[Anterior interosseous nerve lesions revisited in 2004]

When the anterior interosseous nerve (AIN) is involved, a motor deficit of the distal pinch appears. It usually occurred suddenly, with or without pain and the deficit may be complete or partial. Other nerve lesions and some precipitating conditions can be noticed and are important to assess the exact mechanism of the nerve lesion. Partial AIN lesion is frequently misdiagnosed as tendon rupture. The electrodiagnostic examination should always study the pronator quadratus or another muscle innervated by the AIN, the AIN conduction and the motor and sensory median nerve conduction. Thus electrodiagnosis will always assess the AIN lesion and precise its axonal or compressive mechanism. Mononeuritis as neuralgic amyotrophy is the most frequent cause of AIN palsy and never requires surgery. Traumatic lesions are less frequent and usually recover spontaneously. Thus, surgery is rarely required before 12 to 18 months except when no recovery occurs after trauma.