Related Experiment Videos
Memory-contingent saccades and the substantia nigra postulate for essential blepharospasm
1Institute for Medical Research, Santa Clara Valley Medical Center, San Jose, CA 95128.
Brain : a Journal of Neurology
|February 1, 1991
Summary
Essential blepharospasm and cranial dystonia significantly impair saccadic eye movement initiation. These findings suggest a role for subcortical pathways, potentially the substantia nigra pars reticulata, in these focal dystonias.
Area of Science:
- Neurology
- Ophthalmology
- Movement Disorders
Background:
- Essential blepharospasm and cranial dystonia are focal dystonias with unknown causes.
- Blepharospasm in Parkinson's disease is linked to dopamine depletion and saccade restriction, potentially involving the substantia nigra pars reticulata (SNpr).
Purpose of the Study:
- To investigate if essential blepharospasm and cranial dystonia also impair saccadic eye movements.
- To explore the potential involvement of somatotopically arranged subcortical pathways, like the SNpr, in these conditions.
Main Methods:
- Measurement of memory-contingent and visually-guided saccades in patients with essential blepharospasm and cranial dystonia.
- Comparison of saccade latency, accuracy, and peak velocity with age-matched control subjects.
Main Results:
- Patients exhibited significantly prolonged or excessively variable saccade latency for both memory-contingent and visually-guided saccades.
- Saccade accuracy and peak velocity remained comparable to control subjects, indicating preserved basic eye movement parameters.
Conclusions:
- Essential blepharospasm and cranial dystonia demonstrably alter the initiation of saccadic eye movements.
- Subcortical brain regions or pathways, such as the SNpr, which integrate eyelid, saccade, and cranial/cervical motor control, may be implicated in the pathophysiology of blepharospasm.