What are the causes of neuropathy and dizziness?

Causes of Neuropathy and Dizziness

The most common causes of concurrent neuropathy and dizziness include diabetes mellitus (particularly diabetic autonomic neuropathy), vitamin B12 deficiency, neurotoxic medications, alcohol toxicity, and vestibular dysfunction. 1, 2

Diabetic Neuropathy and Associated Dizziness

Diabetic Peripheral Neuropathy

• Diabetes is the most common cause of neuropathy in the United States, affecting up to 50% of patients with type 1 and type 2 diabetes 2
• Symptoms typically include numbness, tingling, pain, and weakness in a length-dependent pattern 1
• Up to 50% of diabetic peripheral neuropathy may be asymptomatic but still increases risk for complications 1

Diabetic Autonomic Neuropathy

• Major cause of dizziness in diabetic patients with neuropathy 1
• Manifests as orthostatic hypotension (dizziness, lightheadedness, or weakness with standing) 1
• Other autonomic symptoms include:
  • Resting tachycardia 1
  • Syncope and exercise intolerance 1
  • Gastrointestinal disturbances (gastroparesis, constipation, diarrhea) 1
  • Genitourinary dysfunction 1
  • Sudomotor dysfunction (abnormal sweating) 1

Screening for Autonomic Neuropathy

• All patients with type 1 diabetes for ≥5 years and all patients with type 2 diabetes should be assessed annually for autonomic neuropathy 1
• Screening includes asking about symptoms of orthostatic intolerance, syncope, exercise intolerance, and gastrointestinal/urinary symptoms 1
• Further testing depends on affected organ systems and may include cardiovascular autonomic testing, sweat testing, urodynamic studies, or gastric emptying studies 1

Non-Diabetic Causes of Neuropathy and Dizziness

Vitamin and Mineral Deficiencies

• Vitamin B12 deficiency can cause both peripheral neuropathy and dizziness 1, 3
• Other vitamin deficiencies that may contribute include thiamine, vitamin E, and copper 3

Medication-Induced

• Neurotoxic medications (e.g., chemotherapy agents) 1, 3
• Ototoxic medications affecting both peripheral nerves and vestibular function 3
• Gabapentinoids can cause both peripheral neuropathy symptoms and dizziness as side effects 4

Toxic Causes

• Alcohol abuse is a common cause of both peripheral neuropathy and vestibular dysfunction 1, 5
• Industrial toxins and heavy metals 3

Other Medical Conditions

• Renal disease can cause both neuropathy and dizziness 1, 5
• Hypothyroidism 1, 5
• Malignancies (e.g., multiple myeloma, bronchogenic carcinoma) 1
• Infections (e.g., HIV) 1
• Inflammatory conditions (e.g., chronic inflammatory demyelinating neuropathy) 1, 5
• Vasculitis 1
• Inherited neuropathies 1, 5

Vestibular Dysfunction

• Present in nearly 60% of diabetic patients with peripheral neuropathy who complain of dizziness 6
• May occur independently of diabetic autonomic neuropathy 6

Predictors of Serious Neurological Causes

When evaluating patients with dizziness, certain factors predict central neurological causes:

• Age ≥65 years (OR=6.13) 7
• Ataxia symptoms (OR=11.39) 7
• Focal neurological symptoms (OR=11.78) 7
• History of previous stroke (OR=3.89) 7
• Diabetes mellitus (OR=3.57) 7

Diagnostic Approach

For Peripheral Neuropathy

• Small-fiber function: pinprick and temperature sensation 1
• Large-fiber function: vibration perception and 10-g monofilament 1
• Protective sensation: 10-g monofilament 1
• Electrophysiological testing or referral to a neurologist is rarely needed unless clinical features are atypical 1

For Autonomic Neuropathy

• Cardiovascular autonomic testing (heart rate variability with deep breathing) 1
• Orthostatic blood pressure measurements 1
• For gastrointestinal symptoms: gastric emptying studies, endoscopy 1
• For genitourinary symptoms: urodynamic studies 1

For Vestibular Dysfunction

• Videonystagmography for patients with dizziness 6

Treatment Considerations

For Diabetic Neuropathy

• Optimize glucose control to prevent or delay neuropathy development in type 1 diabetes and slow progression in type 2 diabetes 1
• Optimize weight, blood pressure, and serum lipid management 1
• For neuropathic pain: gabapentinoids, serotonin-norepinephrine reuptake inhibitors (duloxetine), tricyclic antidepressants, and sodium channel blockers 1
• For orthostatic hypotension: nonpharmacologic measures (adequate salt intake, compressive garments) and pharmacologic treatments 1

For Non-Diabetic Causes

• Treat the underlying condition (e.g., vitamin supplementation, medication adjustment) 3
• Address any reversible or iatrogenic causes 1

Important Pitfalls to Avoid

• Not all neuropathy in diabetic patients is due to diabetes; 10-50% may have additional causes 5
• Failing to screen for autonomic neuropathy in diabetic patients with peripheral neuropathy 1
• Overlooking medication side effects as potential causes 3
• Missing serious central neurological causes of dizziness, especially in older patients with ataxia or focal neurological symptoms 7