RESUMO
RESUMO O objetivo deste trabalho é apresentar a Medicina Evolutiva à comunidade de educação médica brasileira. A Medicina Evolutiva pode ser definida como a aplicação da teoria da evolução por seleção natural à compreensão de problemas de saúde humana. Essa abordagem inovadora provê a medicina de um quadro teórico organizado que contribui para explicar uma grande diversidade de afecções importantes. Originada em princípios da década de 1990, a Medicina Evolutiva procura explicar as doenças tanto com base em causas fisiológicas próximas, normalmente mobilizadas pela medicina, quanto com base em causas evolutivas distantes, responsáveis pelo aparecimento e manutenção, ao longo da história da Terra, de estruturas biológicas úteis e funcionais. A Medicina Evolutiva está estruturada em torno da ideia principal de que as características biológicas funcionais resultam de processos evolutivos, adaptativos. Procura-se com isso entender muitas doenças em termos de vulnerabilidades das adaptações legadas por nossa herança filogenética, como no caso de desajustes do corpo humano em relação ao ambiente moderno. Além de apresentar uma definição de Medicina Evolutiva, discutimos dois problemas que têm sido abordados à luz da teoria da evolução por seleção natural. Em primeiro lugar, discutimos como a emergência e a distribuição geográfica e étnica da intolerância à lactose (e sua contrapartida, a persistência da lactase) só podem ser compreendidas considerando-se a história evolutiva recente de nossa espécie, incluindo suas transformações culturais. As limitações de explicações prévias que prescindiam desses fundamentos são apresentadas. Em seguida, abordamos o caso das hérnias discais. Tentamos demonstrar as relações entre essa condição e os desajustes da postura bípede ao estilo de vida moderno. A compreensão desse desajuste e as restrições à ação da seleção natural ao adaptar a estrutura quadrúpede a uma vida bípede estão entre os conceitos específicos utilizados para formular uma hipótese com potencial diagnóstico relevante. Concluímos este ensaio sugerindo maneiras pelas quais estudantes de Medicina poderiam incorporar esse saber relativamente novo em sua formação.
ABSTRACT The aim of this paper is to introduce some principles of Evolutionary Medicine to the community of medical educators in Brazil. Evolutionary Medicine can be defined as the application of the theory of evolution through natural selection to the understanding of human health problems. This innovative approach provides the medical field with a theoretical framework which contributes to the explanation of a great variety of serious disorders. Evolutionary Medicine, which dates back to the early 1960s, aims to explain diseases based both on recent physiological causes — those most commonly addressed by medicine — and on more distant evolutionary causes — those responsible for the emergence and survival of useful and functional biological structures throughout the history of the planet. Evolutionary Medicine rests on the assumption that functional biological characteristics are the result of evolutionary adaptive processes. Therefore, it is possible to analyze a great number of diseases in terms of adaptive vulnerabilities connected to our phylogenetic inheritance, such as human bodily inadequacies in relation to the modern environment. Besides presenting a definition of Evolutionary Medicine, this paper discusses two health problems recently dealt with in the light of the theory of evolution through natural selection. First, we discuss how the appearance, the ethnic and geographic distribution of lactose intolerance (and, on the other hand, the persistence of lactase) can only be understood taking our species' recent evolutionary history (including its cultural transformations) into consideration. The limitations faced by previous explanations, which lacked evolutionary causes — are discussed. Secondly, the paper discusses herniated spinal disc, trying to demonstrate the link between this condition and the adaptation problems that bipedal posture may entail in view of the demands of modern lifestyle. The understanding of such problems of adaptation, combined with restrictions to natural selection pressures when adjusting a quadruped structure to a biped lifestyle, serve as the basis for the development of specific concepts used to formulate a hypothesis with relevant diagnostic potential. Finally, the paper describes ways in which medical students could incorporate this relatively new knowledge into their education.
RESUMO
STUDY DESIGN: A single-center prospective study. PURPOSE: A magnetic resonance imaging (MRI) scan is undeniably the gold standard for the diagnosis of a lumbar disc prolapse. Unfortunately it shares a strong association with incidental findings. In this study, we aimed to determine the extent to which a 1.5 Tesla MRI correlates with the clinical features and intraoperative findings in cases of lumbar disc prolapse. OVERVIEW OF LITERATURE: Few studies have correlated MRI with clinical findings, and none have extended this correlation to intraoperative findings. METHODS: Over a 2-year period, 50 consecutive patients with lumbar disc herniation requiring discectomy were studied. The MRI findings we observed consisted of the prolapse level, type, position, migration, high-intensity zones (HIZ), lateral recess, and foraminal stenosis. A logistic regression analysis was performed to determine the significance for the various MRI findings. Finally, the MRI observations were confirmed with intraoperative findings and inferences were drawn. RESULTS: MRI scan sensitivity and specificity for determining surgically significant levels was 100% and 94.94%, respectively. Straight leg raising test was positive in 74% of patients, with 85%, 43%, and 75% for paracentral, central, and foraminal levels, respectively. A foraminal compromise was the only MRI parameter to share a significant association with neurological deficits. Patients with a HIZ on the MRI had a significant increase in back pain and 63% exhibited identifiable annular tears intraoperatively. The intraoperative anatomical findings correlated extensively with the MRI findings. CONCLUSIONS: MRI findings strongly correlate with intraoperative features and can serve as a useful tool when planning surgery due to the accurate depiction of the morphometric features. However, the decision for surgery should be made only when detailed clinical findings in conjunction with MRI findings allow for an accurate identification of the culprit fragment and pain generators.