The University of Texas Southwestern Medical CenterUnited States of America
Meniere’s disease, with its characteristic symptom triad of vertigo, balance and hearing disorders has yet to have its pathophysiology outlined conclusively. Any theory must elucidate all aspects of the natural progression, including vestibular and auditory symptoms. While the central dogma revolves around endolymphatic hydrops, this theory is not without flaws, such as its inability to explain all the physiological changes seen in patients, or the often absence of symptoms. While several degenerative changes are observed in temporal bone histopathology, they do not necessarily explain the sequence of events in the development and progress of the disease. This chapter explores the pathophysiology of the disease, focusing on the hydrops theory, while presenting evidence for and against it. Various changes in the inner ear physiology such as pressure changes, ionic disequilibrium, endocochlear potentials; in human and animal models are described. Alternative explanations for symptoms are discussed. This chapter touches briefly upon etiology associated with Meniere’s (and hydrops), and aims to assist a deeper understanding of the relationship of the process to clinical and experimental findings. A clear understanding of the process guides not only the clinical management to improve quality of life but also the direction of future research endeavors.
Part of the book: Up to Date on Meniere's Disease
Hemorrhagic stroke accounts for 15% of all strokes but results in nearly a third of the mortality. Neuroimaging forms the mainstay in diagnosis, which has resulted in improved treatment outcomes. The mandate of neuroimaging includes management, risk assessment, prognostication, and research. This involves rapid identification not only to direct treatment but also to discover the underlying etiology such as vascular malformations or tumors, monitor the evolving course of the hemorrhage and rapidly identify complications. While computed tomography (CT) remains the imaging of choice to rapidly detect acute hemorrhage, growing evidence shows that magnetic resonance imaging (MRI) is comparable to CT for detecting blood in the immediate setting and superior in this regard at subacute and chronic time points. Several advances have been made in the image sequencing protocols to detect bleeds at varying time points and to distinguish possible etiology. Initial and serial imaging is used to identify patients who may benefit from intervention. Advances in this field such as diffusion tensor imaging and functional MRI are being studied for their impact in understanding the extent of injury and possible recovery mechanisms, possibly allowing prognostication for patients.
Part of the book: Hemorrhagic Stroke