François Alesch

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BACKGROUND Long-term high-frequency stimulation of the subthalamic nucleus (STN) improves akinesia in Parkinson disease. The neural correlates of STN stimulation are not well understood. Positron emission tomography can be applied to the in vivo study of the mechanisms of deep brain stimulation. OBJECTIVE To study changes in regional cerebral blood flow(More)
Parkinson's disease involves impaired activation of frontal cortical areas, including the supplementary motor area and prefrontal cortex, resulting from impaired thalamocortical output of the basal ganglia. Electrophysiologically, such impaired cortical activation may be seen as a reduced amplitude of the contingent negative variation (CNV), a slow negative(More)
We report on the pathological findings in the brains of 8 Parkinson's disease patients treated with deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (6 cases) and subthalamic nucleus (2 cases). DBS was performed continuously for up to 70 months. All brains showed well-preserved neural parenchyma and only mild gliosis around the lead(More)
The combination of electrical deep brain stimulation (DBS) with functional imaging offers a unique model for tracing brain circuitry and for testing the modulatory potential of electrical stimulation on a neuronal network in vivo. We therefore applied parametric positron emission tomography (PET) analyses that allow characterization of rCBF responses as(More)
The usefulness of deep brain stimulation (DBS) of thalamic nuclei in Gilles de la Tourette syndrome (GTS) has recently been advocated. We report on a 14-month follow-up study of a patient with intractable GTS in whom bilateral DBS of the internal globus pallidus was carried out. Tic frequency per minute decreased by 73% in the postoperative phase and in(More)
BACKGROUND The functional effects of deep brain stimulation in the nucleus ventralis intermedius (VIM) of the thalamus on brain circuitry are not well understood. The connectivity of the VIM has so far not been studied functionally. It was hypothesized that VIM stimulation would exert an effect primarily on VIM projection areas, namely motor and(More)
Based on Benabid's experimental and clinical findings that low-frequency (50 Hz) electrical stimulation of the ventral intermediate thalamic nucleus may increase tremor, while higher frequencies (>100 Hz) lead to suppression of the tremor, we implanted a stimulation electrode in 33 thalami among 27 patients. Six patients were implanted bilaterally. 23(More)
AIM To evaluate the results of ventral intermediate (Vim) thalamic deep brain stimulation (DBS) in patients with tremor predominant Parkinson's disease (PD) at 6 years post surgery. METHODS This was a prolonged follow-up study of 38 patients from eight centres who participated in a multicentre study, the 1 year results of which have been published(More)
We report a patient with idiopathic Parkinson's disease who underwent bilateral deep brain stimulation (DBS) of the nucleus subthalamicus (STN) and developed visual hallucinations (VH) while taking no medications only when the DBS was turned on. The hallucinations resolved when the stimulator was turned off. The phenomenology and the prompt response to(More)
Ten experiments on pigs were performed to investigate possible postmortem changes of the dielectric properties of brain gray matter in the frequency range of 800-1900 MHz. After keeping the animals in stable anaesthesia for at least 45 min, they were euthanatised by an intravenous injection of hypertonic potassium chloride (KCl), causing cardiac arrest(More)