INTRODUCTION AND OBJECTIVE: Transthyretin-associated familial amyloid 
polyneuropathy (TTR-FAP) is a disease caused by the deposit of abnormal 
transthyretin on tissues, mainly nerves. Small nerve fibers are altered earlier 
during the course of the disease; hence, detection of their involvement may have 
serious consequences on the natural history of disease.
METHODS: A cross-sectional, observational study, was carried out on symptomatic 
patients, involving the conduct of several tests for small nerve fibers: 
Vibration, Touch Pressure (TP) and Heat Pain (HP). Results were compared with 
those obtained during a conventional neurological examination carried out on a 
group of healthy individuals.
RESULTS: Fifteen symptomatic patients were recruited at an early stage of the 
disease (60% stage 1), along with 13 healthy individuals, with both patient 
groups having similar epidemiological characteristics in terms of gender, age, 
weight, height or BMI. A comparison carried out between the neuropsychological 
tests performed revealed statistically significant differences: Vibration 
(P<.05), TP (P<.05) and HP (P<.05, except volar forearm).
CONCLUSIONS: The neurophysiological tests performed revealed significant 
differences between both groups, allowing for an earlier detection of 
neurological injuries compared to conventional neurological examinations.