Ultrasound-Guided Diagnosis and Treatment of Meralgia Paresthetica

Abstract

Meralgia paresthetica refers to the entrapment of the lateral femoral cutaneous nerve at the level of the inguinal ligament. The lateral femoral cutaneous nerve – a purely sensory nerve – arises from the L2 and L3 spinal nerve roots, travels downward lateral to the psoas muscle, and then crosses the iliacus muscle. Close to the anterior superior iliac spine, the nerve courses in contact with the lateral aspect of the inguinal ligament and eventually innervates the lateral thigh. The entrapment syndrome is usually idiopathic but can also ensue due to trauma/ overuse, pelvic and retroperitoneal tumors, stretching of the nerve due to prolonged leg/trunk hyperextension, leg length discrepancies, prolonged standing, external compression by belts, weight gain, and tight clothing. The diagnosis of Meralgia paresthetica is usually clinical, i.e., based on the following symptoms: paresthesia, numbness, burning sensation, dysesthesia, and pain over the anterolateral aspects of the thigh. These complaints may be worsened by walking or prolonged standing and typically disappear after weight loss, abdominal muscle strengthening, or elimination of the underlying cause. Although there are several reports on the confirmatory role of electrodiagnostic studies in the diagnosis of Meralgia paresthetica, electromyographers would usually prefer/suggest not to perform nerve conduction studies in daily clinical practice. Herewith, due to its several advantages, ultrasound imaging has been proposed as an alternative diagnostic method in the recent literature. It not only confirms the entrapment morphologically, but also uncovers a likely underlying cause and provides immediate interventional guidance. The pertinent sonographic findings would be hypoechoic and swollen lateral femoral cutaneous nerve. Key words: Meralgia paresthetica, ultrasound, diagnosis, treatment