What is the recommended workup for a patient with a single episode of facial numbness?

Recommended Workup for a Single Episode of Facial Numbness

A patient with a single episode of facial numbness should undergo targeted diagnostic testing based on clinical suspicion rather than routine laboratory or imaging studies, with particular attention to ruling out stroke in the acute setting. 1

Initial Assessment

Stroke Evaluation (Urgent)

• If facial numbness is sudden in onset, particularly when accompanied by other neurological symptoms, stroke must be ruled out first
• Use validated stroke assessment tools such as:
  • Cincinnati Prehospital Stroke Scale (CPSS) - assess for facial droop, arm weakness, and speech abnormalities 2
  • Los Angeles Prehospital Stroke Screen (LAPSS) 2
• If stroke is suspected, immediate emergency evaluation is warranted as time-sensitive interventions may be indicated

Focused History

• Timing: Sudden vs. gradual onset
• Distribution: Unilateral vs. bilateral, specific areas affected
• Associated symptoms:
  • Weakness (especially unilateral)
  • Visual changes
  • Speech difficulties
  • Headache
  • Dizziness/vertigo
  • Hearing changes or hyperacusis
  • Changes in taste or lacrimation

Physical Examination

• Complete neurological examination focusing on:
  • Cranial nerve function (particularly trigeminal and facial nerves)
  • Motor and sensory function
  • Coordination
  • Presence of other neurological deficits

Diagnostic Testing

Laboratory Testing

• Targeted laboratory testing based on clinical suspicion rather than routine panels 1
• Consider:
  • Complete blood count
  • Electrolytes and renal function
  • Random glucose or HbA1c
  • Vitamin B12 levels when clinically indicated
  • Lyme disease serology in endemic areas 2

Neuroimaging

• Not recommended routinely for isolated facial numbness without other concerning features 1
• Indicated for:
  • Focal neurological deficits
  • Sudden onset with concern for TIA/stroke
  • Progressive symptoms
  • Associated headache
  • Altered mental status
  • History of malignancy or immunocompromise
  • No improvement after 3 months 2

Imaging Modalities When Indicated

• MRI with contrast of the entire course of the facial nerve is the imaging test of choice 2
• Should include both the internal auditory canal and face to image the whole course of the facial nerve
• CT with contrast if MRI is contraindicated 2

Red Flags Requiring More Extensive Workup

• Bilateral facial numbness
• Progressive symptoms
• Associated with other cranial nerve deficits
• No improvement after 3 months
• History of malignancy (particularly head, neck, or cutaneous) 3
• Immunocompromised status

Important Considerations

• Facial numbness can be a concerning symptom with potentially serious underlying causes
• In a case series of patients presenting to ophthalmology with facial numbness, 71% had neoplastic pathology and 57% mortality 4
• Bell's palsy accounts for approximately 70% of facial nerve palsies but is a diagnosis of exclusion 1
• Avoid premature closure or anchoring bias by considering the full differential diagnosis 3

Follow-up

• All patients with facial numbness should have follow-up to ensure resolution of symptoms
• If symptoms persist beyond 3 months, additional workup including neuroimaging is indicated 2