Spontaneous anterior interosseous nerve palsy.

©2003 British Editorial Society of Bone and Joint Surgery doi.10.1302/0301-620X.85B3.14147 $2.00 J Bone Joint Surg [Br] 2003;85-B:313-8. Palsy of the anterior interosseous nerve (AIN) was first described by Tinel1 in 1918 under the title ‘Dissociated paralysis of the median nerve’. In 1948 Parsonage and Turner2 noted six examples of this syndrome in a review of 136 patients with neuralgic amyotrophy, and in 1952 Kiloh and Nevin3 reported two cases of the palsy as an isolated neuritis. In 1955 Lipscomb and Burleson4 described the condition in association with a supracondylar fracture and in 1965 Fearn and Goodfellow5 first observed that an entrapment neuropathy was responsible for some examples of the AIN. The indications for operative treatment for spontaneous AIN palsy are controversial. When the cause of the palsy is an entrapment, the nerve should be explored early. If it is due to neuralgic amyotrophy or an isolated neuritis, surgery is not generally indicated and conservative treatment is followed. However, it is not easy to determine the appropriate method of management because there are no clinical findings or neurophysiological investigations to differentiate these two lesions. Recently, there have been several reports6-8 of cases in which an hourglass-like fascicular constriction was discovered in the main trunk of the median nerve after interfascicular neurolysis. The aetiology and the strategy for treating AIN palsy should therefore be reconsidered. This review describes the anatomy, clinical features, the aetiology and the treatment of an hourglass-like constriction of the fascicles in spontaneous palsy.