Ultrasound-guided aspiration and injection of an intraneural ganglion cyst of the common peroneal nerve.

BACKGROUND: Intraneural ganglion cysts are rare, benign, mucinous lesions that occur within neural sheaths and are thought to involve cystic fluid exiting from nearby synovial joints. They often present as tender masses causing paresthesias in the distribution of the involved nerve, muscle weakness or cramping, or localized or referred pain. CASE DESCRIPTION: We present a case of a patient who initially presented with foot drop due to an intraneural ganglion cyst of the common peroneal nerve. This cyst was successfully treated using ultrasound guidance to aspirate the cyst and inject corticosteroid to prevent further inflammation. LITERATURE REVIEW: Standard of care has previously involved surgical resection, but this has been associated with a high frequency of recurrence. Due to the risks of nerve and vessel damage, there have been efforts to find alternative ways of resolving these cysts. PURPOSES AND CLINICAL RELEVANCE: Aspiration and injection of corticosteroid is a useful and minimally invasive alternative to surgery for managing intraneural ganglion cysts.