Meralgia paresthetica is a neurological disorder characterized by numbness, pain, and tingling in the thigh. The disorder occurs as a result of compression or irritation of the lateral femoral cutaneous nerve. External pelvic compression and post-surgical complications can lead to meralgia paresthetica. The condition is typically treatable and rarely results in chronic damage or impairment.
The Lateral Femoral Cutaneous Nerve
The lateral femoral cutaneous nerve (LFCN) is a sensory nerve in the pelvis, part of the peripheral nervous system. The role of this nerve is to relay sensory messages between the thigh and the spinal cord and brain, including those of sensation and pain. The LFCN originates at the lumbar nerves and travels through the pelvic region of the body, exiting into the thigh.
Causes: Nerve Compression
The exact origin and pathway of the LFCN through the pelvic region and into the thigh varies. In some cases, the nerve may be left vulnerable to compression and injury, making meralgia paresthetica more likely. Due to its role in relaying sensory information, irritation to the LFCN results in abnormal sensation and pain in the thigh.
Discovery of Meralgia Paresthetica
The characteristics of meralgia paresthetica were first described in the late 1800s. Symptoms of the disorder and the compression of the LFCN were initially reported by Martin Bernhardt and Werner Hager in 1878 and 1885, respectively. Roth observed symptoms of the disorder in horse-mounted soldiers, noting compression of the LFCN by tightly-fitted belts. He introduced the term used todayin an 1895 report.
Symptoms: Numbness and Pain
The primary symptoms of meralgia paresthetica are numbness, pain, and tingling in the front and outside of the thigh. Symptoms may range from a deep ache to burning on the skin. These abnormal sensations often occur on only one side of the body. Symptoms often worsen following extended periods of walking or standing and touching the area may aggravate them.
Compression of the LFCN
Pinching of the LFCN may be the result of external compression of the nerve, a medical condition or injury, a surgical procedure, or scar tissue from an appendectomy, hip replacement, or spinal surgery. Tight clothing or prolonged use of a utility belt can also cause meralgia paresthetica, as well as obesity, diabetes, hypothyroidism, and trauma to the pelvis.
Varied Pathways of the LFCN
On its path through the pelvis and into the thigh, the lateral femoral cutaneous nerve travels by and through bone, muscle, and ligament. Depending on the individual route the LFCN takes, nerve thickening, deformity, or displacement may occur, leaving the nerve susceptible to compression or irritation and damage. Some people may experience degeneration of the nerve and loss of myelin, the sheath that protects nerves and aids in message relay.
Diagnosis: Exam and Patient History
Doctors diagnose meralgia paresthetica with a physical exam of the affected area and a patient history investigating symptoms, previous medical conditions and injuries, and recent surgical procedures. Rarely, a doctor may order additional blood, imaging, or nerve conduction tests to identify any underlying disorders contributing to meralgia paresthetica and to rule out other causes of the symptoms.
Tiered Treatment of Meralgia Paresthetica
Treatment of meralgia paresthetica begins with addressing lifestyle changes that can relieve symptoms, including wearing looser clothing, avoiding heavy tool belts, and losing weight. If nerve pain persists and over-the-counter pain relievers do not help, a doctor might prescribe corticosteroids, anti-depressants, or anti-seizure medication. He or she may also suggest physical therapy or electrical nerve stimulation. If the symptoms fail to respond to less invasive treatment, surgery may be necessary.
Cases Requiring Surgery
Surgical treatment of meralgia paresthetica is restricted to cases where the person does not respond to more conservative treatment. Common procedures include a neurectomy or decompression of the nerve. In a neurectomy, the surgeon partially removes or splits LFCN fibers. Decompression involves releasing the pinched nerve from the compressed region. Partial removal or resection of the nerve is the most effective approach for relieving symptoms. It does, however, carry the risk of permanent numbness.
Most cases of meralgia paresthetica resolve completely, some without medical treatment. Addressing pelvic compression through changes in lifestyle often permanently relieves pinching of the nerve and associated symptoms. Surgical intervention also typically yields good outcomes. Chronic or severe cases of the disorder may be more difficult to treat. These symptoms are often manageable long-term with medication and therapy.