Ultrasound for pelvic neuralgia

Abstract

This presentation will discuss in detail the anatomy of the nerves of the lumbar plexus which are: • Iliohypogastric nerve • Ilioinguinal nerve • Genitofemoral nerve • Lateral femoral cutaneous nerve • Obturator nerve • Femoral nerve The etiology of nerve injury and clinical symptoms the patient may experience in these nerve entrapment syndromes will be reviewed. Ilioinguinal and Iliohypogastric nerves are commonly entrapped in the fascia between the internal oblique and transversus abdominis muscles. Entrapment usually occurs after surgery to this area or the presence of an inguinal hernia. Symptoms are generally pain at the region of entrapment. The genitofemoral nerve can be entrapped throughout its course either due to adhesions from previous surgery or intrapelvic trauma. Symptoms may be chronic groin pain and / or paraesthesia in the upper anterior thigh below the inguinal ligament. Entrapment of the lateral femoral cutaneous nerve occurs at ASIS under the inguinal ligament causing burning and numbness over the anterolateral thigh. Obturator tunnel syndrome is a common cause of groin pain in athletes where the obturator nerve is entrapped either in the obturator tunnel or within the proximal adductor muscles. The femoral nerve is the largest branch of the lumbar plexus and can be entrapped at 2 sites – superiorly between the psoas and iliacus muscles and inferiorly at the level of the inguinal ligament. Intrapelvic causes of entrapment can be previous surgery or breech lie in utero or the nerve can be compressed by surrounding pathology such as iliopsoas bursitis or a large hip joint synovitis. The patient may complain of groin pain with numbness in the anterior thigh to the knee. They may have difficulty going up and down stairs and cannot stand from a seated position. The aim of this presentation is to highlight the ease of which these nerves can be assessed with ultrasound and to encourage routine imaging of them in a hip or groin ultrasound study.