Coherence and Phase Locking Disruption in Electromyograms of Patients with Amyotrophic Lateral Sclerosis

Abstract

perpétuo e sem limites geográficos, de arquivar e publicar esta dissertação através de exemplares impressos reproduzidos em papel ou de forma digital, ou por qualquer outro meio conhecido ou que venha a ser inventado, e de a divulgar através de repositórios científicos e de admitir a sua cópia e distribuição com objectivos educacionais ou de investigação, não comerciais, desde que seja dado crédito ao autor e editor. To my colleges Marília and Inês, a big thank you to both for all the funny moments, adventures and help. A special thank you to Marília who stood by me every day with her available support, motivation and cheerfulness. Her daily presence made me win the day and without it, my work would have never been the same.Por último mas mais importante, agradeço à minha família. Sem a sua paciência, motivação, crença e fé em mim, nunca teria chegado onde estou. Aos meus pais, um muito obrigado por tudo na vida e por serem os meus exemplos. Obrigada pelo constante apoio e por sempre aceitarem o caminho que escolho. Ao meu irmão pela constante preocupação que tem por mim. À minha avó e tios, por me fazerem sentir única e precisa. Ao Pedro Santana, um enorme obrigada pela atenção e paciência que sempre tem comigo, mas especialmente por me proporcionar os melhores fins de dia.Às amigas cuja companhia é uma necessidade, obrigada por me aturarem, ouvirem e motivarem.Obrigada pela diversão que fazem do meu dia. Tenho muito orgulho em todos e a vós dedico o meu trabalho. vii viii AbstractIn motor neuron disease, the aim of therapy is to prevent or slow neuronal degeneration and early diagnosis is thus essential. Hypothesising that beta-band (15−30 Hz) is a measure of pathways integrity as shown in literature, coherence and PLF could be used as an electrophysiological indicator of upper and lower neuron integrity in patients with ALS.Before further analysis, synthetic EMG signals were computed to verify the used algorithm. Coherence and PLF analyses were performed for instants of steady contraction from contra and ipsilateral acquisitions. Ipsilateral acquisitions were performed for one member of each group and results present significant differences between both groups.Contrarily, contralateral acquisitions were performed on 6 members of each group and results present no significant differences. PLF analysis was computed for ipsilateral acquisitions and, similarly to coherence, results show significant differences between both groups. PLF was also analysed for contralateral acquisitions, and results show no significant differences within groups, as expected since no coherence was found for the same acquisitions. So, while control subjects present no neuronal or muscular problems and therefore higher synchrony and coherence for beta-band frequencies, patients with ALS do not present synchronism or coherence in any frequency, specially for beta-band. All results allowed to conclude that contralateral coherence is not a good measure of corticospinal pathways integrity. However, ipsilateral acquisitions show promising res...