Meralgia Paresthetica Causes Burning Thigh Pain

Meralgia Paresthetica is a benign yet painful condition.

During the first half of the twentieth century, many physicians were writing about meralgia paresthetica(AKA lateral femoral cutaneous neuropathy), a condition most commonly associated with chronic burning of the thigh.  Even Sigmund Freud documented his own discomfort with the condition, which affected both sides of his body. Today, however, meralgia paresthetica is a more obscure diagnosis despite many people being troubled by this condition.

 

What Is Meralgia Paresthetica?

Meralgia paresthetica results in dysesthesia or anesthesia of the of the lateral thigh. In plain English, meralgia paresthetica involves weird sensations or lack of sensations at the side of your thigh. This syndrome has anatomical underpinnings, and in some people, it lasts weeks while in others it last years. Although meralgia paresthetica affects children and can occur at any age, it commonly hits adults aged 30 to 65.  

Common lateral thigh symptoms of meralgia paresthetica include the following:

  • burning
  • lightening pain
  • coldness
  • deep muscle aches
  • anesthesia
  • tingling
  • local hair loss

In addition to affecting the lateral thigh, the pain and discomfort of meralgia paresthetica can radiate or spread to the knee, calf and hip. Although estimates vary, meralgia paresthetica typically affects only one thigh.  

Meralgia paresthetica is a clinical diagnosis based on physical exam.

Furthermore, a physician can map out a typical pattern of sensory abnormality by injecting anesthetic (lidocaine nerve block) at the level of the inguinal ligament. 

For at least two reasons, it's a good idea to temporarily anesthetize the lateral femoral cutaneous nerve.  First, such nerve block sometimes results in cessation of the problem.

  Second, a temporary nerve block can help a person decide which option is more uncomfortable: 1) living with persistent discomfort or 2) living with a permanent sensory loss of the lateral thigh secondary to surgery.

Of note, when diagnosing meralgia paresthetica, tests like CT and MRI are of little use except to rule out more proximal pathology (other causes farther up the body).

The Anatomy of Meralgia Paresthetica

Meralgia paresthetica is a pathology of the lateral cutaneous femoral nerve which arises from the upper lumbar plexus (think spinal cord) and passes through the inguinal ligament overlying the pelvis. The lateral cutaneous femoral nerve is a sensory nerve which innervates and runs the length of the anterolateral thigh all the way to the knee. The pain and discomfort of meralgia paresthetica mirrors the sensory distribution of this nerve.

Experts believe that compression of the lateral cutaneous femoral nerve at the level of the inguinal ligament (where the nerve exits the pelvis) results in meralgia paresthetica.

Various factors have been implicated in the development of such compression including:

Treatment of Meralgia Paresthetica

After learning that meralgia paresthetica is a benign condition, many people decide to live with the condition without further treatment. In others who are discomforted and bothered by the syndrome, treatment is initially conservative with lifestyle and behavior modification key: weight loss, avoidance of tight or constricting clothing and postural changes.

Medical treatment for meralgia paresthetica consists of nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, aspirin and naproxen; analgesics like a lidocaine patch; medications for neuropathic pain (gabapentin); and steroid injection.

When lifestyle modification, behavioral modification, and drugs fail to cut it, surgery can be tried to treat meralgia paresthetica. In a 2015 article published in a journal titled Clinical Neurology and Neurosurgery, researchers detail results from a prospective study and suggest that neurectomy is a better cure than neurolysis. In other words, it's best to completely remove the lateral cutaneous femoral nerve (neurectomy) rather than to decompress the nerve (neurolysis) at the level of the inguinal ligament.

If you or a loved one suspects meralgia paresthetica is causing burning in the thigh, it's a good idea to make an appointment with a primary care physician, neurologist or orthopedic surgeon to discuss treatment options. Because many physicians are slow to suspect meralgia paresthetica  (or, gasp, know little about it), you may want to suggest this differential diagnosis. Fortunately, meralgia paresthetica is a relatively harmless condition which is limited to sensory (not motor) involvement. Nevertheless, there's no need to live in pain and suffering when successful treatment options exist.

Sources

Amato AA, Barohn RJ. Chapter 384. Peripheral Neuropathy. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012. Accessed April 29, 2015.

Article titled "Comparison of effectiveness of different surgical treatments for meralgia paresthetica: Results of a prospective observational study and protocol for a randomized controlled trial" by GCW de Ruiter and A Kloet from Clinical Neurology and Neurosurgery published in 2015.

Article titled "Meralgia Paresthetica, The Elusive Diagnosis Clinical Experience With 14 Adult Patients" by JK Ivins from Annals of Surgery published in 2000.

Ropper AH, Samuels MA, Klein JP. Chapter 46. Diseases of the Peripheral Nerves. In: Ropper AH, Samuels MA, Klein JP. eds. Adams & Victor's Principles of Neurology, 10e. New York, NY: McGraw-Hill; 2014. Accessed April 29, 2015.

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