Meralgia Paresthetica – a possible reason for thigh pain

Recently I had a patient come in with a 15 year plus complaint of chronic low back pain, with associated posterior thigh and buttock pain.  However the patient also stated he has constant numbness in the front outside area of his thigh.  The thigh wasn’t painful it just felt numb all the time.  The man was middle aged and obese with a large protuberant abdomen wearing his jeans low and belted under his belly.

After the history and physical exam I diagnosed the numbness in the thigh as Meralgia Paresthetica. 

What is Meralgia Paresthetica?

It is a mononeuropathy (injury to one nerve) which causes numbness or pain in the outer thigh not caused by injury to the thigh, but by injury to a peripheral nerve that travels from the spinal cord to the thigh.  This nerve is called the lateral femoral cuntaneous nerve. 

 

The nerve most often becomes injured by entrapment or compression where it passes between the upper front of the hip bone (ilium) and the inguinal ligament near the attachment of the anterior superior iliac spine (the upper point of the hip bone).   Less commonly it could be entrapment by other muscles or structures like the psoas muscle or the tensor fascia latae, or damaged by diabetic or other neuropathy. 

What the causes of Meralgia Paresthetica?

The most interesting aspect of meralgia paresthetica is the multiple different causes. MP has been reported to be caused by obesity, pregnancy and compression from tight pants, belts, uterine fibroids and tumours. Furthermore, MP can be due to direct trauma, like seat belt incidents, surgery complications and even associated with disorders such as diabetes and leprosy.   Recent reports have also surfaced regarding MP being caused by exercise or even prolonged periods of standing that increase compression on the inguinal ligament.

The Pelvic Compression Test

 Nerve conduction studies can often help confirm one’s diagnosis but aren’t easily accessible to manual therapists, like chiropractors.  The following is a fairly new test which can be used by manual therapist to help diagnose Meralgia Paresthetica

This test is based on the premise the LFCN is compressed by the inguinal ligament and by relieving this compression symptoms will temporarily be alleviated. With the patient focusing on their symptoms the examiner attempts to apply a downward and lateral compressive force on the pelvic. The pressure is held for 45 seconds and a positive result is when patients report an alleviation of their symptoms. By compressing the pelvic in this manner the two attachments of the inguinal ligament are brought closer together causing the ligament to become slacker.

 

Treatment Options 

 Conservative manual therapy from a chiropractor or other trained manual therapist should be tried before seeking drugs or surgery.   A chiropractor can manually release (or stretch) the muscles and ligaments that may be entrapping the lateral femoral cutaneous nerve. Soft tissue therapy such as Active Release Techique, Graston therapy, or deep tissue massage may provide relief of symptoms.   However proper education and at home advise must be followed to ensure the benefits of in clinic treatment have a longer lasting effect.    Chiropractic assessment of the pelvis and ilium bone can detect any bony misalignments where adjustments may have an effect.  If conservative treatment is not effective speak to your medical doctor about other options like NSAIDs for pain, or surgical nerve block or release.

 

 

 

Sources:

 

Shimizu, S. (2008). A Novel Approach to the Diagnosis and Management of Meralgia Paresthetica Neurosurgery, 63 (4) DOI: 10.1227/01.NEU.0000325683.55646.90

Dr. Wayne Button DC.  Sports Injuries and Wellness Ottawa.