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SENSORY DISORDERS: Small Fiber

Anatomic definition


Symptoms & Signs 7

  • Sensory loss
    • Modalities
    • Patterns of distribution
      • Length dependent: Earliest & most severe in distal legs
      • Partial length dependent: Early & most severe in both hands & feet
      • Non-length dependent: Early involvement in proximal & distal areas
  • Discomfort
    • Pain: Aching, Burning, Shooting, Prickling, Myalgias
    • Itch
    • Paraesthesias
    • Allodynia
  • Other associated features
    • Autonomic involvement: May occur without sensory features
    • Restless legs syndrome
 

Unmyelinated axons

Differential Diagnosis



Hereditary Sensory Neuropathy I (HSAN I; HSN I)
  HSAN IA ; Serine palmitoyltransferase, long-chain base subunit 1 (SPTLC1) ; Chromosome 9q22.31; Dominant
  HSAN IC ; Serine palmitoyltransferase, long-chain base subunit 2 (SPTLC2) ; Chromosome 14q24.3; Dominant



Hereditary sensory neuropathy with loss of pain perception (HSAN5) 2
  Nerve growth factor-β (NGFB) ; Chromosome 1p13.2; Recessive


Congenital absence of pain perception (HSAN7) 8
  Sodium channel, voltage-gated, Type XI, alpha subunit (SCN11A) ; Chromosome 3p22.2; Dominant (Sporadic)

Familial Episodic Pain 2 (FEPS2)
  Sodium channel, voltage-gated, Type X, alpha subunit (SCN10A) ; Chromosome 3p22.2; Dominant (Sporadic)

Congential insensitivity to pain without anhidrosis (HSAN)
  Recessive

Hereditary Ataxia with Thermoanalgesia & Loss of fungiform papillae 1
  ? Autosomal Dominant with incomplete penetrance or Recessive
Hereditary Ataxia with Thermoanalgesia 3
  ? Autosomal Dominant with incomplete penetrance
Sensory & Autonomic Neuropathy with Chronic Diarrhea 6
  Prion protein (PRNP) ; Chromosome 20p13; Dominant
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References

1. Brain 1996;119:1011-1021
2. Hum Mol Genet 2004; April 2004, J Med Genet 2010 Oct 26
3. J Neurol Neurosurg Psychiatry 2009;80:518-523
4. J Biol Chem 2010; Online Jan
5. American Journal of Human Genetics 2010;87:513522
6. N Engl J Med 2013;369:1904-1914
7. Nat Rev Neurol 2012 May 29
8. Nature Genet 2013; Online Sept
9. Brain 2014 Apr 27

7/29/2014