Anterior Interosseous Neuropathy in Instrumental Musicians

Abstract

The anterior interosseous nerve is a pure motor branch of the median nerve supplying the flexor pollicis longus, flexor digitorum profundus of the index and middle fingers, and pronator quadratus. Anterior interosseous neuropathy is rare and typically causes weakness of flexion of the tips of the thumb and index finger. Four instrumentalists, 3 violinists and 1 pianist (3 males, 1 female), seen from 1986 to 2002 at our clinic, are the subjects of this report. Age at onset ranged from 16 to 76 yrs. A possible precipitating factor was identified in each. One violinist could not hold the bow; two others noted inability to stabilize the distal left first (index) finger. The pianist noted impaired dexterity of the right hand. Examination showed weakness of flexion of the distal phalanx of the index finger and thumb and variable weakness of forearm pronation. Electrodiagnostic testing confirmed the diagnosis in all four patients. All improved over time. One symphony violinist continued to play for over 15 yrs, despite some persisting difficulty with the left index finger. Another violinist recovered function almost completely but suffered a stroke affecting the opposite hand 2.5 years later. The third violinist retired from the symphony on disability because his recovery was delayed for >1 yr. The young pianist is playing 4 to 5 hrs/day. It is likely that at least three of the four had a localized form of neuralgic amyotrophy.