Ultrasonographic appearance of supinator syndrome

Objective. To describe ultrasonographic findings in 4 patients with supinator syndrome (i.e., deep branch of the radial nerve). Methods. Four patients with weakness and pain in their forearm underwent ultrasonographic examination with subsequent electroneurographic testing and surgical nerve inspection. Normal measurements of the deep branch of the radial nerve in 10 healthy volunteers served as comparison for measurements in the patients. Results. An enlarged deep branch of the radial nerve was found in all 4 patients at the affected side. Electroneurographic testing and surgical inspection confirmed the ultrasonographic findings. The mean transverse diameter was 4.2 mm (range, 3.8-4.5 mm), and the anteroposterior diameter was 3.3 mm (range, 2.5-3.8 mm). In volunteers, the mean transverse diameter was 2.13 mm (range, 1.7-2.6 mm), and the mean anteroposterior diameter was 1.3 mm (range, 1.0-1.5 mm). Conclusions. The deep branch of the radial nerve appears enlarged in patients with supinator syndrome.