What other testing is recommended to evaluate paresthesias?

Diagnostic Testing for Paresthesias

For patients presenting with paresthesias, a comprehensive neurological evaluation should be followed by targeted diagnostic testing based on suspected etiology, including electrodiagnostic studies, laboratory testing, and imaging when indicated by clinical findings. 1, 2

Initial Clinical Assessment

• Neurological examination: Assess for:

  • Distribution pattern (stocking-glove, dermatomal, or focal)
  • Associated motor weakness or atrophy
  • Deep tendon reflexes
  • Sensory deficits (light touch, vibration, proprioception)
  • Cranial nerve involvement
  • Signs of ataxia or coordination problems 1

• Timing and progression:

  • Sudden vs. gradual onset
  • Progressive vs. stable symptoms
  • Intermittent vs. constant 2

Laboratory Testing

Laboratory testing should be targeted based on clinical suspicion rather than ordered routinely 1:

• First-line laboratory tests:

  • Complete blood count
  • Comprehensive metabolic panel
  • Fasting blood glucose
  • HbA1c
  • Vitamin B12 level
  • Thyroid-stimulating hormone 3, 4

• Second-line laboratory tests (based on clinical suspicion):

  • Erythrocyte sedimentation rate
  • Serum protein electrophoresis with immunofixation
  • Lyme disease serology (in endemic areas)
  • HIV testing
  • Heavy metal screening
  • Vasculitis panel 3, 4

Electrodiagnostic Studies

• Nerve conduction studies (NCS): To differentiate between:

  • Axonal neuropathy
  • Demyelinating neuropathy
  • Mixed neuropathy
  • Mononeuropathy vs. polyneuropathy 5, 3

• Electromyography (EMG): To assess:

  • Denervation
  • Reinnervation
  • Distribution of nerve involvement
  • Chronicity of the process 3, 4

Imaging Studies

Imaging should not be performed routinely but reserved for specific clinical scenarios 1:

• MRI of the brain/spine: Indicated for:

  • Suspected central nervous system lesions
  • Progressive symptoms
  • Asymmetric findings
  • Associated neurological deficits 6

• Ultrasound: Useful for:

  • Nerve entrapment syndromes
  • Nerve tumors
  • Inflammatory neuropathies 4

Specialized Testing

• Cerebrospinal fluid analysis: Consider for:

  • Suspected Guillain-Barré syndrome
  • Chronic inflammatory demyelinating polyneuropathy
  • Infectious or inflammatory causes 3

• Genetic testing: Consider for:

  • Family history of neuropathy
  • Early onset symptoms
  • Slowly progressive course 1, 4

• Nerve biopsy: Reserved for:

  • Suspected vasculitis
  • Amyloidosis
  • Atypical presentations
  • When diagnosis remains unclear after other testing 3, 4

Common Pitfalls and Caveats

• Avoid routine laboratory testing in all patients with paresthesias; instead, tailor testing to clinical presentation 1
• Don't rely solely on imaging studies without electrodiagnostic confirmation for peripheral nerve disorders 1
• Remember that 25-46% of peripheral neuropathies remain idiopathic despite extensive testing 4
• Consider referral to a neurologist when:
  • Diagnosis remains unclear
  • Symptoms progress rapidly
  • Symptoms are severe or disabling
  • Initial treatments fail 6, 4

By following this systematic approach to diagnostic testing for paresthesias, clinicians can efficiently identify the underlying cause and initiate appropriate treatment to improve patient outcomes.