Subthalamic stimulation improves orienting gaze movements in Parkinson's disease.
OBJECTIVE
To determine the effect of subthalamic stimulation on visually triggered eye and head movements in patients with Parkinson's disease (PD).


METHODS
We compared the gain and latency of visually triggered eye and head movements in 12 patients bilaterally implanted into the subthalamic nucleus (STN) for severe PD and six age-matched control subjects. Visually triggered movements of eye (head restrained), and of eye and head (head unrestrained) were recorded in the absence of dopaminergic medication. Bilateral stimulation was turned OFF and then turned ON with voltage and contact used in chronic setting. The latency was determined from the beginning of initial horizontal eye movements relative to the target onset, and the gain was defined as the ratio of the amplitude of the initial movement to the amplitude of the target movement.


RESULTS
Without stimulation, the initiation of the head movement was significantly delayed in patients and the gain of head movement was reduced. Our patients also presented significantly prolonged latencies and hypometry of visually triggered saccades in the head-fixed condition and of gaze in head-free condition. Bilateral STN stimulation with therapeutic parameters improved performance of orienting gaze, eye and head movements towards the controls' level


CONCLUSIONS
These results demonstrate that visually triggered saccades and orienting eye-head movements are impaired in the advanced stage of PD. In addition, subthalamic stimulation enhances amplitude and shortens latency of these movements.


CONCLUSIONS
These results are likely explained by alteration of the information processed by the superior colliculus (SC), a pivotal visuomotor structure involved in both voluntary and reflexive saccades. Improvement of movements with stimulation of the STN may be related to its positive input either on the STN-Substantia Nigra-SC pathway or on the parietal cortex-SC pathway.
Department of Neurophysiology, University Hospital of Rennes, University of Rennes 1, France.
Paul
P
Sauleau
Department of Clinical and Biological Neurosciences, University Hospital of Grenoble, Grenoble, France; INSERM U 318, University of Grenoble 1, Grenoble, France.
Pierre
P
Pollak
Department of Clinical and Biological Neurosciences, University Hospital of Grenoble, Grenoble, France; INSERM U 318, University of Grenoble 1, Grenoble, France.
Paul
P
Krack
UMR-S 864 INSERM Espace et Action, University of Lyon 1, 16 av Doyen Lepine, 69676 Bron, France; Neuro-Ophthalmology Unit, University Hospital of Lyon, Hospices Civils de Lyon, University of Lyon 1, Bron, France.
Jean-Hubert
JH
Courjon
UMR-S 864 INSERM Espace et Action, University of Lyon 1, 16 av Doyen Lepine, 69676 Bron, France; Neuro-Ophthalmology Unit, University Hospital of Lyon, Hospices Civils de Lyon, University of Lyon 1, Bron, France.
Alain
A
Vighetto
Department of Clinical and Biological Neurosciences, University Hospital of Grenoble, Grenoble, France; INSERM U 318, University of Grenoble 1, Grenoble, France.
Alim-Louis
AL
Benabid
UMR-S 864 INSERM Espace et Action, University of Lyon 1, 16 av Doyen Lepine, 69676 Bron, France; Neuro-Ophthalmology Unit, University Hospital of Lyon, Hospices Civils de Lyon, University of Lyon 1, Bron, France.
Denis
D
Pélisson
UMR-S 864 INSERM Espace et Action, University of Lyon 1, 16 av Doyen Lepine, 69676 Bron, France; Neuro-Ophthalmology Unit, University Hospital of Lyon, Hospices Civils de Lyon, University of Lyon 1, Bron, France. Electronic address: caroline.tilikete@inserm.fr.
Caroline
C
Tilikete
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D005403:Fixation, Ocular; D019416:Head Movements / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology / Q000528:radiation effects*; D009949:Orientation / Q000502:physiology / Q000528:radiation effects*; D010300:Parkinson Disease / Q000628:therapy*; D010775:Photic Stimulation; D011601:Psychophysics; D020530:Subthalamus / Q000502:physiology* / Q000528:radiation effects