Anterior Interosseous Nerve Syndrome

Abstract

Anterior interosseous nerve syndrome (AINS) is a rare form of peripheral neuropathy which involves disruption of the anterior interosseous nerve. The pathophysiology of AINS remains unclear. AINS typically initially presents with forearm pain and may gradually progress to palsy of the deep muscles of the anterior forearm. Diagnosis of AINS requires thorough patient history and physical exam. EMG is the preferred diagnostic study and classically reveals abnormal activity and prolonged latency periods within the evoked action potentials of the FPL and PQ. Due to the self-limiting nature of AINS, there is general agreement that conservative and symptomatic management should be explored for up to 6 months as first line therapy, which usually includes analgesics and nonsteroidal anti-inflammatory drugs, contracture prevention, hand therapy, and hand splinting. Surgical options such as internal neurolysis and minimally invasive endoscopic decompression may be explored if functional recovery from conservative management is limited.

Role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of peripheral nerves in the upper extremity

“…AINS usually results from the compression of the AIN, and presents with acute pain in the proximal forearm followed by weakness on flexion of the thumb at its interphalangeal joint and the index finger at its distal interphalangeal joint. On physical examination, patients are unable to bring the tips of the index finger and thumb together in the shape of an "O", which is called a positive Kiloh-Nevin sign (55) . AINS could result from nerve compression due to repetitive elbow flexion and pronation, compression from a fibrous band of the superficial head of the pronator teres, an aberrant course of the radial artery, or thrombosed anterior interosseous vessels.…”