Eye movement abnormalities in spinocerebellar ataxia type 17 (SCA17)
J Hübner1, A Sprenger, C Klein
1Department of Neurology, University of Luebeck, Luebeck, Germany.
Neurology
|September 12, 2007
Summary
Spinocerebellar ataxia type 17 (SCA17) causes eye movement issues, including impaired smooth pursuit and saccades. These deficits worsen with disease duration, suggesting cerebellar and cortical dysfunction in SCA17 patients.
Area of Science:
- Neuroscience
- Genetics
- Ophthalmology
Background:
- Spinocerebellar ataxia type 17 (SCA17) is a neurodegenerative disorder linked to CAG/CAA repeat expansions in the TATA-binding protein gene.
- Phenotypic heterogeneity in SCA17 suggests potential involvement of multiple brain regions.
Purpose of the Study:
- To quantitatively assess eye movement abnormalities in SCA17 mutation carriers.
- To investigate if oculomotor deficits in SCA17 originate from diverse lesion sites.
Main Methods:
- Compared eye movements (saccades, smooth pursuit) in 15 SCA17 carriers and 15 controls using the EYELINK II system.
- Utilized video-based, two-dimensional eye-tracking for precise measurements.
Main Results:
- Significantly impaired smooth pursuit initiation and maintenance (increased latency, decreased acceleration).
- Visually guided saccades were hypometric; antisaccade and memory-guided saccade error rates were elevated.
- Oculomotor disorders did not correlate with repeat length but worsened with disease duration.
Conclusions:
- Oculomotor deficits in SCA17 are consistent with cerebellar degeneration.
- Elevated antisaccade and memory-guided saccade errors suggest frontal cortical dysfunction, potentially explaining other SCA17 symptoms like dementia and parkinsonism.
Related Concept Videos
01:28Major Somatic Sensory Pathways
Sensory impulses related to touch, pressure, vibration, and proprioception from various body parts, such as the limbs, trunk, neck, and posterior head, travel to the cerebral cortex through the posterior column-medial lemniscus pathway. The pathway’s name derives from the two white-matter tracts that convey the impulses: the spinal cord's posterior column and the brainstem's medial lemniscus. First-order sensory neurons extend their axons into the spinal cord, forming the posterior columns...
01:12Visual Agnosia
Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round end"...