Sonography and MR imaging of bifid median nerve with anatomic and histologic correlation

OBJECTIVE: Imaging of a bifid median nerve has not been previously described in the radiology literature. We present three cases of bifid median nerve. The first is a patient with carpal tunnel syndrome seen on sonography and confirmed at surgery. The other two were found among 10 cadaveric specimens and were imaged with sonography and MR imaging. Confirmation of bifid median nerve in these two specimens was obtained using anatomic and histologic correlation. CONCLUSION: Sonography and MR imaging can allow effective diagnosis and delineation of a bifid median nerve in the wrist. This diagnosis is important to make before carpal tunnel release or other wrist surgeries are performed to avoid nerve injury. Furthermore, the sonographic size criteria for diagnosing carpal tunnel syndrome in nonbifid median nerves may not be accurate in evaluating bifid median nerves.