Mechanism of interrupted saccades in patients with late-onset Tay–Sachs disease

Optican, Lance M.; Rucker, Janet C.; Keller, Edward L.; Leigh, R. John

doi:10.1016/s0079-6123(08)00681-x

Cited by 11 publications

(14 citation statements)

References 4 publications

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“…In contrast, SWJ are traditionally viewed as uncalled for saccades, possibly due to spontaneous excitation or due to disinhibition of the SC or of the fastigial oculomotor region 1 3 4 11. The traditional views of the pathophysiology of these abnormalities do not explain the coexistence of ‘staircase’ saccade and ‘staircase’ SWJ in the same patient.…”

Section: Discussionmentioning

confidence: 96%

“…Excessive inhibition of the saccadic drive, for example, at the SC or at the saccadic burst generators can cause ‘staircase’ visually guided saccades 1 3 4. In contrast, SWJ are traditionally viewed as uncalled for saccades, possibly due to spontaneous excitation or due to disinhibition of the SC or of the fastigial oculomotor region 1 3 4 11.…”

Section: Discussionmentioning

confidence: 99%

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'Staircase' square-wave jerks in early Parkinson's disease

Shaikh

Xu-Wilson

Grill

et al. 2010

British Journal of Ophthalmology

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Loss of dopaminergic neurons in the substantia nigra pars compacta leading to phasic excitation of the substantia nigra pars reticulata and, in turn, phasic inhibition of the superior colliculus (SC), may account for 'staircase' visually guided saccades in these patients. This mechanism, however, does not explain abnormally large SWJ, which in the traditional view results from decreased inhibition upon SC. The abnormally large SWJ could be due to a compensatory increase in frontal eye field activity secondary to the increased inhibition upon the SC. Abnormally large and frequent SWJ are often used clinically to distinguish multi-system atrophy from idiopathic PD. Our study, however, suggests that idiopathic PD cannot be excluded if the patient has large-amplitude SWJ.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

'Staircase' square-wave jerks in early Parkinson's disease

Shaikh

Xu-Wilson

Grill

et al. 2010

British Journal of Ophthalmology

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“…The first possibility, i.e., the premature excitation of the antagonistic, inhibitory burst neuron, might be attributed to an disturbed cerebellar signal [22]. Contemporary concepts of distorted cerebellar output in CD [23–25] to the inhibitory reticular spinal burst neurons favor the possibility of premature activation of the inhibitory burst neurons and interruption of ongoing head saccades.…”

Section: Discussionmentioning

confidence: 99%

Why are voluntary head movements in cervical dystonia slow?

Shaikh

Wong

Zee

et al. 2015

Parkinsonism & Related Disorders

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Introduction Rapid head movements associated with a change in fixation (head saccades) have been reported to be slow in cervical dystonia (CD). Such slowing is typically measured as an increase in time to complete a movement. The mechanisms responsible for this slowing are poorly understood. Methods We measured head saccades in 11 CD patients and 11 healthy subjects using a magnetic search coil technique. Results Head saccades in CD took longer to reach a desired target location. This longer duration was due to multiple pauses in the trajectory of the head movement. The head velocity of each segment of the (interrupted) head movement was appropriate for the desired total movement amplitude. The head velocity was, however, higher for the amplitude of the individual interrupted movements. These results suggest that brain programs the proper head movement amplitude, but the movement is interrupted by pathological pauses. Conclusion Voluntary head saccades have a longer duration in CD due to frequent pauses. The frequent pauses reflect pathological interruptions of normally programmed intended head movement.

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“…Moreover, since multistep saccades have been proposed as a marker of basal ganglia and/or cerebellar impairment (Optican et al . ; Blekher et al . ) we analysed the rate and characteristics of the steps composing such movements.…”

Section: Introductionmentioning

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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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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Mechanism of interrupted saccades in patients with late-onset Tay–Sachs disease

Cited by 11 publications

References 4 publications

'Staircase' square-wave jerks in early Parkinson's disease

'Staircase' square-wave jerks in early Parkinson's disease

Why are voluntary head movements in cervical dystonia slow?

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

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