultrasound (US) imaging tools have any relationship with electrodiagnostic (EDX) study. The objective of this study is to determine the possible correlation between MRI and US measurements with EDX parameters. Methods: Both US and MRI of the median nerve were simultaneously performed in 12 confirmed CTS wrists, at two levels of forearm distal fold (proximal) and the hook of the hamate (distal), to measure various anatomic parameters of the nerve. EDX parameters of median motor distal latency (DL) and median sensory proximal latency (PL) were evaluated in milliseconds. Results: Nerve cross-sectional area (CSA), measured by MRI, correlated with sensory PL at distal level (p = 0.015). At proximal level MRI, nerve width and width to height ratio also correlated with motor DL (p = 0.033 and 0.021, respectively). Median nerve CSA proximal to distal ratio correlated with sensory PL (p = 0.028) at MRI. No correlation was found between US and EDX measurements. Conclusions: Median nerve MRI measurement of nerve CSA at hook of the hamate (distal) level or CSA proximal to distal ratio correlated with EDX parameter of sensory PL. On the other hand, nerve MRI width and width to height ratio at distal level correlated with motor DL in EDX. Level of Evidence: Level III (Diagnostic).