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Sensory Disorders: Large Fiber & Ataxic

Toxic Vitamin B6 cis-platinum Semi-synthetic penicillins Taxol Deficiency/ Malabsorption: Vitamin B12; Vitamin E Immune GALOP Syndrome Anti-MAG antibody syndrome Miller Fisher Syndrome Anti-GD1b antibody syndrome Sensory ganglionopathy Hu (Paraneoplastic) Sjögren's Idiopathic Infection: Syphilis - Tabes dorsalis Hereditary Recessive syndromes a-β-lipoproteinemia (Bassen-Kornzweig) Ataxia Telangectasia Friedreich's Ataxia Mitochondrial Dominant syndromes Sensory ataxic neuropathy Sensory ataxia (SNAX1): 8p12 Posterior column ataxia (Biemond) Sensory neuropathy with scoliosis (Robinson) SCA 4 Also see: Hereditary Sensory & Autonomic Neuropathies Mitochondrial: Sporadic Also see More pathology Large and Small Axon loss Neuropathies Ganglionopathies

Loss of large myelinated axons in peripheral nerve

Posterior column ataxia (Biemond)

• Epidemiology: 2 families
• Onset: 19 to 30 years
• Clinical features
  • Sensory loss
    • Large fiber modalities: Position & Vibration
    • Sensory ataxia: Limbs & Gait; Worse in dark
    • Pain & Temperature sensations: Preserved
    • Course: Progressive
  • Tendon reflexes: Absent
  • Plantar responses: Flexor
  • Scoliosis
• Pathology: Loss of large axons in dorsal root & posterior columns

Sensory neuropathy with scoliosis (Robinson)

• Epidemiology: 2 families
• Onset: 1st to 6th decades
• Clinical features
  • Sensory neuropathy
    • Sensory ataxia: Gait; Romberg positive
    • No ulcerating acropathy or pain
    • Tendon reflexes: Absent
  • No autonomic abnormality
  • Cranial nerves
    • Oculomotor dysfunction: 1 patient
    • Hearing loss: Occasional
  • Extensor plantar response: 1 patient
• Electrophysiology
  • SNAPS: Absent
  • Motor potentials: Normal
• Pathology: Loss of myelinated axons

Sensory ataxic neuropathy ¹

• Epidemiology: 2 generation Dutch family
• Clinical features
  • Onset: After 4th decade
  • Sensory
    • Large fiber loss
      • Vibration: Reduced or Absent
      • Proprioception
      • Distal > Proximal
    • Ataxia: Gait
    • Small fiber loss: Pain sensation mildly reduced
  • Strength: Normal
  • Reflexes: Reduced or absent in legs
  • Eyes: Square wave jerks
  • Course: Slow progression
• Laboratory
  • Nerve conduction
    • SNAP amplitudes: Reduced or Absent
    • Conduction Velocity: Normal
  • Pathology
    • Myelinated axons: Reduced to 10% of normal
    • No regenerating clusters or onion bulbs
  • Sensory evoked potentials: Often unobtainable or reduced amplitude

Toluidine blue stain Loss of large myelinated axons with relative preservation of small myelinated axons