What is Meralgia Paresthetica

Meralgia paresthetica is a condition characterized by tingling, numbness and burning pain in the outer part of your thigh.

What is involved?

Lateral Cutaneous Nerve of Thigh

Location

Lateral Cutaneous Nerve of Thigh in the upper and outer thigh

Common symptoms

• Pain, burning in the thigh
• Poor tolerance to touch, clothes, cover or anything that rubs against thigh
• In mothers (or fathers) pain/burning with children sitting on lap
• No thigh or leg weakness or atrophy
• Usually unilateral
• Symptoms always present, no night/day preference

Onset

• Usually gradual over days, weeks
• May be sudden

Risk factors

• No gender preference
• Diabetes or family history of Diabetes
• Alcoholism or other occupational or nutritional causes of Neuropathies
• HIV infection
• Overweight
• Tight undergarments or clothing in the inguinal area

Exam

• Decreased sensation over upper and lateral area of thigh
• Sometimes decreased sensation all the way to the patella
• Difficult to examine because of pain/burning induced by touching or rubbing
• Normal strength, no atrophy in thigh muscles
• Preserved Knee Jerk (if absent or unilaterally decreased suspect L3 root lesion)

Localization

Pure sensory branch involvement at the upper and lateral end of the inguinal ligament

EMG

• Study Lateral Cutaneous Nerve of Thigh, usually small amplitude (less than 10 μV)
• Study both sides to compare amplitudes
• Response may be absent or significantly (less than 50%) smaller than healthy side
• Nerve Conductions may be difficult to perform in overweight subjects
• Rule out L3 root lesion by studying other Femoral and non-Femoral innervated muscles to include:
  • Vastus Lateralis (derived from Femoral Nerve below Inguinal ligament)
  • Ilio-Psoas (from Femoral Nerve above Inguinal ligament)
  • Thigh Adductors (from Obturator Nerve)

Differential Diagnosis by EMG

• In Meralgia Paresthetica: the needle exam of the Thigh muscles will be normal
• In L3 root lesions: Vastus Lateralis, Ilio-Psoas, Thigh Adductors and/or paraspinals could be involved
• In Femoral Nerve lesions: Vastus Lateralis and Ilio-Psoas, but not Thigh Adductors, are involved
• In Obturator Neuropathy: only Thigh Adductors are involved

Recommendations

• Symptomatic treatment
• Stop/decrease cause, tight undergarments, clothing
• Lose weight
• Anti-epileptics, tricyclics have been tried with various degrees of success
• Nerve blocks/Injections

What else could it be?

• Could be an L3 root lesion if associated muscle weakness (Vastus Lateralis, Ilio-Psoas and/or Thigh adductors) or absent or unilaterally decreased Knee jerk
• Few other conditions can cause the same symptoms