What is the most likely diagnosis for a patient with burning and numbness in the anterolateral thigh, reduced pinprick sensation, and a positive Tinel's sign, with a history of type 2 diabetes and obesity?

Meralgia Paresthetica

The most likely diagnosis is meralgia paresthetica, a lateral femoral cutaneous nerve entrapment syndrome that classically presents with burning pain and numbness in the anterolateral thigh, positive Tinel's sign at the inguinal ligament, and preserved strength and reflexes—all of which are present in this patient. 1, 2

Clinical Reasoning

This patient's presentation is pathognomonic for meralgia paresthetica rather than the other differential diagnoses:

Key Distinguishing Features Supporting Meralgia Paresthetica

• Isolated sensory symptoms in the anterolateral thigh distribution without motor weakness or reflex changes 1, 3
• Positive Tinel's sign at the lateral inguinal ligament, which reproduces the burning discomfort and is highly specific for lateral femoral cutaneous nerve compression 2, 3
• Normal deep tendon reflexes (patella and ankle) and negative straight leg raise, effectively ruling out radiculopathy and cauda equina syndrome 3
• Preserved motor strength throughout lower extremities, excluding femoral neuropathy which would cause quadriceps weakness 1

Risk Factors Present in This Patient

• Obesity (BMI 37 kg/m²) is a well-established risk factor for lateral femoral cutaneous nerve compression 1, 4
• Type 2 diabetes increases the incidence of meralgia paresthetica 1
• Sedentary occupation may contribute to prolonged sitting and nerve compression 4, 3

Why Other Diagnoses Are Excluded

Cauda Equina Syndrome

• Would present with bilateral symptoms, saddle anesthesia, bowel/bladder dysfunction, and abnormal reflexes—none of which are present 3

Diabetic Neuropathy

• Typically presents as distal symmetric polyneuropathy affecting both feet in a stocking distribution with reduced ankle reflexes 5
• This patient has unilateral, proximal symptoms with normal reflexes 5
• While diabetes is present, the clinical pattern does not fit diabetic peripheral neuropathy 5

Femoral Neuropathy

• Would cause quadriceps weakness, impaired knee extension, and reduced or absent patellar reflex—all absent in this patient 3
• Sensory loss would be in the anteromedial thigh and medial leg, not anterolateral 3

S1 Radiculopathy

• Would present with posterior leg and lateral foot pain, positive straight leg raise, reduced ankle reflex, and possible plantar flexion weakness 3
• The anterolateral thigh distribution and negative straight leg raise exclude this diagnosis 3

Diagnostic Confirmation

• Clinical diagnosis is typically sufficient based on characteristic symptoms and positive Tinel's sign at the inguinal ligament 2, 3
• Ultrasound imaging can confirm entrapment by demonstrating a hypoechoic, swollen lateral femoral cutaneous nerve at the inguinal ligament 2
• Electrodiagnostic studies are not routinely recommended in daily clinical practice for meralgia paresthetica 2

Management Approach

First-Line Conservative Treatment

• Weight loss is critical given the patient's BMI of 37 kg/m² 4, 3
• Avoid tight clothing and belts that compress the inguinal region 4, 3
• Limit prolonged standing and modify sedentary work positions 4, 3

Pharmacologic Management if Conservative Measures Fail

• NSAIDs for initial pain control 3
• Neuropathic pain medications (pregabalin, gabapentin, or duloxetine) if burning pain persists 6

Interventional Options for Refractory Cases

• Local anesthetic and corticosteroid injection at the entrapment site provides excellent relief 4, 3
• Ultrasound-guided nerve blocks for diagnostic confirmation and therapeutic benefit 2
• Cryoneurolysis may provide prolonged pain relief (up to 3 months) for intractable cases 7
• Surgical decompression or neurectomy reserved as last resort for persistent symptoms despite conservative and interventional management 3

Important Clinical Pearls

• Prognosis is generally excellent with conservative management, and most cases are self-limiting 4, 3
• The condition typically improves with weight loss and elimination of compressive factors 4, 2
• Diabetes management should be optimized to prevent other neuropathic complications, though it won't directly resolve the mechanical compression 5