Fz and Cz active electrodes positioning can be considered one more resource to help in the P300 clinical analysis.

O P300 é um Potencial Evocado Auditivo denominado potencial endógeno por refletir o uso funcional que o indivíduo faz do estímulo auditivo, sendo altamente dependente das habilidades cognitivas, entre elas atenção e discriminação auditiva. É um procedimento de avaliação objetiva, mas que depende da experiência do avaliador em detectar os picos das ondas, sendo importante a utilização de métodos de registro que facilitem a análise da presença de resposta e a interpretação dos resultados. OBJETIVO: Analisar o Potencial Evocado Auditivo de Longa Latência-P300 obtido com a utilização de dois eletrodos ativos posicionados em Fz e Cz. MATERIAIS E MÉTODOS: Participaram deste estudo 33 indivíduos de ambos os gêneros com idade entre 7 e 34 anos, audição normal e sem fator de risco para problemas mentais. RESULTADOS: Os resultados demonstraram que não houve diferença estatisticamente significante para a latência de N2 e P3 e amplitude do P3 quando analisado o gênero e nem correlação com a idade dos indivíduos. Houve forte correlação destas medidas com o posicionamento dos eletrodos em Fz e Cz. CONCLUSÃO: O posicionamento dos eletrodos ativos em Fz e Cz pode ser considerado um recurso a mais para auxiliar na análise clínica do P300.

Avaliar a função auditiva em usuários de dispositivos eletrônicos aplicados a surdez é muito importante para o processo de reabilitação. Entretanto, nestes indivíduos os procedimentos devem ser realizados em campo livre. OBJETIVO: Analisar a aplicabilidade do potencial cognitivo P300 pesquisado em campo livre. FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODO: Foram avaliados 33 indivíduos de ambos os sexos com idade entre 7 e 34 anos, com audição normal e sem fator de risco para problemas mentais. O potencial cognitivo P300 foi realizado por meio do equipamento Biologic's Evoked Potential System (EP), com fones de inserção (3A) e em campo livre (0º Azimute e 45º Azimute). RESULTADOS: Não houve diferença estatisticamente significante para a latência do N2 e P300 e amplitude do P300 quando analisado o sexo e o modo de realização do teste (fone e campo livre), assim como não houve diferença ao comparar as medidas em campo livre a 0º e 45º Azimute. CONCLUSÃO: A pesquisa do potencial cognitivo P300 em campo livre é um procedimento viável de ser realizado.

Background: the auditory steady state response (ASSR) is an electrophysiological procedure that evaluates, at the same time, the hearing thresholds of both ears at various frequencies. This procedure reduces the time of testing and enables the stimulation of levels close to 125dB HL, characterizing residual hearing. Aim: to verify the applicability of the ASSR to determine the hearing thresholds in different levels of sensorineural hearing loss. Method: 48 individuals aged 7-30 years, with different levels of hearing loss were assessed. The Pure tone Audiometry (PTA) and the ASSR were carried out in following carrier frequencies 0.5; 1; 2 and 4k Hz. The carrier frequencies in the ASSR were modulated in amplitude and frequency, with multiple dicotic stimulation for mild and moderate hearing loss. Simple stimulation was used to test the other hearing deficit levels. Results: there was a significant association (p<0.01) between the thresholds obtained in the PTA and in the ASSR for all of the tested frequencies, especially for the severe levels. However, for some patients, the hearing loss level was overestimated in the ASSR. Conclusion: the ASSR can be used to estimate the PTA threshold; nevertheless, it should not be analyzed in an isolated way, but seen as a complementary procedure to the behavioral auditory assessment. Key Words: Auditory Evoked Potential; Steady-State; Audiometry; Sensorineural Hearing Loss. ResumoTema: a resposta auditiva de estado estável (RAEE) é um procedimento eletrofisiológico que permite avaliar ao mesmo tempo os limiares auditivos de várias freqüências em ambas às orelhas, reduzindo assim o tempo de teste, e permite estimular até níveis próximos a 125dB HL, caracterizando assim a audição residual. Objetivo: verificar a aplicabilidade da RAEE para determinar os limiares auditivos nos diferentes graus de perda auditiva neurossensorial coclear. Método: foram avaliados 48 indivíduos com idade entre sete e trinta anos e diferentes graus de perdas auditivas. A Audiometria Tonal Liminar (ATL) e a RAEE foram avaliadas nas seguintes freqüências portadoras, 0,5; 1; 2 e 4k Hz. As freqüências portadoras na RAEE foram moduladas em amplitude e freqüência, com estimulação múltipla e dicótica nas perdas auditivas de grau leve e moderado. Estimulação simples foi utilizada nos outros graus de perdas auditivas. Resultados: houve associação significante (p < 0,01) entre os limiares obtidos na ATL e RAEE para todas as freqüências testadas, principalmente para perdas auditivas de grau profundo. Contudo em alguns pacientes o grau da perda auditiva pode ser super-estimado. Conclusão: a RAEE pode ser utilizada para predizer os limiares auditivos da ATL, porém não deve ser analisada de forma isolada, mas de forma complementar a avaliação audiológica comportamental.

Di abetes Mellitus may lead to alterations in the eyes, kidneys, cranial nerves, peripheral nerves, ears etc. The cognitive function also seems to be compromised in subjects presented with Diabetes Mellitus, since the cortical and subcortical structures responsible for this function are hindered in some insulin-dependent patients. The cognitive potential P300 has been used as an objective procedure to assess cerebral cognitive functions. Aim: To analyze the sensitivity of P300 cognitive potential for the detection of alterations on the auditory cortex secondary to Diabetes Mellitus. Study design: transversal cohort. Material and Method: Sixteen diabetic subjects of both genders aged 7 to 71 years, and seventeen non-diabetic individuals at the same age range participated in this study. The evaluation procedures were pure tone audiometry (PTA) and P300 cognitive potential. Glycemia of the group presented with Diabetes was assessed prior to applying P300. Results: No statistically significant difference was shown for PTA results. A statically significant difference was observed between groups when analyzing the latency of P300 component measured in Fz. There was a correlation between glycemia and latency and amplitude of P300. Conclusion: The investigation of the cognitive potential of P300 is an important procedure for prevention and early diagnosis of neurological changes in individuals presented with Diabetes Mellitus.

It was concluded that the passive inhalation of cigarette smoke yields important morphological changes in the vocal fold epithelium, which may progress to neoplasia.

Few studies have demonstrated the pathologic reactions yielded by smoke inhalation on the airway in rats. Aim: The aim of this study was to analyze the possible histopathological effects produced by chronic cigarette smoke inhalation on the vocal folds of rats. Study design: Experimental. Material and Method: 36 male rats (Rattus norvergicus Wistar strain), aged 60 days, were kept in cages and exposed to inhalation of the smoke produced by 10 cigarettes lit 3 times a day, 7 days a week, for periods of 25, 50 and 75 days, and their respective controls. Thereafter the animals were killed and their larynxes were dissected and submitted to histological processing for achievement of histological sections, which were stained with Hematoxylin and Eosin and analyzed by light microscopy. Results: The rats exposed to smoke displayed smaller (p< 0,05) body mass than the control group. There was hyperplasia and squamous metaplasia in the free edge of the vocal fold and squamous hyperplasia on the middle portion of the vocal fold in all 3 study periods. Moreover, the 50-day group revealed keratinizing metaplasia in this area. Morphological alterations in other areas of the larynx and inflammatory reaction of the lamina propria were also not observed. Conclusion: It was concluded that the passive inhalation of cigarette smoke yields important morphological changes in the vocal fold epithelium, which may progress to neoplasia.

Aim To evaluate the hearing of children with congenital hypothyroidism (CH) and to analyze the knowledge that parents’ have on the possible auditory impacts of the disease. Methods A total of 263 parents/guardians were interviewed about aspects of CH and hearing. Audiological evaluation was performed on 80 participants, divided into two groups: with CH (n= 50) and without CH (n=30). Clinical and laboratory CH data were obtained from medical records, pure tone auditory thresholds and acoustic reflexes were analyzed. The auditory data was compared between groups. Student’s t-test and Chi-square were used for statistical analysis at a significance level of 5% (p ≤0.05). Results The majority (78%), of the parents were unaware that CH when not treated early is a potential risk to hearing. There was no correlation between socioeconomic class and level of information about CH and hearing (p>0,05; p=0.026). There was a statistically significant difference between the auditory tone thresholds of the groups and between the levels of intensity necessary for the triggering of the acoustic reflex. The group with CH presented the worst results (p≤0.05) and absence of acoustic reflex in a normal tympanometric condition. Conclusions Children with CH are more likely to develop damage to the auditory system involving retrocochlear structures when compared to healthy children, and that the disease may have been a risk factor for functional deficits without deteriorating hearing sensitivity. The possible impacts of CH on hearing, when not treated early, should be more publicized among the parents/guardians of this population.