These findings support the efficacy and safety of the use of bilateral stimulation of the internal globus pallidus in selected patients with primary generalized dystonia.
These preliminary findings suggest that stimulation of the subthalamic nucleus may reduce the symptoms of severe forms of OCD but is associated with a substantial risk of serious adverse events. (ClinicalTrials.gov number, NCT00169377.)
Objective: to analyse 24 parkinsonian patients successfully treated by bilateral STN stimulation for the presence of behavioural disorders. Method: patients were evaluated retrospectively for adjustment disorders (social adjustment scale, SAS), psychiatric disorders (comparison of the results of psychiatric interview and the mini international neuropsychiatric inventory) and personality changes (IOWA scale of personality changes). Results: parkinsonian motor disability was improved by 69.5% and the levodopa equivalent daily dosage was reduced by 60.5%. Social adjustment (SAS) was considered good or excellent in nine patients, moderately (n=14), or severely (n=1) impaired in 15 patients. Psychiatric disorders consisted of amplification or decompensation of previously existing disorders that had sometimes passed unnoticed, such as depressive episodes (n=4), generalised anxiety (n=18), and behavioural disorders with drug dependence (n=2). Appearance of mild to moderate emotional hyperreactivity was reported in 15 patients. Personality traits (IOWA scale) were improved in eight patients, unchanged in seven, and aggravated in eight Conclusion: Improvement in parkinsonian motor disability induced by STN stimulation is not necessarily accompanied by improvement in psychic function and quality of life. Attention is drawn to the possible appearance of personality disorders and decompensation of previous psychiatric disorders in parkinsonian patients who are suitable candidates for neurosurgery. We suggest that a careful psychological and psychiatric interview be performed before surgery, and emphasise the need for psychological follow up to ensure the best possible outcome.
Bilateral continuous high frequency stimulation of the subthalamic nucleus (STN) was recently introduced to treat advanced forms of Parkinson's disease. 1 The method currently used improves motor disability by 33%-67%, motor fluctuations by 73%-83%, and levodopa induced dyskinesias by 55%-88%, and permits a 40%-80% reduction in the doses of antiparkinsonian medication, compared with the preoperative state.
2-6Several factors contribute to the efficacy of the treatment: the stringency of the inclusion criteria, the accuracy of electrode implantation in the STN, and long term optimisation of the stimulation parameters. 5 The surgical intervention has little or no effect on cognitive function. Two recent studies showed that chronic bilateral subthalamic stimulation affects neither memory nor executive functions. 7 8 A third study, however, showed that frontal lobe-like symptomatology can be aggravated in patients 70 years of age or older. 9 The question of behavioural effects of the treatment has not yet been addressed directly, except in a few isolated case reports. 9 We report the results of a retrospective study designed to explore the range of behavioural disorders in 24 patients successfully treated by bilateral STN stimulation.
High-frequency stimulation of the subthalamic nucleus (STN) constitutes one of the most effective treatments for advanced forms of Parkinson's disease. The cost and potential risks of this procedure encourage the determination of clinical characteristics of patients that will have the best postoperative outcome. Forty-one Parkinson's disease patients underwent surgery for bilateral STN stimulation. The selection criteria were severe parkinsonian motor disability, clear response of symptoms to levodopa, occurrence of disabling levodopa-related motor complications and the absence of dementia and significant abnormalities on brain MRI. Clinical evaluation was performed 1 month before and 6 months after surgery. The improvement in the activities of daily living subscale of the Unified Parkinson's Disease Rating Scale, Part II (UPDRS II) and parkinsonian motor disability (UPDRS III) was greater when the preoperative scores for activities of daily living and parkinsonian motor disability, in particular axial symptoms, such as gait disorders and postural instability assessed at the time of maximal clinical improvement (on drug), were lower. Age and disease duration were not predictive, but parkinsonian motor disability tended to be more improved in patients with younger age and shorter disease duration. The severity of levodopa-related motor complications was not a predictive factor. The outcome of STN stimulation was excellent in levodopa-responsive forms of Parkinson's disease, i.e. in patients with selective brain dopaminergic lesions, and moderate in patients with axial motor symptoms and cognitive impairment known to be less responsive or unresponsive to levodopa treatment, i.e. when brain non-dopaminergic lesions develop in addition to the degeneration of the nigrostriatal dopaminergic system. The results are consistent with the classical inclusion criteria for STN stimulation, but imply that the decision to operate on the oldest patients and/or patients with gait and postural disorders, who are poorly responsive to levodopa, should be weighed carefully.
At evaluation 6 months after surgery, continuous STN stimulation was shown to have improved parkinsonian motor disability by 64% and 78% in the "off' and "on" medication states, respectively. Antiparkinsonian drug treatment was reduced by 70% in 10 patients and withdrawn in two patients. The severity of levodopa-induced dyskinesias was reduced by 83% and motor fluctuations by 88%. Continuous high-frequency stimulation of the STN applied through electrodes implanted with the aid of 3D MR imaging and electrophysiological guidance is a safe and effective therapy for patients suffering from severe, advanced levodopa-responsive PD.
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