Feature visualization and classification for the discrimination between individuals with Parkinson's disease under levodopa and DBS treatments.

BACKGROUND: Over the years, a number of distinct treatments have been adopted for the management of the motor symptoms of Parkinson's disease (PD), including pharmacologic therapies and deep brain stimulation (DBS). Efficacy is most often evaluated by subjective assessments, which are prone to error and dependent on the experience of the examiner. Our goal was to identify an objective means of assessing response to therapy. METHODS: In this study, we employed objective analyses in order to visualize and identify differences between three groups: healthy control (N = 10), subjects with PD treated with DBS (N = 12), and subjects with PD treated with levodopa (N = 16). Subjects were assessed during execution of three dynamic tasks (finger taps, finger to nose, supination and pronation) and a static task (extended arm with no active movement). Measurements were acquired with two pairs of inertial and electromyographic sensors. Feature extraction was applied to estimate the relevant information from the data after which the high-dimensional feature space was reduced to a two-dimensional space using the nonlinear Sammon's map. Non-parametric analysis of variance was employed for the verification of relevant statistical differences among the groups (p < 0.05). In addition, K-fold cross-validation for discriminant analysis based on Gaussian Finite Mixture Modeling was employed for data classification. RESULTS: The results showed visual and statistical differences for all groups and conditions (i.e., static and dynamic tasks). The employed methods were successful for the discrimination of the groups. Classification accuracy was 81 ± 6% (mean ± standard deviation) and 71 ± 8%, for training and test groups respectively. CONCLUSIONS: This research showed the discrimination between healthy and diseased groups conditions. The methods were also able to discriminate individuals with PD treated with DBS and levodopa. These methods enable objective characterization and visualization of features extracted from inertial and electromyographic sensors for different groups.

Assessment of inter-examiner agreement and variability in the manual classification of auditory brainstem response.

BACKGROUND: The analysis of the Auditory Brainstem Response (ABR) is of fundamental importance to the investigation of the auditory system behaviour, though its interpretation has a subjective nature because of the manual process employed in its study and the clinical experience required for its analysis. When analysing the ABR, clinicians are often interested in the identification of ABR signal components referred to as Jewett waves. In particular, the detection and study of the time when these waves occur (i.e., the wave latency) is a practical tool for the diagnosis of disorders affecting the auditory system. Significant differences in inter-examiner results may lead to completely distinct clinical interpretations of the state of the auditory system. In this context, the aim of this research was to evaluate the inter-examiner agreement and variability in the manual classification of ABR. METHODS: A total of 160 ABR data samples were collected, for four different stimulus intensity (80dBHL, 60dBHL, 40dBHL and 20dBHL), from 10 normal-hearing subjects (5 men and 5 women, from 20 to 52 years). Four examiners with expertise in the manual classification of ABR components participated in the study. The Bland-Altman statistical method was employed for the assessment of inter-examiner agreement and variability. The mean, standard deviation and error for the bias, which is the difference between examiners' annotations, were estimated for each pair of examiners. Scatter plots and histograms were employed for data visualization and analysis. RESULTS: In most comparisons the differences between examiner's annotations were below 0.1 ms, which is clinically acceptable. In four cases, it was found a large error and standard deviation (>0.1 ms) that indicate the presence of outliers and thus, discrepancies between examiners. CONCLUSIONS: Our results quantify the inter-examiner agreement and variability of the manual analysis of ABR data, and they also allows for the determination of different patterns of manual ABR analysis.

Decomposição e análise dos potenciais evocados auditivos de tronco encefálico / Decomposition and analysis of auditory brainstem response

Os PEATEs são sinais resultantes da combinação de respostas de atividades neurais a estímulos sonoros no córtex. Caracteriza-se por ondas, sendo seus picos nomeados por algarismos romanos (I, II, III, IV, V, VI e VII). O processo clássico de identificação desses picos é baseado na visualização do sinal gerado pela promediação de cada amostra. Nele são identificadas as características morfológicas do sinal e os aspectos temporais relevantes constituídos pelas ondas de Jewett no qual cada onda tem uma relação anatômica com o sítio de origem. No entanto, durante esse processo de identificação visual surgem dificuldades que tornam a análise visual dos PEATE uma fonte constante de dúvidas em relação a fidedignidade e concordância de marcação dos picos pela subjetividade entre os examinadores. Com o objetivo de melhorar o processo de avaliação dos PEATE, foi desenvolvido um sistema de detecção automática para os picos, com capacidade de aprendizado que leva em consideração o perfil de marcação prévia realizado por examinadores, podendo ser considerado também, as marcações futuras de examinadores que utilizarão o software como auxílio em suas análises. Para a detecção de picos foi utilizada a Transformada Wavelet Contínua, associada a um Classificador Probabilístico construído a partir de marcações realizadas pelos examinadores. Para a avaliação do sistema foram utilizadas 748 amostras de PEATE de 11 sujeitos. A avaliação do sistema proposto apresentou uma taxa de acerto 74,3% a 99,7%, entre o sistema e a marcação manual, de acordo com o tipo de onda analisada. O presente estudo foi concebido com a intenção de ser uma ferramenta prática e por isso voltada para a aplicação clínica. Os resultados apresentados mostram uma técnica eficaz e capaz de aperfeiçoar o processo de avaliação dos PEATEs. A técnica proposta se mostra precisa mesmo na presença de ruído, característico de sinais biológicos especialmente no PEATE por ser um sinal de amplitude baixa.

Auditory Brainstem Response (ABR) results from the combination of neural activity responses in the presence of sound stimuli, detected by the cortex and characterized by peaks and valleys. They are identified by Roman numerals (I, II, III, IV, V, VI and VII). The identification of these peaks is carried out by the classical manual process of analysis, which is based on the visual/manual processing of the signals. The morphological and temporal characteristics of the signal carry relevant physiological and anatomical information regarding the auditory system. However, in this visual process of analysis some difficulties may occur, specifically, the results of the analysis may vary according to the type of protocol, settings of equipment employed, and the experience of the examiner. This makes the analysis of ABR subject to the influence of many variables that may interfere on the reliability and agreement of results obtained in distinct research centers and by different examiners. Therefore, the main propose of this study was to develop and assess a system capable of automatically detecting and classifying ABR waves, which are called Jewett waves. A relevant feature of the proposed tool is that it can learn from the experience of examiners continuously. In order to evaluate the system approximately 748 samples of ABR obtained from 11 subjects were analyzed by the automatic system. These results were compared to analyses obtained from five seasoned examiners, and they showed a high level of agreement, ranging for 74.3% to 99.7%, between responses given by the system and the examiners. Thus the proposed technique is proved to be accurate even in the presence of noise, especially characteristic of the ABR that is a sign of low amplitude.

Aplicação do teste SSW em indivíduos com perda auditiva neurossensorial usuários e não usuários de aparelho de amplificação sonora individual / Assessing individuals with bilateral hearing loss users and non-users of hearing aids by the SSW test

OBJETIVO: comparar o desempenho de pacientes usuários e não usuários de AASI, por meio do teste SSW. MÉTODO: o estudo foi realizado em 13 sujeitos com idade entre 55 e 85 anos, com perda auditiva bilateral, sendo seis usuários de prótese auditiva bilateral e sete não usuários de prótese auditiva. O teste de processamento auditivo aplicado foi o teste de reconhecimento de dissílabos em tarefa dicótica SSW. Foi realizado um tratamento estatístico feito por meio da técnica Bootstrap e do Teste de Hipótese Kolmogorov-Smirnov. RESULTADOS: o grupo de usuários apresentou melhor desempenho nas condições estudadas do que o grupo de não usuários, principalmente nas condições competitivas. CONCLUSÃO: os resultados obtidos nessa pesquisa apontam para a eficácia do uso do AASI na melhora da compreensão de fala da população estudada, não somente pela compensação da perda auditiva periférica, mas também pela interferência no processo de envelhecimento do sistema nervoso auditivo central.

PURPOSE: to compare the performance of patients who are users and non-users of hearing aids, through the assessment by the SSW test and reinforce the importance of auditory stimulation through the use of hearing aids in individuals with hearing loss. METHOD: the study was conducted on 13 individuals aged between 55 and 85 year old, with bilateral hearing loss, 6 users of bilateral hearing aids and 7 non-users of hearing aids. The applied test was the SSW test. Before applying the SSW test, these people underwent anamnesis, audiologic and otorhorynolaringologic evaluation. A statistical analysis was performed using the Bootstrap technique and Kolmogorov-Smirnov hypothesis test. RESULTS: the users group showed better performance in the studied conditions then the non-users group, especially under competitive conditions. CONCLUSION: the use of hearing aids contributes to the improvement in speech recognition, through the auditory stimulation.