19- Meralgia Paresthetica (Entrapment of the lateral cutaneous nerve of the thigh)

-What is Meralgia Paresthetica?

The lateral cutaneous nerve of the thigh is a sensory nerve that originates in the nerve roots of the lower back (2nd and 3rd lumbar roots), and supplies sensation to the front and outside portion of the thigh. It passes through and under the inguinal ligament (which forms the groove where the leg attaches to the body at the front), and can sometimes become entrapped under it . An entrapment point is where it goes through an opening or tunnel in the lateral attachment of the inguinal ligament to the anterior superior spine. A second entrapment point is where it pierces the fascia lata.This causes the nerve to malfunction and transmit less sensation (numbness) or distorted sensation (tingling and burning) to the brain. This entrapment and it?s symptoms are called Meralgia Paresthetica (meros = thigh, algia = pain, paresthertica = numbness or abnormal sensation).

















- Who gets Meralgia pareshetica?
Body or trunk shifts can stress the nerve, also adduction of the leg. A traumatic hematoma of the iliacus or stretching in gymnastics can cause paralysis of both the femoral nerve and the lateral femoral cutaneous nerve.
The syndrome is fairly common. Obesity, pregnancy, and diabetes mellitus are frequent contributing factors.




-What makes it worse?
Initially related to sports participation. Later on patients will report numbness of the lateral thigh from the greater trochanter to the lateral knee.
The symptoms are usually worsened by certain body positions, including prolonged sitting or standing.

Diagnosis?Decreased sensation can be found in the lateral thigh. Tests of the lumbar spine are negative. Increase in symptoms can be found with pressure on the iliacus muscle in the area of the inguinal ligament attachment or with pressure on the place where the nerve pierces the fascia lata.Leg length discrepancy must be evaluated.Electromyographic investigation could show decreased latency after stimulation.

-What can I do about it?
Most often no treatment is required due to it?s benign nature. Weight loss may help in overweight people and it often improves in pregnant women after delivery . If there is a lot of associated painful tingling, local steroid injection in the nerve or application of capsaicin ointment is sometimes useful. Rarely, the nerve will have to be removed or cut to relieve the symptoms, but this leaves permanent numbness in the area.

Perineural infiltration of a anesthetic, eventually mixed with a corticosteroid, at the entrapment point may solve the problem. Otherwise surgical treatment, i.e. neurolysis, is suggested.Leg length discrepancy must be corrected by a heel lift in the shoe or a block on the bicycle cleat.

ReferencesBeazell, JR. Entrapment neuropathy of the lateral femoral cutaneous nerve. JOSPT 10 (3) 1988, 85-86
posted by Mohamed rizk