Why is the nystagmus in a BPPV patient rotary? What is the underlying explanation for the rotational characteristic?
Each semicircular canal directly influences a pair of extraocular muscles that move the eye approximately in the plane of that canal, regardless of the initial position of the eye in the orbit. This is the key to your question in that an abnormality or disease that directly affects one semicircular canal may produce nystagmus that rotates the globe of the eye in a plane parallell to that in which the canal lies.
In cases of posterior canal BPPV, when the posterior canal is moved into the Hallpike position (earth-vertical), the net result is to produce false excitory signals from the affected posterior canal. When excited the posterior canal sends excitory signals to the ipsilateral superior oblique eye muscle and the contraslateral inferior rectus. This causes the eye to rotate in the socket towards the down ear in the Hallpike position.
Henry P. Trahan, Au.D. Asst. Professor of Audiology The Arizona School of Health Sciences 5850 E. Still Circle Mesa, AZ 85206
Dr. Trahan is a graduate of LSUHSC, Masters of Communicative Disorders. Graduate of the University of Florida, Doctor of Audiology
Currently: Assistant Professor of Audiology at the Arizona School of Health Sciences. Lead faculty for the 4 year AuD Residential program. Currently also teaching Vestibular Assessment Procedures and Balance Remediation in the ASHS AuD Distance Ed AuD program.
Past: 20 years private practice with significant involvement in assessment of vestibular disorders and vestibular rehabilitation.
Conducted numerous workshops and presentations in regards to Audiologists in private practice adding Vestibular Assessment and Vestibular Rehabilitation to their practices.
This presentation will first provide a brief overview of the video head impulse test followed by a review of three contemporary articles employing this technology. The content will be directed toward those with a clinical background. As a Vanderbilt Journal Club course, this seminar will also include a brief review of other articles to pertinent to audiology practice by host Dr. Gus Mueller.
'I thought the information was very helpful in providing an understanding of what vHIT is and what it is meant to assess'Read Reviews
This journal club will focus on how different types of self-report measures including the Hospital Anxiety and Depression Scale (HADS), the Dizziness Handicap Inventory (DHI) the Structured Interview for Migrainous Vertigo (SIM-V), and a case history questionnaire can be helpful in the assessment of patients presenting with vertigo, dizziness and unsteadiness.
'Easy to understand and follow along with slides'Read Reviews
Join the senior audiology staff and their students at Henry Ford Hospital in Detroit, Michigan as they highlight interesting clinical cases in a grand rounds style format. In addition to the case presentations, a live video feed will capture spontaneous questions, discussion and debate that make the department’s staff meetings lively, insightful and thought-provoking in order to facilitate clinical decision-making and best practices. This session will cover vestibular cases. For information and to register for other courses in this series please visit www.audiologyonline.com/grandrounds
'I love cases and feel that this is an excellent way to learn about issues with the testing process and how the evidence can help inform diagnosis and treatment'Read Reviews
ICS Impulse makes head impulse testing accessible for any clinician. This course will cover what is gained by performing the head impulse, how to perform the head impulse, and how does the data obtained assist in the diagnosis and treatment of the patient and how does it fit into our current battery of tests.
'I enjoyed that each aspect of testing and interpretation were explained in detail and with visual aids'Read Reviews
This journal club will focus on a description of what processes are believed to occur in central compensation following predominantly profound unilateral vestibular system impairment. Also incorporated into this lecture will be illustrative patient data and current beliefs about how the ocular motor system contributes to the process of compensation in unilateral and bilateral peripheral vestibular system impairment.
'Lots of excellent information presented with good visuals to look at'Read Reviews