Comparison of median-ulnar nerve thickness measured by ultrasonography with electrophysiological findings in patient with carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy in upper extremity. In this syndrome, median nerve is trapped in carpal tunnel which is located on the wrist. It may lead various problems in people daily life by causing pain, numbness and tingling. CTS is dominantly seen in middle-aged woman. CTS is the most common entrapment neuropathy with a prevalence of 5.8% and 0.6% in woman and men respectively. Jobs that require frequent use of hands (musicians, computer-typewriter users, carpenters, factory workers, needle workers, tennis players) and some other diseases or conditions (pregnancy, rheumatoid arthritis, chronic renal insufficiency, diabetes mellitus, ankle trauma, amyloidosis, tumors, tendinitis and tenosynovitis) are other reasons that cause CTS. Diagnosis of CTS is made by using anamnesis and clinical examination. Electrophysiological assessment is the diagnostic gold standard. Ultrasound (US) and magnetic resonance imaging (MRI) are ancillary tests which can be used in diagnostic process. USG is frequently used as technical aid in the diagnosis of CTS because of being inexpensive and noninvasive. Median nerve cross-sectional area (MNCSA) measurements has been frequently used and in this study it is aimed to measure ulnar nerve cross sectional area (UNCSA) in addition to this method and to compare with EMG. Total of 121 wrists, from 86 patients diagnosed with CTS by using EMG, were evaluated with USG and MNCSA/UNCSA ratios were calculated, for one year. In 20 healthy volunteers, nerve conductions were shown to be normal by EMG, and median/ulnar nerve cross-sectional area ratios were calculated by USG. In EMG assessment, there were mild CTS in 31 (25.6%) wrists, moderate CTS in 72 (59.5%) wrists and severe CTS in 18 (14.9%) wrists. MNCSA and MNCSA/UNCSA values were predictor of moderate and severe CTS only. After the evaluation of the results, it was seen that MNCSA/UNCSA does not provide additional information. It is also seen that they cannot be used as screening tests because of low sensitivity of cut-off points for both parameter and they had low false positive rate because of high specificity. In CTS diagnosis, USG should be considered as an ancillary test to the EMG and clinical evaluation, because it can be useful for the evaluation of anatomical structures and provides additional information about the etiology. Key words: Carpal tunnel syndrome, ultrasonography, median nerve cross-sectional area, median/ulnar nerve cross-sectional area.