Proximal Sensory

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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

An-α-lipoproteinemia (Tangier disease)

l ATP binding cassette transporter (ABC1)

; Chromosome 9q31; Codominant

Genetic
- Same locus as Familial HDL deficiency
ABC1 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 Neuropathy: "Pseudosyringomyelic"
  - Modalities: Pain & Temperature loss
  - Distribution: Proximal & Patchy
  - Course: Slowly progressive
- Facial diplegia
- Hand muscle wasting
- Mononeuropathies
  - Isolated or multiple
  - Oculomotor; Long thoracic; Limb
  - Exacerbations & remissions may occur
- Sensory-Motor neuropathy: Occasional; Slowly progressive
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
  - Reduced or absent High Density Lipoproteins
  - Triglycerides: High
- Blood: Thrombocytopenia; Reticulocytosis
- CSF: Protein may be elevated
- Electrodiagnostic studies: Mixed axonal, demyelinating features
  - Small SNAPs
  - Entrapments with multiple mononeuropathies
  - Syringomyelic syndrome: Arms > Legs; Axonal loss; Prolonged disatal latencies
Pathology
- Vacuolization
  - Location: Schwann cells; Epithelial cells; Pericytes
  - Not membrane bound
- Macrophages: Accumulation of cholesterol esters
- Lipid staining
- Axonal loss: Often small & large
- Ultrastructure: Cytoplasmic storage vacuoles - Elliptic or round, 0.5-3μm

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12/11/2006