(Kiosk 2) Sartorius Enthesopathy Found in an Adult Undergoing Ultrasound-guided Lateral Cutaneous Nerve of the Thigh Block and Hydrodissection for Meralgia Paresthetica: A Case Report

Case Diagnosis: A 43-year-old male with multiple sclerosis undergoing treatment for meralgia paresthetica (MP) found to have sartorius enthesopathy.

Case Description or Program Description: The patient presented with several months of unilateral anterolateral burning thigh pain without significant back pain or weakness. There was an unclear causal relationship between his symptoms and multiple sclerosis for which he was already receiving treatment. Subsequent electromyography and nerve conduction studies demonstrated absent left lateral cutaneous nerve of the thigh (LCNT) sensory nerve action-potentials without any evidence of femoral neuropathy or lumbar radiculopathy consistent with MP. Because his pain was refractory to conservative management an ultrasound-guided LCNT nerve block and hydrodissection were performed. Sonographic findings were significant for enthesophyte of the sartorius tendon at its origin at the ASIS and a hypoechoic, enlarged appearance of the LCNT. The fascial plane and perineural area surrounding the LCNT were injected with a mixture of: 2cc of 1%-Lidocaine, 1cc of Dexamethasone(10 mg/ml), and 7cc of Normal Saline.

Setting: Sports Medicine Clinic

Assessment/Results: After the injection, the patient noted immediate relief in his symptoms with a significant reduction in numbness along his anterolateral thigh.

Discussion (relevance): MP is caused by injury or entrapment of the LCNT that can arise from external compression, internal pressures, and neuropathies and is most often clinically associated with obesity, pregnancy, and diabetes. In this patient, where those common etiologic factors were absent, injury to his LCNT was likely partially attributed to the enthesopathy of the sartorius given its anatomic proximity to the LCNT. Anatomical variations of the LCNT have been reported in 25% of patients with some variations noted to be susceptible to injury. In this case, the finding of concomitant tendinopathy presents itself as a potential etiologic factor and target for rehabilitation/intervention in the treatment of MP.

Conclusions: Sartorius enthesopathy should be considered a potential cause of neuropathy of the lateral femoral cutaneous nerve.