Entrapment of the lateral femoral cutaneous nerve in the inguinal area
Seen especially in middle-aged overweight persons.
Symptoms include numbness, paraesthesias and burning pain in the anterior and lateral aspects of the thigh, which is aggravated by all movements of the hip region.
The diagnosis is clinical; machine-assisted diagnostic investigations are needed in special cases only.
High tendency of spontaneous recovery
Epidemiology
Incidence 4.3/10 000 person years
Occurs most commonly in the age of 30 to 40 years, more common in men.
Aetiology
The nerve entrapment is mostly located under the inguinal ligament, approximately 2 cm medially of the anterior superior iliac spine, but the location may vary according to the individual anatomical passage of the nerve.
In more than 30% of people the nerve has an aberrant course.
Symptoms are worsened by
mechanical factors at the areas of the nerve passage: overweight, pregnancy, tight clothing
metabolic factors: diabetes, alcohol
iatrogenic factors: hip and back surgery
The aetiological factor is not necessarily found.
May be bilateral.
Diagnosis
Hyperextension of the thigh with the knee flexed increases the pain.
Compression of the entrapment site causes radiating pain into the thigh.
The clinical picture does not include motor symptoms.
Root compression is ruled out by using the straight leg rising test (Lasègue's test) and testing hip movements to rule out osteoarthritis-induced limitation.
Electroneurophysiological tests may be used if necessary in patients with severe symptoms; the interpretation may be problematic in obese patients.
Glucocorticoid + local anaesthetic injections into the entrapment site; the injection can be repeated at a few weeks' intervals according to treatment response. The glucocorticoid may also be injected at multiple sites along the nerve in order to increase the effect.
Nerve decompression by surgery may be considered if the condition is prolonged and shows no signs of spontaneous recovery.
References
Cheatham SW, Kolber MJ, Salamh PA. Meralgia paresthetica: a review of the literature. Int J Sports Phys Ther 2013;8(6):883-93. [PubMed]