Isolated Palsy of the Nerve to Flexor Pollicis Longus

Two cases of isolated paralysis of the nerve to flexor pollicis longus are described, both of which recovered after division of constricting fibrous bands. Anatomical considerations and treatment are described. Isolated paralysis of the anterior interosseous nerve is an interesting and curious neuropathy. Anterior interosseous nerve palsy has been well documented in the past. Kiloh (1952) reported two isolated cases of paresis of the flexor pollicis longus and the flexor digirorum profundus of spontaneous onset. In 1962 Thomas reported two cases of Kiloh-Nevin syndrome. Warren (1963) reported two more cases associated with fracture of the forearm and Fearn (1965) described a case of a nine year old child in whom at surgery a band was found at the level of the median nerve where it gives its branch to the anterior interosseous nerve. In 1970 Spinner performed detailed studies on twenty-five forearms with particular attention to the branches of the anterior interosseous nerve in an attempt to explain the unusual isolated paralysis of the flexor pollicis longus. The usual clinical picture is of loss of function of flexor pollicis longus and the flexor digitorum profundus to the index finger. Clinically these patients often present with an inability to pinch between thumb and index finger