What is the initial workup for a patient presenting to the Emergency Department (ED) with lateral thigh, calf, and foot tingling?

Initial Workup for Lateral Thigh, Calf, and Foot Tingling in the Emergency Department

The initial workup for a patient presenting with lateral thigh, calf, and foot tingling should include a focused neurovascular assessment, laboratory studies, and consideration of peripheral artery disease as a potential cause, with immediate imaging if stroke is suspected.

Neurological Assessment

• Begin with a standardized neurological examination to determine focal neurological deficits and assess severity, using a validated tool such as the National Institutes of Health Stroke Scale (NIHSS) if stroke is suspected 1
• Evaluate for sensory deficits using:
  • Pinprick sensation assessment
  • Vibration threshold testing with a 128-Hz tuning fork
  • Light touch perception using a 10-g monofilament
  • Ankle reflex testing 1
• Start assessment distally (dorsal aspect of the hallux) on both sides and move proximally until threshold is detected 1
• Document the distribution pattern of sensory symptoms to help differentiate between peripheral nerve entrapment, radiculopathy, or more central causes 2

Vascular Assessment

• Perform ankle-brachial index (ABI) measurement, as an ABI <0.90 is diagnostic for lower extremity arterial disease (LEAD) regardless of symptoms 1
• If ABI is elevated (>1.40), conduct other non-invasive tests such as toe-brachial index or duplex ultrasound 1
• Assess for peripheral pulses, particularly dorsalis pedis and posterior tibial 1
• Evaluate for signs of chronic limb-threatening ischemia, including rest pain, tissue loss, or gangrene 1

Laboratory Studies

• Order acute blood work including:
  • Electrolytes
  • Random glucose
  • Complete blood count
  • Coagulation status (INR, aPTT)
  • Creatinine 1
• Consider HbA1c if diabetes is suspected, as diabetic peripheral neuropathy is a common cause of lower extremity tingling 1

Imaging Considerations

• If stroke is suspected based on acute onset and other neurological findings, immediate brain imaging (CT or MRI) should be performed 1
• For suspected peripheral artery disease with below-the-knee symptoms, consider vascular imaging including duplex ultrasound as first-line 1
• If symptoms suggest radiculopathy or spinal pathology, MRI of the lumbar spine may be indicated 3

Differential Diagnosis Considerations

Peripheral Causes

• Peripheral nerve entrapment syndromes:
  • Lateral cutaneous nerve of the calf entrapment may present with lateral calf tingling 4
  • Meralgia paresthetica (lateral femoral cutaneous nerve entrapment) causes anterolateral thigh symptoms 3

Vascular Causes

• Peripheral artery disease, which can present with various leg symptoms including tingling, especially during activity 1
• Chronic limb-threatening ischemia may present with sensory changes 1

Neurological Causes

• Diabetic peripheral neuropathy typically presents with distal, symmetric sensory symptoms 1
• Lumbar radiculopathy, particularly involving L2-L3 nerve roots, can cause thigh symptoms 3
• Sacroiliac joint disorders can refer symptoms to the lateral thigh and calf 5
• Stroke should be considered in the differential diagnosis, especially with acute onset 1

Special Considerations

• For elderly patients, consider a more comprehensive assessment as they are at higher risk for multiple pathologies 1
• In patients with diabetes, annual screening for peripheral neuropathy is recommended, and findings during the ED visit may represent previously undiagnosed neuropathy 1
• Be aware that tingling sensations can be induced by both peripheral pathology and higher cognitive processes such as attention and expectation 6

Next Steps Based on Initial Findings

• If signs of acute limb ischemia are present (pain, pallor, pulselessness, poikilothermia, paresthesias, paralysis), immediate vascular surgery consultation is warranted 1
• If stroke is suspected, follow acute stroke protocols including consideration of thrombolytic therapy if within the appropriate time window 1
• For suspected peripheral neuropathy without acute concerns, appropriate referral for outpatient follow-up with neurology should be arranged 1