Meralgia paresthetica is numbness or pain in the outer thigh not caused by injury to the thigh.
MP is caused by injury to a nerve that extends from the spinal column to the thigh.
A mononeuropathy.
It is a chronic neurological disorder involving the lateral cutaneous femoral nerve of the thigh, which is also called the lateral femoral cutaneous nerve: the syndrome lateral femoral cutaneous neuropathy.
Seen in teenagers wearing skin-tight trousers.
Consists of pain on the outer side of the thigh, occasionally extending to the outer side of the knee, usually constant.
Is associated with a burning sensation, tingling, or numbness in the same area.
Pain is described as tingling, numbness, coldness, sharp pain, and burning pain.
Manifests as pain, dysesthesias, and paresthesias over the anterior lateral thigh.
Pain may be acute.
Patients have more sensitivity to light touch than to firm pressure.
Hypersensitivity to heat may be present.
Occasionally it is associated with aching in the groin area or pain spreading across the buttocks.
Occasionally, patients complain of itching or a bothersome sensation rather than pain in the affected area.
The entire distribution of the nerve is rarely affected by symptoms.
The lateral cutaneous femoral nerve is susceptible to compression with stretching along the course to the thigh and it is caused often by tight clothing or belts.
Risk for its development is increased with diabetes, obesity, and pregnancy.
Treatment consists of conservative measures such as weight loss and looser clothing.
In intractable cases nerve blocks are performed.
Most patients improve with symptomatic support.
The lateral femoral cutaneous nerve is most often injured by entrapment or compression where it passes between the upper front hip bone and the inguinal ligament near the attachment at the anterior superior iliac spine.
Rarely, the nerve may be entrapped by abnormal structures, or damaged by diabetic or other neuropathy or trauma.
Weight gain may make underwear, belts or waistbands to exert higher levels of pressure.
Weight loss or aging may decrease protective fat layers under the skin, allowing the nerve to compress against underwear, clothing, and by belts.
Additionally, long periods of standing or leg exercise can increases tension on the inguinal ligament may also cause pressure.
The lateral cutaneous nerve of the thigh be damaged during laparoscopic hernia repair.
Scarring from the above procedure can lead to meralgia paraesthetica.
Diagnosis is largely based on history: recent surgeries, hip injuries, or repetitive activities that could irritate the nerve.
Examination for sensory differences between the affected leg and the other leg.
Electromyographic (EMG) nerve-conduction studies may be required to establish the diagnosis.
X-rays , and CT or MRI scans may be needed to exclude bone abnormalities or exclude soft tissue causes such as a tumors, that might put pressure on the nerve
Treatment is to remove the cause of compression by modifying patient behavior, to relieve inflammation and pain.
Treatment takes several weeks to months for benefit.
Treatments include:
Wearing looser clothing and suspenders rather than belts
Weight loss if obesity is present
NSAIDs to reduce inflammatory pain
Reducing physical activity
Deep tissue massage
Physical therapy, such as stretching and massage, may help in the management of pain.
Inguinal ligament stretching can rapidly relieve symptoms.
Use of rest periods improves pain.
Lose weight, and exercise to strengthen abdominal muscles.
Apply heat, ice, or electrical stimulation.
Lidocaine patches
Titanium dioxide patches may interfere with the electrostatic effect of the nerves on the surface of the skin.
It may take weeks for the pain to stop, and in some patients, numbness persists.
In severe cases, a local nerve block at the inguinal ligament, may provide relief that may last several weeks.
Persistent and severe cases may require surgery to decompress the nerve.
Resection of the nerve is the last resort and will result in permanent numbness in the area.