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Midbrain disorders of vertical gaze: a quantitative re-evaluation
1Division of Neurology, University Health Network, University of Toronto, Toronto, Ontario, Canada. sharpej@uhnres.utoronto.ca
Annals of the New York Academy of Sciences
|April 19, 2002
Summary
Midbrain lesions impair vertical eye movements, affecting smooth pursuit (SP) and the vestibulo-ocular reflex (VOR). These deficits, often dissociated, reveal subtle supranuclear damage beyond saccade examination.
Area of Science:
- Neuroscience
- Ophthalmology
- Neurology
Background:
- The mesodiencephalic junction controls vertical eye motion.
- Midbrain lesions can cause palsy of vertical saccades.
Purpose of the Study:
- To investigate vertical eye movements in patients with midbrain lesions.
- To analyze smooth pursuit (SP), vestibulo-ocular reflex (VOR), and their interactions with vision.
Main Methods:
- Measured vertical saccades, SP, VOR, and VOR-vision interactions during head motion.
- Studied 21 patients with midbrain lesions affecting vertical saccades.
Main Results:
- Subnormal SP and VOR gains were common, often dissociated.
- Impaired VOR cancellation and visually enhanced VOR were observed.
- Phase lead of the VOR indicated neural integrator damage.
Conclusions:
- Subnormal VOR and SP gains are typical in vertical saccade paresis.
- Dissociations in impairment highlight discrete midbrain damage.
- Findings reveal supranuclear midbrain effects not detected by saccade tests.