(Kiosk 4) Meralgia Paresthetica Mimic: A Case Report

Case Diagnosis: Vastus lateralis trigger point

Case Description or Program Description: A 45-year old male presented for electrodiagnostic evaluationof intermittent left lateral thigh pain. The pain lasted several seconds to minutes at a time without clear aggravating or relieving factors. There was no associated numbness,weakness, recent localized trauma to the thigh, recent weight changes, or tight clothing. Treatment with pregabalin, duloxetine, and chiropractic manipulations provided minimal relief. Initial clinical suspicion was for meralgia paresthetica. The patient had a history of intermittent, non-radiating back pain, with lumbar MRI revealing mild degenerative changes and a right L5 impingement. Prior electrodiagnostic evaluation did not show evidence for radiculopathy, plexopathy, or peripheral neuropathy. On physical examination, a band was palpated in the left anterolateral thigh which reproduced symptoms and caused a jump reaction. Sensation, strength, and reflexes were all intact.

Setting: Electromyography laboratory

Assessment/Results: Nerve conduction studies of the lateral femoral cutaneous nerves had normal sensory nerve action potential amplitudes, distal sensory latencies, and conduction velocities. Insertion of the electromyography needle into the vastus lateralis reproduced the presenting symptoms. Needling the muscle elicited twitch responses and led to resolution of the band and improvement in symptoms.

Discussion (relevance): Mononeuropathy of the lateral femoral cutaneous, also known as meralgia paresthetica, is one of the most common mononeuropathies of the lower limb. It often presents with intermittent pain, numbness, and paresthesia of the anterolateral thigh and is caused by compression of the nerve at the inguinal ligament, stretch injuries, or iatrogenic causes. This patient presented with symptoms mimicking meralgia paresthetica, but physical examination and electrodiagnostic studies led instead to diagnosis of a trigger point in the vastus lateralis. This causes referred pain from the lateral thigh to the knee and, unlike meralgia paresthetica, can resolve with direct needling.

Conclusions: The referred pain patterns of trigger points may mimic common diagnoses. A thorough physical examination and the use of electrodiagnostics can help distinguish nerve pathology from myofascial diagnoses.