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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4606_Библиотеки_им_академика_М_И_Перельмана
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E. R. Anson and Y. Gimmon
a
c
e
b
d
f
g
Fig. 14.6 Example of the Supine Roll treatment for left lateral canal BPPV, (a) shows the starting
position with the head turned 90° to the left elevated 30°, (b) shows the second position with the
head in midline elevated 30°, (c) shows the third position with the head turned 90° to the right
elevated 30°, (d) shows the fourth position with the head in midline and nose down with approximately 30° of chin tuck, (e) Left side-lying position, (f) Supine with head midline, (g) nal position
seated on the mat. Positions a, b and c should be held for 30–45s after vertigo/nystagmus stops
cd
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ab
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Fig. 14.7 Example of Gufoni for left lateral canal BPPV. (a) Shows the starting position with the
head in midline and the patient crossing their arms to grasp the forearms of the clinician, (b) shows
the second position with the head in midline and right side-lying holding for 1min, (c) shows the
third position with the head turned 45° to the right (nose down) holding for 1–2min, (d) shows the
nal position seated on the mat
In some cases particle repositioning maneuvers do not successfully resolve complaints of positional vertigo. For those individuals a habituation approach should be
considered as a nal conservative approach [190]. Habituation exercises can take
the form of an appropriately selected repositioning technique as described above,
Cawthorne–Cooksey exercises [191], or Brandt–Daroff exercises [192]. Habituation
prescription for positional vertigo may include 5–10 repetitions daily of motion
provoking movements. In rare cases, surgical intervention may be appropriate [193].
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E. R. Anson and Y. Gimmon
ab
c
Fig. 14.8 Example of deep head hang technique for anterior canal BPPV. (a) Shows the starting
position with the head in midline and the patient sitting upright, (b) shows the second position with
the head in midline with approximately 60° of head/neck extension, holding for 1min, (c) shows
the third position with the head in midline brought up to a chin-tuck, (d) shows the nal position
seated on the mat
d
Treatments forNonspecic Dizziness
Exposure Therapy
The primary goal for habituation exercises is to desensitize nonspecic dizziness by
gradual repeated exposure to provocative stimuli such as self-movement or visual
stimulating surroundings. The symptom of nonspecic dizziness has been referred
to in several ways including motorists’ disorientation syndrome motorists’ disorientation syndrome [194], space and motion discomfort [103, 195], visual vertigo
[196], and visual-vestibular mismatch [197–199].
Over time, exposure to vestibular and visual motion stimuli leads to reduced
vestibular responses, probably due to changes in velocity storage mechanisms that
mediate ocular and perceptual responses, therefore, reducing sensitivity to
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visual- vestibular mismatches [56, 200, 201]. Vestibular rehabilitation exercises may
include a range of visual environments, virtual reality, and supplementary immersive settings [26, 202, 203]. Incorporating optokinetic stimuli concurrent with vestibular rehabilitation exercises has better outcomes than treatments without
optokinetic stimuli [25, 204]. Vestibular and visual motion stimulation for habituation can also be induced by self-motion, and has been successfully used to address
motion sensitivity aspects of vestibular hypofunction [24].
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Cognitive Behavioral Therapy
Anxiety, depression, and other psychological conditions often present as comorbid
conditions for individuals with dizziness. About 50% of dizzy patients experience
psychiatric comorbidity [99]. Both nonspecic dizziness and psychological disorders can lead to functional limitations. Not surprisingly, habituation principles are
similar for both conditions. The main element of vestibular habituation exercises is
gradual and controlled exposure to sensory input that provokes symptoms. The
main component of cognitive behavior therapy (CBT) is progressively and controlled exposure to the individual’s challenging factors [104, 205, 206].
Psychotherapy such as CBT, together with vestibular rehabilitation, can be a very
effective treatment combination for a dizzy patient, as has been shown in a systematic review [207]. Even for patients with persistent dizziness, this combination of
treatments is feasible and promising; however, the optimal intervention strategy still
needs to be identied [152, 208]. Patients who suffer only from dizziness, without
measurable balance impairments benet even more from CBT treatments [209].
Gaze Instability
The purpose of VOR adaptation exercises is to improve gaze stability by “strengthening” vestibular responses and recruiting substitution mechanisms such as preprogramming eye movements, and the cervico-ocular reex to compensate for the
vestibular hypo function in order to gain stable vision and therefore also improve
postural stability [23, 210–212]. An error signal that causes retinal slip during head
movement is the VOR adaptation’s key stimulus [213–215]. Human VOR adaptation abilities are phenomenal due to neuroplasticity [216, 217]. It has adaptive capabilities for concurrent and opposing directions, i.e., increased VOR response when
moving the head to one side and decreased response as moving the head to the other
side. VOR adaptation is context-specic and depends on the error signal that drives
the adaptation process [218].
The basic clinical VOR adaptation exercise is VOR X1 viewing exercise. For VOR
X1 exercise a patient holds a target in front of the eyes, moves the head side to side
or up and down in a small amplitude but as fast as possible while maintaining a
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perception of a clear and stationary target. To advance in treatment and add extra
challenge to the VOR, a patient can move the target and the head in opposite directions at approximately the same velocity. This kind of exercise is known as VOR X2
viewing. Because of the target movement, the eyes will need to move faster than the
head, increasing the VOR gain [213, 215, 219]. These techniques are very easy to
deliver in the clinic as well as for patients to practice at home. Examples of X1 and
X2 viewing are presented in Fig.14.9. Importantly, these gaze stabilization exercises
can be progressed in difculty starting with sitting and progressing to standing or
walking.
During vestibular rehabilitation, the brain recruits alternative strategies to achieve
better function and gaze stability by substitution mechanisms and central preprogramming eye movements [15, 22]. The level of vestibular recovery determines the
brain strategy to improve gaze stability. Patients with sufcient vestibular end-organ
functional recovery use fewer compensatory saccades [220]. On the other hand,
patients with chronic vestibular hypofunction depend on compensatory saccades to
improve gaze stability [221–223]. Improvement of DVA is a signicant outcome
that indicates better gaze stability. Vestibular rehabilitation exercises that include
head and eye movements lead to better results than general exercises not based on
actions that require visual xation [21, 224]. Additional exercises for improving
gaze stability can include eye and head movements between several targets and even
by moving the head while keeping xation on a remembered target, for examples
Figs.14.10 and 14.11 [225].
Isolated saccades or pursuit eye movement only exercises are not effective for
treating peripheral vestibular hypofunction and should not be prescribed [6]. For
effective vestibular rehabilitation, patients should participate in daily exercises that
include head-eye movements for 12–20min per day of combined gaze stabilization
exercises [6]. This recommendation was based on interpretation of studies that were
not designed to evaluate dosage, and additional research is needed to clarify the
optimum exercises and dosage parameters to improve gaze stability.
E. R. Anson and Y. Gimmon
Disequilibrium
Balance problems and falls are common for individuals with vestibular dysfunction
[35, 40, 226]. Balance problems may manifest while standing still or when in
motion such as while walking [227–229]; thus, balance interventions need to be
specically targeted. Balance exercises must be sufciently challenging [230, 231],
or individuals may not improve. Normal balance ability depends on having an intact
and functional musculoskeletal system and intact peripheral systems and central
sensory processing [232–234]. Balance rehabilitation often incorporates both a
strengthening and a sensory reweighting approach for individuals with vestibular
dysfunction. Sensory reweighting is facilitated by systematically reducing the availability or reliability of specic sensory inputs that are relevant for balance control
[18, 235–238].
a
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b
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c
e
d
f
Fig. 14.9 Example of X1 viewing (a–c) and X2 viewing (d–f) exercises. For X1 viewing, the
target or “X” is world xed and the head is either continuously or impulsively rotated in pitch or
yaw. For X2 viewing, the target is moved in the opposite direction of head motion at approximately
the same velocity which can be done either continuously or impulsively
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E. R. Anson and Y. Gimmon
a
c
b
d
e
Fig. 14.10 Example of eye-then-head exercises to promote substitution. From a to c, progressively the eyes move to the new target and then stay there as the head is turned. In d and e, this
process is reversed moving the eyes then head back to the original target
Standing balance can be progressively challenged in a variety of ways starting
with altering the shape and size of the base of support, wider is more stable [229].
Different surfaces such as foam, tilting boards, narrow beams, or different surface
heights are used to articially create instability leading to a change in how balance
is controlled [239–241]. Sensory availability can be manipulated to increase the
balance challenge by closing the eyes [241–243], standing on a foam cushion [241],
or watching optic ow patterns [204]. Altered head position or adding continuous
ab
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Fig. 14.11 Example of remembered target exercise for gaze stability. (a) The target is visualized,
(b) the eyes are closed maintaining position on the remembered target location, (c) the head is
turned away while the closed eyes continue looking where the target is, (d) the eyes are opened for
visual feedback to see whether they stayed on the target
head motion can further create challenges to standing balance leading to increased
sway [244, 245]. Similar exercise manipulations are often also applied during walking based on identied task difculty on balance tests like the Functional Gait
Assessment or Dynamic Gait Index [79, 81]. Obstacles to step over or navigate
around are also often incorporated into rehabilitation exercises as those are commonly encountered in daily life [246, 247]. Current recommendations for balance
exercises include at least 20 minutes per day for 4-6 weeks or 6-9 weeks for unilateral or bilateral vestibular hypofunction respectively [248]. Additionally, Klatt and
colleagues theorized that 8–12 min of focused balance exercises 2–3 times per week
may be benecial [231]. Research based guidelines on balance exercise dosage
are needed.
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E. R. Anson and Y. Gimmon
Frontiers inVestibular Rehabilitation
Cognition
Although the specic mechanisms are still being elucidated [249], the vestibular
system inuences cognition in several ways [250–256]. Vestibular signals from both
the semicircular canals and otoliths are found in the hippocampus and entorhinal
cortex highlighting the impact of vestibular afferent signals on spatial orientation/
navigation [257–259]. Reduced vestibular function either caused by aging or disease leads to worse performance on tests of spatial orientation and spatial navigation compared to healthy adults [96, 260–264]. In fact, individuals with dementia
are more likely to have vestibular dysfunction compared to older adults with normal
cognition [265]. Because of the broad vestibular connection to cognition, some have
proposed vestibular exercises to improve both cognition and balance [266, 267]. At
present, there is insufcient evidence supporting enhanced cognition from vestibular rehabilitation, but promising research is on the horizon [268, 269].
Innovations
Novel vestibular rehabilitation approaches, especially for patients who do not
respond well to traditional vestibular rehabilitation (e.g., severe BVL patients), are
needed. Some of these promising approaches include the use of invasive vestibular
implants and noninvasive devices that use vibrotactile stimuli to improve balance
control.
Vestibular Prosthesis
One promising approach is providing electrical stimulation via a vestibular prosthesis to mimic vestibular sensation [270–272]. Research using animal models demonstrated that vestibular reexes could be effectively driven by direct electrical
stimulation of vestibular afferent neurons [273, 274]. Similar results have been
reported in humans with BVH who have received a vestibular implant and been
tested in laboratory settings [271, 275–277]. The Labyrinth Devices MVI™
Multichannel Vestibular Implant system is currently the only human vestibular
implant with the prosthesis on continuously 24h/day. Long-term use of this implant
produced stable improvements in VOR eye movement responses [278], more importantly, a phenomenal improvement in quality of life, walking abilities, and postural
control of BVL patients [279]. The potential benets of vestibular rehabilitation
exercises for implanted patients remains to be determined.
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285
Vibrotactile Stimuli
The idea behind vibrotactile belts or shoes is to promote sensory substitution by
“replacing” or augmenting the information that should be provided by a defective
vestibular system by using sensory input from augmented tactile cues. For example,
a belt tted with actuators that deliver vibrotactile stimulus to the waist when the
subject leans signicantly from an upright position [280]. By using such a belt,
patients with UVH showed better control of their body sway during perturbed standing and tandem walking [281]. Even patients with BVH report improved quality of
life as their mobility and balance control are improved after using a vibro-tactile
belt [282]. Interestingly, community-dwelling elderly who used vibrotactile stimulus for 8weeks as part of their balance training improved their vestibular reliance
during postural testing [283]. However, even though vibrotactile stimuli are simple
noninvasive devices as well as showing promising results, the effect of vestibular
rehabilitation together with vibrotactile stimuli remains to be determined.
Virtual Reality/Augmented Reality
Virtual reality has long been available to researchers in the eld of vestibular science and rehabilitation [203, 284–286], and with the recent availability of low cost
consumer systems it is now more available for home and clinic use [287–290].
Immersive virtual reality games that require head motion lead to improvements in
the vestibulo-ocular reex and also improvements in balance [291–294].
Nonimmersive virtual reality game play such as the Nintendo Wii™ has also been
shown to improve outcomes after vestibular rehabilitation [295]. Augmented reality
glasses may also be helpful in certain circumstances for individuals with vestibular
loss to address oscillopsia [296] or imbalance and falls [297]. Additional studies are
needed to determine whether technology driven vestibular rehabilitation consistently leads to better outcomes [284, 293], but it may lead to greater participation
because of higher engagement and adherence [298].
Incremental VOR Adaptation
The downside of more traditional gaze stability exercises is that they cause an
immediate large error signal for large decits in VOR gain. A gradually increasing
error signal drives the VOR more efciently [299]. A novel rehabilitation device for
patients who suffer from reduced VOR gain due to vestibular hypo function showed
promising results by using the incremental VOR adaptation (IVA) paradigm [300,
301]. An interesting case report demonstrates the IVA paradigm’s benets presents
a 51years-old patient who suffered for 20years from bilateral vestibular loss. The
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