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Grossman SN, Calix R, Hudson T, Rizzo JR, Selesnick I, Frucht S, Galetta SL, Balcer LJ, Rucker JC. Accuracy of clinical versus oculographic detection of pathological saccadic slowing. J Neurol Sci 2022; 442:120436. [PMID: 36183516 DOI: 10.1016/j.jns.2022.120436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/23/2022] [Accepted: 09/18/2022] [Indexed: 10/31/2022]
Abstract
Saccadic slowing as a component of supranuclear saccadic gaze palsy is an important diagnostic sign in multiple neurologic conditions, including degenerative, inflammatory, genetic, or ischemic lesions affecting brainstem structures responsible for saccadic generation. Little attention has been given to the accuracy with which clinicians correctly identify saccadic slowing. We compared clinician (n = 19) judgements of horizontal and vertical saccade speed on video recordings of saccades (from 9 patients with slow saccades, 3 healthy controls) to objective saccade peak velocity measurements from infrared oculographic recordings. Clinician groups included neurology residents, general neurologists, and fellowship-trained neuro-ophthalmologists. Saccades with normal peak velocities on infrared recordings were correctly identified as normal in 57% (91/171; 171 = 9 videos × 19 clinicians) of clinician decisions; saccades determined to be slow on infrared recordings were correctly identified as slow in 84% (224/266; 266 = 14 videos × 19 clinicians) of clinician decisions. Vertical saccades were correctly identified as slow more often than horizontal saccades (94% versus 74% of decisions). No significant differences were identified between clinician training levels. Reliable differentiation between normal and slow saccades is clinically challenging; clinical performance is most accurate for detection of vertical saccade slowing. Quantitative analysis of saccade peak velocities enhances accurate detection and is likely to be especially useful for detection of mild saccadic slowing.
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Affiliation(s)
- Scott N Grossman
- Department of Neurology, New York University Grossman School of Medicine, United States of America.
| | - Rachel Calix
- Department of Neurology, New York University Grossman School of Medicine, United States of America
| | - Todd Hudson
- Department of Neurology, New York University Grossman School of Medicine, United States of America; Rusk Institute of Rehabilitation, New York University Grossman School of Medicine, United States of America
| | - John Ross Rizzo
- Department of Neurology, New York University Grossman School of Medicine, United States of America; Rusk Institute of Rehabilitation, New York University Grossman School of Medicine, United States of America
| | - Ivan Selesnick
- Department of Electrical and Computer Engineering, New York University Tandon School of Engineering, United States of America
| | - Steven Frucht
- Department of Neurology, New York University Grossman School of Medicine, United States of America
| | - Steven L Galetta
- Department of Neurology, New York University Grossman School of Medicine, United States of America; Department of Ophthalmology, New York University Grossman School of Medicine, United States of America
| | - Laura J Balcer
- Department of Neurology, New York University Grossman School of Medicine, United States of America; Department of Ophthalmology, New York University Grossman School of Medicine, United States of America; Department of Population Health, New York University Grossman School of Medicine, United States of America
| | - Janet C Rucker
- Department of Neurology, New York University Grossman School of Medicine, United States of America; Department of Ophthalmology, New York University Grossman School of Medicine, United States of America
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Kinoshita M, Sakai Y, Katome K, Matsumoto T, Sakurai S, Jinnouchi Y, Tanaka K. Transition in eye gaze as a predictor of emergence from general anesthesia in children and adults: a prospective observational study. BMC Anesthesiol 2022; 22:320. [PMID: 36253763 PMCID: PMC9575208 DOI: 10.1186/s12871-022-01867-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/11/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND It is useful to monitor eye movements during general anesthesia, but few studies have examined neurological finding of the eyes during emergence from general anesthesia maintained with short-acting opioids and volatile anesthetics. METHODS Thirty children aged 1-6 years and 30 adults aged 20-79 years were enrolled. Patients received general anesthesia maintained with sevoflurane and remifentanil. The timing of three physical-behavioral responses-eye-gaze transition (the cycle from conjugate to disconjugate and back to conjugate), resumption of somatic movement (limbs or body), and resumption of respiration-were recorded until spontaneous awakening. The primary outcome measure was the timing of the physical-behavioral responses. Secondary outcome measures were the incidence of eye-gaze transition, and the bispectral index, concentration of end-tidal sevoflurane, and heart rate at the timing of eye-gaze transition. RESULTS Eye-gaze transition was evident in 29 children (96.7%; 95% confidence interval, 82.8-99.9). After the end of surgery, eye-gaze transition was observed significantly earlier than resumption of somatic movement or respiration (472 [standard deviation 219] s, 723 [235] s, and 754 [232] s, respectively; p < 0.001). In adults, 3 cases (10%; 95% CI, 0.2-26.5) showed eye-gaze transition during emergence from anesthesia. The incidence of eye-gaze transition was significantly lower in adults than in children (p < 0.001). CONCLUSION In children, eye-gaze transition was observed significantly earlier than other physical-behavioral responses during emergence from general anesthesia and seemed to reflect emergence from anesthesia. In contrast, observation of eye gaze was not a useful indicator of emergence from anesthesia in adults.
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Affiliation(s)
- Michiko Kinoshita
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan.
| | - Yoko Sakai
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
| | - Kimiko Katome
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
| | - Tomomi Matsumoto
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
| | - Shizuka Sakurai
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
| | - Yuka Jinnouchi
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
| | - Katsuya Tanaka
- Department of Anesthesiology, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima-shi, Tokushima, 770-8503, Japan
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Robinson DA. Properties of rapid eye movements. PROGRESS IN BRAIN RESEARCH 2022; 267:271-286. [PMID: 35074058 DOI: 10.1016/bs.pbr.2021.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This chapter describes the metrics and kinematics of saccades and quick phases of nystagmus, including microsaccades and large eye-head saccades. Small saccades often display dynamic overshoot, predominantly in the abducting eye. Although the function of these overshoots is unclear, the return movement is saccadic in nature. The saccade kinematics can be quantified by stereotyped relations between amplitude, duration, peak eye velocity, and peak acceleration, which vary somewhat with the initial eye position and saccade direction (centripetal vs centrifugal), possibly due to ocular plant characteristics. Saccades in a structured light environment are considerably faster than when executed in total darkness, although the origin for this facilitation is not known. The horizontal and vertical components of slant saccades are coupled, approximately matching their durations, for which possible underlying neural mechanisms are discussed. The chapter closes with a cross-species comparison of saccade characteristics.
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Affiliation(s)
- David A Robinson
- Late Professor of Ophthalmology, Biomedical Engineering and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
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Ling MLH, Tynan D, Ruan CW, Lau FS, Spencer SKR, Agar A, Francis IC. Assessment of Saccadic Velocity at the Bedside. Neuroophthalmology 2020; 44:71-75. [PMID: 32395153 DOI: 10.1080/01658107.2019.1616776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/04/2019] [Accepted: 05/06/2019] [Indexed: 10/26/2022] Open
Abstract
Saccades are a key component for the assessment and diagnosis of Neuro-ophthalmological disorders. Traditionally, clinicians have been taught to use large amplitude saccades (LAS) to assess saccadic velocity (SV), when small amplitude saccades (SAS) may be more effective. This study aimed to evaluate the advantages of SAS over LAS by presenting a video to 108 clinicians where both methods were used to assess a patient with a unilateral partial 6th nerve palsy. SAS was the preferred method in identifying the 6th nerve palsy by 43/55 (78.2%) of Neurologists, and 36/53 (67.9%) of Ophthalmologists. These findings indicate that SAS may be a more effective method than LAS for determining SV.
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Affiliation(s)
- Melvin L H Ling
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Dominique Tynan
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Claire W Ruan
- Faculty of Medicine, University of New South Wales, Sydney, Australia.,Department of Ophthalmology, Prince of Wales Hospital, Sydney, Australia
| | - Fiona S Lau
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | | | - Ashish Agar
- Faculty of Medicine, University of New South Wales, Sydney, Australia.,Department of Ophthalmology, Prince of Wales Hospital, Sydney, Australia
| | - Ian C Francis
- Faculty of Medicine, University of New South Wales, Sydney, Australia.,Department of Ophthalmology, Prince of Wales Hospital, Sydney, Australia
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Differences in eye movement range based on age and gaze direction. Eye (Lond) 2019; 33:1145-1151. [PMID: 30837710 DOI: 10.1038/s41433-019-0376-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 07/02/2018] [Accepted: 11/23/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To determine the range of eye movement in normal human subjects and to investigate the effect of age and gaze direction on eye movement. PATIENTS AND METHODS A prospective observational study. We enrolled 261 healthy subjects, 5-91 years of age. Photographs were obtained in the cardinal gaze positions and processed using Photoshop. The processed images were analyzed using the Image J program to measure the angle of eye movement. The angle of eye movement was quantified using a modified limbus test. We measured the angle of eye movement in adduction, abduction, elevation, and depression. RESULTS The ranges of eye movement were 44.9 ± 7.2° in adduction, 44.2 ± 6.8° in adduction, 27.9 ± 7.6° in elevation, and 47.1 ± 8.0° in depression. The ranges of eye movement in the younger group were higher than that in the older group in adduction, abduction, and elevation (P < 0.001, P = 0.013, and P < 0.001, respectively), except in depression (P = 0.790). There were significant negative correlations between the angles of horizontal and upward gazes and age (R = -0.294 in adduction, R = -0.355 in abduction, and R = -0.506 in elevation, all P < 0.001). However, the angle of downward gaze was not significantly correlated with age (R = 0.017, P = 0.722). CONCLUSIONS The angle of upward gaze most rapidly decreased with age than the angle of other gaze. Unlike the age-related decline of range in horizontal and upward gazes, only downward gaze was not impaired by increasing age. Differences in eye movement range based on gaze direction and their associated aging mechanisms should be considered when assessing eye movements.
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Serra A, Chisari CG, Matta M. Eye Movement Abnormalities in Multiple Sclerosis: Pathogenesis, Modeling, and Treatment. Front Neurol 2018; 9:31. [PMID: 29467711 PMCID: PMC5807658 DOI: 10.3389/fneur.2018.00031] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/15/2018] [Indexed: 01/13/2023] Open
Abstract
Multiple sclerosis (MS) commonly causes eye movement abnormalities that may have a significant impact on patients’ disability. Inflammatory demyelinating lesions, especially occurring in the posterior fossa, result in a wide range of disorders, spanning from acquired pendular nystagmus (APN) to internuclear ophthalmoplegia (INO), among the most common. As the control of eye movements is well understood in terms of anatomical substrate and underlying physiological network, studying ocular motor abnormalities in MS provides a unique opportunity to gain insights into mechanisms of disease. Quantitative measurement and modeling of eye movement disorders, such as INO, may lead to a better understanding of common symptoms encountered in MS, such as Uhthoff’s phenomenon and fatigue. In turn, the pathophysiology of a range of eye movement abnormalities, such as APN, has been clarified based on correlation of experimental model with lesion localization by neuroimaging in MS. Eye movement disorders have the potential of being utilized as structural and functional biomarkers of early cognitive deficit, and possibly help in assessing disease status and progression, and to serve as platform and functional outcome to test novel therapeutic agents for MS. Knowledge of neuropharmacology applied to eye movement dysfunction has guided testing and use of a number of pharmacological agents to treat some eye movement disorders found in MS, such as APN and other forms of central nystagmus.
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Affiliation(s)
- Alessandro Serra
- Neurology, Louis Stokes VA Medical Center, University Hospitals and Case Western Reserve School of Medicine, Cleveland, OH, United States
| | | | - Manuela Matta
- Neurology, Ospedale San Luigi Gonzaga, Orbassano, Italy
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Kim JH, Lim HW. Range of Eye Movement in a Normal Population and Its Relationship to Age. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2017. [DOI: 10.3341/jkos.2017.58.6.698] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ji Hong Kim
- Department of Ophthalmology, Hanyang University Seoul Hospital, Hanyang University College of Medicine, Seoul, Korea
| | - Han Woong Lim
- Department of Ophthalmology, Hanyang University Seoul Hospital, Hanyang University College of Medicine, Seoul, Korea
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Serra A, Ruff RL, Leigh RJ. Neuromuscular transmission failure in myasthenia gravis: decrement of safety factor and susceptibility of extraocular muscles. Ann N Y Acad Sci 2013; 1275:129-35. [PMID: 23278588 DOI: 10.1111/j.1749-6632.2012.06841.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An appropriate density of acetylcholine receptors (AChRs) and Na(+) channels (NaChs) in the normal neuromuscular junction (NMJ) determines the magnitude of safety factor (SF) that guarantees fidelity of neuromuscular transmission. In myasthenia gravis (MG), an overall simplification of the postsynaptic folding secondary to NMJ destruction results in AChRs and NaChs depletion. Loss of AChRs and NaChs accounts, respectively, for 59% and 40% reduction of the SF at the endplate, which manifests as neuromuscular transmission failure. The extraocular muscles (EOM) have physiologically less developed postsynaptic folding, hence a lower baseline SF, which predisposes them to dysfunction in MG and development of fatigue during "high performance" eye movements, such as saccades. However, saccades in MG show stereotyped, conjugate initial components, similar to normal, which might reflect preserved neuromuscular transmission fidelity at the NMJ of the fast, pale global fibers, which have better developed postsynaptic folding than other extraocular fibers.
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Affiliation(s)
- Alessandro Serra
- Mellen Center for Multiple Sclerosis, Department of Neurology, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
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Serra A, Ruff R, Kaminski H, Leigh RJ. Factors contributing to failure of neuromuscular transmission in myasthenia gravis and the special case of the extraocular muscles. Ann N Y Acad Sci 2011; 1233:26-33. [DOI: 10.1111/j.1749-6632.2011.06123.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Chen AL, Riley DE, King SA, Joshi AC, Serra A, Liao K, Cohen ML, Otero-Millan J, Martinez-Conde S, Strupp M, Leigh RJ. The disturbance of gaze in progressive supranuclear palsy: implications for pathogenesis. Front Neurol 2010; 1:147. [PMID: 21188269 PMCID: PMC3008928 DOI: 10.3389/fneur.2010.00147] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 11/03/2010] [Indexed: 01/20/2023] Open
Abstract
Progressive supranuclear palsy (PSP) is a disease of later life that is currently regarded as a form of neurodegenerative tauopathy. Disturbance of gaze is a cardinal clinical feature of PSP that often helps clinicians to establish the diagnosis. Since the neurobiology of gaze control is now well understood, it is possible to use eye movements as investigational tools to understand aspects of the pathogenesis of PSP. In this review, we summarize each disorder of gaze control that occurs in PSP, drawing on our studies of 50 patients, and on reports from other laboratories that have measured the disturbances of eye movements. When these gaze disorders are approached by considering each functional class of eye movements and its neurobiological basis, a distinct pattern of eye movement deficits emerges that provides insight into the pathogenesis of PSP. Although some aspects of all forms of eye movements are affected in PSP, the predominant defects concern vertical saccades (slow and hypometric, both up and down), impaired vergence, and inability to modulate the linear vestibulo-ocular reflex appropriately for viewing distance. These vertical and vergence eye movements habitually work in concert to enable visuomotor skills that are important during locomotion with the hands free. Taken with the prominent early feature of falls, these findings suggest that PSP tauopathy impairs a recently evolved neural system concerned with bipedal locomotion in an erect posture and frequent gaze shifts between the distant environment and proximate hands. This approach provides a conceptual framework that can be used to address the nosological challenge posed by overlapping clinical and neuropathological features of neurodegenerative tauopathies.
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Affiliation(s)
- Athena L. Chen
- Veterans Affairs Medical Center, University Hospitals Case Medical CenterCleveland, OH, USA
| | - David E. Riley
- Neurological Institute, University Hospitals Case Medical CenterCleveland, OH, USA
| | - Susan A. King
- Veterans Affairs Medical Center, University Hospitals Case Medical CenterCleveland, OH, USA
| | - Anand C. Joshi
- Neurological Institute, University Hospitals Case Medical CenterCleveland, OH, USA
| | - Alessandro Serra
- Veterans Affairs Medical Center, University Hospitals Case Medical CenterCleveland, OH, USA
- Neurological Institute, University Hospitals Case Medical CenterCleveland, OH, USA
| | - Ke Liao
- Veterans Affairs Medical Center, University Hospitals Case Medical CenterCleveland, OH, USA
| | - Mark L. Cohen
- Department of Pathology, University Hospitals Case Medical CenterCleveland, OH, USA
| | | | | | - Michael Strupp
- Department of Neurology and IFB-LMU, University of MunichMunich, Germany
| | - R. John Leigh
- Veterans Affairs Medical Center, University Hospitals Case Medical CenterCleveland, OH, USA
- Neurological Institute, University Hospitals Case Medical CenterCleveland, OH, USA
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The role of the medial longitudinal fasciculus in horizontal gaze: tests of current hypotheses for saccade-vergence interactions. Exp Brain Res 2010; 208:335-43. [PMID: 21082311 DOI: 10.1007/s00221-010-2485-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 10/28/2010] [Indexed: 10/18/2022]
Abstract
Rapid shifts of the point of visual fixation between equidistant targets require equal-sized saccades of each eye. The brainstem medial longitudinal fasciculus (MLF) plays a cardinal role in ensuring that horizontal saccades between equidistant targets are tightly yoked. Lesions of the MLF--internuclear ophthalmoparesis (INO)--cause horizontal saccades to become disjunctive: adducting saccades are slow, small, or absent. However, in INO, convergence movements may remain intact. We studied horizontal gaze shifts between equidistant targets and between far and near targets aligned on the visual axis of one eye (Müller test paradigm) in five cases of INO and five control subjects. We estimated the saccadic component of each movement by measuring peak velocity and peak acceleration. We tested whether the ratio of the saccadic component of the adducting/abducting eyes stayed constant or changed for the two types of saccades. For saccades made by control subjects between equidistant targets, the group mean ratio (±SD) of adducting/abducting peak velocity was 0.96 ± 0.07 and adducting/abducting peak acceleration was 0.94 ± 0.09. Corresponding ratios for INO cases were 0.45 ± 0.10 for peak velocity and 0.27 ± 0.11 for peak acceleration, reflecting reduced saccadic pulses for adduction. For control subjects, during the Müller paradigm, the adducting/abducting ratio was 1.25 ± 0.14 for peak velocity and 1.03 ± 0.12 for peak acceleration. Corresponding ratios for INO cases were 0.82 ± 0.18 for peak velocity and 0.48 ± 0.13 for peak acceleration. When adducting/abducting ratios during Müller versus equidistant targets paradigms were compared, INO cases showed larger relative increases for both peak velocity and peak acceleration compared with control subjects. Comparison of similar-sized movements during the two test paradigms indicated that whereas INO patients could decrease peak velocity of their abducting eye during the Müller paradigm, they were unable to modulate adducting velocity in response to viewing conditions. However, the initial component of each eye's movement was similar in both cases, possibly reflecting activation of saccadic burst neurons. These findings support the hypothesis that horizontal saccades are governed by disjunctive signals, preceded by an initial, high-acceleration conjugate transient and followed by a slower vergence component.
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Matta M, Leigh RJ, Pugliatti M, Aiello I, Serra A. Using fast eye movements to study fatigue in multiple sclerosis. Neurology 2009; 73:798-804. [PMID: 19738175 DOI: 10.1212/wnl.0b013e3181b6bbf4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To investigate whether internuclear ophthalmoparesis (INO) due to demyelination of the medial longitudinal fasciculus (MLF) provides a model for studying the poorly understood symptom of fatigue in multiple sclerosis (MS). We asked whether repetitive horizontal saccades increased eye movement disconjugacy in patients with MS with INO, but not in healthy subjects. METHODS We compared conjugacy of horizontal saccades in 9 patients with INO (4 bilateral, total 13) and 8 controls during minute 1 and minute 10 of a fatigue test; we measured the ratio of abducting/adducting peak velocity (versional disconjugacy index [VDI]). RESULTS VDI values were greater in patients than controls. During the fatigue test, controls showed no changes of VDI, but patients did (p < 0.005) for 10/13 INOs, with increased ratios in 5 cases and a decrease in the other 5. CONCLUSION Fatigue-induced worsening of conjugacy was observed in milder internuclear ophthalmoparesis (INO), and may reflect deteriorated fidelity of saccadic pulse transmission along demyelinated medial longitudinal fasciculus. Improved conjugacy was observed in the more severe INOs, and may be due to adaptive mechanisms, such as recruitment of vergence to aid gaze shifts. INO may provide an accessible, reductionist model to study how decreased neural transmission influences fatigue in multiple sclerosis, how the brain adapts to it, and whether drugs may prove therapeutic.
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Affiliation(s)
- M Matta
- Clinical Neurology, Department of Neuroscience, University of Sassari, Italy
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Serra A, Thurtell MJ, Leigh RJ. Changes in dynamic and kinematic properties of saccades in ocular myasthenia following intravenous immunoglobulin treatment. Ann N Y Acad Sci 2009; 1164:468-71. [PMID: 19645950 DOI: 10.1111/j.1749-6632.2008.03712.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dynamics and kinematics of saccades in a patient with severe ocular myasthenia were studied before and after treatment with intravenous immunoglobulin (IVIG). Before therapy, horizontal saccades were hypometric, but faster than similar-sized saccades made by normal subjects. During a 5-minute test period, saccades decreased in size (fatigue effect), but remained faster than those of controls. Listing's plane of the eye with greater ophthalmoplegia was increased in thickness. After IVIG treatment, the range of eye movements improved, but saccades remained faster than those of controls. Also, no fatigue was observed and the thickness of Listing's plane was reduced toward the normal range. Increased peak velocity, despite progressive hypometria due to fatigue, supports the hypothesis that the pale global extraocular muscle fibers are relatively spared in myasthenia. Involvement of other extraocular muscle-fiber types leads to limited range of eye movements and an increase in the thickness of Listing's plane.
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Affiliation(s)
- Alessandro Serra
- The Daroff-Dell'Osso Ocular Motility Laboratory, Veterans Affairs Medical Center and Case Western Reserve University, Cleveland, Ohio, USA
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