What is the initial evaluation and treatment approach for a patient presenting with bilateral paresthesia of the hands and feet with an unknown etiology?

Evaluation and Management of Bilateral Paresthesia in Hands and Feet

The initial evaluation for bilateral paresthesia of hands and feet should include assessment of small and large fiber function, followed by targeted laboratory testing for common treatable causes including diabetes, vitamin B12 deficiency, hypothyroidism, and renal disease. 1

Initial Neurological Assessment

Physical Examination

• Small-fiber function assessment:
  • Pinprick sensation
  • Temperature sensation
• Large-fiber function assessment:
  • Vibration perception using 128-Hz tuning fork
  • 10-g monofilament testing (particularly important for protective sensation)
  • Lower-extremity reflexes
• Motor function assessment:
  • Muscle strength testing (to identify any associated weakness)
  • Deep tendon reflexes

The neurological examination should focus on identifying patterns of sensory loss, as the most common early symptoms of peripheral neuropathy include pain and dysesthesia (unpleasant sensations of burning and tingling), often in a "stocking and glove" distribution 2, 3.

Laboratory Evaluation

Initial laboratory testing should include:

• Complete blood count
• Comprehensive metabolic profile
• Fasting blood glucose or HbA1c
• Vitamin B12 level
• Thyroid-stimulating hormone (TSH)
• Erythrocyte sedimentation rate
• Serum protein electrophoresis with immunofixation (if monoclonal gammopathy suspected) 1, 3

Common Etiologies to Consider

1. Diabetic peripheral neuropathy

   • Most common cause of bilateral paresthesia
   • Assess for other diabetes symptoms and risk factors 2

2. Nutritional deficiencies

   • Vitamin B12 deficiency
   • Other B vitamin deficiencies 4, 3

3. Metabolic disorders

   • Hypothyroidism
   • Renal disease 1

4. Toxic causes

   • Alcohol abuse
   • Medication-induced (chemotherapy agents, certain antibiotics)
   • Environmental toxins 2, 1

5. Inflammatory/immune-mediated

   • Chronic inflammatory demyelinating polyneuropathy (CIDP)
   • Vasculitis 1

6. Compression neuropathies

   • Carpal tunnel syndrome (for hand symptoms)
   • Tarsal tunnel syndrome (for foot symptoms) 5, 6

7. Other causes

   • Hereditary neuropathies
   • Infections (HIV)
   • Malignancies (multiple myeloma, bronchogenic carcinoma)
   • Psychogenic causes (anxiety, depression) 1, 7

Treatment Approach

For Diabetic Neuropathy (if identified)

1. Optimize glucose control

   • Prevents development in type 1 diabetes
   • Slows progression in type 2 diabetes 2, 1

2. Pain management

   • First-line medications:
     • Pregabalin
     • Duloxetine
     • Gabapentin 2

3. Foot care

   • Comprehensive foot evaluation at least annually
   • Proper footwear
   • Daily foot inspection 2

For Non-Diabetic Causes

• Treat the underlying condition when identified (e.g., vitamin supplementation for deficiencies, thyroid hormone replacement for hypothyroidism)
• Symptomatic treatment for pain using similar medications as for diabetic neuropathy:
  • Gabapentinoids (pregabalin, gabapentin)
  • Serotonin-norepinephrine reuptake inhibitors (duloxetine)
  • Tricyclic antidepressants (use with caution in elderly or those with cardiovascular disease) 1, 3

When to Consider Referral

Consider referral to a neurologist when:

• Symptoms rapidly progress
• Initial evaluation is inconclusive
• Atypical presentation
• No response to initial treatment
• Electrodiagnostic studies are needed 1, 3

Important Considerations

• Don't miss non-diabetic causes even in patients with diabetes, as diabetic neuropathy is a diagnosis of exclusion 1
• Electrophysiological testing is rarely needed except when clinical features are atypical or diagnosis is unclear 2
• Screen for autonomic neuropathy symptoms (orthostatic hypotension, gastroparesis, sexual dysfunction) which can significantly impact mortality and quality of life 2
• Monitor treatment efficacy using standardized pain scales and assess for medication side effects 1

By following this systematic approach to evaluation and treatment, the underlying cause of bilateral paresthesia can often be identified and appropriately managed to improve symptoms and quality of life.