Other Polyneuropathies

  • The following causes all result in axonal loss

Idiopathic

  • Age-related

Metabolic neuropathies

  • Diabetes mellitus - most common cause of neuropathies in developed countries
  • Uraemia
  • Hepatic disease
  • Thyroid disease
  • Acute intermittent porphyria
  • Amyloidosis
  • Vitamin deficiencies
    • B12
    • Folate deficiencies
    • Thiamine (vitamin B1) - Wernicke–Korsakoff’s syndrome
      • Thiamine-responsive encephalopathy due to damage in the brainstem and its connections

Toxic neuropathies

  • Alcohol - polyneuropathy, mainly in the lower limbs, occurs with chronic alcohol use
  • Amiodarone
  • Phenytoin
  • Chemotherapy (cisplatin/vincristine)

Neuropathy in cancer

  • Polyneuropathy is seen as a paraneoplastic syndrome
  • Occurs in myeloma and other plasma cell dyscrasias

Neuropathies in systemic diseases

  • Vasculitic neuropathy occurs in SLE, polyarteritis nodosa, granulomatosis with eosinophilia, and rheumatoid disease

Autonomic neuropathy

  • Autonomic neuropathy causes postural hypotension, urinary retention, erectile dysfunction, nocturnal diarrhoea, diminished sweating, impaired pupillary responses and cardiac arrhythmias
  • Chronic - diabetes, amyloidosis, hereditary
  • Acute - CBS, porphyria

Management

  • Treat cause
  • Symptomatic treatment - physiotherapy, orthotics, neuropathic pain relief
  • Vasculitic neuropathy can be managed with pulsed IV methylprednisolone + cyclophosphamide