1/6. Does stimulation of the GPi control dyskinesia by activating inhibitory axons?A 69-year-old woman with Parkinson's disease and levodopa-induced dyskinesias had a deep brain stimulation (DBS) electrode inserted into the right globus pallidus internus (GPi). During the operation, the GPi was mapped with dual microelectrode recordings. Stimulation through one microelectrode in GPi inhibited the firing of GPi neurons recorded with another microelectrode 600--1,000 microm distant. The inhibition could be obtained with pulse widths of 150 micros and intensities as low as 10 microA. Single stimuli inhibited GPi neurons for approximately 50 ms. Trains of 300 Hz stimuli inhibited GPi neuron firing almost completely. Postoperatively, stimulation through macroelectrode contacts located in the posterior ventral pallidum controlled the patient's dyskinesias. The effect could be obtained with pulse widths of 50 micros and frequencies as low as 70--80 Hz. We postulate stimulation of the ventral pallidum controls dyskinesias by activating large axons which inhibit GPi neurons.- - - - - - - - - - ranking = 1keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |
2/6. Unilateral deep brain stimulation of the internal globus pallidus alleviates tardive dyskinesia.We describe a patient with fluspirilene-induced tardive dyskinesia of the choreiform oro-facial-laryngeal type resistant to various conservative approaches for 7 years who underwent deep brain stimulation of the internal pallidal globe. We found immediate and marked suppression of her perioral involuntary movements with unilateral stimulation at 60 Hz.- - - - - - - - - - ranking = 4keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |
3/6. chorea induced by globus pallidus externus stimulation in a dystonic patient.Bilateral high-frequency stimulation of the internal part of the pallidum has proven its efficacy in improving motor symptoms of dystonia. In Parkinson's disease, the stimulation of the external pallidum (GPe) can induce dyskinesias. This has never been described in dystonia. We report here a case of abnormal movements induced by the stimulation of GPe in a dystonic patient and discuss the pathophysiological mechanisms.- - - - - - - - - - ranking = 4keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |
4/6. Dyskinesia from manganism in a hepatic dysfunction patient.A 14-year-old boy came to the neurological clinic because of involuntary movement. He represented a case of common variable hypogammaglobulinemia, with hepatosplenomegaly noted for 5 years and jaundice for 1 month. Neurological and laboratory examinations revealed choreoathetosis and hyperbilirubinemia, hypoalbuminemia, increased hepatic aminotransferase, and decreased indocyanine green clearance; as well as increased signal change over the globus pallidus, subthalamic area, internal capsule, tegmentum, brain stem and pituitary gland revealed by a brain magnetic resonance (T1-weighted) imaging study. A manganese study confirmed high body manganese loading. trihexyphenidyl administration ameliorated the dyskinesia; however, the patient died from hepatic failure later. Though rare in incidence, manganese intoxication should be considered in cases with dyskinesia and the characteristic brain MRI findings. Even if no environmental exposure is involved, total parenteral nutrition, porto-systemic shunt and chronic hepatic dysfunction could lead to a heavy manganese load resulting in symptomatic manifestation.- - - - - - - - - - ranking = 1keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |
5/6. High-frequency stimulation of the globus pallidus internalis in Parkinson's disease: a study of seven cases.The effectiveness of ventroposterolateral pallidotomy in the treatment of akinesia and rigidity is not a new discovery and agrees with recent investigations into the pathogenesis of Parkinson's disease, which highlight the role played by the unbridled activity of the subthalamic nucleus (STN) and the consequent overactivity of the globus pallidus internalis (GPi). Because high-frequency stimulation can reversibly incapacitate a nerve structure, we applied stimulation to the same target. Seven patients suffering from severe Parkinson's disease (Stages III-V on the Hoehn and Yahr scale) and, particularly, bradykinesia, rigidity, and levodopa-induced dyskinesias underwent unilateral electrode implantation in the posteroventral GPi. Follow-up evaluation using the regular Unified Parkinson's disease Rating Scale has been conducted for 1 year in all seven patients, 2 years in five of them, and 3 years in one. In all cases high-frequency stimulation has alleviated akinesia and rigidity and has generally improved gait and speech disturbances. In some cases tremor was attenuated. In a similar manner, the authors observed a marked diminution in levodopa-induced dyskinesias. This could be an excellent primary therapy for younger patients exhibiting severe bradykinesia, rigidity, and levodopa-induced dyskinesias, which would allow therapists to keep ventroposterolateral pallidotomy in reserve as a second weapon.- - - - - - - - - - ranking = 5keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |
6/6. Effects of increasing doses of apomorphine during stereotaxic neurosurgery in Parkinson's disease: clinical score and internal globus pallidus activity. Short communication.We analysed the firing activity of internal globus pallidus cells in two Parkinson's disease patients undergoing stereotaxic surgery. Both patients showed an advanced rigid-akinetic syndrome with disabling levodopa induced dyskinesias. apomorphine, intraoperatively administered at doses (1-2 mg) inducing a short but clear clinical improvement without involuntary movements, reduced the pallidal discharge rate by > 50% in both patients. An higher apomorphine dose (2.5 mg), tested in one hemisphere, blocked the firing activity with a time course independent from the occurrence of dyskinesias. These finding suggest that the reduction of internal pallidus excitability is one of the mechanisms underlying the efficacy of dopaminergic therapy, but also that changes in other basal ganglia stations are likely to be involved in dyskinesias.- - - - - - - - - - ranking = 5.2158160281163keywords = globus pallidus, pallidus, globus (Clic here for more details about this article) |