Meralgia paresthetica: finding an effective cure

Diagnostic Approach to Lower Limb Entrapment Neuropathies: A Narrative Literature Review

Entrapment neuropathies of the lower limb are a misunderstood and underdiagnosed group of disorders, characterized by pain and dysesthesia, muscular weakness, and specific provoking movements on physical examination. The most frequent of these syndromes encountered in clinical practice are fibular nerve entrapment, proximal tibial neuropathy, sural nerve neuropathy, deep gluteal syndrome or sciatic nerve entrapment, and lateral femoral cutaneous nerve entrapment, also known as meralgia paresthetica. These are commonly mistaken for lumbar plexopathies, radiculopathies, and musculotendinous diseases, which appear even more frequently and have overlapping clinical presentations. A comprehensive anamnesis, physical examination, and electrodiagnostic studies should help clarify the diagnosis. If the diagnosis is still unclear or a secondary cause of entrapment is suspected, magnetic resonance neurography, MRI, or ultrasonography should be conducted to clarify the etiology, rule out other diseases, and confirm the diagnosis. The aim of this narrative review was to help clinicians gain familiarity with this disease, with an increase in diagnostic confidence, leading to early diagnosis of nerve damage and prevention of muscle atrophy. We reviewed the epidemiology, anatomy, pathophysiology, etiology, clinical presentation, and EDX technique and interpretation of the entrapment neuropathies of the lower limb, using articles published from 1970 to 2022 included in the Pubmed, MEDLINE, Cochrane Library, Google Scholar, EMBASE, Web of Science, and Scopus databases.

Targeted dorsal root entry zone stimulation alleviates pain due to meralgia paresthetica

Objective.Meralgia paresthetica (MP) is a mononeuropathy of the exclusively sensory lateral femoral cutaneous nerve (LFCN) that is difficult to treat with conservative treatments. Afferents from the LFCN enter the spinal cord through the dorsal root entry zones (DREZs) innervating L2 and L3 spinal segments. We previously showed that epidural electrical stimulation of the spinal cord can be configured to steer electrical currents laterally in order to target afferents within individual DREZs. Therefore, we hypothesized that this neuromodulation strategy is suitable to target the L2 and L3 DREZs that convey afferents from the painful territory, and thus alleviates MP related pain.Approach.A patient in her mid-30s presented with a four year history of dysesthesia and burning pain in the anterolateral aspect of the left thigh due to MP that was refractory to medical treatments. We combined neuroimaging and intraoperative neuromonitoring to guide the surgical placement of a paddle lead over the left DREZs innervating L2 and L3 spinal segments.Main results.Optimized electrode configurations targeting the left L2 and L3 DREZs mediated immediate and sustained alleviation of pain. The patient ceased all other medical management, reported improved quality of life, and resumed recreational physical activities.Significance.We introduced a new treatment option to alleviate pain due to MP, and demonstrated how neuromodulation strategies targeting specific DREZs is effective to reduce pain confined to specific regions of the body while avoiding disconfort.

Successful application of spinal cord stimulation in a patient with refractory bilateral meralgia paresthetica

We present a 38-year-old morbidly obese male who presented with functionally limiting bilateral anterior thigh pain consistent with meralgia paresthetica. His symptoms had been unresponsive to conservative measures which included physical therapy, oral medications and multiple nerve blocks. Patient underwent a trial of spinal cord stimulation (SCS), experiencing 70% of pain relief. He then underwent permanent SCS implant. At subsequent follow-ups 3 and 6 months later, he continued to report 70% improvement of his pain, as well as improved function and quality of life. To our knowledge, this is only the second reported case of successful treatment of meralgia paresthetica with SCS, and the first in a morbidly obese patient.

Peripheral Nerve Stimulation for the Treatment of Meralgia Paresthetica

Meralgia paresthetica is a condition caused by entrapment of the lateral femoral cutaneous nerve at the level of the inguinal ligament. This nerve is a purely sensory nerve and provides innervation to the anterolateral portion of the thigh. The condition can lead to numbness, paresthesia, dysesthesia, and pain over the anterolateral aspect of the thigh, which are exacerbated with walking, standing, and hip extension. First-line treatment for MP includes conservative measures such as weight loss and eliminating tight-fitted clothing. Neuropathic pain medications and corticosteroid injections are also treatment options for some patients with significant pain complaints. In more refractory cases, surgical intervention can be considered. Peripheral nerve stimulation has also been shown to be a helpful treatment modality for patients with refractory meralgia paresthetica. Here we report our experience utilizing peripheral nerve stimulation in patients with significant pain complaints related to refractory meralgia paresthetica.

Sonographic features of the lateral femoral cutaneous nerve in meralgia paresthetica

Background

The diagnosis of meralgia paresthetica (MP) is usually based on clinical symptoms and physical examination. Therefore, the present study aimed to investigate the lateral femoral cutaneous nerve (LFCN) sonographic features in MP patients.

Methods

A total of 86 clinically suspected MP patients and 40 asymptomatic volunteers were prospectively recruited in the study. The sonographic features of the LFCN were observed by 18 MHz high-frequency ultrasound. At the level of the anterior superior iliac spine, the cross-sectional area of the LFCN was measured.

Results

Of the 86 clinically suspected MP patients, 82 (95.3%) had sonographic findings positive for MP. There were 54, 63, and 44 cases of abrupt caliber change, indistinct perineurium, and abnormal intraneural vascularity. The average value of the cross-sectional area of the LFCN at the level of the anterior superior iliac spine was 4.47±2.64 mm², and the cut-off value was 2.65 mm².

Conclusions

The sonographic diagnosis of MP may be achieved based on the following signs: nerve abrupt caliber change, indistinct perineurium of the nerve, intraneural vascularity, or increased cross-sectional area.