Solitary paralysis of the triceps muscle due to trauma.

We report a rare solitary paralysis of the triceps muscle. The patient, an 18-year-old man who had had a work-related accident, sustained a severe contusion of the proximal posterolateral arm after being struck by a piece of lumber. This injury produced an extraordinary amount of soft-tissue swelling in the region of the trauma. After the accident it was noted that active flexion of the elbow was preserved, but active extension was absent. Three months after injury, surgical exploration of the radial nerve and its rami musculares to the three heads of the triceps muscle was undertaken. Dense adhesions were found fixing the rami musculares to the surfaces of the triceps muscle. Neurolysis of the rami musculares was performed, leading to complete recovery of the triceps muscle. The etiology of this isolated paralysis of the triceps muscle was determined to be dense adhesions compressing and compromising the function of the rami musculares to the three heads of the triceps muscle. These adhesions formed because of severe posttraumatic bleeding into the potential posterior humeral space, where the rami musculares are found.