METHODS: The study population consisted of 165 hands of 114 cases with idiopathic CTS while the remaining 291 hands were asymptomatic. All hands were examined by using an ultrasound scanner with a 5-75 MHz linear transducer. All hands were examined for subjective and objective findings of CTS. To facilitate objective estimation, the carpal tunnel was divided into two anatomical compartments as the median nerve compartment (MNC) and the compartment of flexor digitorum tendons (FDTC). ?

RESULTS: In the hands with idiopathic CTS, it was estimated that the entrapped median nerve made up 85% of MNC. The ratio of MNC to FDTC was found to be 0.07 ± 0.02. In normal hands, the median nerve made up 33% of MNC. The ratio of MNC FDTC was 0.23 ± 0.03. In idiopathic CTS the mean cross-sectional surface area of the whole tunnel decreased at a rate of 20% in comparison with normal hands. The decreasing ratio of MNC was 71% at the level of the hook of the hamate. The cross-sectional surface area of the median nerve only lost its caliber at a rate of 24% in comparison with normal hands. The cross-sectional surface area of MNC and FDTC tendons seems to be a sensitive finding for the neuroradiological diagnosing of idiopathic CTS. ?

CONCLUSION: In conclusion, this study revealed that ultrasonographic neuroexamination may be used for the neuroradiological diagnosis of idiopathic CTS. Keywords : Median nerve, carpal tunnel syndrome, entrapment neuropathy, ultrasonography, ultrasonographic neuroexamination