Challenges in Neuro-Otology

Abstract

This article provides an overview of the current methods of diagnosis and treatment of patients with vertigo, dizziness, or imbalance, as well as an analysis of ongoing problems besetting the field of neuro-otology. Aims and challenges are also described with the hope of stimulating basic and clinical research on these very frequent symptoms. Vertigo and dizziness are among the most frequent symptoms that patients experience at some time in their lives. With a lifetime prevalence of about 30% and an annual incidence that increases with age, vertigo and dizziness will become even more important in the future. Despite this high prevalence and burden of disease, considerable challenges remain. Most patients with acute vertigo and dizziness are uncertain who to consult, because their problem lies inbetween the specializations of ear, nose, and throat (ENT) and neurology, and in some cases, ophthalmology, internal medicine, or psychiatry. While neurologists are very familiar with the anatomy, physiology, and pathophysiology of the central nervous system (central vestibular and ocular motor systems), ENT physicians specialize in the peripheral vestibular and audiological systems. However, very few have detailed knowledge of both the central and peripheral systems. Moreover, most ENT physicians practice mainly as ENT surgeons, and therefore, they are not necessarily specialists on vertigo and dizziness. With a few exceptions (South Korea, and some centers in the USA, UK, and Australia) cooperation between neurology and ENT as well as neuro-otology and oto-neurology is far from perfect. The underlying diseases resulting in vertigo and dizziness cover a broad spectrum of anatomical structures. Possible etiologies include ischemia, infection, autoimmune disorders, mechanical inner ear disorders, psychosomatic, and somatoform disorders. Therefore, the approach to patients requires a broad-based knowledge of anatomy, physiology, pathophysiology, and pharmacology as well as in-depth practical experience with the different methods available for evaluating the vestibular and ocular motor systems. Medical education in neuro-otology is also less than optimal. The problem begins in Medical School, where the vestibular and ocular motor systems are assumed to be among the most complicated anatomical and physiological systems of humans. Therefore, most medical students are not attracted to this field, which may also explain their limited knowledge of the subject. This downward trend continues during post-graduate training for most neurologists and ENT physicians, and is further exacerbated by the above-mentioned overlapping of the two disciplines. Moreover, to establish a correct diagnosis, physicians must examine the vestibular, audiological, and ocular motor systems. Furthermore, many physicians have difficulties examining the ocular motor system and ultimately interpreting their findings. What is pathological and what do the findings mean? Thus, topographical anatomical diagnosis remains a challenge: it is imperative to be able to discriminate between peripheral and central vestibular lesions is imperative. The link between basic physiology and the modeling of the vestibular and the ocular motor systems, on the one hand, and their clinical implications and applications, on the other, are far from ideal. While we know the detailed workings of the vestibular and ocular motor systems and can model their function and dysfunction, this knowledge has not yet been fully integrated in clinical practice. Conversely, clinical findings have to be linked with basic knowledge in order to stimulate the knowledge of physiology and the modeling of these systems. State-of-the-art randomized controlled clinical trials on the frequent causes of vertigo and dizziness as well as their underlying disorders are still lacking. This is true for phobic postural vertigo, vestibular migraine, Meniere's disease, vestibular paroxysmia, downbeat and upbeat nystagmus, episodic ataxia, and perilymphatic fistula. The number of studies available on the impact of vertigo and dizziness, as well as impaired vestibular function on patients’ quality of life and functioning are limited. Long-term studies on the natural course of the different forms of vertigo, their recurrence rates, or the long-term efficacy of available treatments are non-existent. This is true for most forms of vertigo and dizziness. In brief our growing knowledge of the anatomy and physiology of the vestibular and related ocular motor systems, as well as basic and clinical research must still overcome a number of shortcomings and limitations to improve diagnosis, develop new diagnostic criteria, and better understand the pathophysiology of these disorders. Hopefully, new treatment strategies and state-of-the-art prospective clinical trials will improve the quality of life and functioning in patients with vertigo and dizziness.