Navegando por Palavras-chave "Evoked potentials"
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- ItemSomente MetadadadosAmplitude modulated vestibular evoked myogenic responses: a study of carrier and modulating frequencies(Informa Healthcare, 2014-08-01) Oliveira, Aline Cabral de; Pereira, Liliane Desgualdo [UNIFESP]; Colafemina, Jose Fernando [UNIFESP]; Menezes, Pedro de Lemos; Univ Fed Sergipe; Universidade Federal de São Paulo (UNIFESP); Estadual Univ Hlth Sci AlagoasConclusion: Responses with greater amplitude were recorded when carrier frequencies were modulated at 37, 40, and 43 Hz. These responses can be recorded even in patients with significant sensorineural hearing loss, from the sternocleidomastoid (SCM) muscle for a 500 Hz tone, 100% modulated at 40 Hz. Objective: To determine the best carrier and modulating frequencies to evoke steady-state myogenic responses. Methods: the present study investigated 156 ears of 78 normal-hearing young adults, with carrier frequencies of 250, 500, and 1000 Hz, modulated at 20, 37, 40, 43, 70, 77, and 80 Hz, with an intensity of 95 dBA. Furthermore, we observed responses evoked by stimulus carrier frequency of 500 Hz, modulated at 40 Hz, with an intensity of 95 dBA in a group of five subjects with severe sensorineural loss. Results: Responses were found for all stimuli studied (p < 0.01). Modulated stimuli at frequencies of 37, 40, and 43 Hz evoked better steady-state vestibular evoked myogenic potential (S-VEMP) (p < 0.05). No statistically significant differences were found between the group of normal hearers and the group of subjects with hearing loss (p = 0.431), for the stimulus used.
- ItemAcesso aberto (Open Access)Avaliação dos potenciais evocados relacionados a eventos (ERP-P300) em pacientes com cirrose hepática sem encefalopatia(Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE Colégio Brasileiro de Cirurgia Digestiva - CBCD Sociedade Brasileira de Motilidade Digestiva - SBMD Federação Brasileira de Gastroenterologia - FBGSociedade Brasileira de Hepatologia - SBHSociedade Brasileira de Endoscopia Digestiva - SOBED, 2008-03-01) Teodoro, Vinicius Vasconcelos [UNIFESP]; Bragagnolo Junior, Maurício; Lucchesi, Ligia Mendonça [UNIFESP]; Kondo, Mario [UNIFESP]; Tufik, Sergio [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)BACKGROUND: In hepatic cirrhosis structural liver alterations occur leading to the loss of the organ functions with neuro-psychiatric consequence, as cognitive dysfunctions. One of the most effective ways of objectively evaluating cognition is to measure electrophysiological activity in the central nervous system trough event-related potentials (ERP-P300). AIM: To assess the value of the event-related potential (ERP) in order to determine cognitive disturbances in patients with liver cirrhosis and to assist in the diagnosis of minimal hepatic encephalopathy. METHODS: Fifty patients with liver cirrhosis were selected, without clinical symptoms of hepatic encephalopathy and 35 healthy volunteers, matched by sex and age. The patients were submitted to clinical-neurological and laboratorial examination. The ERP-P300 was performed by the two groups to determine cognitive disturbances. RESULTS: The study showed significant differences between the ERP-P300 latency averages of the two groups. CONCLUSION: The ERP-P300 is simple to use and depends on controllable variables. It is also easy to reproduce and, when properly used, can be useful both to determine cognitive disturbances in patients with hepatic cirrhosis and to assist in minimal hepatic encephalopathy diagnosis.
- ItemAcesso aberto (Open Access)Comparação das alterações do potencial evocado somatosensorial no tratamento cirúrgico da escoliose idiopática entre técnicas com e sem amarrilha sublaminar(Sociedade Brasileira de Coluna, 2010-09-01) Ueta, Renato Hiroshi Salvioni [UNIFESP]; Del Curto, David [UNIFESP]; Wajchenberg, Marcelo [UNIFESP]; Martins Filho, Délio Eulálio [UNIFESP]; Ferreira, Ricardo [UNIFESP]; Puertas, Eduardo Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)OBJECTIVE: to compare the number of events with alteration in the somatosensory evoked potentials (SSEP) and its repercussion between different techniques of surgical treatment for idiopathic scoliosis, with and without sublaminar wiring. METHODS: twenty-five surgical procedures with flexible curves for treatment of idiopathic scoliosis were reviewed in the period of November 1996 to September 1999. They were divided into two groups: without sublaminar wiring (Cotrel-Dubousset's system) (Group I); and with sublaminar wiring (Harrington-Luque's system and rectangle of Hartshill) (Group II). In all surgeries, the intraoperative neurophysiologic monitoring with Somatosensory Evoked Potentials (SSEPs) was used. RESULTS: according to the findings, a bigger frequency of monitoring changes was observed during and at the end of the surgery in Group II. A high incidence of false-negative changes was also verified. No patient with neurological damages was observed. CONCLUSION: There are still doubts about the safest method for the surgical treatment of idiopathic scoliosis. The results presented in this study suggest a smaller incidence of SSEPs changes in the patients treated with Cotrel-Dubousset's system.
- ItemSomente MetadadadosContribuição ao estudo do potencial evocado auditivo de longa latência em crianças(Universidade Federal de São Paulo (UNIFESP), 1996) Diniz Junior, Jose [UNIFESP]; Albernaz, Pedro Luiz Mangabeira [UNIFESP]; http://lattes.cnpq.br/9472525082323183
- ItemSomente MetadadadosDysfunction in the fellow eyes of strabismic and anisometropic amblyopic children assessed by visually evoked potentials(Consel Brasil Oftalmologia, 2016) Andrade, Eric Pinheiro [UNIFESP]; Berezovsky, Adriana [UNIFESP]; Sacai, Paula Yuri [UNIFESP]; Pereira, Josenilson Martins [UNIFESP]; Rocha, Daniel Martins [UNIFESP]; Salomao, Solange Rios [UNIFESP]Purpose: To evaluate visual acuity and transient pattern reversal (PR) visual evoked potentials (VEPs) in the fellow eyes of children with strabismic and/or anisometropic amblyopia. Methods: Children diagnosed with strabismic and/or anisometropic amblyopia were recruited for electrophysiological assessment by VEPs. Monocular grating and optotype acuity were measured using sweep-VEPs and an Early Treatment Diabetic Retinopathy Study chart, respectively. During the same visit, transient PR-VEPs of each eye were recorded using stimuli subtending with a visual angle of 60', 15', and 7.5'. Parameters of amplitude (in mu V) and latency (in ms) were determined from VEP recordings. Results: A group of 40 strabismic and/or anisometropic amblyopic children (22 females: 55%, mean age = 8.7 +/- 2.2 years, median = 8 years) was examined. A control group of 19 healthy children (13 females: 68.4%, mean age = 8.2 +/- 2.6 years, median = 8 years) was also included. The fellow eyes of all amblyopes had significantly worse optotype acuity (p = 0.021) than the control group, regardless of whether they were strabismic (p = 0.040) or anisometropic (p = 0.048). Overall, grating acuity was significantly worse in the fellow eyes of amblyopes (p = 0.016) than in healthy controls. Statistically prolonged latency for visual angles of 15' and 7.5' (p = 0.018 and 0.002, respectively) was found in the strabismic group when compared with the control group. For the smaller visual stimulus (7.5'), statistically prolonged latency was found among all fellow eyes of amblyopic children (p< 0.001). Conclusions: The fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PR-VEP detected as prolonged latencies for smaller size stimuli when compared with eyes of healthy children. These findings show the deleterious effects of amblyopia in several distinct visual functions, mainly those related to spatial vision.
- ItemAcesso aberto (Open Access)Electrophysiological study of hearing in full-term small-for-gestational-age newborns(Sociedade Brasileira de Fonoaudiologia, 2012-01-01) Angrisani, Rosanna Mariangela Giaffredo; Azevedo, Marisa Frasson de [UNIFESP]; Carvallo, Renata Mota Mamede; Diniz, Edna Maria De Albuquerque; Matas, Carla Gentile; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)PURPOSE: To describe the Brainstem Auditory Evoked Potential (BAEP) results of full-term small-for-gestational-age newborns, comparing them to the results of full-term appropriate-for-gestational-age newborns, in order to verify whether the small-for-gestational-age condition is a risk indicator for retrocochlear hearing impairment. METHODS: This multicentric prospective cross-sectional study assessed 86 full-term newborns - 47 small- (Study Group) and 39 appropriate-for-gestational-age (Control Group - of both genders, with ages between 2 and 12 days. Newborns with presence of transient evoked otoacoustic emissions and type A tympanometry were included in the study. Quantitative analysis was based on the mean and standard deviation of the absolute latencies of waves I, III and V and interpeak intervals I-III, III-V and I-V, for each group. For qualitative analysis, the BAEP results were classified as normal or altered by analyzing these data considering the age range of the newborn at the time of testing. RESULTS: In the Study Group, nine of the 18 (38%) subjects with altered BAEP results had the condition of small-for-gestational-age as the only risk factor for hearing impairments. In the Control Group, seven (18%) had altered results. Female subjects from the Study Group tended to present more central alterations. In the Control Group, the male group tended to have more alterations. CONCLUSION: Full-term children born small or appropriate for gestational age might present transitory or permanent central hearing impairments, regardless of the presence of risk indicators.
- ItemAcesso aberto (Open Access)Estudo do potencial evocado miogênico vestibular na vertigem posicional paroxística benigna(Universidade Federal de São Paulo (UNIFESP), 2010-08-25) Dorigueto, Ricardo Schaffeln [UNIFESP]; Munhoz, Mário Sérgio Lei [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Introduction: Benign Paroxysmal Positional Vertigo (BPPV) is a highly last longing disorder. Despite being benign, it may follow a chronic and resistive course. Therefore, it may lead to serious difficulties to patients’ quality of life. The study of the performance of otoliths organs by Vestibular Evoked Myogenic Potential (VEMP) testing may be the key to understand the involvement and recurrent function in BPPV. Objective: It is to determine if there is statistically meaningful difference in the saccule-collic reflex in a Control group when compared to patients with BPPV as well as between the recurrent and non recurrent form of BPPV. Method: The transversal study by VEMP diagnostic intervention, where the Control group and patients with recurrent or non-recurrent BPPV forms went through an assessment. Results: The frequency of changes in VEMP was significantly greater in the BPPV patient group than the Control group (p<0,001). Changes were found related to the lack of response, the asymmetric index (AI) and the latencies of p13 and n23, however, just the lack of responses (p<0,001) and asymmetric index (p<0,001) results showed statistically significant difference related to the Control group. There has been no statistic difference between the recurrent and non recurrent forms of BPPV associated with VEMP result (p=0,09). Conclusion: There has been statistically significant difference in the saccule-collic reflex behavior from the group with BPPV when related to the Control group. There has been no statistically significant difference in the saccule-cholic reflex behavior between the recurrent and non recurrent form of BPPV.
- ItemAcesso aberto (Open Access)Hemorragia peri-intraventricular: estudo do efeito de supressão nas vias auditivas.(Universidade Federal de São Paulo (UNIFESP), 2018-12-07) Sousa, Elaine Colombo [UNIFESP]; Azevedo, Marisa Frasson de [UNIFESP]; http://lattes.cnpq.br/3499728717437032; http://lattes.cnpq.br/5031701812524795; Universidade Federal de São Paulo (UNIFESP)OBJECTIVE: Determine the functioning of the efferent auditory system in premature newborns with intraventricular hemorrhage. METHOD: The study group was composed of 22 newborns with intraventricular hemorrhage and the control group was composed of 22 newborns without intraventricular hemorrhage, matched to the study group for gestational age, correct gestational age and sex. The groups were submitted to the study of otoacoustic emissions evoked by a transient stimulus and suppression in otoacoustic emissions (equipment ILOv6Otodynamics Ltda®) and the study of the auditory evoked potential with and without contralateral noise (equipment SmartEPIntelligent Hearing Systems®). RESULTS: Newborns with intraventricular hemorrhage exhibited a higher occurrence of central hearing alteration as well as a greater occurrence of the absence of the suppression in otoacoustic emissions and auditory evoked potential compared to the newborns without this condition. An association was found between central hearing alteration and a lower occurrence of suppression. Agreement was found between the suppression test on otoacoustic emissions and the suppression test on latency of the auditory evoked potential. CONCLUSION: Premature newborns with intraventricular hemorrhage have a greater occurrence of functional abnormality of the afferent auditory system, which can be effectively identified through an evaluation of the suppression of otoacoustic emissions evoked by a transient stimulus and the latency in the brainstem auditory evoked potential.
- ItemSomente MetadadadosPattern-reversal visual evoked potentials as a diagnostic tool for ocular malingering(Consel Brasil Oftalmologia, 2016) Soares, Tarciana de Souza [UNIFESP]; Sacai, Paula Yuri [UNIFESP]; Berezovsky, Adriana [UNIFESP]; Rocha, Daniel Martins [UNIFESP]; Watanabe, Sung Eun Song [UNIFESP]; Salomao, Solange Rios [UNIFESP]Purpose: To investigate the contributions of transient pattern-reversal visual evoked potentials in the diagnosis of ocular malingering at a Brazilian university hospital. Methods: Adult patients with suspected malingering in one or both eyes were referred for visual evoked potential testing. Data from patients' medical records were reviewed and analyzed retrospectively. Data analysis included the distance optotype visual acuity based on a ETDRS retro-illuminated chart and the transient pattern-reversal visual evoked potential parameters of latency (milliseconds) and amplitude (microvolts) for the P100 component, using checkerboards with visual subtenses of 15' and 60'. Motivations for malingering were noted. Results: The 20 subjects included 11 (55%) women. Patient ages ranged from 21 to 61 years (mean = 45.05 +/- 11.76 years
- ItemAcesso aberto (Open Access)Potenciais cognitivos evocados durante a codificação de itens distintos e relacionados entre si: efeitos sobre a recordação livre(Universidade Federal de São Paulo (UNIFESP), 2006-01-27) Ruiz, Ana Maria Nogueira [UNIFESP]; Bueno, Orlando Francisco Amodeo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Rationale: In free-recall tasks there is a facilitation in recall of semantically related words inserted in the middle serial positions of lists of words with no other relations between them. This facilitation can be due to a series of undetermined cognitive processes such as: a) distinctiveness of the related items; b) activation of preexistent representations in memory; c) processes involved in the integration of related items. The present study sought to investigate the involvement of these processes in the facilitation effect employing both behavioural data and event related potential (ERP) alterations during encoding of words. Methods: Twenty-three undergraduates studied 80 fifteen-word lists in 4 sessions (20 random lists per session). The words in the lists were unrelated except for those in serial positions 7, 8, e 9 de 60 lists, resulting in 4 list types (20 of each) with: a) semantic relations (e.g. milk, cheese, butter); b) phonetic relations (e.g. sea, fee, knee); c) perceptual relations (words related by the type font); d) no relations (control lists). Free-recall was obtained after presentation of each list. ERPs were registered from Fz, Cz and Pz during encoding of words in positions 7, 8, 9 and 10. Results: Recall facilitation varied between lists (semantic> phonetic> perceptual > control). ERPs showed modulations of components identified as P300, N400 and another late positive component (LPC) that varied according to type of relation and electrode location. Among perceptually related words, only that in the 7th serial position was more recalled than in the control list and it led to a positivity that corresponded to a P300. In the 8th and 9th words in the lists with semantic and phonetic relations the N400 was less negative than in control lists but did nor reflect the recall pattern (semantic > phonetic). An LPC occurred only in the 8th word in the semantic lists at FZ and in the 9th in all electrodes in both lists with semantic and phonetic relations which reflected the recall pattern. Conclusion: Results suggest that semantic facilitation effects can be attributed to different processes that occur together at encoding of related stimuli and that are not only due to P300 changes triggered by distinctiveness. P300 amplitude predicted recall only of single distinct items. When there was an opportunity of grouping two or three items such as in the semantic and phonetic lists, N400 and LPC participated in the facilitation effect.
- ItemAcesso aberto (Open Access)Potencial evocado auditivo de estado estável em crianças e adolescentes com perda auditiva neurossensorial de grau severo e profundo e descendente(Academia Brasileira de Audiologia, 2014-09-01) Luiz, Cyntia Barbosa Laureano; Azevedo, Marisa Frasson de [UNIFESP]; http://lattes.cnpq.br/3499728717437032; http://lattes.cnpq.br/7124829402433968; Universidade Federal de São Paulo (UNIFESP)PurposeTo verify the correlation between the electrophysiological thresholds in Auditory Evoked Potential Steady State (ASSR) and behavioral thresholds obtained with pure tone audiometry in children and adolescents with severe to profound sensorineural hearing loss and steeply sloping hearing loss. MethodTwenty subjects from both gender aged between five and 15 years-old were evaluated and divided into the following groups: 10 subjects with steeply sloping sensorineural hearing loss and 10 subjects with severe to profound sensorineural hearing loss. The subjects underwent pure tone audiometry, speech audiometry (SRT and SDT), acoustic immittance measures and ASSR. ResultIn the group with steeply sloping hearing loss, the correlation was 0.68 and 0.94. In the group with severe to profound hearing loss, the correlation was 0.59 to 0.86. Mean differences between ASSR and audiometry threshold were 1.4 and 7.5 dB in the group with steeply sloping hearing loss and -0.40 e-8.5 dB in the group with severe to profound hearing loss. ConclusionThere was a positive correlation between the electrophysiological and behavioral thresholds in children and adolescents with severe to profound hearing loss and steeply sloping hearing loss.