Oculomotor Abnormalities in<i>Dyssynergia Cerebellaris Myoclonica</i>

Wiest, Gerald; Mueller, Conrad G.; Wessely, P; Steinhoff, Nikolaus; Trattnig, Sigfried; Deecke, Lüder

doi:10.3109/00016489509125279

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…In two patients with olivo‐dentato‐rubral system degeneration, saccades showed increased latency and reduced velocity and amplitude (Wiest et al . ). Thus, while an involvement of DN in oculomotion seems well supported, its role remains unclear.…”

Section: Discussionmentioning

confidence: 97%

“…In SCA20, a spinocerebellar ataxia with DN calcifications, saccades were qualitatively reported as hypermetric (Knight et al 2004). In two patients with olivo-dentato-rubral system degeneration, saccades showed increased latency and reduced velocity and amplitude (Wiest et al 1995). Thus, while an involvement of DN in oculomotion seems well supported, its role remains unclear.…”

Section: Figure 3 Amplitude Dependence Of Saccadic Peak Velocity Andmentioning

confidence: 99%

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The role of dentate nuclei in human oculomotor control: insights from cerebrotendinous xanthomatosis

Rosini

Pretegiani

Mignarri

et al. 2017

The Journal of Physiology

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It is well known that the medial cerebellum controls saccadic speed and accuracy. In contrast, the role of the lateral cerebellum (cerebellar hemispheres and dentate nuclei, DN) is less well understood. Cerebrotendinous xanthomatosis (CTX) is a lipid storage disorder due to mutations in CYP27A1, typically characterized by DN damage. CTX thus provides a unique opportunity to study DN in human oculomotor control. We analysed horizontal and vertical visually guided saccades and horizontal antisaccades of 19 CTX patients. Results were related to the presence/absence of DN involvement and compared with those of healthy subjects. To evaluate the contribution of other areas, abnormal saccadic parameters were compared with global and regional brain volumes. CTX patients executed normally accurate saccades with normal main sequence relationships, indicating that the brainstem and medial cerebellar structures were functionally spared. Patients with CTX executed more frequent multistep saccades and directional errors during the antisaccade task than controls. CTX patients with DN damage showed less precise saccades with longer latencies, and more frequent directional errors, usually not followed by corrections, than either controls or patients without DN involvement. These saccadic abnormalities related to DN involvement but were independent of global and regional brain atrophy. We hypothesize that two different cerebellar networks contribute to the metrics of a movement: the medial cerebellar structures determine accuracy, whereas the lateral cerebellar structures control precision. The lateral cerebellum (hemispheres and DN) also participates in modulating goal directed gaze behaviour, by prioritizing volitional over reflexive movements.

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Section: Discussionmentioning

confidence: 97%

Section: Figure 3 Amplitude Dependence Of Saccadic Peak Velocity Andmentioning

confidence: 99%

The role of dentate nuclei in human oculomotor control: insights from cerebrotendinous xanthomatosis

Rosini

Pretegiani

Mignarri

et al. 2017

The Journal of Physiology

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Deficits of cortical oculomotor mechanisms in cerebellar atrophy patients

2012

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Commonly, the cerebellum is not associated with cortical components of saccadic eye movement programming. The present study investigates cerebellar effects on visually guided saccades in reflexive tasks (step, gap, overlap) and on internally driven saccades in intentional tasks (anti, memory, short memory sequences of four targets) in five patients with isolated cerebellar atrophy. The cerebellar dysfunction led to impairments in both reflexive and intentional saccades. Cerebellar atrophy patients showed an increase in the gain variability and an increase in the saccade latency. Furthermore, in the memory and anti task, suppression and pro-saccade errors were more frequent in the atrophy group compared to the control group. In the sequence task, patients had difficulties reproducing all four target locations in the order of the displayed sequence. The high variability of the saccade gain is a common observation in cerebellar atrophy patients and can be explained by the general variability present in the saccadic system. The increase in the saccade latency could be due to a cerebellar contribution to cortical processes related to fixation and target selection preceding the initiation of a saccade. Furthermore, the frequent occurrence of saccade errors in the memory and anti task suggests a cerebellar involvement in frontal inhibition of unwanted reflexive saccades. The impaired reproduction of saccade sequences in atrophy patients points to a deficit in short-term memory processes. Thus, this study provides further evidence that the cerebellum is involved in different cortical mechanisms related to the control of saccadic eye movements.

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Effects of cerebellar infarcts on cortical processing of saccades

2012

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The objective of the present study was to investigate cerebellar influences on cortical components of saccadic eye movement programming in human subjects. In 24 patients with a localized cerebellar lesion, saccadic eye movements were recorded in different reflexive (step, gap, overlap) and intentional (anti, memory, short memory sequences) tasks and compared to 23 healthy controls. The cerebellar lesions led to impairments in different saccade parameters. Cerebellar patients tended to show hypermetria and increased latencies compared to the control group. In particular, they executed significantly more erroneous saccades specifically in the memory task (suppression errors) but not in the anti task (pro-saccade errors). Moreover, while reproducing short sequences of saccades from memory, patients with cerebellar infarcts made more errors with regard to the sequence order than controls. The influence of cerebellar hemispheric lesions on the saccade latency, the task-specific lesion effects on the frequency of suppression errors, and the effects on the number of order errors suggest that the cerebellum is involved in cortical processes such as target selection and sequence reproduction.

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Oculomotor Abnormalities inDyssynergia Cerebellaris Myoclonica

Cited by 4 publications

References 6 publications

The role of dentate nuclei in human oculomotor control: insights from cerebrotendinous xanthomatosis

The role of dentate nuclei in human oculomotor control: insights from cerebrotendinous xanthomatosis

Deficits of cortical oculomotor mechanisms in cerebellar atrophy patients

Effects of cerebellar infarcts on cortical processing of saccades

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