What is the most common cause of neuropathy at night?

Diabetic Peripheral Neuropathy is the Most Common Cause of Neuropathy at Night

Diabetic peripheral neuropathy (DPN) is the most common cause of neuropathy at night, characterized by pain that is typically more severe during nighttime hours and often disrupts sleep. 1, 2

Characteristics of Nighttime Neuropathic Pain

• Pain from DPN is characteristically more severe at night, resulting in significant sleep disturbance 1
• Severely affected patients often complain of constant fatigue due to sleep deprivation 1
• Common descriptors of neuropathic pain include:
  • Burning sensation
  • "Electrical shock" type shooting pain
  • "Stabbing" or "knife-like" pains
  • Uncomfortable tingling (paresthesia)
  • Contact pain from bedclothes (allodynia)
  • Sensations of altered temperature (feet feeling very warm or cold)
  • Aching feelings and cramp-like sensations 1

Epidemiology and Prevalence

• DPN is present in up to 50% of all diabetic patients with long-duration disease 1
• Up to 50% of patients with DPN may experience painful symptoms 1
• Peripheral neuropathy prevalence is estimated at 1% in the general population, increasing to 7% in persons over 65 years 3
• Diabetes is the most common identifiable cause of peripheral neuropathy in developed countries 4

Diagnostic Approach for Nighttime Neuropathy

1. Clinical Assessment:

   • Screen for DPN using simple clinical tests:
     • Pinprick sensation
     • Vibration threshold using 128-Hz tuning fork
     • Light touch perception using 10-g monofilament
     • Ankle reflexes 1, 2
   • Assessment should follow typical DPN pattern, starting distally (dorsal aspect of hallux) on both sides and moving proximally 1

2. Differential Diagnosis:

   • Rule out other causes of neuropathy, even in patients with diabetes:
     • Neurotoxic medications
     • Heavy metal poisoning
     • Alcohol abuse
     • Vitamin B12 deficiency
     • Renal disease
     • Chronic inflammatory demyelinating neuropathy
     • Inherited neuropathies
     • Vasculitis 1, 2
   • Distinguish from Restless Legs Syndrome (RLS), which:
     • Affects 21% of individuals with type 2 diabetes
     • Has similar symptoms (numbness, tingling)
     • Typically occurs at night or at rest
     • Results in an urge to move the legs 5

Management of Nighttime Neuropathic Pain

1. First-line Pharmacological Treatments:

   • Tricyclic antidepressants (TCAs)
   • Serotonin and noradrenaline reuptake inhibitor duloxetine
   • Anticonvulsants pregabalin and gabapentin 1, 2

2. Second-line Approaches:

   • Opiates such as tramadol
   • Morphine and oxycodone-controlled release 1
   • α2δ Ligands (gabapentin enacarbil) 6

3. Glycemic Control:

   • Tight glycemic control is the only strategy convincingly shown to:
     • Prevent or delay DPN development in type 1 diabetes
     • Slow progression in some patients with type 2 diabetes 1, 2

4. Foot Care:

   • Comprehensive foot examination annually
   • Daily foot inspection
   • Proper footwear
   • Regular foot washing 2
   • More frequent examinations for patients with insensate feet, foot deformities, or ulcers 1

Monitoring and Follow-up

• Use standardized pain scales to assess treatment efficacy
• Monitor for medication side effects
• Follow-up frequency based on risk classification:
  • Low risk: every 6-12 months
  • Moderate risk: every 3-6 months
  • High risk: every 1-3 months 2

Important Considerations

• Sleep disturbance from neuropathic pain significantly impacts quality of life and daily activities 1
• Chronic painful DPN is associated with depression, anxiety, and profound sleep loss 1
• Relief of pain improves sleep, and the degree of sleep loss predicts response to analgesics 1
• Electrophysiological testing or referral to a neurologist is rarely needed except when clinical features are atypical or diagnosis is unclear 1, 2
• Don't overlook autonomic neuropathy symptoms, which can significantly impact mortality 2