Ultrasonographic and Surgical Findings of Acute Radial Neuropathy Following Blunt Trauma.

Ultrasonographic study is useful for decision making of treatment for focal neuropathy with unusual electrodiagnostic findings. We present a patient with severe acute radial neuropathy with sensory sparing around the distal arm secondary to twisting of the radial nerve following blunt trauma. A 24-year-old man with a 2-week history of left wrist drop and severe pain around the left elbow presented after hitting the left distal arm on the doorknob. The left wrist and finger extensions were grade 0, but elbow extension could not be tested because of severe pain during this action. The left superficial radial sensory territory was intact. Electrodiagnostic findings suggested severe left radial neuropathy around the distal arm with sensory sparing. Ultrasonographic study demonstrated 2 stenotic lesions around the distal arm and absence of the left superficial radial sensory nerve. Surgical exploration revealed 2 stenotic lesions with twisting of the nerve, concordant with ultrasonographic study. End-to-end anastomosis was performed in the proximal lesion. Sixteen months later, wrist and finger extension was grade 3, and reinnervation signs in the radial-innervated muscles except extensor indicis muscle were observed. The complementary relationship between electrophysiologic and ultrasonographic examinations is very important for precise lesion location and decision making for treatment of peripheral nerve injury.