eMedicine Specialties > Orthopedic Surgery > Hip

Meralgia Paresthetica

Author: Ira Kornbluth, MD, MA, Managing Partner, Spine Medicine and Rehabilitation Therapies
Coauthor(s): Phillip J Marone, MD, MSPH, Clinical Professor, Department of Orthopedic Surgery, Jefferson Medical College
Contributor Information and Disclosures

Updated: Mar 16, 2009

Introduction

Background

Meralgia paresthetica is a common but underrecognized condition that is manifested by pain, numbness, and tingling in the anterior and lateral parts of the thigh. Bernhardt first described symptoms corresponding to meralgia paresthetica in 1878. In 1885, Hagar correctly suggested that lateral femoral cutaneous nerve compression was the source of this symptom complex; surgical correction of meralgia paresthetica also dates back to Hagar at this time.

The lateral femoral cutaneous nerve provides sensory innervation to the anterolateral thigh. Courtesy of Essentials of Physical Medicine and Rehabilitation, Hanley & Belfus Publishers, 2001, used with permission.

[ CLOSE WINDOW ]

The lateral femoral cutaneous nerve provides sensory innervation to the anterolateral thigh. Courtesy of Essentials of Physical Medicine and Rehabilitation, Hanley & Belfus Publishers, 2001, used with permission.

A decade later, Roth coined the term meralgia paresthetica from the Greek words meros (thigh) and algos (pain). Anecdotally, Sigmund Freud is said to have diagnosed himself and his son with this condition.

Problem

Meralgia paresthetica is caused by entrapment of the lateral femoral cutaneous nerve, which then results in pain and sensory abnormalities in the anterolateral thigh. The lateral femoral cutaneous nerve is a pure sensory nerve that typically receives its innervation from the L2-3 lumbar nerve roots and includes sudomotor fibers. Sudomotor changes, such as mild sweating in the nerve distribution, may be evident, although this is uncommon. Because the lateral femoral cutaneous nerve is purely sensory, no associated motor or reflex findings should be present.^1,2

Frequency

The prevalence of meralgia paresthetica has been estimated at 3 cases per 10,000 individuals, and this condition has been reported in up to 35% of patients referred for evaluation of leg discomfort. However, these symptoms are often not recognized or they may be mistaken for other conditions such as lumbar radiculopathy. In a large case series,³ the presumptive diagnosis by the referring physician was meralgia paresthetica in 47 of 120 patients (39%). This condition has been described in toddlers and elderly persons, but most cases occur in patients aged 30-65 years. Whether a sex predominance exists is unclear. Meralgia paresthetica is usually unilateral but may be bilateral in as many as 50% of cases.

Etiology

Metabolic conditions, such as diabetes, alcoholism, and thyroid disorders, can contribute to the development of a neuropathy in the lateral femoral cutaneous nerve and other peripheral nerves. In most instances, the etiology of meralgia paresthetica involves excessive pressure on the nerve at various sites of possible entrapment. Pressure may be from internal causes such as obesity, pregnancy, or pelvic tumors.

There is a higher incidence of obesity in patients with meralgia paresthetica, which strongly suggests that obesity is an independent risk factor.⁴ Alternatively, external causes such as tight belts worn around the waist may be identified as the culprit.^5,6 In addition, the lateral femoral cutaneous nerve may be injured iatrogenically from local trauma during surgical procedures. Hip replacement, iliac crest bone grafting, appendectomy, inguinal lymph node dissection, aortofemoral bypass, uterine surgery, cesarean section, and quadriceps surgery have all been implicated as causative for meralgia paresthetica.

Pathophysiology

Along its course, the lateral femoral cutaneous nerve is vulnerable to compression at several sites. The nerve emerges from the psoas muscle, intersects with the inguinal ligament, curves around the anterior superior iliac spine, and exits from the fascia lata. Meralgia paresthetica most commonly occurs from compression of the nerve as it exits the pelvis.^7,8

Peripheral nerve injuries are described in terms of the nature of the insult and the associated prognosis. Thus, a compressive force results in a neuropraxic injury to the nerve, which is characterized by the loss of myelin without affecting the axon or its axonal sheath. Neuropraxic injuries have the best prognosis and may heal over hours to months, depending on the severity. Loss of the axon or its axonal sheath constitutes a more severe nerve injury and a worse prognosis for healing, because the nerve undergoes wallerian degeneration or destruction of the nerve fibers distal to the injury site.⁹

If the injury involves only the axons and spares the axonal sheath (axonotmesis), the patient may make a full, but likely slow, recovery. If the axonal sheath is affected such that the nerve is in discontinuity (neurotmesis), then the prognosis for spontaneous recovery is poor. Most commonly, compressive forces tend to result in neuropraxic injuries, and relief of the compressive force initiates the healing process.

Presentation

A thorough medical and surgical history is important for the correct diagnosis of meralgia paresthetica, including questioning the patient about the possibility of any relevant trauma.^10,11,12 The physical examination in patients with meralgia paresthetica is remarkable for the findings of altered sensation in the anterolateral thigh, including pain, numbness, burning, hyposensitivity, and tingling. Typically, the symptoms begin insidiously and do not extend below the knee. The pain tends to be sharp or burning but also may be dull or achy.

The examiner should also consider whether any abnormal postures or movements are contributing to the patient's symptoms. Prolonged standing and standing up from a seated position may aggravate the condition. Motor and reflex examination findings should be normal. If the patient has evidence of motor weakness or low back pain, other diagnoses should be considered because the lateral femoral cutaneous nerve is purely sensory, and a neurologic examination should be conducted. Trigger points, lumbar radiculopathy, plexopathy, and hip pathology can masquerade as meralgia paresthetica. A positive Tinel sign finding may be elicited near the anterior superior iliac spine.

Meralgia paresthetica may affect a very large region of the anterior and lateral thigh. However, the involved area can vary significantly depending on the site of entrapment and anatomic variations of the nerve. In a large case series³ of 120 patients, 88 (73%) had symptoms solely in the lateral aspect of the distal thigh. In 11 of the 120 patients (9.2%), the anterior aspect of the thigh was exclusively involved.

Indications

Treatment for meralgia paresthetica is directed toward identification and relief of the compressive force on the lateral femoral cutaneous nerve. In many instances, the nerve spontaneously heals if the compression is relieved. If symptoms continue, anti-inflammatory medications, local injection, and other nonsurgical modalities can be considered (see Treatment). If these methods fail, surgery may be an option. The decision to pursue surgery depends on the extent and nature of the symptoms. Neurolysis alone, neurolysis with transposition of the nerve, and transection of the nerve are the most commonly performed surgical procedures for meralgia paresthetica.

Relevant Anatomy

The lateral femoral cutaneous nerve typically arises from lumbar nerve roots, specifically those at the L2-3 levels, although the nerve can arise from different combinations of the L1-3 nerve roots. The lateral femoral cutaneous nerve pierces the psoas muscle, travels across the iliacus muscle toward the anterior superior iliac spine, and then enters the anterolateral thigh by passing under, through, or above the inguinal ligament. In most individuals, the lateral femoral cutaneous nerve crosses into the anterolateral thigh approximately 1 cm medial to the anterior superior iliac spine. However, the relationship of the lateral femoral cutaneous nerve to the anterior superior iliac spine is quite variable. The nerve may cross into the anterolateral thigh as much as 2 cm lateral or 6 cm medial to the anterior superior iliac spine. A bifurcation into anterior and posterior divisions occurs approximately 5-12 cm below the anterior superior iliac spine.

Cadaver dissections have demonstrated that anatomic variations are also found in the origin of the lateral femoral cutaneous nerve. As many as 30% of lateral femoral cutaneous nerves may be derived partially or entirely from adjacent genitofemoral or femoral nerves.

Contraindications

No absolute contraindications are recognized for lateral femoral cutaneous nerve surgery. Relative contraindications include any comorbidities that place the patient at increased general surgical risk.

• Search for CME/CE on This Topic »

• Meralgia Paresthetica (Physical Medicine and Rehabilitation)
• Meralgia Paresthetica (Neurology)
• Groin Injury (Sports Medicine)
• Nerve Entrapment Syndromes (Neurosurgery)