Hourglass-Like Constriction of the Brachial Plexus in an Adult Patient: A Case Report

Parsonage-Turner syndrome is a rare disorder characterized by sudden onset of severe pain in the upper limb, followed by muscle weakness or atrophy, and remains a challenge for clinicians. Although the etiology remains unknown, surgical identification of nerve torsions and recent advances in diagnostic imaging, particularly high-resolution ultrasound and MRI, have introduced a distinct entity known as hourglass-like constriction (HLC), which may be a manifestation of Parsonage-Turner syndrome. This case report presents the first-known case of HLC involving the brachial plexus in an adult patient.

A 66-year-old man developed brachial plexus palsy after arthroscopic rotator cuff surgery, initially manifesting as severe pain and later, after pain relief, progression to paralysis of the deltoid, biceps, and muscles innervated by the radial nerve. Despite initial conservative treatment, minimal recovery was observed at 6 months, which warranted surgery. Exploration showed a severe fibrous thickening of the anterior division was found, revealing an HLC. The unsalvageable nerve portion was resected, and direct suture was performed. Complete recovery of the deltoid nerve (M5) and almost complete recovery of the radial and musculocutaneous nerves (M4+ and M4, respectively) were noted at 30 months.

The case highlights the importance of considering HLC in cases of idiopathic brachial plexus palsy, even when imaging does not exhibit clear torsions. Surgery should be considered especially if there is no spontaneous recovery after 6 months. The choice of surgical technique should depend on the severity of the constriction and the expertise of the surgeon.