Meralgia paraesthetica

Meralgia paraesthetica or meralgia paresthetica (see spelling differences) (me-ral'-gee-a par-es-thet'-i-ka) is numbness or pain in the outer thigh not caused by injury to the thigh, but by injury to a nerve that extends from the thigh to the spinal column. This chronic neurological disorder involves a single peripheral nerve, namely the Lateral cutaneous nerve of thigh (also called the Lateral femoral cutaneous nerve). The term meralgia paraesthetica comprises four Greek roots, which together denote "thigh pain involving anomalous perception."

Aetiology
The lateral cutaneous nerve of thigh most often becomes injured by entrapment or compression where it passes between the upper front hip bone (ilium) and the inguinal ligament near the attachment at the anterior superior iliac spine (the upper point of the hip bone). Less commonly, the nerve may be entrapped by other anatomical or abnormal structures, or damaged by diabetic or other neuropathy or trauma such as from seat belt injury in an accident.

Restrictive clothing and weight gain are two common ways that the nerve may be pinched. Pressure may also be caused by long periods of standing or leg exercise which increase tension on the inguinal ligament.

Signs and symptoms

 * Pain on the outer side of the thigh, occasionally extending to the outer side of the knee
 * A burning sensation, tingling, or numbness in the same area
 * Occasionally, aching in the groin area or pain spreading across the buttocks
 * Usually only on one side of the body
 * Usually more sensitive to light touch than to firm pressure

Diagnosis
Diagnosis is largely made on the description given by the patient and relevant details about recent surgeries, injury to the hip, or repetitive activities that could irritate the nerve. An examination will check for any sensory differences between the affected leg and the other leg. An abdominal and pelvic examination may be required to exclude any problems in those areas.

Electromyography (EMG) nerve conduction studies may be required. X-rays may be needed to exclude bone abnormalities that might put pressure on the nerve; likewise CT or MRI scans to exclude soft tissue causes such as a tumor.

Treatment
Treatments will vary. In most cases, the best treatment is to remove the cause of the compression by modifying patient behavior, in combination with medical treatment to relieve inflammation and pain. The following treatments are examples.


 * Rest periods to interrupt long periods of standing, walking, cycling, or other aggravating activity
 * Weight loss in overweight individuals and exercise to strengthen abdominal muscles
 * Wearing clothing that is loose at the upper front hip area
 * Heat, ice, or electrical stimulation
 * Nonsteroidal anti-inflammatory medications for 7-10 days

It may take time for the pain to stop and, in some cases, numbness will persist despite treatment. In severe cases a local nerve block can be done at the inguinal ligament using a combination of local anaesthetic (lidocaine) and corticosteroids to give relief that may lest several weeks. Pain modifier drugs for neuralgic pain (such as amitriptyline, carbamazepine or gabapentin) may be tried, but are often not as helpful in the majority of patients.

In persistent and severe cases, surgery may be needed to decompress the nerve or as a last resort to resect the nerve. The latter treatment results in permanent numbness in the area.