30
Vol. 66, No. 1 2015
Northeast Florida Medicine
Otolaryngology
VOR by triggering small corrective torsional movements
that compensate for changes in head tilt (ocular counter
roll). Thus the otolith mediated VOR aligns the horizontal
meridian of the retina with the horizon while the semicir-
cular canal mediated VOR maintains stable vision during
head rotations.
1
The otolith organs also interact with cerebellar structures
to maintain muscle tone in the large anti-gravity muscles
in the neck, spine and lower limbs. They also influence
autonomic control of digestion and certain cardiovascular
reflexes to compensate for changes in gravitational and
inertial forces that vary with changes in body posture and
movement. Not surprisingly, the cardinal signs of vestib-
ulopathy are vertigo (VOR mediated illusions of rotation
or head movement), lightheadedness or heavy-headedness
sensations and imbalance (absent or aberrant VSR reflexes,)
nausea and other autonomic symptoms.
1,2
The visual and proprioceptive systems also contribute
to balance and spatial orientation. As a cause of dizziness,
the contribution of vision is often overlooked. The human
visual system is really two separate systems. Each provides
important cues about head and body position in space.
With head movement, macular vision can detect changes
in the relationships between objects in the environment
(visual perspective). The depth of field cues arising from
binocular vision can provide additional information about
fore/aft sway.
Peri-macular vision is particularly sensitive to movement
arising from head movement or movement arising from the
environment. When visual motion is detected in a large
portion of the visual field, vestibular sensory information
helps resolve the source of the movement. If the vestibular
systemdoes not detect headmovement, something must be
occurring “out there” in the environment. If head move-
ment is detected, the brain correlates the two information
streams to determine if there is any additional movement
in the external environment. This necessitates a careful
registration between vestibular and peri-macular “visual
flow” sensory information.
The sensory inputs from all three systems are both syn-
ergistic and redundant. “Synergistic” meaning that some
information from each sense is unique and is interpreted
optimallywith context from the other systems; “Redundant”
means that some information provided by any particular
sense is also available from the other senses. Synergism
and redundancy underpins resiliency in spatial orientation
and balance abilities. Redundancy is also important for
maintaining the registration of converging sensory infor-
mation– particularly when there are changes in the fidelity
of any one sense. When registration is faulty, dizziness and
imbalance can occur. Anyone who has had to adjust to
prescriptive eye glasses for the first time has experienced
this form of dizziness. With redundancy, the brain can
adapt to lawful changes in visual flow by correlating the
visual flow with vestibular information. When adjusting
to new eye glasses, central adaptation is complete over the
course of a few days and dizziness resolves.
With age or disease, sensory fidelity may deteriorate.
If two or more senses are impaired, even to a seemingly
trivial extent, loss of registration can be a serious disruption
in the person’s ability to stand, walk or otherwise remain
spatially oriented.
BPPV and the Epley Omniax Chair
Case #1:
An 84-year-old diabetic male with peripheral
neuropathy and periventricular shunt was referred by
neurosurgery for persistent dizziness and fall history. His
fall history began four months earlier with an inadvertent
stumble and blow to the head. Prior to his fall, he ambulated
with a cane. Following the fall, he was wheelchair bound.
After an extensive work-up (including continuing control
of intracranial pressure), no clear cause of his inability to
walk could be found. He was subsequently referred for
vestibular evaluation.
On presentation, he was a tall gentleman complaining
of chronic lightheadedness and disequilibrium. His audi-
ological evaluation demonstrated a bilateral symmetrical
mild sensorineural hearing loss. His vestibular assessment
demonstrated mild bilateral vestibular weakness. These
were in keeping with his stated age. There was no evidence
of acute or focal vestibulopathy.
This gentleman had significant neck kyphosis. As a
result, standard Dix-Hallpike maneuvers were difficult
to perform. He did not complain of vertigo so this could
have been easily overlooked. He did undergo evaluation
for positional dizziness using an Epley Omniax Chair. The
Epley Omniax Chair is a motorized device that can tilt
patients into positions that can provoke BPPV symptoms
emanating from any semicircular canal. Because the pa-
tient is immobilized in the chair with full body support,
the head can be moved into any attitude without flexing
or extending the neck. On this evaluation, he was found
to have bilateral posterior canal canalithiasis.
This patient subsequently underwent treatments for bilat-
eral posterior canal BPPV using the Epley Omniax Chair.
After four treatments he was no longer dizzy and returned to
using a cane to ambulate. Over time, his appetite improved
and he gained leg strength. Three years later, he has had
recurrences of BPPV about every six to eight months. When
he is clear, he is able to safely walk with a cane.
