Deep brain stimulation (DBS) has become the treatment of choice for advanced stages of Parkinson's disease, medically intractable essential tremor, and complicated segmental and generalized dystonia. ...In addition to accurate electrode placement in the target area, effective programming of DBS devices is considered the most important factor for the individual outcome after DBS. Programming of the implanted pulse generator (IPG) is the only modifiable factor once DBS leads have been implanted and it becomes even more relevant in cases in which the electrodes are located at the border of the intended target structure and when side effects become challenging. At present, adjusting stimulation parameters depends to a large extent on personal experience. Based on a comprehensive literature search, we here summarize previous studies that examined the significance of distinct stimulation strategies for ameliorating disease signs and symptoms. We assess the effect of adjusting the stimulus amplitude (A), frequency (f), and pulse width (pw) on clinical symptoms and examine more recent techniques for modulating neuronal elements by electrical stimulation, such as interleaving (Medtronic®) or directional current steering (Boston Scientific®, Abbott®). We thus provide an evidence-based strategy for achieving the best clinical effect with different disorders and avoiding adverse effects in DBS of the subthalamic nucleus (STN), the ventro-intermedius nucleus (VIM), and the globus pallidus internus (GPi).
Subthalamic local field potentials in the beta band are considered as potential biomarkers for closed-loop deep brain stimulation. To investigate the subthalamic beta band peak amplitudes in a ...Parkinson’s disease patient over an extended period of time by using a novel and commercially available neurostimulator with permanent sensing capability. We recorded local field potentials of the subthalamic nucleus using the Medtronic Percept™ implantable neurostimulator at rest and during physical activity (gait) with and in response to deep brain stimulation. We found a double-peaked beta activity on both sides. Increasing stimulation and physical activity resulted in a decreased beta band amplitude, but was accompanied by the appearance of a second, and previously unrecognized peak at 13 Hz in the right hemisphere. Our results will support the investigation of distinct different peaks in the beta band and their relevance and usefulness as closed-loop biomarkers.
Objective:
To evaluate the effects of visual cues combined with treadmill training on gait performance in patients with Parkinson’s disease and to compare the strategy with pure treadmill training.
...Design:
Pilot, exploratory, non-blinded, randomized controlled trial.
Setting:
University Hospital of Munich, Germany.
Subjects:
Twenty-three outpatients with Parkinson’s disease (Hoehn and Yahr stage II–IV).
Interventions:
Patients received 12 training sessions within five weeks of either visual cues combined with treadmill training (n = 12) or pure treadmill training (n = 11).
Main measures:
Outcome measures were gait speed, stride length and cadence recorded on the treadmill. Functional tests included the Timed Up and Go Test, the Unified Parkinson’s Disease Rating Scale and the Freezing of gait-questionnaire. Assessments were conducted at baseline, after the training period and at two months follow-up.
Results:
After the training period (n = 20), gait speed and stride length had increased in both groups (p ⩽ 0.05). Patients receiving the combined training scored better in the Timed Up and Go Test compared with the patients receiving pure treadmill training (p ⩽ 0.05). At two months follow-up (n = 13), patients who underwent the combined training sustained better results in gait speed and stride length (p ⩽ 0.05) and sustained the improvement in the Timed Up and Go Test (p ⩽ 0.05).
Conclusions:
This pilot study suggests that visual cues combined with treadmill training have more beneficial effects on gait than pure treadmill training in patients with a moderate stage of Parkinson’s disease. A large-scale study with longer follow-up is required.
Deep brain stimulation has developed into an established treatment for movement disorders and is being actively investigated for numerous other neurological as well as psychiatric disorders. An ...accurate electrode placement in the target area and the effective programming of DBS devices are considered the most important factors for the individual outcome. Recent research in humans highlights the relevance of widespread networks connected to specific DBS targets. Improving the targeting of anatomical and functional networks involved in the generation of pathological neural activity will improve the clinical DBS effect and limit side-effects. Here, we offer a comprehensive overview over the latest research on target structures and targeting strategies in DBS. In addition, we provide a detailed synopsis of novel technologies that will support DBS programming and parameter selection in the future, with a particular focus on closed-loop stimulation and associated biofeedback signals.
Synucleinopathies such as Parkinson's disease, multiple system atrophy and dementia with Lewy bodies are characterized by deposition of aggregated α-synuclein. Recent findings indicate that ...pathological oligomers rather than fibrillar aggregates may represent the main toxic protein species. It has been shown that α-synuclein oligomers can increase the conductance of lipid bilayers and, in cell-culture, lead to calcium dyshomeostasis and cell death. In this study, employing a setup for single-channel electrophysiology, we found that addition of iron-induced α-synuclein oligomers resulted in quantized and stepwise increases in bilayer conductance indicating insertion of distinct transmembrane pores. These pores switched between open and closed states depending on clamped voltage revealing a single-pore conductance comparable to that of bacterial porins. Pore conductance was dependent on transmembrane potential and the available cation. The pores stably inserted into the bilayer and could not be removed by buffer exchange. Pore formation could be inhibited by co-incubation with the aggregation inhibitor baicalein. Our findings indicate that iron-induced α-synuclein oligomers can form a uniform and distinct pore species with characteristic electrophysiological properties. Pore formation could be a critical event in the pathogenesis of synucleinopathies and provide a novel structural target for disease-modifying therapy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Local field potentials (LFP) of the subthalamic nucleus (STN) recorded during walking may provide clues for determining the function of the STN during gait and also, may be used as biomarker to steer ...adaptive brain stimulation devices. Here, we present LFP recordings from an implanted sensing neurostimulator (Medtronic Activa PC + S) during walking and rest with and without stimulation in 10 patients with Parkinson's disease and electrodes placed bilaterally in the STN. We also present recordings from two of these patients recorded with externalized leads. We analyzed changes in overall frequency power, bilateral connectivity, high beta frequency oscillatory characteristics and gait-cycle related oscillatory activity. We report that deep brain stimulation improves gait parameters. High beta frequency power (20-30 Hz) and bilateral oscillatory connectivity are reduced during gait, while the attenuation of high beta power is absent during stimulation. Oscillatory characteristics are affected in a similar way. We describe a reduction in overall high beta burst amplitude and burst lifetimes during gait as compared to rest off stimulation. Investigating gait cycle related oscillatory dynamics, we found that alpha, beta and gamma frequency power is modulated in time during gait, locked to the gait cycle. We argue that these changes are related to movement induced artifacts and that these issues have important implications for similar research.
Summary Background Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces motor symptoms in patients with Parkinson's disease (PD) and improves their quality of life; however, the ...effect of DBS on cognitive functions and its psychiatric side-effects are still controversial. To assess the neuropsychiatric consequences of DBS in patients with PD we did an ancillary protocol as part of a randomised study that compared DBS with the best medical treatment. Methods 156 patients with advanced Parkinson's disease and motor fluctuations were randomly assigned to have DBS of the STN or the best medical treatment for PD according to the German Society of Neurology guidelines. 123 patients had neuropsychological and psychiatric examinations to assess the changes between baseline and after 6 months. The primary outcome was the comparison of the effect of DBS with the best medical treatment on overall cognitive functioning (Mattis dementia rating scale). Secondary outcomes were the effects on executive function, depression, anxiety, psychiatric status, manic symptoms, and quality of life. Analysis was per protocol. The study is registered at ClinicalTrials.gov , number NCT00196911. Findings 60 patients were randomly assigned to receive STN-DBS and 63 patients to have best medical treatment. After 6 months, impairments were seen in executive function (difference of changes DBS–best medical treatment in verbal fluency semantic −4·50 points, 95% CI −8·07 to −0·93, Cohen's d =−;0·4; verbal fluency phonemic −3·06 points, −5·50 to −0·62, −0·5; Stroop 2 naming colour error rate −0·37 points, −0·73 to 0·00, −0·4; Stroop 3 word reading time −5·17 s, −8·82 to −1·52, −0·5; Stroop 4 colour naming time −13·00 s, −25·12 to −0·89, −0·4), irrespective of the improvement in quality of life (difference of changes in PDQ-39 10·16 points, 5·45 to 14·87, 0·6; SF-36 physical 16·55 points, 10·89 to 22·21, 0·9; SF-36 psychological 9·74 points, 2·18 to 17·29, 0·5). Anxiety was reduced in the DBS group compared with the medication group (difference of changes in Beck anxiety inventory 10·43 points, 6·08 to 14·78, 0·8). Ten patients in the DBS group and eight patients in the best medical treatment group had severe psychiatric adverse events. Interpretation DBS of the STN does not reduce overall cognition or affectivity, although there is a selective decrease in frontal cognitive functions and an improvement in anxiety in patients after the treatment. These changes do not affect improvements in quality of life. DBS of the STN is safe with respect to neuropsychological and psychiatric effects in carefully selected patients during a 6-month follow-up period. Funding German Federal Ministry of Education and Research (01GI0201).
Six α-synuclein (aSyn) point mutations are currently known to be associated with familial parkinsonism: A30P, E46K, H50Q, G51D, A53E, and A53T. We performed a comprehensive in vitro analysis to study ...the impact of all aSyn mutations on lipid binding and aggregation behavior. Markedly reduced lipid binding of A30P, moderately attenuated binding of G51D, and only very slightly reduced binding for the other mutants were observed. A30P was particularly prone to form metal ion induced oligomers, whereas A53T exhibited only weak tendencies to form oligomers. In turn, fibril formation occurred rapidly in H50Q, G51D, and A53T, but only slowly in A30P, suggesting mutants prone to form oligomers tend to form fibrils to a lesser extent. This was supported by the observation that fibril formation of wild type aSyn, A30P, and A53T was impaired in the presence of ferric iron. Additionally, we found the aggregation kinetics of mixtures of A30P or A53T and wt aSyn to be determined by the faster aggregating aSyn variant. Our results implicate differential mechanisms playing a role in aSyn pathology on the molecular level. This might contribute to a better understanding of Parkinson’s disease pathogenesis and provide potential links to develop prevention strategies and disease-modifying therapy.
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