Neurotology

What exactly is a neurotologist? I googled the term to see if there was an accepted definition. There were three different definitions in the first three hits: (1) An ear-nose-throat medical specialist who obtains an additional subspecialty in conditions of the ear; (2) a medical doctor who specializes in medical and surgical treatments for the ear; and (3) the medical study of the nervous system as it affects the ear and hearing loss. Being a neurologist by training I was most comfortable with the third definition, but I must admit that the first two definitions are more commonly accepted. Neurotology has primarily been a subspecialty of otolaryngology and the “neuro” has been deemphasized. It is time to reemphasize the “neuro” component of neurotology and this volume of Seminars is a good beginning. I have selected a group of neurologists from around the world who are experts in the vestibular and auditory systems (brain and ear). They cover a broad range of topics summarizing recent progress in the diagnosis and treatment of common neurotologic disorders.

Drs. Hannelore Neuhauser and Thomas Lempert review their work on the epidemiology of vertigo. This is an important area of neurotology that has been largely neglected. They have conducted systematic surveys of the German population to determine the prevalence and incidence of different types of vertigo. This type of information is invaluable for clinical decision making and for improving patient care.

Dr. Kevin Kerber focuses on the common causes of vertigo seen in the emergency department. The key differential diagnosis is between benign inner ear disorders and acute stroke or impending stroke. Dr. Kerber describes how to make the diagnosis based on patient history and several simple bedside tests. He also offers guidelines as to when to order imaging studies.

Dizziness and balance disorders are among the most common symptoms experienced by older people. Dr. Gail Ishiyama addresses the importance of age-related changes in the vestibular system. She and her colleagues have been pioneers in the use of unbiased quantitative stereology for examining peripheral and central vestibular structures.

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo and there is a simple bedside maneuver that cures the disorder in most patients. Dr. Terry Fife has been at the forefront in training and educating neurologists on performing the particle repositioning maneuver. He recently chaired the committee that generated a position paper on treatment of BPPV for the American Academy of Neurology. All physicians, but particularly neurologists, should be familiar with the diagnosis and treatment of BPPV.

Drs. Michael Strupp and Thomas Brandt have performed pivotal experiments on the pathophysiology and treatment of vestibular neuritis. Their work solidified the “latent herpes simplex” theory of causality and they conducted the first large randomized placebo controlled treatment trial. They provide a comprehensive up-to-date review of this common neurotologic disorder.

Most of us have experienced a transitory rocking sensation after disembarking from a boat, so-called sea legs. A small percentage of subjects have a persistent rocking sensation that lasts from months to years and is often disabling, the mal de debarquement syndrome (MdD). Dr. Yoon-Hee Cha reviews the clinical features, pathophysiology, and treatment of MdD. She has conducted the first systematic clinical study of MdD and has begun a series of research studies in an attempt to understand the pathophysiology of MdD.

Although there are many genetic disorders with bilateral hearing loss and normal vestibular function so far there are no genetic disorders with bilateral vestibular loss and normal hearing. Dr. Joanna Jen reviews the common causes of bilateral vestibular loss and concludes that many of the idiopathic cases are likely genetic. She describes several clinical syndromes and presents preliminary data on a genetic locus for bilateral vestibular loss with normal hearing. This is a field that will be rapidly expanding over the next few years.

Vertigo and hearing loss are common symptoms associated with stroke in the posterior circulation. Drs. Ji Soo Kim and Hyung Lee have conducted key clinical studies on how to identify patients at risk for stroke. They have developed a large stroke registry in South Korea and have systematically performed clinical and laboratory examinations on all patients who enter the registry. They clearly show that isolated vertigo and/or hearing loss can be the initial symptom of impending stroke (particularly within the territory of the anterior inferior cerebellar artery).

For the first time there is a simple quantitative test of the gravity-sensing otolith organs of the inner ear. Dr. Krister Brantberg suggests that vestibular evoked myogenic potentials (VEMPs) are the most important new test in neurotology since the development of the caloric test in the early 20th century. Dr. Brantberg has been at the forefront in evaluating the clinical usefulness of VEMP testing and he systematically reviews his experience using VEMPs for diagnosing common neurotologic syndromes.