title: The diagnostic accuracy of Sudoscan in transthyretin familial amyloid polyneuropathy.
abstract: 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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  Abnormal feet responses on Sudoscan support early diagnosis in TTR-FAP.
authors.affiliation: Department of Neurosciences and Mental Health, Neurology, Hospital de Santa Maria-CHLN, Lisbon, Portugal; Instituto de Medicina Molecular, Institute of Physiology, Faculty of Medicine-University of Lisbon, Portugal. Electronic address: jose.zecastro25@gmail.com.
authors.forename: José
authors.initials: J
authors.lastname: Castro
authors.affiliation: Department of Neurosciences and Mental Health, Neurology, Hospital de Santa Maria-CHLN, Lisbon, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Miranda
authors.affiliation: Department of Neurosciences and Mental Health, Neurology, Hospital de Santa Maria-CHLN, Lisbon, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Castro
authors.affiliation: Department of Neurosciences and Mental Health, Neurology, Hospital de Santa Maria-CHLN, Lisbon, Portugal; Instituto de Medicina Molecular, Institute of Physiology, Faculty of Medicine-University of Lisbon, Portugal.
authors.forename: Mamede
authors.initials: M
authors.lastname: de Carvalho
authors.affiliation: Department of Neurosciences and Mental Health, Neurology, Hospital de Santa Maria-CHLN, Lisbon, Portugal; Instituto de Medicina Molecular, Institute of Physiology, Faculty of Medicine-University of Lisbon, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Conceição
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D028227:Amyloid Neuropathies, Familial / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000503:physiopathology*; D004568:Electrodiagnosis / Q000379:methods*; D005260:Female; D005528:Foot / Q000503:physiopathology; D005712:Galvanic Skin Response / Q000502:physiology; D006225:Hand / Q000503:physiopathology; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013497:Sural Nerve / Q000503:physiopathology*
keywords: Diagnosis; Small fiber neuropathy; Sudomotor function; Sudoscan; Transthyretin familial amyloid polyneuropathy