Meralgia paraesthetica comes from the Greek words meros (thigh) and algos (pain). Meralgia paraesthetica is usually an entrapment neuropathy of the lateral femoral cutaneous nerve (LFCN). It may be iatrogenic after medical or surgical procedures, or result from a neuroma. The segmental origin is L2/L3 and it is a purely sensory nerve with no motor fibres.
The most common cause of impingement of the LFCN is entrapment of the nerve under the inguinal ligament, which can occur spontaneously or develop after an injury.
The nerve originates from the L2/L3 segments and travels down, lateral to the psoas muscle. It crosses the iliacus muscle deep to the fascia and then passes through or under the lateral part of the inguinal ligament. It runs superficially and divides into anterior and posterior branches to innervate the lateral thigh. The course of the nerve can be variable.
An incidence has been estimated at 4.3 per 10,000 person years. It occurs most commonly in people between the ages of 30 to 40 years. The condition is thought to be much rarer in children. It has a higher predilection in men than in women.
Meralgia paraesthetica can occur in pregnancy, in obesity and if there is tense ascites. It may be a result of trauma, surgery (such as pelvic osteotomy, spinal surgeries, laparoscopic hernia repair and bariatric surgery) or, in some cases, may arise from abduction splints used to treat Perthes' disease, also called Calvé-Legg-Perthes disease.
Various sports and physical activities have been implicated, including gymnastics, baseball, soccer, bodybuilding and strenuous exercise. Lying for long periods of time in the fetal position and lying prone after lumbar spine surgery have also been identified as possible causes. Risk factors can arise in the most unlikely scenarios. Most cases are idiopathic.
It occurs more commonly in those with diabetes than in the general population.
Entrapment causes burning or numbness down the upper lateral aspect of the thigh. In children and adolescents the presentation may be severe pain causing marked restriction of activities. It may be bilateral. The symptoms are usually aggravated by standing and relieved by sitting.
The pain can be reproduced by deep palpation just below the anterior superior iliac spine (pelvic compression) and also by extension of the hip. There is altered sensation over the anterolateral aspect of the thigh. There is no motor weakness.
Very often the diagnosis is slow to be made. Pain in the lateral thigh can arise from the back or hip. It is important to consider the possibility of the diagnosis and to try deep palpation medial to the anterior superior iliac spine and extension of the hip. Injection with local anaesthetic appears to be a good test.
Other conditions that may need to be ruled out include:
- Diabetic lumbosacral plexopathy.
- Lumbar degenerative disc disease.
- Lumbar facet arthropathy.
- Lumbar spondylolysis and spondylolisthesis.
- Mononeuritis multiplex.
- Neoplastic lumbosacral plexopathy.
Rarely, pressure on the lateral cutaneous femoral nerve can arise from a mass in the retroperitoneal space - eg, tumours, iliacus haematoma.
- The pelvic compression test is highly sensitive and the diagnosis can often be made with this test alone.
- Injection of the nerve with local anaesthetic will abolish the pain. Ultrasound is effective both for diagnosis and for guiding injection therapy.
- Nerve conduction studies may be useful.
- MRI neurography of the lateral cutaneous nerve may be used to assist in diagnosis.
Other tests to rule out differential diagnoses might include fasting blood glucose, MRI of the lumbar spine and radiographs for possible pelvic fracture or cancer.
The evidence base for the treatment of meralgia paraesthetica is weak; randomised controlled trials are needed.
- In the case of obesity, loss of weight may cure the condition but is not guaranteed. It should resolve after pregnancy and tapping of ascites should help.
- Idiopathic meralgia paraesthetica usually improves with non-operative modalities, such as removal of compressive agents, non-steroidal anti-inflammatory drugs (NSAIDs), anticonvulsants or tricyclics and, if necessary, local corticosteroid injections.
- Transcutaneous electrical nerve stimulation (TENS) has been found helpful, especially when combined with pregabalin.
- Other physical therapies reported in being helpful in relieving chronic symptoms include mobilisation/manipulation for the pelvis, myofascial therapy for the rectus femoris and iliopsoas, transverse friction massage of the inguinal ligament, stretching exercises for the hip and pelvic musculature, and pelvic stabilisation/abdominal core exercises.
- Ultrasound is effective, both for diagnosis and for guiding injection therapy.
- If the pain is severe, operative decompression should be considered. A supra-inguinal or infra-inguinal approach may be used.
Most cases are self-limiting. However, although paraesthesia tends to resolve over time, numbness can persist.
Further reading and references
Harney D, Patijn J; Meralgia paresthetica: diagnosis and management strategies. Pain Med. 2007 Nov-Dec8(8):669-77.
Dharmasaroja P, Dharmasaroja P; Meralgia paresthetica-like syndrome may be caused by transient lumbar nerve root injury without definite compression: a case report. J Med Assoc Thai. 2010 Dec93 Suppl 7:S307-10.
Cheatham SW, Kolber MJ, Salamh PA; Meralgia paresthetica: a review of the literature. Int J Sports Phys Ther. 2013 Dec8(6):883-93.
Lateral Femoral Cutaneous Nerve; Wheeless' Textbook of Orthopaedics, 2012
Chopra PJ, Shankaran RK, Murugeshan DC; Meralgia paraesthetica: Laparoscopic surgery as a cause then and a cure now. J Minim Access Surg. 2014 Jul10(3):159-60. doi: 10.4103/0972-9941.134883.
Nouraei SA, Anand B, Spink G, et al; A novel approach to the diagnosis and management of meralgia paresthetica. Neurosurgery. 2007 Apr60(4):696-700
Feinberg J, Sethi S; Sciatic neuropathy: case report and discussion of the literature on postoperative sciatic neuropathy and sciatic nerve tumors. HSS J. 2006 Sep2(2):181-7. doi: 10.1007/s11420-006-9018-z.
Yi TI, Yoon TH, Kim JS, et al; Femoral neuropathy and meralgia paresthetica secondary to an iliacus hematoma. Ann Rehabil Med. 2012 Apr36(2):273-7. doi: 10.5535/arm.2012.36.2.273. Epub 2012 Apr 30.
Klauser AS, Abd Ellah MM, Halpern EJ, et al; Meralgia paraesthetica: Ultrasound-guided injection at multiple levels with 12-month follow-up. Eur Radiol. 2016 Mar26(3):764-70. doi: 10.1007/s00330-015-3874-1. Epub 2015 Jun 21.
Khalil N, Nicotra A, Rakowicz W; Treatment for meralgia paraesthetica. Cochrane Database Syst Rev. 2012 Dec 1212:CD004159. doi: 10.1002/14651858.CD004159.pub3.
Chung KH, Lee JY, Ko TK, et al; Meralgia paresthetica affecting parturient women who underwent cesarean section - A case report. Korean J Anesthesiol. 2010 Dec59 Suppl:S86-9. doi: 10.4097/kjae.2010.59.S.S86. Epub 2010 Dec 31.
Patijn J, Mekhail N, Hayek S, et al; Meralgia Paresthetica. Pain Pract. 2011 May-Jun11(3):302-8. doi: 10.1111/j.1533-2500.2011.00458.x.
Barbarisi M, Pace MC, Passavanti MB, et al; Pregabalin and transcutaneous electrical nerve stimulation for postherpetic neuralgia treatment. Clin J Pain. 2010 Sep26(7):567-72. doi: 10.1097/AJP.0b013e3181dda1ac.
Houle S; Chiropractic management of chronic idiopathic meralgia paresthetica: a case study. J Chiropr Med. 2012 Mar11(1):36-41. doi: 10.1016/j.jcm.2011.06.008.
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