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Sensory involvement: Proximal

• Neuronopathies
  • Paraneoplastic (anti-Hu)
  • Autoimmune: Sjogren's
  • Hereditary
  • Toxic
    • Pyridoxine intoxication
    • cis-platinum
• Hereditary neuropathy
  • An-α-lipoproteinemia (Tangier)
  • Acute Intermittent Porphyria
• Small fiber neuropathies: Proximal pain
• Local neuropathy
  • Thoracic neuropathies
    • Diabetic
    • Herpes Zoster
  • Other proximal nerves
    • Meralgia paresthetica: Lateral cutaneous nerve of thigh
    • Brachial plexopathy
• Rule out: Myelopathy

• Genetics
  • Allelic disorder: HDL deficiency, type 2
• ABCA1 Protein
  • Energy dependent transport of substrates across membranes
  • Intracellular cholesterol transport
  • Other ABC defects
    • Systemic: Cystic fibrosis; Familial intrahepatic cholestasis
    • Neural: Adrenoleukodystrophy; Zellweger
    • Eye: Stargardt; Retinitis pigmentosa; Cone-Rod dystrophy
• Neurologic features
  • Onset
    • 1st to 7th decade
    • Neuropathy presenting feature in 30%
  • Sensory-Motor Neuropathy: "Pseudosyringomyelic"
    • Sensory loss
      • Proximal, Distal & Patchy
      • Modalities: Pain & Temperature loss
    • Hand muscles: Weakness; Wasting
    • Course: Slowly progressive
  • Facial diplegia
  • Mononeuropathies
    • Isolated or Multiple
    • Oculomotor; Long thoracic; Limb
    • Exacerbations & remissions may occur
• Systemic features
  • Tonsils: Orange-yellow; Large; Lobulated
  • Enlarged liver, spleen & lymph nodes
  • Premature coronary artery disease: 6-fold higher between 35 to 65 years
  • Cholesterol ester deposits in tonsils, spleen, liver, rectal mucosa, cornea
• Laboratory
  • Serum
    • Hypocholesterolemia
    • High Density Lipoproteins: Reduced or Absent
    • Triglycerides: High
    • Apolipoprotein A1: Reduced
  • Blood: Thrombocytopenia; Reticulocytosis
  • CSF: Protein may be elevated
  • Electrodiagnostic studies: Axon loss ± Demyelinating features
    • SNAPs: Small amplitude
    • NCV: 27 to 45 M/s
    • Entrapments with multiple mononeuropathies
    • Syringomyelic syndrome: Arms > Legs; Axonal loss; Prolonged disatal latencies
• Pathology: Nerve
  • Vacuolization & Lipid storage
    • Location: Schwann cells; Epithelial cells; Pericytes
    • Not membrane bound
  • Macrophages: Accumulation of cholesterol esters
  • Lipid staining
  • Axon loss: Often small & large
  • Ultrastructure: Cytoplasmic storage vacuoles - Elliptic or round, 0.5-3μm