Your Questions
L’utilisation d’appareils de physiothérapie entraînant un échauffement des tissus (appareils de diathermie) sont contre-indiqués au niveau du chef, de la région cervicale et du tronc, en raison du risque de survenue de lésions cérébrales irréversibles et fatales. La réalisation d’une IRM chez des sujets porteurs de matériel de neurostimulation est possible mais sous certaines conditions. Par ailleurs, des conseils concernant les risques liés à l’exposition à des ondes électromagnétiques vous seront prodigués.
La durée de vie moyenne d’un neurostimulateur dépend des paramètres électriques chroniques. Elle est de l’ordre de trois à cinq ans dans le cas d’une stimulation bilatérale du noyau sous-thalamique. Des pacemakers rechargeables sont maintenant disponibles.
Yes, deep-brain stimulation is indeed entirely reversible; it can be stopped at any time, either temporarily, or permanently, by turning the stimulator off and/or by taking the electrodes out of the brain. The neurostimulator will be declared malfunctioning or turned off entirely, in the symptoms come back rapidly or forcefully after the stimulation has started, in which case it will have to be looked over.
Parkinson’s Disease: choosing the target-areas and the consequent results
Deep-brain stimulation generally takes place near the subthalamic nucleus (STN), as that is the target which impact motricity the most efficiently, with certain patients reporting more than 60% benefits. Parkinson’s trio of motor symptoms, rigidity, akinesia, and tremors -, dystonia – muscle contractions – even in down-time, and dopa sensitive axial motor symptoms – like walking disorders, posture disorders, speech disorders, or even difficulties swallowing, are improved tremendously. This allows for the doses of dopaminergic treatments to be lowered – sometimes by more than half -, thusly limiting their secondary effects.
Parkinson’s Disease’s very strong dopa sensitivity if still a key factor of why STN stimulation can get extremely efficient results. That is why that very same dopa sensitivity is one of the selection criteria for being chosen for deep brain stimulation. Other factors will also have an impact on the technique’s result, if the disease is too advanced. Being older than most when Parkinson starts, under-scoring on the down-time axial symptoms, or REM sleep behavior disorder are all some of the known factors that will contribute to a less-than-optimal functioning of SNT stimulation.
The motor capabilities are still improved after five years have passed, but dopa resistant axial symptoms occurring, as is typical in your disease’s typical evolution, does limit the stimulation’s functional stimulation.
SNT stimulation does not alter cognitive functions which were not already altered before the intervention. However, a discrete dysexecutive syndrome (a partial or total inability to develop or plan one’s behavior in order to achieve a goal) can be observed in certain patients, and get progressively worse. These disorders most likely have different factors of origin: it might indeed be a direct consequence of the STN stimulation, or from the decrease of the dopaminergic treatment, or the disease getting worse. Behavioral consequences are possible, especially apathy, which is made likely by decreasing the dose of the anti-Parkinson treatment. They are prevented by reducing the dopaminergic-aimed treatment a few days before the electrodes are implanted. There are factors, other than the changes in the treatments, which play a role in any behavioral disorders occurring; like the patient’s personality, the stress of the operation, and the consequences that modifying motor capabilities can have on one’s social life.
Stimulating the Vim nucleus of the thalamus allows for control over contralateral rest tremors in 80% of cases and reduce the treatment somehow. Its impact over rigidity is limited and other symptoms are not modified, except dyskinesia sometimes. As such, that target is only chosen for a few cases of patients which are very affected by tremors. Internal palladium stimulation can reduce contralateral dyskinesia, by 40 to 80%. That stimulation is made in a bilateral manner. Parkinson’s trio of motor symptoms can be made better, but only minimally. As such, anti-Parkinson treatments must be kept, if not increased. Levodopa-bound dyskinesia getter better lasts on the long time, whereas the initial beneficial effects on the motor symptoms fades after a few years. Choosing target-areas is thus privileged for patients who are very old and dyskinetic – who might eventually have a discrete cognitive decline and moderate walking disorders – which contra-indicate STN stimulation.