1. Meralgia Paresthetica
“Entrapment of lateral femoral cutaneous nerve”
By Ali Noureldin ElSayed

2. Anatomy

3. Anatomy of lateral femoral cutaneous nerve
The lateral femoral cutaneous nerve is a branch of the lumbar plexus, exiting
the spinal cord between the L2 and L3 vertebrae. It emerges at the lateral
edge of the psoas muscle group, below the ilioinguinal nerve, and then passes
beneath the iliac fascia and the inguinal ligament. It divides into two branches
– anterior and posterior – eight to ten centimeters below the spine, where it
also emerges from the fascia lata. The anterior branch supplies the skin of the
anterior and lateral regions of the thigh to the knee, while the posterior
branch supplies the lateral portion of the thigh, from the greater trochanter in
the hip, to mid-thigh, just above the knee.

5. Signs and symptoms
• Pain on the outer side of the thigh, occasionally extending to the outer side of the knee,
usually constant.
• A burning sensation, tingling, or numbness in the same area.
• Occasionally, aching in the groin area or pain spreading across the buttocks
• Usually more sensitive to light touch than to firm pressure
• Hypersensitivity to heat (warm water from shower feels like it is burning the area)
• Occasionally, patients may complain of itching sensation rather than pain in the affected
area.

6. Causes:
Mechanical:
• Pregnancy (or any condition that increases abdominal pressure).
• Obesity.
• wearing tight clothing/belts in the waist area.
• different leg lengths.
• pubic symphysis (pelvic girdle) dysfunction.
Metabolic:
• neuropathy (from diabetes).
• hypothyroidism.
• lead poisoning.
Iatrogenic:
• Prolonged traction during spine surgery.
• injury to the nerve during retroperitoneal dissection.

7. Etiology

8. Etiology
Reviewing the anatomy of the LFCN is essential for
understanding the mechanism of its injury (see the images
below).
The LFCN originates directly from the lumbar plexus and
has root innervation from L2-3.
The nerve runs through the pelvis along the lateral border of
the psoas muscle to the lateral part of the inguinal ligament.
Here, it passes to the thigh through a tunnel formed by the
lateral attachment of the inguinal ligament and the anterior
superior iliac spine. The crossover into the thigh is the most
common site of entrapment. The crossover typically occurs 1
cm medial to the anterior superior iliac spine; however,
regional variations are common.

9. Investigation

10. ● Neurological examination:
sensory testing with pinprick and
light touch should show an area
along the upper outer thigh that has
reduced sensation to these
modalities. There should be a normal
motor examination, negative straight
leg raise test, and no hip/knee joint
abnormality. ’’No Motor
Weakness’’
Physical Examination

11. ● Pelvic Compression:
○ Highly sensitive and the diagnosis can often be made with this test alone.
○ Position: Side-lying with their symptomatic side facing up
○ Steps:.
■ The examiner applies a downward, compression force to the pelvis and
maintains pressure for 45 seconds.
■ If the patient reports an alleviation of symptoms the test is considered positive.
■ The test is based upon the idea that the LCNT is compressed by the inguinal
ligament and a downward force to the innominate will relax the ligament and
temporarily alleviate the patient's symptoms.
Physical Examination

12. Pelvic Compression
Test

13. Physical Examination
● Neurodynamic Testing :
○ Position: Side-lying with the symptomatic side up and the bottom knee bent.
○ Steps:
■ The examiner stabilizes the pelvis with the cranial hand and grasps the lower
extremity at the knee with the caudal hand.
■ The examiner then bends the knee and adducts the hip in order to tension the
LCNT
■ A positive test would be the reproduction of the patient's neurologic symptoms
versus feeling tension in the soft‐tissue structures of the hip.

14. Neurodynamic Testing
for LFCN

15. Electrodiagnosis
● Nerve Conduction Study :
○ Sensory nerve conduction velocity (SNCV): The normal range for SNCV in the
lateral femoral cutaneous nerve is typically between 40-60 meters/second
(m/s).
○ Sensory nerve action potential (SNAP): The normal amplitude for SNAP in the
lateral femoral cutaneous nerve is typically between 10-30 microvolts (μV).
○ Normal motor nerve conduction: As the LFCN is a purely sensory nerve and
does not supply any muscles, motor nerve conduction studies will typically be
normal in meralgia paresthetica.
it is important to note that, as with most studies, there are limitations to nerve conduction studies
examining the LCNT. One such limitation is that among individuals with increased adipose tissue
which makes this type of study difficult to perform.

16. Electrodiagnosis
● Lateral Femoral Cutaneous Nerve Block by Lidocaine :
○ The patient lies on their back, and the injection site is cleaned and numbed with a
local anesthetic. The needle is then inserted near the lateral femoral cutaneous
nerve, and the anesthetic medication e.g: Lidocaine is injected.

17. ● EMG :
The needle EMG study is normal in meralgia paresthetica but
abnormal in characteristic patterns in radiculopathies, femoral
neuropathies, and plexopathies.
Electrodiagnosis

18. Imaging
● Magnetic resonance imaging (MRI): This imaging technique can help to identify the cause of nerve
compression, such as a herniated disc or a tumor. In meralgia paresthetica, MRI may show a thickening
or compression of the lateral femoral cutaneous nerve as it passes through the inguinal ligament.
● Ultrasound: Ultrasound can be used to visualize the lateral femoral cutaneous nerve and may reveal
compression, thickening, or swelling of the nerve.
● Computed tomography (CT) scan: This imaging technique can help to identify bony abnormalities
that may be causing nerve compression, such as a bone spur or herniated disc.

19. Intervention

20. Intervention
Treatment For most people, the symptoms of meralgia paresthetica ease in a few months.
Treatment focuses on relieving nerve compression.
❑ Conservative measures
Wearing looser clothing
Losing excess weight
Taking OTC pain relievers such as acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin IB, others) or
aspirin
❑ Medications:
If symptoms persist for more than two months or your pain is severe, treatment might include :
Corticosteroid injections. Injections can reduce inflammation and temporarily relieve pain. Possible side
effects include joint infection, nerve damage, pain and whitening of skin around the injection site.

21. Physical Therapy Management
❑ Kinesio-Taping :
Small-scale pilot studies assert that Kinesio-Taping must be part of the therapy in patients with
MP. Kinesio-Taping would reduce the symptoms experienced by a patient. The exact physiological
mechanisms are still unknown. This method is hypothesized to help increase lymphatic and vascular
flow, decrease pain, enhance normal muscle function, increase proprioception, and help correct
possible articular malalignments. Despite the hypothesized benefits, the current evidence is insufficient
for MP. Future randomized placebo controlled trials are needed
❑ Acupuncture
The benefits of Acupuncture as an intervention (e.g. needling and cupping) for MP has been shown in
clinical trials. The available literature suggests that acupuncture may be effective in the treatment of
MP. However, the exact physiological mechanisms are still under investigation. Further investigation is
needed
❑ Neurostimulation Techniques
Neurostimulation techniques including transcranial magnetic stimulation (TMS) and cortical electrical
stimulation (CES), spinal cord stimulation (SCS) and deep brain stimulation (DBS) have also been found
effective in the treatment of neuropathic pain as MP

22. Physical Therapy Management
❑ Transcutaneous Electrical Nerve Stimulation
Transcutaneous electrical nerve stimulation (TENS or TNS) is effective in the treatment of painful
peripheral neuropathy like MP. It is suggested that TENS activates central mechanisms to provide
analgesia. Low frequency TENS activates μ-opioid receptors in spinal cord and brain stem while high
frequency TENS produces its effect via δ-opioid receptors
❑ Exercise
Exercising for just 30 minutes a day on at least three or four days a week will help you with chronic pain
management by increasing:
❖ Muscle Strength
❖ Endurance
❖ Stability in the joints
❖ Flexibility in the muscles and joints

23. References

24. References
● Carai A, Fenu G, Sechi E, Crotti FM, Montella A. Anatomical variability of the lateral femoral cutaneous
nerve: findings from a surgical series. Clin Anat. 2009 Apr. 22(3):365-70.