Workup for Meralgia Paresthetica
The diagnosis of meralgia paresthetica is primarily clinical, based on characteristic symptoms of numbness, paresthesias, and pain in the anterolateral thigh distribution, with diagnostic nerve block serving as the key confirmatory test when the diagnosis is uncertain. 1, 2
Clinical Diagnosis
Essential Clinical Features to Identify
Pain and sensory symptoms must be localized to the anterolateral thigh in the distribution of the lateral femoral cutaneous nerve (LFCN), presenting as numbness, paresthesias, tingling, stinging, or burning sensations 1, 3
Identify exacerbating factors including tight clothing, belts, weight gain, prolonged standing, or hip extension that compress the nerve as it exits the pelvis beneath the inguinal ligament 1, 2
Document any history of iatrogenic causes such as anterior iliac crest bone graft harvesting, anterior pelvic procedures, prone positioning for spine surgery, or other surgical interventions near the anterior superior iliac spine 1
Examine for mechanical compression sources throughout the entire course of the LFCN, particularly where the nerve exits the pelvis, as the regional anatomy is highly variable and susceptible to local trauma 1
Diagnostic Nerve Block
Perform a diagnostic LFCN block with local anesthetic at the anterior superior iliac spine to confirm the diagnosis when clinical presentation is uncertain 1, 2
Relief of pain and paresthesias after local anesthetic injection establishes the diagnosis and serves both diagnostic and therapeutic roles 1, 2
If no improvement occurs with the block, seek proximal LFCN irritation as an alternative source of nerve compression 1
Adjunctive Diagnostic Testing (When Diagnosis Remains Uncertain)
Electrophysiological testing including electromyography and nerve conduction studies can be utilized when clinical diagnosis is challenging, though these play a secondary role to clinical assessment 2, 4
Ultrasound or MRI imaging may be considered as adjunctive modalities when the diagnosis remains unclear after clinical evaluation and nerve block 4
Important Caveat
Meralgia paresthetica is often a diagnosis of exclusion, requiring differentiation from other neurologic disorders affecting the thigh, particularly lumbar radiculopathy or other proximal nerve lesions 1, 4
The highly variable anatomy of the LFCN around the anterior superior iliac spine accounts for its susceptibility to trauma and may complicate localization during diagnostic procedures 1