The lateral femoral cutaneous nerve, a pure sensory nerve, is susceptible to compression as it courses from the lumbosacral plexus, through the abdominal cavity, under the inguinal ligament, and into the subcutaneous tissue of the thigh. Meralgia paresthetica is the term used to describe the clinical syndrome of pain, dysesthesia, or both in the anterolateral thigh associated with compression of the nerve . (See "Evaluation of the adult with hip pain".)
ETIOLOGY AND EPIDEMIOLOGY
The majority of meralgia paresthetica cases result from entrapment of the lateral femoral cutaneous nerve as it passes under the inguinal ligament. The most frequent associated conditions are obesity, diabetes mellitus, and older age . Additional associations include large abdomens with overlying panniculus , tight belts or garments around the waist [4-6], scar tissue near the lateral aspect of the inguinal ligament, and pregnancy [7-9].
Injury during local or regional surgery (eg, spine procedures, iliac crest bone harvesting, hip prosthesis, aorto-bifemoral bypass) is another important cause of meralgia paresthetica , accounting for 17 percent of cases in one series of 120 patients . Seat belt injury following motor vehicle accident is a less frequent cause . Meralgia has also been reported after long-distance walking and cycling, possibly as a consequence of local ischemia during repetitive muscle stretching .
In a retrospective population-based study from Minnesota, 262 patients with meralgia paresthetica were compared with 262 normal controls and 262 body mass index-matched controls . The following observations were reported:
- The adjusted incidence of meralgia paresthetica in people with diabetes mellitus was seven-fold greater than that of the general population (247 versus 33 per 100,000 population)
- Among subjects with both meralgia paresthetica and diabetes, most developed diabetes after the diagnosis of meralgia
- Patients with meralgia were significantly more likely to have diabetes than controls matched for body mass index (odds ratio 2, 95% CI 1.3-3.0)
- The mean body mass index of patients with meralgia was significantly greater than that of matched controls (30.1 versus 27.3 kg/m2)
- The mean age at meralgia paresthetica diagnosis was 50 years
- The incidence rates of meralgia paresthetica were similar for men and women