Meralgia Paresthetica (MP) is a nerve entrapment syndrome affecting the outer thigh. It arises from the compression of a peripheral nerve, leading to characteristic sensory symptoms. Because its primary symptoms—numbness, tingling, and burning pain—are common to many neurological and orthopedic issues, MP is frequently misdiagnosed. A precise differential diagnosis is paramount, as the underlying cause could range from simple mechanical pressure to a complex spinal or systemic disease.
The Defining Sensory Profile of Meralgia Paresthetica
MP represents a mononeuropathy, affecting only the Lateral Femoral Cutaneous Nerve (LFCN). This nerve is purely sensory, carrying signals related to touch and sensation but containing no motor fibers. Consequently, symptoms are entirely confined to sensory changes on the anterolateral aspect of the thigh.
Patients typically describe a combination of burning pain, numbness, tingling, or increased sensitivity to light touch in this area. The symptoms are often unilateral, affecting only one thigh, and are commonly aggravated by prolonged standing or hip extension. The defining feature of a pure LFCN entrapment is the absence of associated muscle weakness, changes in reflexes, or motor difficulty.
Spinal and Nerve Root Impingement Mimics
Conditions originating in the lumbar spine are common mimics of Meralgia Paresthetica. Lumbar Radiculopathy involves the impingement of spinal nerve roots as they exit the vertebral column, often presenting with pain or sensory changes in the thigh. Compression of the L2 or L3 nerve roots can cause symptoms that overlap with the LFCN distribution, leading to diagnostic confusion.
Spinal nerve roots contain both motor and sensory fibers. Unlike MP, L2 or L3 radiculopathy may present with a broader pain distribution, potentially wrapping around the thigh or extending beyond the lateral area. Radiculopathy at these levels can also lead to measurable motor weakness in the hip flexors or quadriceps muscles, which is never seen in pure MP. The pain associated with spinal issues is frequently positional, changing noticeably with sitting, standing, or bending.
Systemic and Metabolic Neuropathies
Diabetic Neuropathy is the most common systemic cause that can lead to localized nerve issues or predispose an individual to LFCN entrapment. The generalized form, known as polyneuropathy, typically follows a “stocking-glove” pattern.
This pattern affects the longest nerves first, causing sensory loss and paresthesia to begin in the feet and hands before progressing upward. This bilateral and progressive pattern differs from the focal, unilateral, and non-progressive sensory deficit that defines classic Meralgia Paresthetica. Other systemic causes, such as chronic alcoholism, hypothyroidism, or nutritional deficiencies, can also cause generalized nerve damage mistakenly attributed to a local entrapment.
Local Musculoskeletal and Hip Conditions
Pain originating from the hip joint or surrounding soft tissues can be misinterpreted as the burning nerve pain of Meralgia Paresthetica. Trochanteric Bursitis, which involves inflammation of the fluid-filled sac over the outer hip bone, is a frequent mimic. This condition causes pain that is typically deep and aching, localized around the greater trochanter of the hip.
Hip Osteoarthritis is another common source of thigh pain. These musculoskeletal conditions are characterized by pain predictably exacerbated by movement, weight-bearing activities, or lying directly on the affected side. Neither trochanteric bursitis nor hip osteoarthritis causes the specific superficial numbness or tingling (paresthesia) that is the hallmark of LFCN entrapment. They produce deep joint or soft tissue pain rather than a superficial sensory disturbance.