Role of sonography in the diagnosis and treatment of a ganglion cyst compressing the lateral branch of deep peroneal nerve

Selective compression neuropathy of the lateral branch of the deep peroneal nerve is rare. A 55-year-old woman with ankle instability and mild weakness of extension of the toes was examined with sonography (US), which revealed the presence of a ganglion cyst compressing selectively the lateral branch of the deep peroneal nerve. US-guided aspiration of the cyst resulted in nerve decompression and progressive resolution of symptoms. This case demonstrates the importance of examining the deep peroneal nerve and its branches when performing US in the clinical setting of ankle instability. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:108-111, 2017.