title: Neurophysiological markers in familial amyloid polyneuropathy patients: early changes.
abstract: OBJECTIVE
  Familial amyloid polyneuropathy-type I (FAP-I) is a hereditary, axonal, sensory-motor and autonomic polyneuropathy, with early involvement of small fibres. Liver transplantation is the only effective therapy in FAP, but should be performed early in the course of the disease. Reliable quantitative methods that could allow the determination of early changes in the peripheral nerve function are essential. Our aim was to find sensitive neurophysiological markers in FAP-I.
  
  
  METHODS
  Eighty-one FAP-I patients were included in this study. They were divided into two groups (G1, asymptomatic FAP-I mutation carriers; G2, early symptomatic). Seventy-six healthy controls formed a control group (G3). Nerve conduction studies, needle electromyography with motor unit potential analysis of the extensor digitorum brevis, RR interval and sympathetic skin response (SSR) were analyzed.
  
  
  RESULTS
  The amplitudes of the motor response of the peroneus nerve and of the plantar SSR were significantly lower in G1 compared to G3. No other differences were found between those two groups. With a cut-off point of 0.2mV for plantar SSR, its sensitivity and specificity are 0.53 and 0.95, respectively. The positive predictive value and the negative predictive value are 0.82.
  
  
  CONCLUSIONS
  SSR response at foot is a useful measurement to detect early dysfunction of peripheral nerve fibres in FAP-I. Its abnormality should be considered a warning sign and lead to a careful clinical assessment.
  
  
  CONCLUSIONS
  SSR is a useful neurophysiological marker in FAP-I.
authors.affiliation: Department of Neurology, Hospital de Santa Maria and Neuromuscular Unit, Institute of Molecular Medicine, Faculty of Medicine, Av Prof Egas Moniz, 1649-028 Lisbon, Portugal. imconceicao@fm.ul.pt
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Conceição
authors.forename: José F
authors.initials: JF
authors.lastname: Castro
authors.forename: Manuel
authors.initials: M
authors.lastname: Scotto
authors.forename: Mamede
authors.initials: M
authors.lastname: de Carvalho
mesh_terms: D000328:Adult; D028227:Amyloid Neuropathies, Familial / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D005528:Foot / Q000294:innervation; D006225:Hand / Q000294:innervation; D006801:Humans; D008297:Male; D009431:Neural Conduction; D012680:Sensitivity and Specificity; D012867:Skin / Q000294:innervation*; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D015415:Biomarkers