What is the diagnosis and treatment for a patient experiencing numbness and tingling sensation in both hands, possibly related to conditions such as carpal tunnel syndrome or vitamin B12 deficiency?

Bilateral Hand Numbness and Tingling: Diagnosis and Management

Immediate Life-Threatening Exclusions

Rule out cervical cord pathology and Guillain-Barré syndrome first, as these require urgent intervention and can present with bilateral hand symptoms. 1, 2

• Obtain urgent MRI of the entire cervical spine if the patient has any lower extremity symptoms, burning dysesthesias in the forearms, or upper motor neuron signs (hyperreflexia, clonus, extensor plantar responses). 1, 2
• Central cord syndrome presents with greater upper extremity than lower extremity weakness, bilateral hand numbness, and burning dysesthesias in the forearms. 1, 2
• Assess for rapidly progressive bilateral weakness with paresthesias to exclude Guillain-Barré syndrome, which requires immediate respiratory monitoring as 20% develop respiratory failure. 2
• Check for areflexia/hyporeflexia and recent infection within 6 weeks (Campylobacter, CMV, Mycoplasma) if Guillain-Barré is suspected. 2

Primary Diagnostic Algorithm

Step 1: Characterize the Distribution Pattern

• Bilateral symmetric "glove" distribution starting in fingers suggests peripheral neuropathy rather than carpal tunnel syndrome, which typically causes nocturnal symptoms in the thumb, index, middle, and radial ring fingers. 3, 4, 5
• Carpal tunnel syndrome causes numbness specifically in the median nerve distribution (thumb, index, middle, and radial half of ring finger), often worse at night. 4, 5
• True bilateral carpal tunnel syndrome is less common than peripheral neuropathy presenting with bilateral hand symptoms. 6

Step 2: Perform Targeted Physical Examination

• Test pinprick and temperature sensation (small fiber function) and vibration with 128-Hz tuning fork (large fiber function) starting at the toes and moving proximally. 3, 1
• Perform the Durkan maneuver (firm digital pressure across the carpal tunnel) which is 64% sensitive and 83% specific for carpal tunnel syndrome. 5
• Check ankle reflexes and assess for lower extremity involvement, as a stocking-glove pattern starting distally suggests systemic peripheral neuropathy. 3, 7
• Examine for muscle weakness, particularly thumb opposition weakness in carpal tunnel syndrome or distal foot muscle atrophy in peripheral neuropathy. 3, 5

Step 3: Order Essential Laboratory Tests

• Fasting glucose and hemoglobin A1c to assess for diabetes mellitus, the most common cause of peripheral neuropathy. 3, 7
• Vitamin B12 level, as deficiency causes peripheral neuropathy and must be excluded. 3
• Thyroid function tests (TSH) to rule out hypothyroidism-related neuropathy. 3, 7
• Creatinine and eGFR to assess for uremic neuropathy. 2
• Consider hepatitis C testing if risk factors present, as HCV-related neuropathy occurs in up to 50% of infected patients. 2

Step 4: Obtain Electrodiagnostic Testing When Indicated

• Nerve conduction studies are more than 80% sensitive and 95% specific for carpal tunnel syndrome and should be ordered if carpal tunnel is suspected or if the diagnosis remains unclear after initial evaluation. 5
• Electrodiagnostic testing helps differentiate carpal tunnel syndrome from cervical radiculopathy, peripheral neuropathy, or proximal nerve compression. 3, 5
• In peripheral neuropathy, sensory nerve action potentials show reduced amplitude with preserved or mildly reduced conduction velocity in axonal patterns. 3

Treatment Based on Diagnosis

For Carpal Tunnel Syndrome (Unilateral or Bilateral)

• Begin with wrist splinting in neutral position, particularly at night, which provides temporary symptom relief. 5
• Local corticosteroid injection into the carpal tunnel provides temporary relief and is appropriate first-line therapy for mild to moderate cases. 4, 5
• Surgical carpal tunnel release (open or endoscopic) is the only definitive cure and should be offered to patients with moderate to severe symptoms, persistent symptoms despite conservative treatment, or evidence of thenar muscle weakness. 4, 5

For Peripheral Neuropathy

Duloxetine 60 mg once daily is the first-line pharmacologic treatment for painful peripheral neuropathy, with option to increase to 120 mg daily if needed. 1, 7

Disease-Modifying Management

• Optimize glycemic control in diabetic neuropathy with individualized HbA1c targets to prevent progression, though this does not reverse existing neuronal loss. 3, 1, 7
• Correct vitamin B12 deficiency if identified, as this is a reversible cause of neuropathy. 3
• Treat thyroid dysfunction if present. 3, 7

Symptomatic Management

• Prescribe pregabalin or gabapentin as alternative first-line agents for neuropathic pain. 7
• Tricyclic antidepressants (amitriptyline 25-75 mg/day) are effective but have significant anticholinergic side effects. 7
• Recommend regular physical activity, which has been demonstrated to improve neuropathic pain. 1, 7
• Offer acetaminophen, NSAIDs, or acupuncture for associated pain. 1, 7

For Chemotherapy-Induced Peripheral Neuropathy

• Duloxetine is the only agent with appropriate evidence for established painful chemotherapy-induced peripheral neuropathy, though benefit is limited. 7
• Physical activity should be offered to all patients with chemotherapy-induced neuropathy. 1, 7

Critical Pitfalls to Avoid

• Do not assume bilateral hand numbness is carpal tunnel syndrome without confirming median nerve distribution and obtaining electrodiagnostic testing. True bilateral carpal tunnel syndrome is less common than peripheral neuropathy. 5, 6
• Do not miss cervical cord pathology by failing to examine lower extremities and check for upper motor neuron signs in patients with bilateral hand symptoms. 1, 2
• Do not attribute symptoms to occupation without excluding intrinsic factors such as diabetes, obesity, and vitamin deficiencies first. 4
• Do not delay urgent imaging and neurosurgical consultation if any red flags for central pathology are present (lower extremity involvement, burning dysesthesias, upper motor neuron signs). 1, 2
• Screen diabetic patients annually for peripheral neuropathy starting at diagnosis of type 2 diabetes and 5 years after diagnosis of type 1 diabetes. 3, 7