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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4382_Библиотеки_им_академика_М_И_Перельмана
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18 Rotational Vestibular Assessment
turntable upon which they mounted a second
counterrolling table that was eccentrically positioned 2 feet from the center axis of rotation on
the main table (see Figure 1–14). Rotation of the
table occurred such that, for every rotation of
the main table, the second table completed one
rotation, only in the opposite direction. Johnson
claimed such an eccentric-driven table was capable of producing horizontal nystagmus and, given
enough time and research, could eventually be
adopted for use in routine vestibular laboratory
testing.
With the newly discovered corneoretinal
potential, the analysis of rotationally induced nystagmus also advanced at an exponential rate. Mathog (1972) is credited with one of the first reports
detailing the various response parameters analyzed from the nystagmus during sinusoidal acceleration testing (Goulson, McPherson, & Shepard,
2016). In his report, Mathog described rotational
analysis parameters of directional preponderance
and VOR gain in response to sinusoidal rotations
delivered at low-, mid-, and high-frequency accelerations. Such analyses bridged the way to current methods of sinusoidal rotational analysis.
A few years prior, Wilmot (1966) was arguing for a
thorough examination of the vestibular system to
include rotational measures that detected thresh-
old of motion perception. With a custom built
rotational chair, Wilmot showed that vestibular
threshold detection measures could reliably be
obtained with the use of single-eye electrooculography (EOG) recordings. Electrooculography
recordings were crude at that time. However, Dix,
Hallpike, and Hood (1963) were improving current methods by introducing direct current amplification to record both sustained eye deviations, as
well as dynamic nystagmus movements. Despite
using enhanced EOG recording methods, the idea
to record vestibular threshold detection responses
(much like auditory thresholds) was highly novel.
Wilmot (1966) is also likely the first to describe
the use of rotational testing as a screening tool to
detect early pathological vestibular changes. In
his report, Wilmot argued for the use of angular
rotations to record threshold detection measures
for the early identification of vestibular disease to
promote early medical intervention (McNally &
Stuart, 1967).
Since the 1970s, various manufacturers have
increased the level of sophistication in signal
processing, both in the recording of the ocular
response (EOG versus videooculography, VOG),
as well as in the delivery of the various rotational stimuli. Stimuli delivery was particularly
improved when rotational chairs transitioned
from DC- to AC-driven torque motors. Motors
were now capable of delivering highly precise
stimuli with little to no vibration noise independent of patient weight.
The military and aerospace divisions have
long been given credit for a great deal of research
using human centrifuges. William J. White published an elaborately illustrated work entitled A
History of the Centrifuge in Aerospace Medicine in
1964, which describes the use of rotational systems
to explore the effects of various environments on
the human vestibular system. As early at 1935, the
military and aerospace facilities led much of the
way in the development and production of human
centrifuge research. The Wright Field Centrifuge
located in Riverside, Ohio, (Wilbur Wright Field,
now part of Wright-Patterson Air Force Base) was
the first human centrifuge constructed in North
American (Figure 1–16). The largest and most
powerful human centrifuge (even to this day) was
constructed in 1950 in Warminster, Pennsylvania,
at the Johnsville Naval Air Development Center
(NADC) (Figure 1–17). With a 50-foot radius, the
Johnsville Centrifuge was capable of producing
40 g while traveling at a velocity of 175 mph. Its
use significantly impacted the success of aerospace missions, and functioned up until 2004, at
which time the Johnsville Centrifuge facility was
decommissioned. Although the facility has since
been repurposed, much of the history (as well as
the original Mercury 7 Johnsville gondola) has
been preserved under the care of the Johnsville
Centrifuge and Science Museum. Considered to
be of equal notoriety to the Johnsville Centrifuge,
the Karolinska Centrifuge in Stockholm, Sweden,
was equally impressive, with a 40-foot radius
capable of producing 30 g (Figure 1–18). Finally,
Guedry, Kennedy, Harris, and Graybiel (1962)
reported on the absence of any psychological or
physiologic effects on four servicemen during a
two-week exposure in the Pensacola Slow Rotation Room in Pensacola, Florida.
A
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B
FIGURE 1–16. The Wright Field Centrifuge (1935). A. The first
human centrifuge in North America by Drs. H.G. Armstrong and
J. W. Heim. Consisted of a 10-foot radius tubular aluminum frame
with a side-mounted adjustable seat (gondola) on one end. Source:
Reprinted with the courtesy of Special Collections and Archives,
Wright State University, Dayton, OH. B. Sketch of the pilot position
held within the centrifuge gondola. From A History of the Centrifuge in
Aerospace Medicine by W. J. White, 1964, Santa Monica, CA, Douglas Aircraft Company, Inc.
19
A
B
FIGURE 1–17. The Johnsville Centrifuge, Warminster, PA (1950–2004). Johns-
ville Naval Air Development Center (NADC) constructed the largest and most powerful human centrifuge ever built, even to this day, with a 50-foot radius, capable of
producing up to 40 g at 175 mph. A. Reprinted with permission from Boeing Aircraft
Company. B. Reprinted with permission from the Johnsville Centrifuge Science
Museum.
20
1. Historical Perspective of Human Rotation and Centrifugation 21
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FIGURE 1–18. The Karolinska Centrifuge, Stockholm, Sweden, (1954). Swedish
Committee for Aeronautical and Naval Medical Research at the Karolinksa Institute
built this 40-foot radius, 30 g human centrifuge. Source: Reprinted with permission
from the Karolinska Institute, Department of Physiology and Pharmacology.
Between the 1970s and 1990s, clinical rotation research and the application of clinical rotational assessments also grew at an exponential
rate. There were a number of proprietary rotational chairs at the time, as well as some commercially available clinical rotational chairs, that were
designed and constructed with the sole purpose
of evaluating the vestibular response. Such clini-
cal rotational chairs included the Tönnies apparatus (Figure 1–19) and the ICS, Inc. rotational chair
(Figure 1–20). Although the system processors
were large, (see Figures 1–19 and 1–20), and the
analysis often tedious and limited, (compared to
current analysis standards), the stimuli and EOG
recording methods were a vast improvement over
the mid-twentieth century rotational suites.
B
FIGURE 1–19. Tönnies apparatus rotational chair (A) and com-
puter console (B). From Normal Values of Post-Rotatory and PerRotatory ENG Parameters by R. Mösges, and L. Klimek, 1993. In
I. K. Arenberg (Ed.) Dizziness and Balance Disorders: An Interdisciplinary Approach to Diagnosis, Treatment and Rehabilitation New
A
York, NY, Kugler Publications. Reprinted with permission.
B
FIGURE 1–20. A. ICS rotational chair. From National Institutes of
Health. B. ICS Rotational Chair adapted for pediatric testing. From
Vestibular Assessment by D. G. Cyr, 1991. In W. F. Rintelmann, Per-
spectives in Audiology Series: Hearing Assessment (2nd ed., pp.
739–803). Boston, MA: Allyn & Bacon. Reprinted with permission.
A
22
1. Historical Perspective of Human Rotation and Centrifugation 23
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ROTATIONAL TESTING IN
HE PRESENT DAY
T
Rotational test suites and the precision of rotational stimuli have continued to develop over the
past two decades. In particular, vestibular test
equipment in general has seen some of the fastest development over the past decade alone. With
the introduction of video head impulse testing
(vHIT), as well as ocular vestibular evoked myogenic potential (VEMP) testing, the comprehensive nature of vestibular testing has flourished.
Advancements in rotational testing have similarly
seen increased success. Some of these successes
are reviewed in the final chapter when discussing
the future advancement of rotational testing.
The current state of rotational testing employs
exacting stimuli with high-grade, digital videographic displays, and extremely fast infrared video
goggles, with ultra-precise digital sampling rates.
Advanced research MOOG platforms (Moog,
Inc., Buffalo, NY) (Figure 1–21) have significantly
enhanced the delivery of highly specialized stimuli that can be presented to the vestibular system.
Furthermore, all data can now be recorded, measured, and analyzed using specialized software
algorithms that have tremendously enhanced
our sensitivity to identify even more subtle vestibular dysfunction. Finally, highly specialized
research rotational chairs, capable of rotating
in all axes, (both horizontal and vertically), are
greatly expanding our reach into vestibular science. Rotational test suites like the “Roto Tilt
A B
FIGURE 1–21. A. MOOG six-degrees-of-freedom motion platform
Inc. B. Application of a MOOG six-degrees-of-freedom motion platform (6DOF2000E). From “Moving Along the
Mental Number Line: Interactions Between Whole-Body Motion and Numerical Cognition” by M. Hartmann, L.
Grabherr, and F. Mast, 2012, Journal of Experimental Psychology: Human Perception and Performance. 38(6),
1416–1427. Reprinted with permission.
©
. Reprinted with permission from MOOG,
24 Rotational Vestibular Assessment
Chair” at the University of Alabama (Figure 1–22)
is one such device that will continue to challenge
our understanding of vestibular responses for
some time to come. Moreover, the advancement
of human disorientation devices (HDDs), such as
the GRYPHON GL-6000 at Wright-Patterson Air
Force Base (Figure 1–23) continues to stretch the
boundaries of what may seem humanly possible.
Although designed for military and aerospace
research and training, the application to medicine
is never too far behind.
Although rotational chairs and human disorientation devices, such as the “Roto Tilt Chair” and
GRYPHON GL-6000, respectively, likely seemed
implausible during the days of the simple Bárány
chair, we must continue to remind ourselves that
the physiology of the vestibular system is (if noth-
ing else) extraordinarily complex. We must be
cognizant that just because a chair can be built,
does not necessarily mean we will be able to fully
understand the physiologic output. Ultimately,
the complex physiologic response must still be
correctly interpreted. The interpretation of such
exceedingly complex results may appear to be an
insurmountable challenge, particularly given the
obstacles clinicians face with the interpretation of
certain current rotational tests, such as OVAR testing (Chapter 8). Throughout the entire historical
perspective of vestibular assessment, since the days
of Ernst Mach and Robert Bárány, one thing has
remained a fundamental and resolute truth — that
a thorough understanding of vestibular anatomy and physiology are essential to the understanding and advancement of vestibular science.
FIGURE 1–22. “Roto Tilt Chair.” Source: Images courtesy of the University of Alabama, Tuscaloosa, AL.
1. Historical Perspective of Human Rotation and Centrifugation 25
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FIGURE 1–23. A Naval Medical Research Unit Dayton’s (NAMRU-D) Disorientation
Research Device (DRD); the GRYPHON GL-6000. Nicknamed thye “Kraken” by the U.S.
Navy, the GRYPHON is a one-of-a-kind research platform capable of multi-axis motion as
experienced by up to two subjects in yaw, pitch, roll, and heave while undergoing planetary
and linear accelerations, up to 3 Gz. NAMRU-D’s mission is to maximize warfighter performance and survivability through premier aeromedical and environmental health effects
research by delivering solutions to the Field, the Fleet, and for the Future. NAMRU-D is
located at Wright-Patterson Air Force Base, Dayton, OH. Source: https://www.etcusa.com/
ribbon-cutting-ceremony-for-etcs-gryphon-gl-6000-held-by-naval-med ical-research-unitdayton-located-at-wright-patterson-air-force-base/. Reprinted with permission from VP Aircrew Training Systems Environmental Tectonics Corporation (ETC) and the Office of Public
Affairs, Naval Medical Research Unit, Dayton, OH.
For it was not from complex and ultra-sophisticated
rotational devices that gave us Ewald’s Laws
and the “hydrodynamic theory of semicircular
canal function,” but rather it was the result of an
excellent marriage in thought between the understanding of stimuli and physiologic outcomes.
enter a new renaissance of clinical discovery. By
combining unprecedented complex stimuli with
a vast array of physiological understanding, new
research using such highly advanced devices will
undoubtedly expand our understanding of vestibular function, and dysfunction.
The current state of vestibular science is poised to
2
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Anatomy and Physiology of the
Peripheral Vestibular System
ROLE OF THE VESTIBULAR
SYSTEM: AN OVERVIEW
In more highly developed mammals, the primary
responsibility of the vestibular system is to provide
postural orientation for basic stabilization during
movement (Gacek, 2005). Although this responsibility is shared and refined by the proprioceptive,
autonomic reflex, and visual systems, the central
vestibular pathways are integral to the synergistic
coordination of the sensory information required
for effective and efficient postural stability during
movement, and at rest. The vestibular system is
fundamental to postural stability and control during locomotion for most multicellular organisms.
In light of this, it is no surprise that the vestibular
system is one of the oldest central nervous system
reflex pathways, both phylogenetically, as well as
otogenetically (Gacek, 2005).
In humans, a secondary, but equally important, role of the vestibular system is to provide
gaze stabilization of the visual environment during brief head movements. An accurate and efficient translation of head and body movement into
neural signals must effectively be represented to
the central nervous system for a subjective awareness of head and body movement in space. More-
over, the neural signals conveyed to the brain
from the vestibular sense organs are paramount to
producing compensatory eye movements during
head movement in order to provide visual stability
of a particular image on the retina. This is critical,
because without such compensatory eye movements, a subsequent blurring and visual “jerking”
of the visual field (known as oscillopsia) would
occur with every movement of the head (Leigh
& Zee, 2006). The vestibular system is primarily
responsible for providing this effective visual stabilization during brief head movements, as well as
maintaining successful posture and equilibrium.
PERIPHERAL VESTIBULAR
SYSTEM ANATOMY:
AN OVERVIEW
The vestibular system is located within the otic
capsule, which is located within the petrous portion of each temporal bone. Within the otic capsule is the bony labyrinth of the inner ear, which is
filled with perilymph, an extracellular fluid that is
rich in sodium. Encased within the bony labyrinth
is the membranous labyrinth where the cochlear
and the vestibular sensory end organs are bathed
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