Ultrasound-guided steroid injection for obturator neuralgia.

Obturator neuralgia (ON) presents with pain in the groin, medial thigh, and sometimes the medial aspect of the knee. The causes include trauma, obturator hernia, pelvic cancer, pelvic surgery, hip surgery, following pelvic fractures, endometriosis, retroperitoneal hematoma, pregnancy, and delivery. Ultrasound (US) guidance facilitates real-time imaging, identification of vascular structures, and improves patient comfort in situations where nerve stimulation can be unpleasant. This is a case report of ON successfully treated with US-guided steroid injection. A 55-year-old man was referred to the pain clinic with groin pain and allodynia in the medial thigh and knee following a fall. He had tried multiple other therapies and none of them provided significant relief. Using a 10-5-MHz multi-frequency, 38-mm linear array transducer, the obturator nerve was scanned in both longitudinal and transverse directions. Under real-time imaging 10 mg of medroxy-progesterone in a volume of 1 mL was injected. Following the injection, a small area of the medial side of knee was still tender to light touch. A second injection was placed inferiorly and provided pain relief for more than 5 months. This successful demonstration of US guidance in ON may further encourage US guidance in pain clinic interventions.