Treatment of posterior interosseous nerve entrapment syndrome with ultrasound-guided hydrodissection: A case report.

Background: Posterior interosseous nerve (PIN) entrapment syndrome is one of the causes of weakness and pain of the arm muscles, which is prone to missed diagnosis and misdiagnosis in clinic practice. This paper reports a case of PIN entrapment syndrome, with PIN injury indicated by electrophysiology. Musculoskeletal ultrasound was applied to identify that the entrapment point was located at the inlet of the Frohse arch and the outlet of the supinator muscle. Treatment with ultrasound-guided nerve hydrodissection was performed on the entrapment point, which significantly improved the symptoms. Ultrasound-guided nerve hydrodissection is an effective therapeutic method for PIN entrapment syndrome.

Case Summary: A male patient, 35 years old, worked as an automobile mechanic. He felt slightly weak extension activity of his right fingers 2 years ago but sought no treatment. Later, the symptoms gradually became aggravated and led to finger drop, particularly severe in the right middle finger, accompanied by supination weakness of the right forearm. Neural electrophysiological examination showed that the patient had partial PIN injury of the right radius. Musculoskeletal ultrasound examination indicated PIN entrapment at the inlet of the Frohse arch and the outlet of the supinator muscle. Therefore, PIN entrapment syndrome was diagnosed. After treatment with ultrasound-guided nerve hydrodissection around the entrapment point, the dorsiflexion weakness of the right hand was significantly improved compared with before treatment.

Conclusion: Ultrasound-guided hydrodissection is efficacious for PIN entrapment syndrome, with high clinical value and great application prospects.