Biomedical subjects
Publications and source records attributed to Bettina Schrader.
Detrusor hyperreflexia is a relevant clinical symptom for patients suffering from Parkinson's disease. In a series of 16 patients, we demonstrated that subthalamic deep brain stimulation has a significant and urodynamically recordable effect leading to a normalization of pathologically increased bladder sensibility.
The optimal stimulation site in subthalamic deep brain stimulation (STN-DBS) was evaluated by correlation of the stereotactic position of the stimulation electrode with the electrophysiologically specified dorsal STN border. In a series of 25 electrodes, best clinical results with least energy consumption were found in contacts located in the dorsolateral border zone, whereas contacts within the subthalamic white matter, e.g., zona incerta, were significantly less effective. We suggest that the dorsolateral STN border should be covered by STN-DBS.
We studied 48 patients after bilateral subthalamic nucleus deep brain stimulation (STN-DBS) who were evaluated 6 months after the surgical procedure using the Unified Parkinson's Disease Rating Scale (UPDRS) in a standardized levodopa test. Additional follow-up was available in 32 patients after 12 months and in 20 patients after 24 months. At 6 months follow-up, STN-DBS reduced the UPDRS motor score by 50.9% compared to baseline. This improvement remained constant at 12 months with 57.5% and at 24 months with 57.3%. Relevant side effects after STN-DBS included intraoperative subdural hematoma without neurological sequelae (n = 1), minor intracerebral bleeding with slight transient hemiparesis (n = 1), dislocation of impulse generator (n = 2), transient perioperative confusional symptoms (n = 7), psychotic symptoms (n = 2), depression (n = 5), hypomanic behaviour (n = 2), and transient manic psychosis (n = 1). One patient died because of heart failure during the first postoperative year. The current series demonstrates efficacy and safety of STN-DBS beyond the first year after surgical procedure. Complications of STN-DBS comprise a wide range of psychiatric adverse events which, however, were temporary.
Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy for Parkinson's disease (PD). A manic episode with psychotic symptoms induced by STN-DBS occurred in a previously psychiatrically healthy patient, focusing on the role of STN-DBS in influencing not only motor but also emotional behaviour.
Deep-brain stimulation of the subthalamic nucleus appears to reduce levodopa-induced dyskinesias, but whether this effect is caused by the reduction of the total levodopa ingestion or represents a direct effect on the motor system is unknown. Precision grip force of grasping movements and levodopa-induced dyskinesias was analyzed in 10 parkinsonian patients before and after 3 months of deep-brain stimulation of the subthalamic nucleus. Peak grip force was abnormally increased before surgery in the off-drug state and, particularly, in the on-drug state (sensitization). This grip force upregulation normalized with chronic deep-brain stimulation in both conditions (desensitization). Peak-dose dyskinesias also improved, and off-dystonia was completely abolished. Mean dosage of dopaminergic drugs was reduced, but force overflow and dyskinesias were equally improved in 2 patients without a reduction. Despite the same single levodopa test dose, force excess and levodopa-induced dyskinesias were drastically reduced after 3 months of deep-brain stimulation of the subthalamic nucleus. This indicates that direct effects of deep-brain stimulation of the subthalamic nucleus on levodopa-induced dyskinesias are likely to occur. Grip force overflow is a promising parameter to study the desensitizing effect of chronic deep-brain stimulation on levodopa-induced dyskinesias.
In evaluating the success of deep brain stimulation (DBS), the benefit for the patient is the most important criteria. Nevertheless, correct placement of electrodes should also be determined in terms of their anatomic position. Therefore, we propose a suite of different imaging modalities and further processing, which leads to an exact anatomic and statistically comparable documentation of electrode localization. Forty-three consecutive patients with a total of 85 implanted DBS electrodes were evaluated with respect to postoperative imaging. T1-weighted magnetic resonance imaging (T1-MRI) was performed in all patients, 34 patients received T2-MRI, in 18 patients stereotactic X-ray of the scull was performed in anteroposterior and lateral projections, whereas 6 patients were additionally evaluated by pre- and postoperative MR-image fusion between T1-data sets and calculation of coordinates for electrode contacts. In T1-MRI, the artefacts of each electrode contact could be delineated in relation to anatomic reference structures, whereas T2-MRI allowed reproducibly for delineation of electrode artefacts within subthalamic nucleus or globus pallidus pars interna. By MR-image fusion it could be shown that the difference between planned target coordinates and coordinates of the active electrode contact ranged below 1 mm except for the z axis. The comparison with values obtained from stereotactic X-ray confirmed these results. The sequential and complementary use of the described imaging modalities and further image processing provide clinically reliable and statistically comparable results to prove the exact anatomic electrode positioning in DBS in addition to the objective and subjective improvements of the patients' symptoms.