Carpal Tunnel Syndrome (CTS) is the most common peripheral neuropathy. The pathology is due to pressure on the median nerve at the wrist. Ultrasonography shows the soft tissues as well as other pathological conditions as edema, synovitis, soft tissue tumors or bonny pathology of the carpal tunnel and its contents. The test can be dynamic and can provide the clinician with important information regarding the flexor tendons/muscles movement into the canal. The present study aimed to find sonographic criteria for the diagnosis of CTS. Pressure on the median nerve under the carpal ligament causes narrowing of the nerve (hourglass deformity). The ratio between nerve width proximal to the canal and the width of the most compressed part of the nerve under the ligament was selected as our indicator. Our assumption was that in healthy individuals the ratio would be 1 or close to 1. Standardization was based on values taken from a group of healthy volunteers (47 hands). Mean value of this ratio in the healthy group was x-=0.95, standard deviation 0-=0.13. 79% (37/47) of the control group were in the range of ±1 and 97% (44/47) were in the range of ±2 standard deviations from mean value. Based on these figures, we defined a probable diagnosis of CTS as a ratio under two standard deviations from the mean value. Our database included 450 patients operated for CTS at our department between 1998 and 2000. Out of this group, 99 patients had met our inclusion criteria (positive anamnesis, positive clinical examination, complete Ultrasound and EMG studies). We could define an indicator and analysis of the results of our study show a significant and positive statistical correlation between this indicator and a positive motor latency electrodiagnostic finding. Conclusion: EMG is the current Gold Standard for the diagnosis of CTS. Based on our findings concerning the indicator we have defined Ultra Sonography is a reliable, readily available, low cost auxiliary test to help diagnose CTS. A larger scale study of this indicator is in progress.
