Meralgia Paraesthetica (MP) is a neurological disorder characterised by paraesthesia and numbness in the anterolateral region of the thigh, due to a lesion (compression) and/or dysfunction of the lateral cutaneous femoral nerve.
MP may have many different causes, which can be divided into two main groups: spontaneous and iatrogenous.
Spontaneous MP occurs when no previous surgery has taken place. It can be subdivided into an idiopathic, metabolic and mechanical form. Although spontaneous occurrence of this disorder is seen in patients of all ages, it is most commonly seen between the ages of 30 and 40, and is more frequent in males.
Other causes are obesity, diabetes and pregnancy. However, MP is also seen in children with a relatively slender build.
Signs and symptoms
Symptoms in MP usually consist of an unpleasant tingling sensation on the outside of the thigh. In most cases, MP occurs unilaterally, with 20% of patients experiencing it bilaterally.
Patients complain of a characteristic burning, stabbing pain with a tingling sensation in the thigh. They usually feel the pain in the skin itself. Although allodynia has been reported, most patients describe an unpleasant change of sensation (dysaesthesia), rather than pain.
Symptoms can be brought on by stretching the hip backwards, by posture in general, and by prolonged standing. Sitting sometimes relieves the symptoms.
On physical examination, painful palpation of the lateral inguinal ligament is frequently present near the point where the nerve crosses this ligament. Some patients experience hair loss in the region of the lateral cutaneous femoral nerve, due to constant rubbing in this area.
Additional Somatic Diagnostics
- X-ray to exclude osseous tumours.
- When malignancies (including retroperitoneal) in the pelvis are suspected, MRI scan or ultrasound is indicated.
- When metabolic aetiology is suspected, blood tests are indicated, including thyroid function.
- A positive test block of the lateral cutaneous femoral nerve can confirm the diagnosis. However, a negative test block can also be explained by an aberrant course of the lateral cutaneous femoral nerve.
Additional Psycho-cognitive Diagnostics
- RAND-36 (quality of life)
- VAS Pain (maximal, minimal, actual, average/week)
- PCS (catastrophising)
- HADS (fear and depression)
Whether or not somatic treatment is indicated is based on the pain diagnosis. Based on the findings of the pain questionnaires, additional diagnostics can necessary and/or multidisciplinary treatment comprising various non-somatic treatments may be necessary.
- Psychological Treatment
- Depression Treatment
- Cognitive-Behavioural Treatment
- Rehabilitation Treatment
- Tricyclic antidepressants
- Anticonvulsives: carbamazepine, oxcarbazepine, gabapentine and pregabaline.
Interventional Pain Treatment
- Local infiltration of the lateral cutaneous femoral nerve
- PRF treatment of the lateral cutaneous femoral nerve
- Surgery of MP is only indicated in very rare case, when other psycho-cognitive factors have been excluded.