References of "Gharabaghi, Alireza"
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See detailAnodal tDCS modulates cortical activity and synchronization in Parkinson's disease depending on motor processing.
Schoellmann, Anna; Scholten, Marlieke; Wasserka, Barbara et al

in NeuroImage. Clinical (2019), 22

BACKGROUND: Transcranial direct current stimulation (tDCS) may alleviate motor symptoms in Parkinson's disease (PD). However, the neurophysiological effects of tDCS on cortical activation, synchronization ... [more ▼]

BACKGROUND: Transcranial direct current stimulation (tDCS) may alleviate motor symptoms in Parkinson's disease (PD). However, the neurophysiological effects of tDCS on cortical activation, synchronization, and the relation to clinical motor symptoms and motor integration need characterization. OBJECTIVE: We aimed to explore the effect of tDCS over the left sensorimotor area on clinical motor outcome, right hand fine motor performance as well as cortical activity and synchronization in the high beta range. METHODS: In this double-blind randomized sham-controlled clinico-neurophysiological study we investigated ten idiopathic PD patients and eleven matched healthy controls (HC) on two days during an isometric precision grip task and at rest before and after 'verum' and 'sham' anodal tDCS (20min; 1mA; anode [C3], cathode [Fp2]). We measured clinical outcome, fine motor performance, and analysed both cortical frequency domain activity and corticocortical imaginary coherence. RESULTS: tDCS improved PD motor symptoms. Neurophysiological features indicated a motor-task-specific modulation of activity and coherence from 22 to 27Hz after 'verum' stimulation in PD. Activity was significantly reduced over the left sensorimotor and right frontotemporal area. Before stimulation, PD patients showed reduced coherence over the left sensorimotor area during motor task compared to HC, and this increased after 'verum' stimulation in the motor task. The activity and synchronization modulation were neither observed at rest, after sham stimulation nor in healthy controls. CONCLUSION: Verum tDCS modulated the PD cortical network specifically during fine motor integration. Cortical oscillatory features were not in general deregulated in PD, but depended on motor processing. [less ▲]

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See detailLong-Term Effect of GPi-DBS in a Patient With Generalized Dystonia Due to GLUT1 Deficiency Syndrome.
Hanci, Idil; Kamm, Christoph; Scholten, Marlieke et al

in Frontiers in neurology (2018), 9

Treatment outcomes from pallidal deep brain stimulation are highly heterogeneous reflecting the phenotypic and etiologic spectrum of dystonia. Treatment stratification to neurostimulation therapy ... [more ▼]

Treatment outcomes from pallidal deep brain stimulation are highly heterogeneous reflecting the phenotypic and etiologic spectrum of dystonia. Treatment stratification to neurostimulation therapy primarily relies on the phenotypic motor presentation; however, etiology including genetic factors are increasingly recognized as modifiers of treatment outcomes. Here, we describe a 53 year-old female patient with a progressive generalized dystonia since age 25. The patient underwent deep brain stimulation of the globus pallidus internus (GPi-DBS) at age 44. Since the clinical phenotype included mobile choreo-dystonic features, we expected favorable therapeutic outcome from GPi-DBS. Although mobile dystonia components were slightly improved in the long-term outcome from GPi-DBS the overall therapeutic response 9 years from implantation was limited when comparing "stimulation off" and "stimulation on" despite of proper electrode localization and sufficient stimulation programming. In order to further understand the reason for this limited motor symptom response, we aimed to clarify the etiology of generalized dystonia in this patient. Genetic testing identified a novel heterozygous pathogenic SLC2A1 mutation as cause of glucose transporter type 1 deficiency syndrome (GLUT1-DS). This case report presents the first outcome of GPi-DBS in a patient with GLUT1-DS, and suggests that genotype relations may increasingly complement phenotype-based therapy stratification of GPi-DBS in dystonia. [less ▲]

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See detailEffects of Subthalamic and Nigral Stimulation on Gait Kinematics in Parkinson's Disease.
Scholten, Marlieke; Klemt, Johannes; Heilbronn, Melanie et al

in Frontiers in neurology (2017), 8

Conventional subthalamic deep brain stimulation for Parkinson's disease (PD) presumably modulates the spatial component of gait. However, temporal dysregulation of gait is one of the factors that is ... [more ▼]

Conventional subthalamic deep brain stimulation for Parkinson's disease (PD) presumably modulates the spatial component of gait. However, temporal dysregulation of gait is one of the factors that is tightly associated with freezing of gait (FOG). Temporal locomotor integration may be modulated differentially at distinct levels of the basal ganglia. Owing to its specific descending brainstem projections, stimulation of the substantia nigra pars reticulata (SNr) area might modulate spatial and temporal parameters of gait differentially compared to standard subthalamic nucleus (STN) stimulation. Here, we aimed to characterize the differential effect of STN or SNr stimulation on kinematic gait parameters. We analyzed biomechanical parameters during unconstrained over ground walking in 12 PD patients with subthalamic deep brain stimulation and FOG. Patients performed walking in three therapeutic conditions: (i) Off stimulation, (ii) STN stimulation (alone), and (iii) SNr stimulation (alone). SNr stimulation was achieved by stimulating the most caudal contact of the electrode. We recorded gait using three sensors (each containing a tri-axial accelerometer, gyroscope, and magnetometer) attached on both left and right ankle, and to the lumbar spine. STN stimulation improved both the spatial features (stride length, stride length variability) and the temporal parameters of gait. SNr stimulation improved temporal parameters of gait (swing time asymmetry). Correlation analysis suggested that patients with more medial localization of the SNr contact associated with a stronger regularization of gait. These results suggest that SNr stimulation might support temporal regularization of gait integration. [less ▲]

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See detailThe subthalamic nucleus modulates the early phase of probabilistic classification learning.
Weiss, Daniel; Lam, Judith M.; Breit, Sorin et al

in Experimental brain research (2014), 232(7), 2255-62

Previous models proposed that the subthalamic nucleus (STN) is critical in the early phase of skill acquisition. We hypothesized that subthalamic deep brain stimulation modulates the learning curve in ... [more ▼]

Previous models proposed that the subthalamic nucleus (STN) is critical in the early phase of skill acquisition. We hypothesized that subthalamic deep brain stimulation modulates the learning curve in early classification learning. Thirteen idiopathic Parkinson's disease patients (iPD) with subthalamic deep brain stimulation (STN-DBS), 9 medically treated iPD, and 21 age-matched healthy controls were tested with a probabilistic classification task. STN-DBS patients were tested with stimulation OFF and ON, and medically treated patients with medication OFF and ON, respectively. Performance and reaction time were analyzed on the first 100 consecutive trials as early learning phase. Moreover, data were separated for low and high-probability patterns, and more differentiated strategy analyses were used. The major finding was a significant modulation of the learning curve in DBS patients with stimulation ON: although overall learning was similar to healthy controls, only the stimulation ON group showed a transient significant performance dip from trials '41-60' that rapidly recovered. Further analysis indicated that this might be paralleled by a modulation of the learning strategy, particularly on the high-probability patterns. The reaction time was unchanged during the dip. Our study supports that the STN serves as a relay in early classification learning and directs attention toward unacquainted content. The STN might play a role in balancing the short-term success against strategy optimization for improved long-term outcome. [less ▲]

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See detailNigral stimulation for resistant axial motor impairment in Parkinson's disease? A randomized controlled trial.
Weiss, Daniel; Walach, Margarete; Meisner, Christoph et al

in Brain : a journal of neurology (2013), 136(Pt 7), 2098-108

Gait and balance disturbances typically emerge in advanced Parkinson's disease with generally limited response to dopaminergic medication and subthalamic nucleus deep brain stimulation. Therefore ... [more ▼]

Gait and balance disturbances typically emerge in advanced Parkinson's disease with generally limited response to dopaminergic medication and subthalamic nucleus deep brain stimulation. Therefore, advanced programming with interleaved pulses was put forward to introduce concomittant nigral stimulation on caudal contacts of a subthalamic lead. Here, we hypothesized that the combined stimulation of subthalamic nucleus and substantia nigra pars reticulata improves axial symptoms compared with standard subthalamic nucleus stimulation. Twelve patients were enrolled in this 2 x 2 cross-over double-blind randomized controlled clinical trial and both the safety and efficacy of combined subthalamic nucleus and substantia nigra pars reticulata stimulation were evaluated compared with standard subthalamic nucleus stimulation. The primary outcome measure was the change of a broad-scaled cumulative axial Unified Parkinson's Disease Rating Scale score (Scale II items 13-15, Scale III items 27-31) at '3-week follow-up'. Secondary outcome measures specifically addressed freezing of gait, balance, quality of life, non-motor symptoms and neuropsychiatric symptoms. For the primary outcome measure no statistically significant improvement was observed for combined subthalamic nucleus and substantia nigra pars reticulata stimulation at the '3-week follow-up'. The secondary endpoints, however, revealed that the combined stimulation of subthalamic nucleus and substantia nigra pars reticulata might specifically improve freezing of gait, whereas balance impairment remained unchanged. The combined stimulation of subthalamic nucleus and substantia nigra pars reticulata was safe, and of note, no clinically relevant neuropsychiatric adverse effect was observed. Patients treated with subthalamic nucleus and substantia nigra pars reticulata stimulation revealed no 'global' effect on axial motor domains. However, this study opens the perspective that concomittant stimulation of the substantia nigra pars reticulata possibly improves otherwise resistant freezing of gait and, therefore, highly warrants a subsequent phase III randomized controlled trial. [less ▲]

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See detailLong-term follow-up of subthalamic nucleus stimulation in glucocerebrosidase-associated Parkinson's disease.
Weiss, Daniel; Brockmann, Kathrin; Srulijes, Karin et al

in Journal of neurology (2012), 259(9), 1970-2

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See detailCombined STN/SNr-DBS for the treatment of refractory gait disturbances in Parkinson's disease: study protocol for a randomized controlled trial.
Weiss, Daniel; Wachter, Tobias; Meisner, Christoph et al

in Trials (2011), 12

BACKGROUND: Severe gait disturbances in idiopathic Parkinson's disease (PD) are observed in up to 80% of all patients in advanced disease stages with important impact on quality of life. There is an unmet ... [more ▼]

BACKGROUND: Severe gait disturbances in idiopathic Parkinson's disease (PD) are observed in up to 80% of all patients in advanced disease stages with important impact on quality of life. There is an unmet need for further symptomatic therapeutic strategies, particularly as gait disturbances generally respond unfavourably to dopaminergic medication and conventional deep brain stimulation of the subthalamic nucleus in advanced disease stages. Recent pathophysiological research pointed to nigro-pontine networks entrained to locomotor integration. Stimulation of the pedunculopontine nucleus is currently under investigation, however, hitherto remains controversial. The substantia nigra pars reticulata (SNr)--entrained into integrative locomotor networks--is pathologically overactive in PD. High-frequent stimulation of the substantia nigra pars reticulata preferentially modulated axial symptoms and therefore is suggested as a novel therapeutic candidate target for neuromodulation of refractory gait disturbances in PD. METHODS: 12 patients with idiopathic Parkinson's disease and refractory gait disturbances under best individual subthalamic nucleus stimulation and dopaminergic medication will be enroled into this double-blind 2 x 2 cross-over clinical trial. The treatment consists of two different stimulation settings using (i) conventional stimulation of the subthalamic nucleus [STNmono] and (ii) combined stimulation of distant electrode contacts located in the subthalamic nucleus and caudal border zone of STN and substantia nigra pars reticulata [STN+SNr]. The primary outcome measure is the change of the cumulative 'axial score' (UPDRS II items '13-15' and UPRDS III items '27-31') at three weeks of constant stimulation in either condition. Secondary outcome measures include specific scores on freezing of gait, balance function, quality of life, non-motor symptoms, and neuropsychiatric symptoms. The aim of the present trial is to investigate the efficacy and safety of a three week constant combined stimulation on [STN+SNr] compared to [STNmono]. The results will clarify, whether stimulation on nigral contacts additional to subthalamic stimulation will improve therapeutic response of otherwise refractory gait disturbances in PD. TRIAL REGISTRATION: The trial was registered with the clinical trials register of http://www.clinicaltrials.gov (NCT01355835). [less ▲]

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See detailCentral oscillators in a patient with neuropathic tremor: evidence from intraoperative local field potential recordings.
Weiss, Daniel; Govindan, Rathinaswamy B.; Rilk, Albrecht et al

in Movement disorders : official journal of the Movement Disorder Society (2011), 26(2), 323-7

Present pathophysiological concepts of neuropathic tremor assume mistimed and defective afferent input resulting in deregulation of cerebello-thalamo-cortical motor networks. Here, we provide direct ... [more ▼]

Present pathophysiological concepts of neuropathic tremor assume mistimed and defective afferent input resulting in deregulation of cerebello-thalamo-cortical motor networks. Here, we provide direct evidence of central tremor processing in a 76-year-old female who underwent bilateral deep brain stimulation of the ventral intermedial nucleus of the thalamus (Vim-DBS) because of neuropathic tremor associated with IgM paraproteinemia. Electrophysiological recordings of EEG and EMG were performed in three perioperative sessions: (1) preoperatively, (2) intraoperatively, and (3) 4 days after surgery in both rest and postural tremor conditions. Tremor-related synchronization (coherence) between motor cortex (M1) and muscles (M. extensor digitorum, M. flexor digitorum) was assessed, and additional intraoperative local field potential (LFP) recordings from Vim allowed comprehensive coherence mapping in thalamo-cortico-muscular networks. Directionality of information flow was determined by directed transfer function (DTF) and phase analyses. Stimulation effects on tremor and corticomuscular coherence were assessed and the patient was followed for 12 months on clinical outcome measures (Tremor Rating Scale, CADET-Score). Vim-DBS reduced tremor (59%) and improved motor functionality in daily activities (31%, CADET-A) after 12 months. Intraoperative recordings demonstrated significant coherence in the tremor frequency (4 Hz) between M1 and contralateral muscle, Vim and ipsilateral M1, Vim and contralateral muscle, but not between Vim and contralateral M1. Information flow was directed from M1 to Vim and bidirectional between M1 and muscle and between Vim and muscle, respectively. Corticomuscular coherence at tremor frequency was completely suppressed by Vim-DBS. Our case study demonstrates central oscillators underlying neuropathic tremor and implies a strong pathophysiological rationale for Vim-DBS. [less ▲]

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See detailCombined stimulation of the substantia nigra pars reticulata and the subthalamic nucleus is effective in hypokinetic gait disturbance in Parkinson's disease.
Weiss, Daniel; Breit, Sorin; Wachter, Tobias et al

in Journal of neurology (2011), 258(6), 1183-5

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See detailInvoluntary eyelid closure after STN-DBS: evidence for different pathophysiological entities.
Weiss, Daniel; Wachter, Tobias; Breit, Sorin et al

in Journal of neurology, neurosurgery, and psychiatry (2010), 81(9), 1002-7

OBJECTIVE: Involuntary eyelid closure (IEC) may occur after deep brain stimulation of the subthalamic nucleus (STN-DBS) in Parkinson's disease (PD) and is often categorised as apraxia of lid opening (ALO ... [more ▼]

OBJECTIVE: Involuntary eyelid closure (IEC) may occur after deep brain stimulation of the subthalamic nucleus (STN-DBS) in Parkinson's disease (PD) and is often categorised as apraxia of lid opening (ALO), albeit the appropriateness of this term is under debate. To gain insight into the hitherto undefined pathophysiology of IEC after STN-DBS, we performed a comprehensive clinical and electrophysiological characterisation of lid function in a total of six PD patients. METHODS: The study was carried out in six PD patients who developed IEC after STN-DBS. They underwent neurological examination and electromyography recording of activity in the orbicularis oculi muscle (OO) upon varying stimulation patterns. Intraoperative studies were performed in one patient. RESULTS: Increasing STN-DBS intensity induced IEC in four patients, whereas it improved the condition in two. Needle EMG showed tonic hyperactivity of the OO in STN-DBS induced IEC, while variable patterns of OO activity (irregular and tonic) were seen in patients with STN-DBS-relieved IEC. Intraoperative analysis in one patient showed evidence for IEC being induced by activation of corticobulbar fibres. CONCLUSIONS: We identified two groups of IEC after STN-DBS based on clinical and EMG patterns: (1) STN-DBS induced IEC associated with tonic OO overactivity and (2) STN-DBS relieved IEC presenting with variable EMG patterns. Our findings provide relevant information on pathophysiology of STN-DBS related IEC and implications for its therapeutic management. [less ▲]

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See detailSevere muscular fasciculations as an uncommon side-effect due to microdefect of an extension wire in deep brain stimulation.
Wachter, Tobias; Weiss, Daniel; Breit, Sorin et al

in Movement disorders : official journal of the Movement Disorder Society (2009), 24(14), 2161-2

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