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Eye movements in chorea-acanthocytosis.
Libe Gradstein1, Adrian Danek, Jordan Grafman
1Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. libe@nei.nih.gov
Investigative Ophthalmology & Visual Science
|May 26, 2005
Summary
Chorea-acanthocytosis (ChAc) patients show significant eye movement abnormalities, including saccadic intrusions and impaired saccades. These findings suggest brainstem involvement and aid in ChAc diagnosis and monitoring.
Area of Science:
- Neuro-ophthalmology
- Neurodegenerative diseases
- Genetics
Background:
- Chorea-acanthocytosis (ChAc) is a rare, autosomal recessive neurodegenerative disorder characterized by movement abnormalities and acanthocytosis.
- Mutations in the VPS13A gene cause ChAc, leading to basal ganglia degeneration.
- Ocular involvement in ChAc has been historically understudied compared to other neurodegenerative conditions like Huntington's disease.
Purpose of the Study:
- To systematically describe and quantify eye movement abnormalities in patients diagnosed with chorea-acanthocytosis (ChAc).
- To investigate potential neurodegeneration in brainstem regions beyond the basal ganglia in ChAc patients.
- To evaluate the utility of eye movement recordings for diagnosing ChAc and monitoring disease progression.
Main Methods:
- Included three ChAc patients (ages 26, 30, 44) and six healthy controls (ages 31-48).
- Patients exhibited clinical signs of ChAc, including dystonia, chorea, parkinsonism, and cognitive deficits, alongside acanthocytosis and VPS13A mutations.
- Neuro-ophthalmic examinations and magnetic search coil technique recorded eye movements (fixation, saccades, pursuit, antisaccades) for comparison between patients and controls.
Main Results:
- ChAc patients displayed significantly increased square-wave jerks (>30/min) compared to controls (0-8/min).
- Abnormalities included fractionated, hypometric saccades, and reduced saccadic peak velocity, particularly for vertical movements.
- Low gain in pursuit and abnormal antisaccade testing were observed in patients, suggesting widespread ocular motor dysfunction.
Conclusions:
- Eye movement abnormalities in ChAc indicate neurodegeneration extending to the brainstem, beyond the basal ganglia.
- Pronounced ocular motor deficits are characteristic of this progressive neurodegenerative disease.
- Eye movement analysis offers a valuable tool for ChAc diagnosis, progression monitoring, and potential therapeutic assessments.