Peripheral Neuropathy

Peripheral Neuropathy 2018-01-30T16:37:12+08:00

Approach

  1. What systems are involved? Motor, sensory, autonomic or combinations?
    • Pure motor
      • Motor neurone disease (LMN variant)
      • Multifocal motor neuropathy
      • Spinal muscular atrophy
      • Kennedy’s disease
      • Motor-predominant CIDP
      • Lead neuropathy
      • Acute porphyric neuropathy
    • Sensory predominant – see (3) below
    • Motor and sensory
      • AIDP
      • CIDP
      • Vasculitic neuropathy
    • Autonomic predominant
      • Diabetic neuropathy
      • Amyloidosis
      • AIDP
  1. What is the distribution of weakness? Distal, proximal, generalized, asymmetrical or symmetrical?
    • Distal symmetrical weakness in axonal (length-dependent) neuropathy
      • Infections
        • Human immunodeficiency virus
        • Lyme disease
        • Leprosy
        • Herpes zoster
        • Hepatitis C
      • Diabetic neuropathy
      • Alcoholic neuropathy
      • Drug-induced neuropathy
        • Antibiotics: isoniazid, nitrofurantoin, Ethambutol, metronidazole
        • Chemotherapy: vincristine, cisplatin, etoposide, docetaxel
        • Antivirals: zidovudine, stavudine
        • Immunosuppressants: TNF-α antagonists, tacrolimus
        • Pyridoxine toxicity (doses exceeding 50mg/day)
      • Inherited neuropathies
        • Charcot-Marie-Tooth
        • Hereditary neuropathy with susceptibility to pressure palsy
      • B12 deficiency
    • Proximal and distal weakness
      • CIDP
      • AIDP
      • Guillain-Barré syndrome
    • Asymmetrical
      • Radiculopathy
      • Plexopathy
      • Mononeuritis multiplex
      • Tumours of nerve sheath or sarcomas causing compression
      • Compression neuropathy
      • Diabetic amyotrophy
      • Leprosy
  1. What modality of sensation is involved? Pain and temperature or proprioceptive loss?
    • Pain – caused by small fiber involvement
      • Diabetes
      • Amyloidosis
      • Fabry disease
      • Inflammatory disorders
        • Vasculitic neuropathy (usually with mononeuritis multiplex)
        • AIDP
    • Proprioceptive loss
      • Asymmetrical – sensory ganglionopathy
        • Paraneoplastic, usually associated with anti-Hu antibodies
        • Sjögren’s syndrome
      • Symmetrical
        • AIDP
        • IgM paraprotein demyelinating neuropathy
        • Degeneration of dorsal column – not peripheral neuropathy
          • B12 deficiency
          • Tabes dorsalis
  1. Is there any evidence of upper motor neurone involvement?
    • Motor neurone disease
    • B12 deficiency
    • Friedreich’s ataxia
    • Taboparesis
    • Cervical myelopathy
    • Two pathologies: peripheral neuropathy with UMN lesion, e.g. stroke
  2. What is the temporal evolution? Acute, sub-acute, chronic (wasting)
  3. Is there any evidence for a hereditary neuropathy? Family history, skeletal deformities, pressure palsies

Relevant physical signs

  • Inspection
    • Wasting
    • Fasciculations
    • Diabetic dermopathy
    • Vasculitic rashes (purpura, livedo reticularis)
    • Hyperpigmentation (POEMS syndrome)
    • Oral ulcers (Behcet’s disease, HIV, SLE)
    • Hair loss over the extremities (lead poisoning, length-dependent neuropathies)
    • Deformities – pes cavus (CMT), Charcot foot
  • Limbs
    • Tone: flaccid
    • Reflexes: diminished or absent
    • Power: distribution of weakness
    • Sensation
      • Which sensory modality is affected
      • Demonstrate length-dependency (polyneuropathy)
      • Pattern of innervation in mononeuritis
      • Dermatomes involved if radiculopathy or plexopathy
    • Coordination normal unless too weak to test
  • Ask for:
    • Vitals and postural blood pressure (dysautonomia)
    • Examine the cranial nerves

 Investigations

  • Nerve conduction studies to confirm diagnosis
  • Consider magnetic resonance imaging of the spine in radiculopathies or plexopathies
  • Fasting blood glucose, HbA1c measurement
  • Vitamin B12 with methalmalonic acid and homocysteine measurement
  • Consider evaluation for connective tissue disease if history and clinical findings correlate
    • ANA
    • Anti-dsDNA
    • ANCA
    • Cryoglobulins secondary to hepatitis C
  • In pure motor neuropathies, consider anti-GM1 ganglioside antibodies for MMN
  • Consider age-appropriate malignancy screening and anti-Hu antibodies for paraneoplastic syndrome
  • If autonomic neuropathy dominant: consider rectal fat pad biopsy for amyloidosis
  • Consider genetic testing if not previously done in the family

Management

  • Multidisciplinary team approach
  • Patient education
  • Physiotherapy and occupational therapy to preserve and maximize function
  • Analgesia for pain
  • Orthotics / walking aids as necessary

Peripheral Neuropathy

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