Two patients with Parkinson’s disease with pedunculopontine nucleus (PPN) stimulation for gait impairments reported “trembling vision” during the setting of the electrical parameters, although there was no clinically observable abnormal eye movement. Oculomotor recordings revealed frequency locked voltage dependent vertical or oblique movements of the eye ipsilateral to the active contact, suggesting current spreading to the mesencephalic oculomotor fibres. These results emphasise the difficulty of stimulating this mesencephalic region.
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Funding: We gratefully acknowledge the Michael J Fox Foundation and the Fondation de France for financial support. Medtronic Inc provided the implanted pulse generators for PPN stimulation. This work was promoted by the Centre Hospitalier Universitaire de Grenoble, project FREESTIPP, and the Hospices Civils de Lyon, project HCL/P/2002.303. The authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Competing interests: None.
Ethics approval: The study was approved by the local ethics committee.