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SENSORY DISORDERS: Small Fiber

Definition
Differential Diagnosis
Features


Anatomic definition


Small Fiber Neuropathy Features: Symptoms, Signs, Laboratory 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
    • Insensitivity to pain
  • Discomfort
  • Other associated features
    • Autonomic involvement
      • Postganglionic unmyelinated small axons
      • May occur without sensory features
    • POTS
    • Restless legs syndrome
  • Unexpected Motor Features
    • Cramps 17
    • Fasciculations
    • Myalgias 16
    • Denervation: Intrinsic foot muscles 15
    • Serum CK: Moderate elevation
  • Serum antibodies 18
 
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
Congenital Insensitivity to Pain with Preserved Temperature sensation 11
  Clathrin, heavy polypeptide-like 1 (CLTCL1; CHC22) ; Chromosome 22q11.21; Recessive
Congenital Insensitivity to Pain with Hypohidrosis (HSAN8; HSAN VII) 10
  PR domain zinc finger protein 12 (PRDM12) ; Chromosome 9q33-q34; Recessive
Insensitivity to Pain (Marsili syndrome) 12
  Zinc finger homeobox protein 2 (ZFHX2) ; Chromosome 14q11.2; Dominant
Pain Insensitivity (PAINQTL1) 14
  FAAH-OUT (FAAH pseudogene; FAAH1) ; Chromosome 1p33; Digenic
  Fatty acid amide hydrolase (FAAH) ; Chromosome 1p33; Digenic
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
10. Nature Genetics 2015; May 25
11. Brain 2015; Online June
12. Brain 2017; Online Dec
13. Medicine (Baltimore) 2017;96:e8149
14. Brit J Anaesthesia 2019; March
15. Muscle Nerve 2020 Feb 7
16. Muscle Nerve 2015;51:514-521
17. Muscle Nerve 2013 Aug;48(2):252-255
18. Muscle Nerve 2019 Oct 25
19. Muscle Nerve 2020 Feb 3
20. Lancet Neurol 2017;16:144-157, Muscle Nerve 2020 Jan 14
21. Neuropathol Appl Neurobiol 2021 Jan 9
22. J Peripher Nerv Syst 2020;25:308-311
23. Nat Med 2021 May 31


6/3/2021