Distal posterior interosseous nerve syndrome.

Six patients selected from 13 patients presenting with dorsal wrist pain related in onset to repetitive dorsiflexion maneuvers are described. Clinical examination revealed tenderness over the fourth extensor compartment. Wrist dorsiflexion reproduced their symptoms. All patients were relieved by selective bupivacaine (Marcaine) block of the posterior interosseous nerve 3 cm proximal to the wrist joint. Of the 13 patients presenting, seven improved on immobilization and anti-inflammatory drugs. The six patients not relieved underwent surgical exploration with the specific findings of an enlarged, fibrotic, posterior interosseous nerve. Histologic analysis revealed perineural fibrosis without inflammatory changes. The perineural fibrosis was four times greater in affected nerves than in control specimens. We propose distal posterior interosseous nerve syndrome as another entity causing dorsal wrist pain that is distinct from the usual causes, such as dorsal ganglia, degeneration of the scapholunate ligament, and dorsal wrist syndrome.