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Introduction
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August 2017 - present
September 2000 - July 2006
November 2015 - June 2016
Education
October 2010 - September 2012
September 2000 - July 2006
Publications
Publications (64)
Comparatively high excitability of myelinated fibers suggests that they represent a major mediator of deep brain stimulation effects. Such effects can be modeled using different levels of abstraction, ranging from simple electric field estimates to complex multicompartment axon models. In this study, we explore three approaches to estimate axonal a...
Deep brain stimulation is an efficacious treatment for dystonia. While the internal pallidum serves as the primary target, recently, stimulation of the subthalamic nucleus (STN) has been investigated. However, optimal targeting within this structure and its surroundings have not been studied in depth. Indeed, historical targets that have been used...
Gilles de la Tourette Syndrome (GTS) is a chronic tic disorder, characterized by unwanted motor actions and vocalizations. While brain stimulation techniques show promise in reducing tic severity, optimal target networks are not well-defined. Here, we leverage datasets from two independent deep brain stimulation (DBS) cohorts and a cohort of tic-in...
Up-to-date estimates of stroke burden and attributable risks and their trends at global, regional, and national levels are essential for evidence-based health care, prevention, and resource allocation planning. We aimed to provide such estimates for the period 1990–2021. We estimated incidence, prevalence, death, and disability-adjusted life-year (...
Background: Up-to-date estimates of stroke burden and attributable risks and their trends at global, regional, and national levels are essential for evidence-based health care, prevention, and resource allocation planning. We aimed to provide such estimates for the period 1990–2021.
Methods: We estimated incidence, prevalence, death, and disabilit...
Background
Segmented electrodes for deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson’s disease (PD) enable directional current steering leading to expanded programming options.
Objective
This retrospective study covering a longitudinal period of up to 7 years compares the efficacy of segmented and non-segmented leads in m...
Objective: Dyskinetic cerebral palsy (DCP) encompasses a group of predominantly perinatally acquired complex motor disorders that present with dystonia and/or choreoathetosis and are frequently associated with brain lesions in neuroimaging. Recently, lesion network mapping provided a tool to redefine neurological disorders as circuitopathies. In th...
Background
Postoperative delirium (POD) is a serious complication following deep brain stimulation (DBS) but only received little attention. Its main risk factors are higher age and preoperative cognitive deficits. These are also main risk factors for long-term cognitive decline after DBS in Parkinson’s disease (PD).
Objective
To identify risk fac...
Thalamic aphasia results from focal thalamic lesions that cause dysfunction of remote but functionally connected cortical areas due to language network perturbation. However, specific local and network-level neural substrates of thalamic aphasia remain incompletely understood. Using lesion symptom mapping, we demonstrate that lesions in the left ve...
Deep brain stimulation is a viable and efficacious treatment option for dystonia. While the internal pallidum serves as the primary target, more recently, stimulation of the subthalamic nucleus (STN) has been investigated. However, optimal targeting within this structure and its complex surroundings have not been studied in depth. Indeed, multiple...
Background
Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensiv...
Gilles de la Tourette Syndrome (GTS) is the most severe form of chronic tic disorders, characterized by uncontrollable motor actions and vocalizations. While brain stimulation techniques show promise in reducing tic severity, optimal target networks are not well-defined. Here, we leveraged datasets from two independent deep brain stimulation (DBS)...
Oculogyric crises are acute episodes of sustained, typically upward, conjugate deviation of the eyes. Oculogyric crises usually occur as the result of acute D2-dopamine receptor blockade, but the brain areas causally involved in generating this symptom remain elusive. Here, we used data from 14 previously reported cases of lesion-induced oculogyric...
Background
Additional stimulation of the substantia nigra (SNr) has been proposed to target axial symptoms and gait impairment in patients with Parkinson’s disease (PD).
Objective
This study aimed to characterize effects of combined deep brain stimulation (DBS) of the subthalamic nucleus (STN) and SNr on gait performance in PD and to map stimulati...
Background
Cerebellar mutism syndrome (CMS) is a common and debilitating complication of posterior fossa tumor surgery in children. Affected children exhibit communication and social impairments that overlap phenomenologically with subsets of deficits exhibited by children with Autism spectrum disorder (ASD). Although both CMS and ASD are thought t...
Introduction:
Deep brain stimulation (DBS) is an established treatment in patients of various ages with pharmaco-resistant neurological disorders. Surgical targeting and postoperative programming of DBS depend on the spatial location of the stimulating electrodes in relation to the surrounding anatomical structures, and on electrode connectivity t...
Tics are sudden stereotyped movements or vocalizations. Cases of lesion-induced tics are invaluable, allowing for causal links between symptoms and brain structures. While a lesion network for tics has recently been identified, the degree to which this network translates to Tourette syndrome has not been fully elucidated. This is important given th...
Introduction
Deep brain stimulation (DBS) is an established treatment in patients with pharmaco-resistant neurological disorders of different ages. Surgical targeting and postoperative programming of DBS depend on the spatial location of the stimulating electrodes in relation to the surrounding anatomical structures and on electrode connectivity to...
Every decision that we make involves a conflict between exploiting our current knowledge of an action's value or exploring alternative courses of action that might lead to a better, or worse outcome. The sub-cortical nuclei that make up the basal ganglia have been proposed as a neural circuit that may contribute to resolving this explore-exploit 'd...
Background:
Despite increased recognition of cognitive impairment in Multiple System Atrophy (MSA), its neuroanatomical correlates are not well defined. We aimed to explore cognitive profiles in MSA with predominant parkinsonism (MSA-P) and Parkinson's disease (PD) and their relationship to frontostriatal structural and metabolic changes.
Methods...
Background:
Subthalamic nucleus (STN) beta (13 - 35 Hz) activity is a biomarker reflecting motor state in Parkinson's disease (PD). Adaptive deep brain stimulation (DBS) aims to use beta activity for therapeutic adjustments, but many aspects of beta activity in real-life situations are unknown.
Objective:
The aim was to investigate Christmas-rel...
Following its introduction in 2014 and with support of a broad international community, the open-source toolbox Lead-DBS has evolved into a comprehensive neuroimaging platform dedicated to localizing, reconstructing, and visualizing electrodes implanted in the human brain, in the context of deep brain stimulation (DBS) and epilepsy monitoring. Expa...
Background
Gait disturbances are frequent side effects related to chronic thalamic deep brain stimulation (DBS) that may persist beyond cessation of stimulation.
Objective
We investigate the temporal dynamics and clinical effects of an overnight unilateral withdrawal of DBS on gait disturbances.
Methods
10 essential tremor (ET) patients with gait...
Current efforts to optimize subthalamic deep brain stimulation in Parkinson's disease patients aim to harness local oscillatory activity in the beta frequency range (13–35 Hz) as a feedback-signal for demand-based adaptive stimulation paradigms. A high prevalence of beta peak activity is prerequisite for this approach to become routine clinical pra...
Introduction: Tremor is defined as an involuntary, rhythmic oscillatory movement of a body part and represents one of the most common symptoms in movement disorders, existing across several diseases. Particularly, in advanced states of tremor-related diseases such as Parkinson’s disease (PD) and Essential tremor syndrome (ET), response to pharmacot...
Every decision that we make involves a conflict between exploiting our current knowledge of an action’s value or exploring alternative courses of action that might lead to a better, or worse outcome. The sub-cortical nuclei that make up the basal ganglia have been proposed as a neural circuit that may contribute to resolving this explore-exploit ‘d...
Dystonia is a debilitating disease with few treatment options. One effective option is deep brain stimulation (DBS) to the internal pallidum. While cervical and generalized forms of isolated dystonia have been targeted with a common approach to the posterior third of the nucleus, large-scale investigations regarding optimal stimulation sites and po...
Adaptive deep brain stimulation (aDBS) is a promising concept for feedback-based neurostimulation, with the potential of clinical implementation with the sensing-enabled Percept neurostimulator. We aim to characterize chronic electrophysiological activity during stimulation and to validate beta-band activity as a biomarker for bradykinesia. Subthal...
Background:
Subthalamic nucleus deep brain stimulation (STN-DBS) effectively treats motor symptoms and quality of life (QoL) of advanced and fluctuating early Parkinson's disease. Little is known about the relation between electrode position and changes in symptom control and ultimately QoL.
Objectives:
The relation between the stimulated part o...
Objective:
To obtain individual clinical and neuroimaging data of patients undergoing Deep Brain Stimulation for essential tremor from five different European centers to identify predictors of outcome and to identify an optimal stimulation site.
Methods:
We analysed retrospectively baseline covariates, pre- and postoperative clinical tremor scor...
Objective:
With a growing appreciation for interindividual anatomical variability and patient-specific brain connectivity, advanced imaging sequences offer the opportunity to directly visualize anatomical targets for deep brain stimulation (DBS). The lack of quantitative evidence demonstrating their clinical utility, however, has hindered their br...
Brain lesions are a rare cause of tic disorders. However, they can provide uniquely causal insights into tic pathophysiology and can also inform on possible neuromodulatory therapeutic targets. Based on a systematic literature review, we identified 22 cases of tics causally attributed to brain lesions and employed ‘lesion network mapping’ to interr...
Objective: With a growing appreciation for interindividual anatomical variability and patient-specific brain connectivity, advanced imaging sequences offer the opportunity to directly visualize anatomical targets for deep brain stimulation (DBS). The lack of quantitative evidence demonstrating their clinical utility, however, has hindered their bro...
The subthalamic nucleus and internal pallidum are main target sites for deep brain stimulation in Parkinson’s disease. Multiple trials that investigated subthalamic versus pallidal stimulation were unable to settle on a definitive optimal target between the two. One reason could be that the effect is mediated via a common functional network.
To tes...
Dystonia is a debilitating disease with few conservative treatment options but many types of isolated dystonia can be effectively treated using deep brain stimulation (DBS) to the internal pallidum.
While cervical and generalized forms of isolated dystonia have been targeted with a common approach to the posterior third of the nucleus, large-scale...
Introduction:
Deep brain stimulation (DBS) is a highly efficacious treatment for essential tremor (ET). Still, the optimal anatomical target in the (sub)thalamic area is a matter of debate. The aim of this study was to determine the optimal target of DBS for ET regarding beneficial clinical outcome and impact on activities of daily living as well...
Background: Multiple deep brain stimulation (DBS) targets have been proposed for treating intractable obsessive-compulsive disorder (OCD). Here, we investigated whether stimulation effects of different target sites would be mediated by one common or several segregated functional brain networks.
Methods: Seeding from active electrodes of four patien...
The subthalamic nucleus and internal pallidum are main target sites for deep brain stimulation in Parkinson's disease. Multiple trials that investigated subthalamic versus pallidal stimulation were unable to settle on a definitive optimal target between the two. One reason could be that the effect is mediated via a common network. To test this hypo...
Treating brain disorders with the aim of modulating brain connections or networks has been a concept since before 1900. However, with the introduction of the human connectome in 2005, a more formal way of analyzing whole-brain connectivity measures was introduced. Shortly after, the concept of connectomic surgery was proposed, harnessing the power...
Background
In addition to the typical motor symptoms, a majority of patients suffering from Parkinson’s disease experience language impairments. Deep Brain Stimulation of the subthalamic nucleus robustly reduces motor dysfunction, but its impact on language skills remains ambiguous.
Method
To elucidate the impact of subthalamic deep brain stimulat...
Multiple surgical targets for treating obsessive-compulsive disorder with deep brain stimulation (DBS) have been proposed. However, different targets may modulate the same neural network responsible for clinical improvement. We analyzed data from four cohorts of patients (N = 50) that underwent DBS to the anterior limb of the internal capsule (ALIC...
Objective
Phasic bursts of beta band synchronisation have been linked to motor impairment in Parkinson’s disease (PD). However, little is known about what terminates bursts.
Methods
We used the Hilbert–Huang transform to investigate beta bursts in the local field potential recorded from the subthalamic nucleus in nine patients with PD on and off l...
Cover image: Structural and functional connectivity profiles seeded from volume of tissue activated predict deep brain stimulation-induced improvement in patients with essential tremor. From Al-Fatly et al. Connectivity profile of thalamic deep brain stimulation to effectively treat essential tremor. Pp. 3086–3098.
Essential tremor is the most prevalent movement disorder and is often refractory to medical treatment. Deep brain stimulation offers a therapeutic approach that can efficiently control tremor symptoms. Several deep brain stimulation targets (ventral intermediate nucleus, zona incerta, posterior subthalamic area) have been discussed for tremor treat...
Essential tremor is the most prevalent movement disorder and is often refractory to medical treatment. Deep brain stimulation offers a therapeutic approach that can efficiently control tremor symptoms. Several deep brain stimulation targets (ventral intermediate nucleus, zona incerta, posterior subthalamic area) have been discussed for tremor treat...
Deep brain stimulation is a powerful neurostimulation technique that proved its efficacy in treating a group of neurological diseases. Several scientific works tried to understand the mechanism of action of deep brain stimulation. Wang et al (J Neurosci 38:4556-4568, 2018) demonstrated a new evidence on the role of inter-regional neuro-oscillatory...
Motor action is a complex process that requires interplay between different motor network structures. Sensorimotor integration is an important aspect of this interplay, which can be studied using short-afferent (SAI) and long-afferent (LAI) inhibition. Kinesthetic motor imagery (KI) is known to use the same machinery as real movement. However, how...
Guillain–Barré syndrome (GBS) is an acute peripheral neuropathy that develops as a result of post-infectious immune-mediated nerve injury. It can be classified into classic and variant GBS. Acute motor axonal neuropathy (AMAN) is a subtype of GBS with the key clinical features of pure motor weakness, areflexia, absence of sensory symptoms, and lack...
Questions
Questions (7)
Hi FSL users,
any hint on how to use FSL topup on two phase encoded DTI scan each with 63 directions and 1 b0, the data is actually from PPMI dataset (PD patients) and am trying to correct for susceptibility distortion using topup. I know it can be used for one DTI scan and 2 b0 but have no experience with two scans!
Thanks in advance
Bassam
Surgical lesioning, like thalamotomy, is usually targeted using AC-PC coordinates. Does anyone know of thalamotomy coordinates in MNI space?
What are the causes of the artefact appearing in the second image (attached) before the mep wave?
Before we didn't encounter such artefact (first image).
Some pitfalls which could be related to the condition:
1. We are not grounding our devices (like TMS, 1902 amplifier or 1401 console).
2. Paste used for emg recording appear to break the signal throughout recording procedures or sometimes we are getting flat line when we attach the electrodes to the subject from the beginning. We tried to use more soluble gel like EEG paste, we achieve some recording but the artefacts appear larger and might even hide the mep.
NB. MEP sometimes get distorted by this initial artefacts which is getting bigger and annoying even if we use the original paste. We have changed our location to another building when the problem appeared. The problem of flat line when attaching the electrodes was already there before our location change, and we used to change couples of electrode until we get some reponse which could be unstable during the recording procedure)
Looking forward to hearing some helpful answers!
How we could trigger TMS pulse using CED SIGNAL software after an interval from a tone produced by the computer soundcard or an external speaker, or after giving a visual cue? Do we need a special software? or we can simply make SIGNAL software to produce a sound from soundcard and then trigger the pulse?
I was thinking of recording SEPs in patients with movement disorders. We are using CED signal software in our lab to register MEPs. It has been stated on the software website that it can be used for SEPs recording, however I don't know what are the requirements? are there any specific scripts that we should enter? or it is a matter of simply setting a protocol with electrical stimulation coming from our digitimer stimulator and recording 500-1000 frame of seps from the scalp?
Is there a way of single pulse electrical stimulation through DBS electrodes after they have already attached to the pulse generator? or, the only way is to stimulate through the externalized electrode immediately after surgical operation in the period before the electrode will get attached to the pulse generator? are there any pulse generators capable of doing single pulse? Medtronic ones are able to produce 3Hz stimulation as the lowest stimulation frequency.
I know this might seem difficult in the sense of how to predict when the subject will start imagination, but: How can I trigger TMS stimulus with the beginning of the process of imagining a movement in order to secure effects on MEP outcome parameters changes? I heard that we can train the subject to imagine the movement when he will hear some kind of sound! When should I apply TMS pulse, at the beginning or during sustained state of the imagined movement?
