Anterior Interosseus Nerve Syndrome Masqueraded by a Functional Gantzer Muscle Variant: A Report of 3 Cases.

CASE: We present 3 patients with anterior interosseous nerve syndrome (AINS) who demonstrated thumb interphalangeal flexion despite complete denervation of the flexor pollicis longus. Advanced imaging revealed a Gantzer muscle in all cases that was confirmed at surgery in the 2 patients who required microneurolysis.

CONCLUSION

In patients with suspected AINS, retention of thumb IP flexion should prompt suspicion for a Gantzer muscle. Preservation or return of thumb flexion does not rule out AINS nor indicate recovery.