Synonym: deep radial nerve syndrome
Clinical features of the posterior interosseous nerve syndrome:
(1) pain in the forearm
(2) tenderness in the nerve to palpation at the level of the supinator muscle
(3) weakness in the extensor muscles of the fingers, resulting in flexion (palmar "drooping") of the fingers
(4) weakness of the extensor carpi ulnaris muscle, resulting in the hand deviating radially
(5) absence of numbness or sensory changes in the hand
(6) absence of involuntary wrist flexion in the palmar direction (flexion present in complete radial nerve palsy)
Nerve conduction studies:
(1) may be normal or equivocal
(2) show prolongation or block at the level of the compression
Differential diagnosis:
(1) lateral epicondylitis
