What is the appropriate workup for a patient presenting with paresthesia (abnormal sensations such as tingling or numbness)?

Diagnostic Workup for Paresthesia

A thorough diagnostic approach for paresthesia should begin with identifying the distribution pattern, onset, and associated symptoms, followed by targeted neurological examination and appropriate testing based on suspected etiology.

Initial Assessment

History

• Distribution pattern: Determine if paresthesia is focal, multifocal, or generalized
• Onset and progression: Acute (within days), subacute, or chronic
• Associated symptoms: Weakness, pain, autonomic dysfunction, or other neurological deficits
• Risk factors: Diabetes, alcohol use, vitamin deficiencies, toxic exposures, trauma, or family history

Physical Examination

• Complete neurological assessment: Test all facial nerve branches including forehead to distinguish central from peripheral causes 1
• Sensory testing: Pinprick, temperature sensation (small-fiber function), vibration perception, and 10-g monofilament (large-fiber function) 2
• Motor testing: Check for weakness, atrophy, or fasciculations
• Reflexes: Deep tendon reflexes and pathological reflexes
• Vascular assessment: Pulses, skin temperature, and color changes

Diagnostic Algorithm Based on Distribution Pattern

1. Focal/Localized Paresthesia

• Entrapment neuropathies (most common cause):

  • Carpal tunnel syndrome (median nerve)
  • Cubital tunnel syndrome (ulnar nerve)
  • Peroneal nerve compression
  • Diagnostic tests: Nerve conduction studies, ultrasonography to visualize nerve enlargement 3

• Radiculopathy:

  • Diagnostic tests: MRI of affected spinal region
  • Physical findings: Dermatomal distribution, reflex changes

2. Bilateral/Symmetric Distal Paresthesia

• Polyneuropathy workup:
  • Laboratory tests: Glucose/HbA1c, vitamin B12, folate, thyroid function, complete blood count, comprehensive metabolic panel, serum protein electrophoresis 2, 3
  • Specialized tests: Consider nerve conduction studies/EMG

3. Facial Paresthesia

• Bell's palsy assessment:
  • Evaluate all facial nerve branches
  • Check for vesicular lesions, other cranial nerve deficits
  • Document eye closure ability 1
  • No routine laboratory testing or imaging unless specific alternative diagnoses are suspected 2

4. Acute/Rapidly Progressive Paresthesia

• Emergency evaluation for:
  • Guillain-Barré syndrome: Progressive ascending weakness with paresthesia
  • Stroke: When accompanied by unilateral weakness, speech changes
  • Acute limb ischemia: Check for 5 P's (pain, pallor, paresthesia, paralysis, pulselessness) 2

Special Considerations

When to Order Imaging

• MRI/CT indicated when:
  • Suspected central nervous system lesion
  • Progressive neurological deficits
  • Focal neurological signs
  • Atypical presentation or lack of improvement 1

When to Order Laboratory Tests

• Targeted testing based on suspected etiology:
  • Diabetes: Fasting glucose, HbA1c
  • Vitamin deficiencies: B12, folate levels
  • Thyroid dysfunction: TSH, free T4
  • Inflammatory/autoimmune: ESR, CRP, ANA
  • Infection: Consider Lyme disease testing in endemic areas 4

Red Flags Requiring Urgent Evaluation

• Acute onset with rapidly progressive symptoms
• Associated weakness or autonomic dysfunction
• Asymmetric or proximal distribution
• Severe pain
• Signs of systemic illness 3

Follow-up Recommendations

• Reassessment if symptoms worsen or fail to improve
• Referral to specialists (neurology, rheumatology) for:
  • Diagnostic uncertainty
  • Progressive symptoms
  • Failed initial management 2

By following this systematic approach, clinicians can efficiently identify the underlying cause of paresthesia and implement appropriate management strategies to address morbidity and improve quality of life.