Uso del test de cuantificación sensitiva para el estudio de la neuropatía de fibra pequeña

Abstract

Introduction The small fiber neuropathies alter myelinized Aδ fibers and non-myelinized type C fibers, involved in autonomic functions, nociception, thermal perception and sweating. Genetic mutation TTR-Val30Met a most common etiology of Familial Amyloid Polineuropathy, compromised earlier the small nerve fibers. Conventional neurophysiological studies are unable to detect those abnormalities, delaying specific treatments. Methods The main goal of the present study was to evaluate the Quantitative Sensory Testing –QST, as an early diagnostic tool, identifying abnormalities in patients with the genetic mutationVal30Met in transthyretin (TTR) gene, followed at Santa María Hospital, Lisbon, Portugal. Patients were classified in 3 groups according to symptoms and neurological examination. Thresholds for cold perception, heat-pain and vibration were assessed in the different groups, compared to healthy controls. Results 33 cases and 18 controls, divided in asymptomathic (24.2%), symptomatic with normal neurological examination (42.4%) and symptomatic with abnormal neurological examination (33.3%). There were no differences between asymptomatic patients and healthy controls. The abnormalities on cold threshold detection (p=0,042) and intermediate severity of heat-pain response (HP5) (p=0,007), can occur before changes in the neurological examination. In patients with abnormal neurological examination differences also include the stimulus-response slope (HP 5-0,5) between intermediate severity (HP 5.0) and onset perception of pain with heat (HP 0.5) (p=0,009). Discussion The Quantitative Sensory Testing showed to be a useful tool in the detection of earlier abnormalities in patients withTTR Val30Met mutation.