see also:

• paraesthesiae or numbness
• groin pain
• wikipedia
• Emedicine

• meralgia paraesthetica comes from the Greek words meros (thigh) and algos (pain).
• it is due to compression of the lateral cutaneous femoral nerve (LCFN) of the thigh (which arises from L2 and L3 nerve roots), usually as it passes under the lateral aspect of the inguinal ligament ~10-15mm medial to the ASIS, but it may be up to 5cm medial.
• this results in usually fairly constant pain and numbness over the lateral aspect of the thigh which may be exacerbated when the nerve is stretched (eg. by extension of the hip) or compressed (eg. sitting with tight jeans on).
• occasionally, aching in the groin area or pain spreading across the buttocks
• usually more sensitive to light touch than to firm pressure
• hypersensitivity to heat (warm water from shower feels like it is burning the area)
• as this nerve does not supply muscle there is no associated weakness.
• mainly a condition of middle aged adults, but when it does occur in children 50% are bilateral

(image from wikimedia commons)

• tight jeans
• tight belts including carpenter's tool belts or policeman's duty belts
• truncal obesity
• pregnancy
• tense ascites
• abduction splints as used to Rx Perthe's disease
• trauma, including pelvic fracture
• bony spurs
• previous surgery
• body armour worn by soldiers
• lying in the fetal position for prolonged periods also has been implicated, as has prone positioning after lumbar spinal surgery
• idiopathic
• rarely, impingement of the LFCN by masses (eg, neoplasms, contained iliopsoas hemorrhages) in the retroperitoneal space before it reaches the inguinal ligament can cause the same symptoms

• primarily clinical based on the combination of numbness or pain over lateral aspect of thigh not due to lumbar pathology, and with no muscle weakness which may have one or more of the following features:
  • increased symptoms with extension of the hip (eg. prolonged walking or standing)
  • tenderness at the lateral aspect of the inguinal ligament where the nerve passes and is entrapped or compressed (the pelvic compression test)
  • increased symptoms when sitting if compression by obesity, tight jeans, etc is the cause
  • resolution of pain following injection of local anaesthetic to site of nerve compression

• diabetic lumbosacral plexopathy
• lumbar disk prolapse
• lumbar facet arthropathy
• lumbar spondylolysis and spondylolisthesis
• mononeuritis multiplex
• neoplastic lumbosacral plexopathy

• nerve conduction study
• fasting glucose to exclude diabetes
• MRI L/S spine to exclude lumbar pathology
• pelvis X-ray to exclude bony impingements

• loosen clothing around the waist
• consider suspenders rather than tight belts
• bed rest for several days if severe pain
• ensure adequate rest periods when doing activities that exacerbate the symptoms such as long periods of standing, walking, cycling
• weight reduction if obesity, although may not resolve the problem
• ascitic tap if ascites
• remove external compression such as by tight jeans
• trial of non-steroidal anti-inflammatory drugs (NSAIDs) for 7- 10 days, or even steroid injection
• if non-responsive and severe, then surgical decompression may be warranted