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Published on: October 13, 2023
Visual and Positional Modulation of Pendular Seesaw Nystagmus: Implications for the Mechanism
Sung-Hee Kim1, Hyo-Jung Kim, Sea-Won Oh
1Department of Neurology (S-HK), Kyungpook National University School of Medicine, Kyungpook National University Chilgok Hospital, Daegu, Korea; Research Administration Team (H-JK), Seoul National University Bundang Hospital, Seongnam, South Korea; Dizziness Center (S-WO, J-SK), Seoul National University Bundang Hospital, Seongnam, Korea; and Department of Neurology (J-SK), Seoul National University College of Medicine, Seoul, Korea.
Background:
The mechanisms of pendular seesaw nystagmus (SSN) remain unknown.
Methods:
We evaluated modulation of pendular SSN by removal of visual fixation, convergence, and positional changes in 2 patients, one with bitemporal hemianopia due to a traumatic damage of the optic chiasm and the other with platybasia compressing the medulla and lower cerebellum.
Results:
In both patients, the pendular SSN markedly decreased or disappeared with convergence, without visual fixation in darkness, during static head tilt toward each shoulder while sitting and while supine.
Conclusions:
The similar patterns of nystagmus modulation observed in our patients with a different etiology indicate a common role of both visual and otolithic inputs in generating pendular SSN.
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