Case of the Month #44: Meralgia Paraesthetica

Meralgia paraesthetica (MP) is a neuropathic pain condition resulting from entrapment of the lateral femoral cutaneous nerve (LFCN). It typically manifests as sensory disturbances, including pain, tingling, and burning sensations over the lateral aspect of the thigh. Although MP is commonly seen as a unilateral condition, bilateral presentations represent 20% of cases¹.

• Relevant Anatomy²

The lateral femoral cutaneous nerve (LFCN) is a sensory nerve originating from the lumbar plexus (L2-L3). It travels beneath the inguinal ligament, passing through or near the iliacus fascia before emerging to supply the skin over the anterolateral aspect of the thigh. This anatomical course makes the LFCN vulnerable to compression, particularly at the inguinal ligament, where it can become entrapped.

• Risk factors³

Obesity: Increased body weight and abdominal girth can compress the LFCN as it passes under the inguinal ligament.

Tight clothing or belts: Pressure over the inguinal region can impinge the nerve.

Pregnancy: The expanding uterus may increase abdominal pressure, affecting the nerve.

Diabetes: Metabolic factors in diabetes can predispose individuals to peripheral nerve entrapments.

Hormonal and endocrine disorders, such as PCOS, may also contribute to weight gain and fat distribution patterns that increase the risk of nerve compression.

In this case, the patient’s elevated BMI and history of PCOS are likely contributing factors, predisposing her to bilateral LFCN entrapment.

• How is the severity of MP assessed?

The diagnosis of meralgia paraesthetica is primarily clinical, relying on the characteristic symptoms of lateral thigh pain and paraesthesia. A detailed neurological examination is essential to rule out other causes of thigh pain, such as lumbar radiculopathy, and to assess the distribution of sensory loss.

• What is the relevance of BMI in MP?

Obesity is a recognised risk factor for MP, likely due to increased pressure on the LFCN at the inguinal ligament as it passes below the inguinal ligament. In this patient, her elevated BMI likely predisposed her to bilateral nerve entrapment. The diagnosis of MP in obese patients is important as the condition can be refractory to conservative treatments⁴.

• What types of pain are experienced in MP?

MP primarily involves neuropathic pain, characterised by burning, tingling, and sharp sensations in the LFCN distribution. The involvement of both nociceptive and neuropathic mechanisms can complicate treatment, as in this case where pharmacological management alone was insufficient to fully control the symptoms.

Bilateral meralgia paraesthetica highlights the importance of considering patient-specific factors like obesity and hormonal disorders in the diagnosis and management of neuropathic pain. The chronic nature of MP in this patient, combined with her BMI and comorbidities, necessitated a multidisciplinary approach to pain management, integrating physiotherapy, pharmacological and interventional techniques.

• What are the options for managing refractory MP?

For patients whose symptoms are not adequately managed with medications, interventional procedures like PRF denervation provide an option to modulate nerve transmission and reduce pain. PRF denervation is a minimally invasive procedure that avoids thermal damage to the nerve, offering a safe and effective option for long-term pain relief⁵.

PRF denervation offers a targeted intervention for patients with neuropathic pain that is refractory to conservative treatment.

• Key Learning Points

Bilateral Meralgia Paraesthetica is a clinical presentation that requires careful consideration of systemic factors such as obesity, which can increase the risk of nerve entrapment.

Pulsed Radiofrequency Denervation is an effective interventional option for managing chronic neuropathic pain that does not respond to conservative treatment.

A multidisciplinary and multimodal approach to pain management, including physiotherapy, pharmacological and interventional strategies, is essential for optimal patient outcomes in chronic neuropathic pain.