Early Surgical Decompression for the Treatment of Hourglass-Like Constriction of the Posterior Interosseus Nerve

Posterior interosseous nerve (PIN) syndrome refers to a rare compressive neuropathy of the PIN resulting in motor dysfunction of the forearm extensor compartment. Often, surgical exploration will reveal extrinsic structures that mechanically compress the nerve. Less frequently, PIN syndrome has been reported with a visible hourglass-like constriction and no identifiable causative adjacent structures. In our report, we describe an adolescent patient with PIN syndrome and associated hourglass-like constriction of the PIN. For diagnosis, we used physical examination, preoperative imaging, nerve studies, and intraoperative findings. To monitor recovery, we performed serial neurological examinations and documented patient-reported functional outcomes. The patient underwent early surgical decompression (< 6 weeks from presentation). Complete resolution of pain was reported 2 weeks after surgery. Complete resolution of wrist extension motor function occurred at 28 weeks after surgery. We demonstrate effective pain relief and complete motor recovery with early surgical release in this adolescent high-level athlete.