[Bifid median nerve in the carpal tunnel: integrated imaging]. / Nervo mediano bifido a livello del tunnel carpale: imaging integrato.

PURPOSE: Carpal Tunnel Syndrome (CTS) is a neuropathy caused by compression of the median nerve at the level of the wrist, which is caused by different pathologic conditions. In some cases it has been associated with anatomic variations of the median nerve, mainly with the early duplication of the nerve inside the carpal tunnel (III Group of Lanz). The treatment of CTS is mainly surgical consisting in decompression by transection of the transverse carpal ligament, which is better performed by endoscopic release. The aim of our study was to evaluate the possibility to detect this anatomic variant by integrated imaging and assess the value of this information for planning treatment. MATERIAL AND METHODS: We report 6 cases of bifid median nerve examined by Ultrasonography (US) using mechanic sectorial and linear array transducers operating at 10 to 13 MHz, and by MR imaging using 0.2 T equipment. RESULTS: In all cases US transverse scans showed two adjacent oval formations with a structure similar to that of the median nerve. CONCLUSIONS. MR imaging confirmed the sonographic findings in all cases. All patients underwent open surgical treatment by decompression of the median nerve; in all cases an early duplicated median nerve was confirmed.

Evaluation of bifid median nerve with sonography and MR imaging.

Bifid median nerve is an anatomic variation that may be associated with carpal tunnel syndrome. It is important for the surgeon to be aware of the existence of this condition preoperatively in order to plan the carpal tunnel release. We report the correlation between ultrasonographic findings and magnetic resonance imaging results in six patients with bifid median nerve, selected from a population of 294 patients with carpal tunnel syndrome, who were studied by ultrasonography using a high frequency transducer. Sonography showed two structures inside the carpal tunnel with the same pattern as the median nerve in all six patients. Magnetic resonance imaging confirmed the sonographic findings. The patients underwent open surgery, and a bifid median nerve was found. In conclusion, bifid median nerve is an anatomic variant that can be demonstrated ultrasonographically. It is important to be aware of this anomaly when planning carpal tunnel release surgery.