An unusual cause of posterior interosseous nerve palsy and contribution of ultrasonography to electromyography in a patient with neurofibroma

Neurofibroma, a benign peripheral nerve sheath tumor, represents a rare cause of posterior interosseous nerve syndrome. Electrodiagnostic studies may not identify the exact site of nerve compression, a possible lesion that compresses the nerve and do not provide information about the morphological changes. Ultrasound is a cost-effective, practical modality that provides the opportunity for dynamic tracking in the peripheral nerves, and it is widely considered as the initial imaging modality for peripheral nerves. Herein, we report a case of posterior interosseous nerve palsy in a 13-year-old boy with neurofibroma of posterior interosseous nerve diagnosed with ultrasound. The benefit of ultrasound in localizing and determining the etiology of the posterior interosseous nerve palsy is emphasized in this case report. A meticulous ultrasound examination is recommended in suspected peripheral nerve lesions, regardless of the results of electrophysiological and imaging modalities.