What is Meralgia Paresthetica?

The lateral femoral cutaneous nerve is a nerve that only senses feelings and is susceptible to being compressed as it moves from the network of nerves in your lower back, known as the lumbosacral plexus, towards a band of tissue in your groin area called the inguinal ligament and into the skin tissue of the front of the thigh. A condition called Meralgia Paresthetica happens when there is pain and abnormal sensations in the front and side of the thigh due to the compression of this nerve. It’s also known by other names like Bernhardt Roth syndrome, lateral femoral cutaneous nerve syndrome, or lateral femoral cutaneous neuralgia.

What Causes Meralgia Paresthetica?

This condition happens when the lateral femoral cutaneous nerve (LFCN) – a nerve that’s found in your leg – is injured or trapped in some way. There are two ways this can happen – spontaneously or due to medical procedures.

Spontaneous reasons might include illnesses like diabetes, lead poisoning, alcoholism, and an underactive thyroid, which could all lead to this nerve problem. Some other reasons include mechanical causes like pressure on the LFCN because of tight seat belts, belts, or tight clothes. Other mechanical causes might include increased abdominal pressure (when there’s too much pressure in the stomach area) from things like being overweight, pregnancy, or tumors. Having one leg longer than the other, degenerative defects of the pubic symphysis (a joint at the front of the pelvis), or a rare bone tumor located at the top of the hip bone could also play a part.

Medical procedures can also cause this condition. These include hips or spine surgeries, laparoscopic inguinal repair (a type of hernia repair surgery), pelvic osteotomy (a surgical procedure to correct hip dysplasia), surgeries around the hip bone, some bone graft procedures, surgeries for hip fractures, laparoscopic myomectomy (a surgery to remove fibroids), laparoscopic cholecystectomy (a surgery to remove the gallbladder), vein harvesting for heart bypass surgeries, or weight loss surgery.

Risk Factors and Frequency for Meralgia Paresthetica

Carpal tunnel syndrome, while it can affect anyone, is often seen more in women than men, and is also common among military personnel. Its frequency tends to increase in people who are in their 40s or 50s, but it can happen at any age. It’s particularly normal in pregnant individuals or people with obesity. It’s estimated that 3 to 4 out of every 10,000 people each year will develop this condition. Moreover, having carpal tunnel syndrome puts you at a higher risk of developing another condition called meralgia paresthetica.

Carpal Tunnel Syndrome is more common in women and military personnel.
It’s usually seen in people in their 40s or 50s, but can happen at any age.
The condition is often found in pregnant people or those with obesity.
About 3-4 of every 10,000 people will get this condition each year.
If you have Carpal Tunnel Syndrome, you’re at a higher risk for meralgia paresthetica, another condition.

Signs and Symptoms of Meralgia Paresthetica

Patients often come in reporting a burning sensation or pain, tingling feelings, and reduced sensitivity on the upper outer part of one thigh. These symptoms usually appear gradually over a few days or weeks. Patients often demonstrate their discomfort by pointing to or rubbing that specific area of the thigh, and it’s not uncommon to see hair loss in the area due to this repeated rubbing. The discomfort typically doesn’t change whether they’re sitting or standing. However, it may get worse with extended periods of walking, standing, or getting up from a seated position. On the other hand, bending the hip, like when sitting, can make the symptoms feel better. Occasionally, straining while holding your breath, or anything else that increases pressure in the belly, might make the symptoms worse.

Upon examination, it’s important to ask the patients if they’ve recently worn tight clothes, had any injuries, gained significant weight, or are pregnant. The feeling of tingling or numbness usually sticks to a specific area, which can be determined during the exam. As the involved nerve – the Lateral Femoral Cutaneous Nerve (LFCN) – doesn’t control any muscles, any symptoms are entirely related to sensation.

One way to diagnose this condition is with a pelvic compression test. This involves the patient lying on the unaffected side while the examiner puts pressure on the patient’s hip for around 45 seconds. The test is deemed positive and indicative of the condition if the symptoms reduce, with reports showing high accuracy and reliability of 95% and 93%, respectively. The absence of motor weakness, abnormal lower limb reflexes, sensory loss outside the LFCN area, or other neurological symptoms is important, as these are not typically associated with the condition.

Testing for Meralgia Paresthetica

Diagnosing this condition usually comes down to a doctor’s review of a patient’s symptoms and a physical examination. This can involve checking for changes in sensation, such as touch and prickling sensations, within a particular area of the upper thigh. Generally, this area is about the size of a standard notebook. The examination also includes testing reflexes, muscle strength, leg mobility, as well as checking for any pain or abnormalities in the back, hip or sacroiliac (the joint where the lower part of the spine connects with the pelvis).

X-rays aren’t usually necessary for a diagnosis if the symptoms match and the physical examination supports it. Tests that involve nerve stimulation with electricity can have mixed results, can be hard to perform on patients who are overweight, and aren’t commonly used in a diagnosis unless the doctor needs to rule out issues with the spinal nerve roots or the group of nerves at the lower end of the spinal cord. It’s rare, but sometimes a doctor might give an injection to block a specific nerve (the lateral femoral cutaneous nerve, a nerve in the thigh) to help identify the source of the pain and confirm the diagnosis.

In some cases, the doctor might request a blood test if they suspect an issue with the body’s metabolism. If they suspect a tumor or arthritis, they might order an X-ray of the pelvis. In some instances, the doctor might also request an ultrasound or an MRI (a test that uses magnetic fields and radio waves to produce detailed images of the body’s structures) to check for a tumor in the pelvis or the area at the back of the abdomen.

Treatment Options for Meralgia Paresthetica

Meralgia paresthetica is a generally harmless condition that often gets better on its own. Treatment mainly involves comforting patients and teaching them ways to reduce pressure and irritation on the nerve in the groin region. This can be done by wearing loose clothing, losing weight if the person is overweight, and applying ice to the area to reduce inflammation.

Some medicines, like non-steroidal anti-inflammatory drugs (NSAIDs), capsaicin, lidocaine, or tacrolumus, can help with skin sensitivity or discomfort. Some abdominal exercises might decrease the pressure, but physical therapy has not been proven to be effective for this condition. If symptoms persist after trying these methods for 1 to 2 months, other medicines like gabapentin, phenytoin, or carbamazepine may be considered to help with the nerve pain.

In some cases, a doctor who specializes in anesthesia might inject a nerve block, which is a local anesthetic or a medicine that reduces inflammation, into the nerve.

Surgery is rarely done but might be needed for ongoing, severe cases. There are two types of surgeries: a nerve release procedure that keeps the sense of feeling but is usually less effective, or a nerve sectioning procedure that removes feeling permanently and is used only for severe pain. About 80% of patients reported feeling better in a survey of 167 patients who had one of these surgeries.

All these recommendations for treatments are based on the observed outcomes from previous cases, including some reports that have shown improvement in hard-to-treat cases with methods like stimulating the nerves with pulsed radio frequencies, electroacupuncture, and applying a special kind of medical tape known as kinesiology tape.

To accurately diagnose meralgia paresthetica, a condition causing tingling, numbness, and burning pain in the outer thigh, doctors need to rule out other conditions that may cause similar symptoms. These conditions can include:

Lumbar radiculopathy, a condition where a nerve in the lower back is pinched. However, this typically also involves back pain and not just localized symptoms in the thigh.
Abdominal masses or pelvic tumors, which may press on nerves causing pain.
Metastases in the iliac crest, which refers to cancer spreading to the upper part of the pelvic bone.
Avulsion fractures, where a part of the bone is ripped off by a force pulling on a ligament or tendon.
Hip osteoarthritis, a common form of arthritis that affects the joint at the top of the thigh.
Chronic appendicitis, a persistent inflammation of the appendix that may cause recurrent pain.

What to expect with Meralgia Paresthetica

About 85% of people with a condition known as meralgia paresthetica typically get better on their own with non-invasive, conservative treatments. If this condition is caused as a side effect of a medical treatment or procedure (iatrogenic cause), it usually gets better within 3 months. Meanwhile, meralgia paresthetica experienced during pregnancy generally improves after the baby is delivered.

Possible Complications When Diagnosed with Meralgia Paresthetica

The complications for meralgia paresthetica come from surgically cutting the nerve on the outer thigh, known as the lateral femoral cutaneous nerve. This can cause permanent loss of feeling in the front and outer part of the thigh.

Complications of Meralgia Paresthetica: