New AAN Guideline on Vertigo
In the May 27 Neurology, the AAN Quality Standards Subcommittee published guidelines for the diagnosis and treatment of benign paroxysmal positional vertigo.
We asked Subcommittee member Timothy C. Hain, MD, professor of neuroscience at Northwestern University's Feinberg School of Medicine in Chicago, to help explain the new guidelines. Dr. Hain is an expert on dizziness and hearing loss.
In a sidebar, Subcommittee member Joseph M. Furman, MD, PhD, professor of otolaryngology and neurology and director of the Division of Balance Disorders at the University of Pittsburgh Medical Center, provides a case example to demonstrate how a physician might apply the recommendations.
WHAT IS BENIGN PAROXYSMAL POSITIONAL VERTIGO (BPPV)?
BPPV is a clinical syndrome characterized by brief recurrent episodes of vertigo triggered by changes in head position with respect to gravity. BPPV is the most common cause of recurrent vertigo, with a lifetime prevalence of 2.4 percent.
Typical signs of BPPV are evoked when the head is positioned so that the plane of the affected semicircular canal is spatially vertical and aligned with gravity. This produces a paroxysm of vertigo and nystagmus, or involuntary eye movements, after a brief latency. The duration, frequency, and intensity of symptoms of BPPV vary, and spontaneous recovery occurs frequently.
WHAT CAUSES IT?
BPPV results from abnormal stimulation of the cupula within any of the three semicircular canals in the inner ear, although most cases affect the posterior canal. As fluid in the inner ear rushes by the cupula, hair cells sense rotational acceleration and transmit this information to the brain through the vestibulocochlear nerve. The brain then makes appropriate physical adjustment to maintain balance and equilibrium. Abnormal stimulation of these hair cells is often caused by canaliths.
The most common cause of BPPV in people younger than age 50 is head injury. In older people, the most common cause is degeneration of the vestibular system of the inner ear. BPPV becomes much more common with advancing age. In half of all cases, BPPV are idiopathic.
WHAT ARE CANALITHS?
Canaliths are tiny particles of calcium carbonate, or limestone, attached to tiny hairs in the inner ear. They are found in all normal ears, but sometimes become detached from the hair cells and can cause dizziness when they move about within the inner ear canals.
DESCRIBE THE THREE BASIC TYPES OF BPPV: POSTERIOR, ANTERIOR, AND HORIZONTAL CANAL BPPV.
Within the inner ear there are three semicircular canals, and a specific type of BPPV is associated with each one. The most common type is posterior canal (PC) BPPV. It is the most common because it is the lowest canal in the inner ear and therefore detached canaliths tend to remain there. In PC BPPV, dizziness and nystagmus are triggered when the head rotates about the axis of the PC, usually, but not always, when a patient lies down on one side. PC BPPV is only triggered on one side. The nystagmus direction — a mixture of upbeating and torsion — is unusual in other conditions, so PC BPPV can be easily diagnosed. [Nystagmus can be horizontal (on lateral gaze) or vertical (upbeating or downbeating, determined by the faster component — up or down).]
The second most common type of BPPV is horizontal canal (HC) BPPV. Canaliths that fall into it also tend to easily move out again. In HC BPPV dizziness and nystagmus is triggered when the head is moved to either side. HC BPPV nystagmus is horizontal rather than upbeating, and it is generally stronger than the nystagmus of PC BPPV. Horizontal nystagmus similar to that of HC BPPV can occur in other conditions, such as cerebellar disorders, but HC BPPV is nevertheless the most common source of this nystagmus pattern.
The least common type of BPPV is anterior canal (AC) BPPV. In order to get into the anterior canal, canaliths must migrate upward with respect to the upright head, and this is unusual. In AC BPPV, symptoms are mainly triggered with the positioned head straight but turned backwards, and nystagmus is down beating, although this can also occur in other central conditions.
WHAT IS THE RECURRENCE OR RELAPSE RATE FOR BPPV?
Short-term relapses rates range from 7 percent to nearly 23 percent within a year of treatment. Over about five years, long-term recurrences may approach 50 percent.
WHAT TECHNIQUES CAN BE USED TO TREAT POSTERIOR CANAL BPPV?
Canalith repositioning maneuvers, originated by John Epley, MD, and Alain Semont, MD, are used for treating PC BPPV. Both maneuvers take about 10 minutes to perform, and involve a series of positions of the head in which canaliths are allowed to move within the inner ear. At the end of a successful maneuver, the canaliths have been moved into an insensitive part of the inner ear. There is strong evidence for the effectiveness of the Epley maneuver. The Semont maneuver does not have as much evidence for effectiveness, but the head positioning is similar to the Epley maneuver.
WHAT TECHNIQUES CAN BE USED FOR ANTERIOR AND HORIZONTAL CANAL BPPV?
Similar canalith repositioning maneuvers for treatment of anterior and horizontal canal BPPV have been proposed, but convincing evidence for their effectiveness is not yet available. Maneuvers for PC BPPV do not work for HC BPPV. The head positions of the proposed specific maneuvers are modified in order to move canaliths within these canals which are perpendicular to the posterior canal. The HC maneuvers are moderately effective for HC BPPV. There is no current recommendation of a maneuver for AC BPPV.
ARE ANY RESTRICTIONS NECESSARY FOR PATIENTS AFTER UNDERGOING THESE POSITIONING TECHNIQUES?
Most studies indicate that restrictions are not necessary.
WHAT IS MASTOID VIBRATION AND IS IT IMPORTANT FOR THE EFFICACY OF THESE MANEUVERS?
Mastoid vibration is the use of a massager-like device to oscillate the affected ear during the canalith repositioning maneuvers. Most studies indicate that mastoid vibration is of no benefit.
WHAT ARE HABITUATION EXERCISES, AND HOW ARE THEY USED TO TREAT PATIENTS?
Habituation exercises are procedures designed to elicit symptoms over and over, in the hopes that this will provoke a CNS reaction that will diminish the response. These exercises are ineffective.
The Brandt-Daroff exercises are an early form of canalith repositioning exercises. They are less effective than the later maneuvers developed by Epley and Semont.
There are self-administered variants of both the Epley and Semont maneuvers for PC BPPV. There is presently insufficient evidence regarding the effectiveness of either of these maneuvers.
ARE ANY MEDICATIONS EFFECTIVE FOR BPPV?
Medications are not recommended for routine treatment of BPPV.
ARE THERE ANY EFFECTIVE SURGICAL TREATMENTS?
Posterior canal occlusion is a surgical treatment that inactivates the part of the ear that causes most BPPV. Singular neurectomy is another surgical treatment in which the nerve to the posterior canal is cut. While all available studies suggest that surgery is effective, the studies were not of high enough quality to provide strong evidence of efficacy. Surgical treatments also are associated with a small risk of deafness.
WHAT RESOURCES ARE AVAILABLE FOR CLINICIANS TO LEARN MORE ABOUT THESE TECHNIQUES?
Courses are given at the AAN on these maneuvers. Descriptions of all the maneuvers are available at this URL: www.dizziness-and-balance.com/disorders/bppv/bppv.html.
WHAT RESEARCH IS NEEDED TO BETTER UNDERSTAND AND TREAT THIS DISORDER?
Class I (prospective, blinded) studies are still needed to clarify the best treatments for horizontal and anterior canal BPPV. •