An Unusual Post‐Bariatric Surgery Presentation: Not Foot Drop, but Finger Drop, and the Use of Ultrasound in Both Diagnosis and Treatment: A Case Report

This case describes posterior interosseous nerve (PIN) palsy that developed 15 months after bariatric surgery and the resulting finger drop. Electrophysiological studies confirmed an acute axonal lesion of the PIN. No underlying metabolic pathology was identified. In a patient who showed no improvement despite conventional physiotherapy including electrical stimulation and exercises, mechanical entrapment at the level of the arcade of Frohse was first identified on ultrasound, and subsequently three sessions of ultrasound‐guided hydrodissection with 5% dextrose were performed, resulting in complete functional recovery. To the best of our knowledge, this case represents the first reported example of isolated PIN palsy following bariatric surgery. These findings once again highlight the important role of ultrasound in both diagnosis and treatment.