Meralgia Paresthetica

What is Meralgia Paresthetica?
Meralgia Paresthetica, or lateral femoral cutaneous nerve entrapment, is a clinical syndrome consisting of pain and/or dysesthesia in the anterolateral thigh due to compression of the lateral femoral cutaneous nerve.

Who is at risk?
Risk factors and associations include:

Med school was so long ago. Can I have an anatomy review?
The lateral femoral cutaneous nerve arises from the dorsal divisions of L2-L3. It commonly runs along the lateral border of the iliacus muscle, then under the lateral aspect of the inguinal ligament about 1-2 cm medial to the anterior superior iliac spine and over sartorius muscle. It then splits into anterior and posterior/lateral branches and ends above the knee.

Anatomic variations can be present such as the nerve going superficial to the inguinal ligament, superficial to and deep to the inguinal ligament, superficial to the iliac crest, or more medial.

How does it present?
Classically, it presents subacutely as burning pain, paresthesia, or hypesthesia over the upper outer thigh. It can be unrelated to position but also be worsened by thigh extension, prolonged standing, or Valsalva maneuvers. In severe cases, it can be debilitating and distracting enough to affect activities of daily living (ADLs) and prevent sleep.

How is the diagnosis made?
History and physical exam! Sensory abnormalities such as abnormal pinprick and light touch tests on lateral and/or anterior thigh should be present, as is an absence of neurological abnormalities in the lower leg. The straight leg test is negative. Deep tendon reflexes and distal motor strength are also preserved.

The pelvic compression test can also help with diagnosis. One very small study showed > 90% sensitivity and specificity. This test is performed by applying lateral to medial (i.e. downward) pressure on the pelvis with the patient laying on his/her side with the affected side up. A positive test is a relief of symptoms after 45 sec of lateral compression.

There must be other tests that can help me, right?
No, not really. Nerve blocks can help confirm the diagnosis but aren’t typically performed. Other tests like the ones listed below either are unreliable or not really needed unless you’re unsure of the diagnosis.
– Imaging: not needed (or useful) unless trying to rule out another diagnosis (e.g. spinal stenosis, disc disease, etc)
– Electrodiagnostic studies: unreliable
– Electromyography: can be helpful to rule out radiculopathy or plexopathy

How do I treat?
Luckily, most cases are self-limited, benign, and resolve spontaneously. Conservative measures such as reducing the pressure over the nerve in the groin area, weight loss, avoiding tight garments, physical therapy, and NSAIDs are sufficient for 90% of patients. In persistent cases, other treatments can be explored. These include medications (e.g. carbamazepine, phenytoin, or gabapentin), local nerve block with anesthetics and/or steroids, or surgery for decompression/release or transection (only done in very severe cases). Other unproven treatments include manual therapy, kinesiotape, and acupuncture.

References:
1. Cheatham, Kolber, et al. MERALGIA PARESTHETICA: A REVIEW OF THE LITERATURE. Int J Sports Phys Ther. 2013 Dec; 8(6): 883–893
2. Parisi, Mandrekar, Dyck, Klein. Meralgia paresthetica Relation to obesity, advanced age, and diabetes mellitus. Neurology. 2011 Oct 18; 77(16): 1538–1542.

Thanks to Dr deSouza, Dr Tu, and Dr Valesky for their input in creating this post.

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• Meralgia Paresthetica - November 1, 2017