What is the next step in evaluating and managing a 76-year-old patient with balance issues, weakness, gait instability, numbness, and tingling in the legs?

Diagnostic Workup for Peripheral Neuropathy in a 76-Year-Old

Order a comprehensive metabolic panel, fasting glucose, HbA1c, vitamin B12, TSH, complete blood count, and serum protein electrophoresis with immunofixation as initial laboratory testing. 1

Initial Laboratory Evaluation

The combination of balance issues, weakness, gait instability, numbness, and tingling in the legs in a 76-year-old strongly suggests peripheral neuropathy with loss of protective sensation (LOPS). 2 The priority is identifying treatable causes through targeted laboratory work.

Essential First-Line Tests

• Fasting blood glucose and HbA1c: Diabetes is the most common identifiable cause of peripheral neuropathy, and diabetic peripheral neuropathy (DPN) was found to be a component cause in 78% of patients with ulcerations. 2, 1
• Vitamin B12 level: Nutritional deficiencies are common reversible causes. 2, 1
• Complete blood count (CBC): Screens for hematologic abnormalities. 1
• Comprehensive metabolic profile: Evaluates renal function and electrolyte abnormalities. 1
• Thyroid-stimulating hormone (TSH): Hypothyroidism can cause neuropathy. 1
• Serum protein electrophoresis with immunofixation: Detects paraproteinemia and monoclonal gammopathies. 2, 1

Additional Screening Based on Risk Factors

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): If the patient reports scalp tenderness, jaw claudication, or pain, immediately check these to evaluate for giant cell arteritis. 2
• Serum ferritin: If restless legs syndrome symptoms are present (urge to move legs, worse at rest, relieved by movement, worse in evening), obtain ferritin as values <50 ng/mL suggest iron deficiency-related restless legs syndrome. 2

Physical Examination Priorities

Neurological Assessment

Perform a focused neurological examination emphasizing: 2

• 10-g monofilament testing: The most useful test to diagnose LOPS. 2
• At least one additional sensory test: Pinprick, temperature, vibration (128-Hz tuning fork), or ankle reflexes. 2
• Motor strength testing: Assess for distal weakness or atrophy, which indicates later-stage neuropathy. 1
• Gait and balance assessment: Observe standing balance with eyes open and closed, as gait instability increases fall risk 12-fold in symptomatic older adults. 2

Vascular Assessment

• Pedal pulse palpation: Assess dorsalis pedis and posterior tibial pulses. 2
• Capillary refill time, rubor on dependency, pallor on elevation, and venous filling time: Screen for peripheral arterial disease (PAD). 2
• If decreased/absent pulses or claudication symptoms: Refer for ankle-brachial index with toe pressures. 2

Falls Risk Assessment

Given the 12-fold increased fall risk with dizziness in older adults and the high prevalence of falls in elderly patients with balance disorders, conduct immediate falls screening: 2

• Have you fallen in the past year? How many times?
• Do you feel unsteady when standing or walking?
• Do you worry about falling? 2

If positive responses, consider detailed assessment with Get Up and Go test, Tinetti Balance Assessment, or Berg Balance Scale. 2

When to Order Neuroimaging or Electrodiagnostic Studies

Do not routinely order MRI or nerve conduction studies initially. 1 These are reserved for specific indications:

Indications for Neuroimaging (MRI spine with/without contrast)

• Other cranial neuropathies present 2
• Signs of elevated intracranial pressure 2
• Rapidly progressive symptoms 2
• Asymmetric presentation suggesting radiculopathy or plexopathy 2
• Concern for spinal cord compression (especially with bilateral symptoms, upper motor neuron signs, or bowel/bladder dysfunction) 2

Indications for Electrodiagnostic Studies (EMG/NCS)

• Initial laboratory evaluation is inconclusive 1
• Need to differentiate axonal from demyelinating neuropathy 1
• Asymmetric or focal deficits suggesting mononeuropathy 2
• Consider neurology referral if these studies are needed 2, 1

Common Pitfalls to Avoid

• Do not order extensive neuroimaging before basic laboratory work: In elderly patients with vasculopathic risk factors (hypertension, diabetes, hyperlipidemia), evaluation may be limited to blood pressure, glucose, and HbA1c initially. 2
• Do not miss giant cell arteritis: In any elderly patient with scalp tenderness, jaw claudication, or pain, immediately check ESR and CRP before proceeding with other workup. 2
• Do not overlook medication-induced neuropathy: Review medications for agents that worsen neuropathy (opioids, anticholinergics, tricyclic antidepressants). 2
• Do not ignore fall risk: Address home safety and supervision needs immediately, as 53% of elderly patients with vestibular disorders (including balance issues) had fallen in the past year. 2

Management Considerations While Awaiting Results

• Assess for diabetic foot complications: If diabetes is suspected, inspect feet for skin integrity, deformities, and ulcers at this visit. 2
• Initiate fall prevention counseling: Assess home safety and consider activity restrictions until diagnosis is established. 2
• Screen for autonomic dysfunction: Ask about orthostatic symptoms, as orthostatic hypotension commonly coexists with peripheral neuropathy in elderly patients. 2