Adaptations and Deficits in the Vestibulo-Ocular Reflex After Third Nerve Palsy

Wong, Agnes M. F.; Sharpe, James

doi:10.1001/archopht.120.3.360

Cited by 14 publications

(13 citation statements)

References 93 publications

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“…In light, visual input increases gain of the paretic eye in the motion fields of both paretic agonist muscles and their antagonist muscles, when the paretic eye is used for fixation, while VVOR gains in the non-paretic eye remain normal; this provides further evidence of selective adaptation of innervation to the paretic eye. Torsional dynamic VOR and VVOR gains of the paretic eye are reduced for both extortion and intorsion in IIIrd and IVth nerve palsies (Wong and Sharpe, 2002;Wong et al, 2002a;Sharpe et al, 2003). Motion of the eyes after nerve palsies exemplifies monocular adaptation of the VOR in three dimensions.…”

Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 93%

“…Any recovery towards normal values was not assessed and abnormalities are interpreted as deficits, or adaptation to those deficits (Wong and Sharpe, 2002;Wong et al, 2002a, b). Results were compared with recordings from 15 normal subjects.…”

Section: Methodsmentioning

confidence: 99%

“…However gains are also reduced in the fields of actions of their intact antagonist muscles after IIIrd, IVth, or VIth nerve palsies (Wong and Sharpe, 2002;Wong et al, 2002a, b). VOR gains in the nonparetic eye remain normal, implicating a selective adjustment of the paretic eye, specifically to the antagonists of paretic muscles.…”

Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 99%

“…Monocular adaptation of VOR and saccadic gain to weakening ocular muscles has been detected in monkeys (Snow et al, 1985;Viirre et al, 1988), but selective effects on paretic muscles or their intact antagonists had not been identified. Selective reduction of VOR gains during action of the antagonist of the paretic muscle by reducing its innervation is apparently the strategy that the brain uses to balance the VOR (Wong and Sharpe, 2002;Wong et al, 2002a, b;Sharpe et al, 2003).…”

Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 99%

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Ocular motor nerve palsies: implications for diagnosis and mechanisms of repair

Sharpe¹,

Wong²,

Fouladvand³

2008

Progress in Brain Research

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Measurements of the dynamics of the eyes in ocular motor nerve palsies may aid diagnosis, characterize peripheral and central palsies, and reveal adaptive properties of the brain. Saccadic and vestibulo-ocular reflex (VOR) functions of patients with peripheral and central sixth, and peripheral third and fourth nerve palsies were studied by three dimensional magnetic field search coil oculography. Combined third and fourth cranial nerve microvascular ischaemic palsy in diabetes mellitus produced low ratios of intorsion to adduction amplitudes. Presumed isolated third nerve palsy caused higher ratios of adduction to intorsion and violations of Listing's law. The VOR in third, fourth, and sixth nerve palsies reveals adaptive equilibration of the action of paretic agonist and their non-paretic antagonist muscles in violation of Hering's law during head motion. Saccadic speeds in the field of paretic agonists are repaired in chronic peripheral palsies despite limited ductions, but remain reduced in central palsies. Limited intorsion with third nerve palsy is attributed to concurrent fourth nerve ischaemia in the distribution of the inferolateral trunk of the intracavernous carotid artery. Adaptive repair of the VOR after ocular motor nerve palsies reduces asymmetric retinal image slip and binocular disparity, and repair of saccadic velocity drives both eyes rapidly and simultaneously into the paretic field of motion.

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Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 99%

Section: Adaptations and Deficits In The Vestibulo-ocular Reflexmentioning

confidence: 99%

See 2 more Smart Citations

Ocular motor nerve palsies: implications for diagnosis and mechanisms of repair

Sharpe¹,

Wong²,

Fouladvand³

2008

Progress in Brain Research

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“…[6][7][8] The duration and age of onset of diplopia, the presence or absence of risk factors for ischemia (diabetes mellitus and hypertension), and associated neurologic symptoms and signs were determined. The magnitude of strabismus was measured objectively using the prism and cover test and subjectively using the Maddox rod and prism test.…”

Section: Methodsmentioning

confidence: 99%

Adaptations and Deficits in the Vestibulo‐Ocular Reflex after Peripheral Ocular Motor Palsies

Sharpe¹,

Tweed²,

Wong³

2003

Annals of the New York Academy of Sciences

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Palsy of a nerve might be expected to lower vestibulo-ocular reflex (VOR) responses in its fields of motion, but effects of peripheral neuromuscular disease were unknown. We recorded the VOR during sinusoidal head rotations in yaw, pitch, and roll at 0.5-2 Hz and static torsional gain in 43 patients with unilateral nerve palsies. Sixth nerve palsy (n = 21) reduced both abduction and adduction VOR gains in darkness. In light, horizontal visually enhanced VOR (VVOR) gains were normal in moderate and mild palsy. In severe palsy, horizontal VVOR gains remained low in the paretic eye when it was fixating, whereas gains in the nonparetic eye became higher than normal. Third nerve palsy (n = 10) decreased VOR and VVOR gains during abduction, adduction, elevation, depression, extorsion, and intorsion. Fourth nerve palsy (n = 13) reduced VOR gains of the paretic eye during intorsion, extorsion, elevation, depression, abduction, and adduction, but in light vertical and horizontal VVOR gains were normal. In the nonparetic eye, all gains were normal. Reduced VOR gains in the direction of paretic muscles and also in the direction of their antagonists, together with normal gains in the nonparetic eye, indicate a selective adjustment to the antagonists of paretic muscles. Increase of VVOR gains to normal in the paretic eye, when used for fixation, without conjugate increase in gains in the occluded nonparetic eye, provides further evidence of selective adaptation for the paretic eye. Motions of the eyes after nerve palsies indicate monocular VOR adaptation in three dimensions.

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