Contribuição dos potenciais visuais evocados ao estudo funcional da via óptica em crianças e adultos com tumores cerebrais primários

• Ano de defesa: 2020
• Autor(a) principal: Dotto, Patricia De Freitas [UNIFESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Vision Disorders; Adult; Children; Evoked Visual Potentials; Potenciais Visuais Evocados; Acuidade Visual; Criança; Adulto; Transtornos Da Visão
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=10056704; https://hdl.handle.net/11600/64866

PURPOSES: This thesis aims to investigate the contribution of visually-evoked potentials (VEP) to the functional evaluation of the visual system in primary cerebral tumors, including four distinct papers with the following purposes: a) to characterize possible changes in VEPs by pattern reversal (PRVEP) and flash (FVEP) stimulation in children and adolescents with low-grade gliomas, with and without neurofibromatosis type 1 (NF1) (Paper 1); b) to estimate deficits on grating visual acuity (GVAD) in children unable to perform optotype acuity (Paper 2); c) to define gender-based normative values for PVEPR and FVEP, in healthy adults (Paper 3) and, d) based on normative results, to study visual function in adults with orbital and brain tumors (Paper 4). METHODS: Paper 1: PVEPRs and PVEF results were categorized and associated with NF1 by Firth logistic regression, adjusted for age, sex and tumor resection. Cut-off values for amplitude (in microvolts) and latency (in milliseconds) for PVEPRs (15’ and 60’) were, respectively, ≥9.0 µV and ≤103.0 ms. Paper 2: Age-based GVAD were calculated and classified as mild (0.10-0.39 logMAR), moderate (0.40-0.79 logMAR) or severe (≥0, 80 logMAR). Paper 3: Gender-based normative values for PRVEPs with stimuli subtending visual angles of 15 ’and 60’ and for PVEF were determined. Paper 4: Electrophysiological changes in affected and unaffected (contralateral) eyes were identified by comparison with a control and also with age-based normative limits. RESULTS: Paper 1: In 68% (15 male, 60% non-NF1; age = 9.2 ± 3.8 years), reduced amplitudes (46% NF1 and 83% non-NF1) and prolonged latencies (38% NF1 and 89% non-NF1) were detected; sporadic gliomas were marginally associated with reduced amplitudes (p = 0.055). Paper 2: All cases (13 boys; age = 35.1 ± 25.9 months; 24 gliomas and 1 embryonic tumor, 84% hypothalamic/chiasmatic) presented visual impairment (GVAD = 0.60 ± 0.36 logMAR, as 40% mild, 32% moderate and 28% severe). Paper 3: In 54 healthy adults (28 women) aging from 25 and 74 years (mean age= 40.4 ± 13.7 years) cut-off values for P100 on monocular evaluations were established for PRVEP60' (men = 2,5µV/106.1ms; women= 2.6µV/104.5ms) and PRVEP15' (men= 3.6µV/107.2; women= 1.4µV/105.8ms) and for N2P2 from FVEP (men= 1,8µV /76.3ms; women= 4.8µV/71.4ms). Mean monocular and binocular responses were more robust and marginally faster in females. Paper 4: Affected or worse vision eyes in 21 adults (17 women; age = 49.2 ± 11.9 years) with orbital or cerebral tumors presented reduced and prolonged PRVEPs (P<0.001) and reduced FVEPs (P<0.001). Similar results were also seen in 6/16 contralateral (unaffected) eyes with normal visual acuity in patients with unilateral orbital tumors. CONCLUSIONS: The functional study of the optic pathways by visually-evoked potentials in children and adults with primary cerebral tumors allows to quantify and to classify both evident and subclinical visual deficits, by an objective and non-invasive way, and helps to characterize underlying mechanisms of tumor damage that may lead to visual impairment and blindness.