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The neck-eye reflex in patients with reduced vestibular and optokinetic function
A M Bronstein1, S Mossman, L M Luxon
1Medical Research Council Human Movement and Balance Unit, National Hospital for Neurology and Neurosurgery, London, UK.
Brain : a Journal of Neurology
|February 1, 1991
Summary
The neck-eye loop (cervico-ocular reflex, COR) did not show plastic enhancement in patients with multisystem atrophy, unlike those with isolated vestibular loss. This suggests cerebellar involvement or disrupted pathways may prevent gaze stability adaptation.
Area of Science:
- Neuroscience
- Ophthalmology
- Vestibular System Research
Background:
- The cervico-ocular reflex (COR) typically enhances after vestibular function loss, aiding gaze stability.
- This plastic enhancement is thought to compensate for impaired vestibular input during head movements.
Observation:
- This study examined the COR in two patients with multisystem atrophy affecting the vestibular system and cerebellum, alongside reduced smooth pursuit-optokinetic eye movements (SP-OKN).
- Unlike previous findings in patients with isolated vestibular loss, the COR was not enhanced in these patients.
Findings:
- Measurements showed no enhancement of the COR in patients with combined vestibular and cerebellar atrophy.
- The neck-eye loop did not contribute to gaze stability during head movements in these patients, as indicated by identical eye movement velocities during COR-OKN and SP-OKN stimuli.
- Absence of COR plastic enhancement may stem from interrupted SP-OKN pathways or vestibulocerebellar involvement.
Implications:
- The findings suggest that the vestibulocerebellum plays a critical role in mediating adaptive plasticity of the cervico-ocular reflex.
- Understanding these pathways is vital for developing therapeutic strategies for gaze instability in patients with complex neurological disorders.