Meralgia paresthetica or Meralgia paraesthetica 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 nerve—the lateral cutaneous nerve of thigh, which is also called the lateral femoral cutaneous nerve (and hence the syndrome lateral femoral cutaneous neuropathy).
Pain on the outer side of the thigh, occasionally extending to the outer side of the knee, usually constant following: A burning sensation, tingling, or numbness in the same area, Multiple bee-sting like pains in the affected area, Occasionally, aching in the groin area or pain spreading across the buttocks.
The lateral femoral cutaneous nerve 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.
Diagnosis is largely based on patient description and relevant details about recent surgeries, hip injuries, or repetitive activities that could irritate the nerve. Examination checks for sensory differences between the affected leg and the other leg. Accurate diagnosis may require an abdominal and pelvic examination to exclude problems in those areas. Electromyographic (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.
Patients marked a VAS-pain of 4.3+/-1.5. In the affected side, thresholds for warm and heat pain sensations were elevated and the amplitude of CHEPs was reduced in comparison to the non-affected side and controls (Bonferroni's test; p<0.001 for all comparisons). The amplitude of CHEPs correlated inversely with duration of the symptoms (r=-0.57, p=0.002), as well as with heat pain thresholds (r=-0.18, p=0.01).