External Neurolysis for Posterior Interosseous Nerve Syndrome with Refractory Motor Weakness: Clinical Outcomes in a Seven-Patient Case Series
- Author:
Kihyuk YUN
1
;
Jinseo YANG
;
Yong-Jun CHO
;
Gwang Yoon CHOI
;
Mu Seung PARK
Author Information
- Publication Type:Clinical Article
- From: The Nerve 2026;12(1):19-24
- CountryRepublic of Korea
- Language:English
-
Abstract:
Objective:Posterior interosseous nerve (PIN) syndrome (PINS) is a compressive neuropathy of the deep branch of the radial nerve that primarily presents with motor weakness of finger and thumb extension. Although some patients respond to conservative management, others develop persistent motor deficits requiring surgical decompression. This study aimed to evaluate the clinical outcomes of external neurolysis in patients with PINS presenting with refractory motor weakness.
Methods:Seven patients with clinically diagnosed PINS who exhibited persistent motor weakness despite conservative treatment and subsequently underwent surgical decompression were retrospectively reviewed. Clinical characteristics, magnetic resonance imaging (MRI) findings, intraoperative compression sites, and postoperative motor recovery were analyzed. Motor strength was evaluated using the Medical Research Council grading system. Preoperative and postoperative motor strength grades were compared using the Wilcoxon signed-rank test.
Results:The patients presented with progressive weakness of finger extension, resulting in impaired hand opening. MRI demonstrated denervation-related signal changes and atrophy in the affected muscles innervated by the PIN. Surgical exploration revealed compressive structures within the radial tunnel, most commonly at the arcade of Frohse. Significant improvement in motor strength was observed within 2 months postoperatively (thumb extension, p = 0.018; second digit extension, p = 0.011; third to fifth digit extension, p = 0.009). One patient experienced symptom recurrence approximately 6 months after the initial surgery and subsequently underwent revision decompression.
Conclusion:External neurolysis provides meaningful recovery of finger extension in patients with PINS presenting with refractory motor weakness. MRI may support the diagnosis by demonstrating denervation-related morphological changes in the affected muscles. Recurrence of PINS may occur even after initial recovery, highlighting the importance of careful postoperative follow-up.
