Causes of Meralgia Paresthetica
Meralgia paresthetica is caused by compression or injury of the lateral femoral cutaneous nerve (LFCN), most commonly at the inguinal ligament, with both traumatic and non-traumatic etiologies contributing to nerve dysfunction.
Primary Mechanism
The LFCN, derived from L2-L3 spinal nerves, is anatomically vulnerable due to its course under the inguinal ligament where it can be compressed, stretched, or entrapped 1. This unique anatomical pathway predisposes the nerve to inflammation, trauma, and mechanical compression 2.
Non-Traumatic Causes
The most common non-traumatic causes include:
- Obesity - increases mechanical pressure on the nerve 3, 2
- Tight clothing - direct external compression at the inguinal ligament 1, 2
- Pregnancy - combination of weight gain and anatomical changes 1
- Diabetes mellitus - metabolic nerve vulnerability 3
- Idiopathic - many cases have no identifiable cause 3, 4
Traumatic and Iatrogenic Causes
Iatrogenic injury represents the most frequent traumatic cause, particularly from 4:
- Procedures around the anterior superior iliac spine
- Intra-abdominal surgical procedures
- Perioperative positioning - prolonged surgical positioning can cause direct pressure on susceptible peripheral nerves 5
- Hip or lumbar spine surgery 3
- Bariatric surgery 2
In a surgical database of 187 cases, 14 involved traumatic LFCN injury and 4 were related to mass lesions 4.
Mass Lesions and Compression
Less commonly, meralgia paresthetica results from compression by space-occupying lesions along the nerve's anatomical course. When evaluating patients, consider mass lesions if symptoms are atypical, bilateral, or accompanied by motor deficits 4.
Post-Infectious Etiology
Emerging evidence suggests post-infectious inflammatory mechanisms may trigger bilateral meralgia paresthetica following febrile illnesses, though this remains uncommon 6.
Clinical Pitfalls
Critical caveat: If symptoms extend beyond the typical LFCN distribution, are bilateral, or include motor/reflex abnormalities, consider alternative diagnoses including lumbar radiculopathy, adjacent nerve involvement, or anatomical LFCN variations 1. The concurrent occurrence with other entrapment neuropathies (such as piriformis syndrome) is rare but possible 6.
Most cases are self-limited, though a small proportion develop refractory, disabling symptoms requiring escalated intervention 3.