BACKGROUND AND IMPORTANCE: 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. CLINICAL PRESENTATION: 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. CONCLUSION: 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.

Introduction: Lateral epicondylitis (LE) typically affects the extensor carpi radialis brevis (ECRB) tendon, while isolated degeneration of the extensor digitorum communis (EDC) origin is rare and poorly characterized. Surgical debridement of these lesions may result in capsular exposure requiring soft-tissue coverage, which can be achieved through a vascularized muscle flap to enhance tendon healing potential and reduce recurrence. This study aimed to describe a modification of the anconeus rotation flap as originally described by Almquist in 1998, and to evaluate its clinical and functional outcomes in patients with isolated EDC tendinopathy. The modified technique consists of a simpler muscle advancement (AMA) that preserves the distal vascular pedicle and reduces soft-tissue dissection. Methods: A retrospective study was conducted on 12 consecutive patients with lateral epicondylitis with isolated EDC tendon involvement (10.71% of all operative cases at our Institution between 2019 and 2022), who were surgically treated with the anconeus muscle advancement modification. Clinical outcomes, including the visual analog pain scale (VAS), grip strength and patient-reported outcome measures (PROMs), which include the QuickDASH score, the Mayo Elbow Performance Score (MEPS) and the Patient-Rated Tennis Elbow Evaluation (PRTEE) score were assessed. Paired statistical tests with 95% confidence intervals and minimal clinically important difference (MCID) thresholds were applied. Results: At a mean follow-up of 38 months, all outcomes demonstrated statistically significant and clinically meaningful improvements (p < 0.05). Reductions in pain/disability (VAS, QuickDASH, PRTEE scores) and functional gains (Grip strength, MEPS) far exceeded their respective MCID thresholds, with 100% attainment for each outcome. Conclusions: This modified anconeus muscle advancement appears to be a technically feasible option for managing isolated EDC-related lateral epicondylitis, preserving vascular integrity while limiting dissection. Although favorable results were obtained, the small retrospective cohort precludes definitive conclusions regarding efficacy. The findings support the technical feasibility of the proposed modification and warrant further prospective comparative investigations.