Prognosis in Bilateral Vestibular Hypofunction

Gillespie, M. Boyd; Minor, Lloyd B.

doi:10.1097/00005537-199901000-00008

Cited by 106 publications

(109 citation statements)

References 22 publications

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“…Loss of input from both vestibular labyrinths can cause chronic disequilibrium, postural instability, and decreased visual acuity due to illusory movement of the world during head motion (Grunbauer et al 1998;Minor 1998;Gillespie and Minor 1999). Bilateral loss of vestibular sensation is caused by several ear disorders, including ototoxic drug exposure, ischemia, infection, genetic abnormality, and trauma.…”

Section: Introductionmentioning

confidence: 99%

Directional Plasticity Rapidly Improves 3D Vestibulo-Ocular Reflex Alignment in Monkeys Using a Multichannel Vestibular Prosthesis

Dai

Fridman

Chiang

et al. 2013

JARO

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Bilateral loss of vestibular sensation can be disabling. We have shown that a multichannel vestibular prosthesis (MVP) can partly restore vestibular sensation as evidenced by improvements in the 3-dimensional angular vestibulo-ocular reflex (3D VOR). However, a key challenge is to minimize misalignment between the axes of eye and head rotation, which is apparently caused by current spread beyond each electrode's targeted nerve branch. We recently reported that rodents wearing a MVP markedly improve 3D VOR alignment during the first week after MVP activation, probably through the same central nervous system adaptive mechanisms that mediate cross-axis adaptation over time in normal individuals wearing prisms that cause visual scene movement about an axis different than the axis of head rotation. We hypothesized that rhesus monkeys would exhibit similar improvements with continuous prosthetic stimulation over time. We created bilateral vestibular deficiency in four rhesus monkeys via intratympanic injection of gentamicin. A MVP was mounted to the cranium, and eye movements in response to whole-body passive rotation in darkness were measured repeatedly over 1 week of continuous head motion-modulated prosthetic electrical stimulation. 3D VOR responses to whole-body rotations about each semicircular canal axis were measured on days 1, 3, and 7 of chronic stimulation. Horizontal VOR gain during 1 Hz, 50°/s peak whole-body rotations before the prosthesis was turned on was G0.1, which is profoundly below normal (0.94±0.12). On stimulation day 1, VOR gain was 0.4-0.8, but the axis of observed eye movements aligned poorly with head rotation (misalignment range ∼30-40°). Substantial improvement of axis misalignment was observed after 7 days of continuous motionmodulated prosthetic stimulation under normal diurnal lighting. Similar improvements were noted for all animals, all three axes of rotation tested, for all sinusoidal frequencies tested (0.05-5 Hz), and for high-acceleration transient rotations. VOR asymmetry changes did not reach statistical significance, although they did trend toward slight improvement over time. Prior studies had already shown that directional plasticity reduces misalignment when a subject with normal labyrinths views abnormal visual scene movement. Our results show that the converse is also true: individuals receiving misoriented vestibular sensation under normal viewing conditions rapidly adapt to restore a well-aligned 3D VOR. Considering the similarity of VOR physiology across primate species, similar effects are likely to occur in humans using a MVP to treat bilateral vestibular deficiency.

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Section: Introductionmentioning

confidence: 99%

Directional Plasticity Rapidly Improves 3D Vestibulo-Ocular Reflex Alignment in Monkeys Using a Multichannel Vestibular Prosthesis

Dai

Fridman

Chiang

et al. 2013

JARO

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“…Because input from the vestibular labyrinths normally mediates perception of movement and reflexes that stabilize posture and visual gaze, loss of this input causes chronic disequilibrium, postural instability, and visual blur due to illusory movement of the world during head motion (Grunbauer et al 1998;Minor 1998;Gillespie and Minor 1999). A multichannel neuro-electronic prosthesis that senses rotation of the head in three dimensions and delivers corresponding stimuli to the ampullary branches of the vestibular nerve should restore sensation of head rotation, which in turn should help to stabilize gaze and at least partially restore perception of head movement.…”

Section: Introductionmentioning

confidence: 99%

Vestibulo-Ocular Reflex Responses to a Multichannel Vestibular Prosthesis Incorporating a 3D Coordinate Transformation for Correction of Misalignment

Fridman

Davidovics

Dai

et al. 2010

JARO

128

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There is no effective treatment available for individuals unable to compensate for bilateral profound loss of vestibular sensation, which causes chronic disequilibrium and blurs vision by disrupting vestibulo-ocular reflexes that normally stabilize the eyes during head movement. Previous work suggests that a multichannel vestibular prosthesis can emulate normal semicircular canals by electrically stimulating vestibular nerve branches to encode head movements detected by mutually orthogonal gyroscopes affixed to the skull. Until now, that approach has been limited by current spread resulting in distortion of the vestibular nerve activation pattern and consequent inability to accurately encode head movements throughout the full 3-dimensional (3D) range normally transduced by the labyrinths. We report that the electrically evoked 3D angular vestibulo-ocular reflex exhibits vector superposition and linearity to a sufficient degree that a multichannel vestibular prosthesis incorporating a precompensatory 3D coordinate transformation to correct misalignment can accurately emulate semicircular canals for head rotations throughout the range of 3D axes normally transduced by a healthy labyrinth.

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“…In normal humans subjected to passive sinusoidal or transient head rotation in light or darkness over the range of head movements typical of walking, jogging or even vigorous head shaking (>300°/s and >5000°/s 2 over ~0. [5][6][7][8][9][10][11][12][13][14][15][16], the AVOR gain (conventionally defined as the absolute value of the ratio of eye and head velocity about the axis of head rotation for sinusoids [or of acceleration for transients]) is near 1 and its latency is only 7-9 ms. [9;10;2; 11]. The gain of the AVOR in darkness falls as head rotation frequency decreases below ~0.1 Hz, where vision-dependent tracking mechanisms dominate.…”

Section: Introductionmentioning

confidence: 99%

A Multichannel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3-D Vestibular Sensation

Santina

Migliaccio²,

Patel³

2007

IEEE Trans. Biomed. Eng.

150

211

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Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode's targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior.

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Prognosis in Bilateral Vestibular Hypofunction

Abstract: Poor rehabilitation results may be attributable to increased severity of vestibular insult, progressive peripheral or central vestibular dysfunction, and multiple medical problems.

Cited by 106 publications

References 22 publications

Directional Plasticity Rapidly Improves 3D Vestibulo-Ocular Reflex Alignment in Monkeys Using a Multichannel Vestibular Prosthesis

Directional Plasticity Rapidly Improves 3D Vestibulo-Ocular Reflex Alignment in Monkeys Using a Multichannel Vestibular Prosthesis

Vestibulo-Ocular Reflex Responses to a Multichannel Vestibular Prosthesis Incorporating a 3D Coordinate Transformation for Correction of Misalignment

A Multichannel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3-D Vestibular Sensation

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