What is the workup for a patient presenting with burning and tingling in the leg?

Workup for Burning and Tingling in the Leg

The workup for burning and tingling in the leg should focus first on identifying peripheral neuropathy, particularly diabetic peripheral neuropathy, as the most common cause, followed by assessment for vascular conditions, spinal pathology, or other neurological disorders that may cause these symptoms.

Initial Assessment

History

• Detailed symptom characterization:
  • Onset (sudden vs. gradual)
  • Distribution (symmetric vs. asymmetric)
  • Quality (burning, electrical, stabbing, tingling)
  • Timing (worse at night, constant vs. intermittent)
  • Aggravating/relieving factors
• Associated symptoms:
  • Weakness
  • Numbness
  • Pain with walking (claudication)
  • Changes in skin color or temperature
  • Urinary or bowel dysfunction (suggests spinal cord involvement)
• Medical history:
  • Diabetes
  • Cardiovascular disease
  • Prior trauma or surgery
  • Cancer history (chemotherapy exposure)
  • Alcohol use
  • Medication review (statins, chemotherapy agents)

Physical Examination

• Neurological assessment:
  • 10-g monofilament testing or Ipswich touch test 1
  • Pinprick sensation
  • Temperature sensation
  • Vibration testing
  • Deep tendon reflexes
  • Motor strength assessment
• Vascular assessment:
  • Peripheral pulses
  • Capillary refill time
  • Rubor on dependency
  • Pallor on elevation
  • Venous filling time 1
• Skin examination:
  • Color changes
  • Trophic changes
  • Ulcerations
  • Edema
  • Temperature differences

Diagnostic Testing

First-Line Tests

1. Laboratory studies:

   • Complete blood count
   • Comprehensive metabolic panel
   • Hemoglobin A1c
   • Thyroid function tests
   • Vitamin B12 level
   • Erythrocyte sedimentation rate
   • C-reactive protein

2. Electrodiagnostic studies:

   • Nerve conduction studies
   • Electromyography (if motor symptoms present)

Second-Line Tests (Based on Clinical Suspicion)

1. For vascular etiology suspicion:

   • Ankle-brachial index (ABI) with toe pressures 1
   • Duplex ultrasound for suspected deep vein thrombosis or arterial disease

2. For spinal pathology suspicion:

   • MRI of the spine (especially with urinary retention, bilateral symptoms, or weakness) 2

3. For small fiber neuropathy suspicion:

   • Thermoregulatory sweat testing 3
   • Skin biopsy for epidermal nerve fiber density

Specific Etiologies and Focused Workup

Diabetic Peripheral Neuropathy

If diabetes is present or newly diagnosed:

• Comprehensive foot examination annually 1
• Assessment for other diabetes complications
• Consider pregabalin for symptomatic treatment 4

Vascular Causes

For patients with leg fatigue, claudication, decreased pulses:

• Refer for vascular assessment if ABI abnormal 1
• Consider CT angiography or MR angiography for suspected arterial disease 1
• Venous ultrasound for suspected superficial vein thrombosis 1

Neuropathic Pain from Other Causes

• Consider cancer-related neuropathy (especially with chemotherapy history) 1
• Evaluate for alcohol-related neuropathy
• Medication review for potential neurotoxic agents

Management Approach

Based on the diagnostic findings, treatment should target the underlying cause:

1. For diabetic neuropathy:

   • Optimize glycemic control
   • Medication options include:
     • Anticonvulsants (pregabalin, gabapentin)
     • Antidepressants (duloxetine)
     • Opioids for refractory cases 1

2. For vascular causes:

   • Antiplatelet therapy
   • Risk factor modification
   • Referral to vascular specialist if severe 1

3. For spinal pathology:

   • Urgent neurosurgical referral if acute myelopathy 2
   • Pain management
   • Physical therapy

Red Flags Requiring Urgent Evaluation

• Sudden onset of symptoms with motor weakness
• Associated urinary retention or bowel dysfunction
• Bilateral progressive symptoms
• Recent trauma
• Fever or signs of infection
• History of cancer

Follow-up Recommendations

• Patients with identified peripheral neuropathy should have regular follow-up
• Those with diabetic neuropathy should have comprehensive foot examinations at every visit 1
• Patients with vascular disease should have periodic vascular assessments

By following this systematic approach to the workup of burning and tingling in the legs, clinicians can identify the underlying cause and initiate appropriate treatment to address both symptoms and the primary condition.