The diagnostic accuracy of Sudoscan in transthyretin familial amyloid polyneuropathy

Clin Neurophysiol. 2016 May;127(5):2222-7. doi: 10.1016/j.clinph.2016.02.013. Epub 2016 Feb 27.


Objective: Transthyretin familial amyloid polyneuropathy (TTR-FAP) is an axonal sensory-motor and autonomic neuropathy. Reliable quantification of sudomotor function could prove essential in the diagnosis and early treatment management. We aim to assess the diagnostic value of a new sudomotor test (Sudoscan) in TTR-FAP.

Methods: One hundred and thirty-three TTR-FAP Val30Met carriers, divided in asymptomatic and symptomatic stage 1, were compared with 37 healthy controls. We analyzed the right sural sensory nerve action potential (SNAP), the plantar sympathetic skin response (SSR) and the electrochemical skin conductance (ESC) measured by Sudoscan in both hands and feet.

Results: All neurophysiological measures were significantly worse in the symptomatic group. However, feet ESC was the only test distinguishing symptomatic patients with autonomic dysfunction from those without autonomic dysfunction, and both groups from asymptomatic subjects and healthy controls. Feet ESC was a significant independent predictor for the presence of symptoms and autonomic failure, after adjusting for demographic characteristics, sural SNAP and SSR amplitudes (p<0.05). Feet ESC showed 76% sensitivity and 85% specificity for detection of dysautonomia.

Conclusion: Feet ESC is a sensitive test to assess early autonomic dysfunction in TTR-FAP subjects. This investigation should be considered for routine assessment in this population.

Significance: Abnormal feet responses on Sudoscan support early diagnosis in TTR-FAP.

Keywords: Diagnosis; Small fiber neuropathy; Sudomotor function; Sudoscan; Transthyretin familial amyloid polyneuropathy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Adult
  • Amyloid Neuropathies, Familial / diagnosis*
  • Amyloid Neuropathies, Familial / genetics
  • Amyloid Neuropathies, Familial / physiopathology
  • Autonomic Nervous System / physiopathology*
  • Electrodiagnosis / methods*
  • Female
  • Foot / physiopathology
  • Galvanic Skin Response / physiology
  • Hand / physiopathology
  • Heterozygote
  • Humans
  • Male
  • Middle Aged
  • Sensitivity and Specificity
  • Sural Nerve / physiopathology*

Supplementary concepts

  • Amyloidosis, Hereditary, Transthyretin-Related