Michael Samuel's research while affiliated with King's College Hospital NHS Foundation Trust and other places
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Publications (95)
Subthalamic nucleus (STN) beta-triggered adaptive deep brain stimulation (ADBS) has been shown to provide clinical improvement comparable to conventional continuous DBS (CDBS) with less energy delivered to the brain and less stimulation induced side-effects. However, several questions remain unanswered. First, there is a normal physiological reduct...
Parkinson’s disease (PD) is a complex neurodegenerative disorder, leading to impairment of various neurological faculties, including motor, planning, cognitivity, and executive functions. Motor- and non-motor symptoms of the disease may intensify a patient’s restrictions to performing usual tasks of daily living, including driving. Deep Brain Stimu...
Subthalamic nucleus (STN) beta-triggered adaptive deep brain stimulation (ADBS) has been shown to provide clinical improvement comparable to conventional continuous DBS (CDBS) in people with Parkinson's disease (PD) with less energy delivered to the brain and less stimulation induced side-effects. However, several questions remain unanswered. First...
To identify predictors of 36-month follow-up quality of life (QoL) outcome after bilateral subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson’s disease (PD). In this ongoing, prospective, multicenter international study (Cologne, Manchester, London) including 73 patients undergoing STN-DBS, we assessed the following scales preoperati...
Device-aided therapies, including levodopa-carbidopa intestinal gel infusion, apomorphine subcutaneous infusion, and deep brain stimulation, are available in many countries for the management of the advanced stage of Parkinson’s disease (PD). Currently, selection of device-aided therapies is mainly focused on patients’ motor profile while non-motor...
Background
Fatigue is a common and disabling non-motor symptom (NMS) in Parkinson’s disease (PD) patients. However, the effect of subthalamic nucleus (STN) deep brain stimulation (DBS) on fatigue has not been widely studied.
Objective
To determine the effect of STN DBS on fatigue in PD patients, measured by the Non-motor symptoms scale (NMSS).
Me...
A 61-year-old man with no significant medical history developed fever, headache and mild shortness of breath. He tested positive for SARS-CoV-2 and self-isolated at home, not requiring hospital admission. One week after testing positive, he developed acute severe burning pain affecting his whole body, subsequently localised distally in the limbs. T...
IntroductionDystonic opisthotonus is defined as a backward arching of the neck and trunk, which ranges in severity from mild backward jerks to life-threatening prolonged severe muscular spasms. It can be associated with generalized dystonic syndromes or, rarely, present as a form of axial truncal dystonia. The etiologies vary from idiopathic, genet...
Introduction:
Deep brain stimulation (DBS) surgery is an established treatment for movement disorders. Advances in neuroimaging techniques have resulted in improved targeting accuracy that may improve clinical outcomes. This study aimed to evaluate the safety and feasibility of using the Medtronic O-arm device for the acquisition of intraoperative...
Objective: This study aimed to evaluate the safety and feasibility of using the Medtronic O-arm device for the acquisition of intraoperative stereotactic imaging, targeting, and localization of DBS electrodes compared with standard stereotactic MRI or CT. The outcomes evaluated included targeting accuracy, total surgical time, length of time of acq...
Beta oscillations are readily observed in motor cortex and the basal ganglia, but to which extent they are functionally relevant is unclear. To understand how activity transfer between different nodes of the cortico-basal ganglia network is affected by cortical beta oscillations in different behavioural conditions, we recorded local field potential...
Dystonia secondary to cerebral infarcts presents months to years after the initial insult, is usually unilateral and causes significant morbidity. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is established as the most frequent target in the management of the dystonic symptoms. We report our experience with subthalamic nucleus...
Background
Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and sleep symptoms in Parkinson’s disease (PD). However, the long-term effects of STN-DBS on sleep and its relationship with QoL outcome are unclear.Methods
In this prospective, observational, multicenter study including 73 PD patients undergoin...
Objective
To examine 36-month effects of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on non-motor symptoms (NMS) compared with standard-of-care medical treatment (MED) in Parkinson’s disease (PD).
Methods
Here we report the 36-month follow-up of a prospective, observational, controlled, international multicentre study of the NIL...
Objectives
Unilateral subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson's disease (PD) improves ipsilateral symptoms, but how this occurs is not well understood. We investigated whether unilateral STN DBS suppresses contralateral STN beta activity in the local field potential (LFP), since previous research has shown that activity...
Introduction: Deep brain stimulation (DBS) is an established treatment for movement disorders. We have previously shown that in our practice, the majority of adult patients prefer fixed-life implantable pulse generators (IPG), although rechargeable batteries are increasingly used. The aim of this study was to evaluate patients’ long-term satisfacti...
Beta power suppression in the basal ganglia is stronger during movements that require high force levels and high movement effort but it has been difficult to dissociate the two. We recorded scalp EEG and basal ganglia local field potentials in Parkinson's disease patients (11 STN, 7 GPi) ON and OFF dopaminergic medication while they performed a vis...
Introduction:
Deep brain stimulation (DBS) markedly improves motor function in advanced Parkinson's disease (PD), but its effect on sleep is less clear.
Patients and methods:
Forty PD patients who had subthalamic DBS (STN-DBS) were identified from an on-going non-motor naturalistic longitudinal study (NILS). All patients were followed up for at...
Objective:
Patients' expectations are considered to play an important role in STN DBS. We explored the relationship between expectations, satisfaction and outcome 6 years after surgery.
Methods:
15 patients with Parkinson disease (9 males, mean age 60.5 ± 6.4 years) undergoing STN DBS completed a modified PDQ-39 questionnaire (incorporating an a...
Background
Deep brain stimulation (DBS) is increasingly used to treat a wide variety of neurological and psychiatric disorders. Implantable pulse generators (implantable pulse generators/batteries) for DBS were originally only available as a nonrechargeable option. However, there is now a choice between fixed‐life and rechargeable batteries, with e...
Gait disturbances in Parkinson’s disease are commonly refractory to current treatment options and majorly impair patient’s quality of life. Auditory cues facilitate gait and prevent motor blocks. We investigated how neural dynamics in the human subthalamic nucleus of Parkinsons’s disease patients (14 male, 2 female) vary during stepping and whether...
Background
Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in Parkinson's disease (PD). Few studies have investigated the influence of the location of neurostimulation on NMS.
Objective
To investigate the impact of active contact location on NMS in STN-DBS in PD.
Methods
I...
Background:
Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in advanced Parkinson's disease (PD). However, considerable inter-individual variability has been observed for QoL outcome.
Hypothesis:
We hypothesized that demographic and preoperative NMS characteristics can pr...
Objective:
The optimal timing of subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) is a topic of ongoing debate. In patients with short disease duration an improvement of quality of life (QoL) has been demonstrated for patients aged younger than 61 years. However, this has not been systematically investigated in ol...
Objective:
The purpose of this study was to investigate how quality of life outcome after bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) depends on age.
Methods:
In this prospective, open-label, multicenter study including 120 PD patients undergoing bilateral STN-DBS, we investigated the PDQuestionna...
Motor imagery involves cortical networks similar to those activated by real movements, but the extent to which the basal ganglia are recruited is not yet clear. Gamma and beta oscillations in the subthalamic nucleus (STN) vary with the effort of sustained muscle activity. We recorded local field potentials in Parkinson's disease patients and invest...
Objectives:
Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the...
Deep brain stimulation (DBS) is a well-established treatment modality for patients with Parkinson’s disease (PD), especially in those with motor complications such as fluctuations and dyskinesias. There is good long-term evidence confirming the efficacy of DBS in improving motor symptoms and quality of life in advanced PD. A recent study has additi...
In their JNNP paper, Gooneratna et al 1 review long-term studies of three surgical therapies for pharmacoresistant focal epilepsy: vagal nerve stimulation, which provides the most evidence, anterior thalamic nucleus deep brain stimulation (ANT DBS) and cortical responsive stimulation (CRS). Written for the generalist, the review describes the three...
Background:
Deep brain stimulation (DBS) within or adjacent to the subthalamic nucleus (STN) currently represents the most common stereotactic procedure performed for Parkinson's disease. Better STN imaging is often regarded as a requirement for improving stereotactic targeting. But, remarkably enough, it is unclear whether there is a consensus ab...
Background
Parkinson’s disease is a chronic degenerative movement disorder. The mainstay of treatment is medical. In certain patients Deep Brain Stimulation (DBS) may be offered. However, DBS has been associated with post-operative neuropsychology changes, especially in verbal memory.
Objectives
Firstly, to determine if pre-surgical thalamic and h...
Linear modelling of change in test score and clinical variables.
Table to show the results of linear modelling investigating the relationship of test score change with age, duration of symptoms and UPDRS Part III score. The absolute test score change in the test of interest was used as the outcome variable. Age, duration of symptoms or UPDRS Part I...
Linear modelling of pre-surgical test score and volumetric and clinical variables.
Table to show linear modelling of pre-surgical test scores to structural volumetric data and clinical variables. The outcome variable was the pre-surgical test score of interest. The structural volume or clinical variable of interest was used as the predictor. No sta...
Background:
Postoperative imaging is essential for verifying electrode location in patients undergoing deep brain stimulation (DBS). MRI offers better visualisation of brain targets, but concerns about adverse events have limited its use. Preoperative stereotactic MRI fused with a postoperative stereotactic CT, demonstrating the electrode position...
Motor complications in Parkinson’s disease (PD) result from the short half-life and irregular plasma fluctuations of oral levodopa. When strategies of providing more continuous dopaminergic stimulation by adjusting oral medication fail, patients may be candidates for one of three device-aided therapies: deep brain stimulation (DBS), continuous subc...
Background
Impulse‐control behaviors (ICBs) are increasingly recognized in Parkinson's disease (PD) as drug‐related effects of dopaminergic mediation that occur in 15% to 35% of patients with PD. The authors describe the design and evaluation of a new, clinician‐rated severity scale for the assessment of syndromal and subsyndromal forms of impulse‐...
Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease...
Background
STN-DBS is well established to improve motor symptoms and quality of life in patients with PD. While non-motor symptoms are crucial for quality of life in these patients, only neuropsychiatric and neuropsychological symptoms have been systematically studied in a longitudinal design so far. However, these are only a part of the non-motor...
In Parkinson disease (PD), compulsive behaviors, cumulatively termed impulse control disorders (ICDs), are known to develop in patients receiving dopamine-replacement therapy with oral dopamine agonists being particularly implicated. However, the effects of continuous infusion therapies have not been explored.
We report data from a 3-year clinical...
High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is now ending its second decade as an established modality for treating Parkinson's disease (PD). Knowledge of the pathophysiology of PD and clinical applications for STN DBS is burgeoning. Despite this, the mechanism of how STN DBS works remains an enigma. Furthermore, mo...
Impulse control disorders in Parkinson's disease are a group of impulsive behaviors most often associated with dopaminergic treatment. Presently, there is a lack of high quality evidence available to guide their management. This manuscript reviews current management strategies, before concentrating on the concept of dopamine agonist withdrawal synd...
Background
Limited trial evidence suggests that cognitive-behavioral therapy (CBT) may be effective in managing impulse control behavior (ICBs) in Parkinson's disease.AimsTo examine predictors of outcome in trial, participants (N = 42) receiving treatment immediately or after a waiting time.Methods
Dependent variables were Clinical Global Impressio...
Subcutaneous apomorphine infusion (Apo) and intrajejunal levodopa infusion (IJLI) are two treatment options for patients with advanced Parkinson's disease (PD) and refractory motor complications, with varying cost of treatment. There are no multicenter studies comparing the effects of the two strategies. This open-label, prospective, observational,...
Myoclonus dystonia syndrome (MDS) is a young-onset movement disorder. A proportion of cases are due to mutations in the maternally imprinted SGCE gene. We assembled the largest cohort of MDS patients to date, and determined the frequency and type of SGCE mutations. The aim was to establish the motor phenotype in mutation carriers and utility of cur...
Levodopa has been effective against the motor features of Parkinson's disease for several decades. However, it is observed that long-term treatment with levodopa can be complicated by the development of various types of response fluctuations as well as dyskinesias. The latter, once established, tend to remain persistent although they can be reduced...
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established therapy for patients with Parkinson's disease (PD), especially those with advanced motor complications. The effect of STN DBS on non motor symptoms (NMS) of PD is less well studied. In this article, we review the pertinent literature on the impact of STN DBS on NMS...
In last month's edition of BJHM, Sauerbier and Chaudhuri (2014) described a variety of symptoms in Parkinson's disease. Traditionally, Parkinson's disease has been thought of as a movement (motor) disorder, but these non-motor symptoms are additional to motor symptoms, and so widen the spectrum of the phenotypes of the illness.
BACKGROUND AND PURPOSEMRI studies in Parkinson's Disease have shown volumetric reductions of subcortical structures such as the thalamus, putamen, globus pallidus, and caudate nucleus. However, there are no studies which look at the relationship between subcortical structure volumes and clinical variables, such as age and motor severity scores. MET...
Objectives
Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established treatment for advanced Parkinson’s disease. However, some patients feel less satisfied with the outcome of surgery. We sought to study the relationship between expectations, satisfaction and outcome in STN DBS for Parkinson’s disease.
Methods
22 consecutive patient...
What do patients expect from a treatment? A patient-centred approach to treatment is becoming necessary given the choices for invasive treatments for Parkinson's disease. Patient's perceptions of severity and expectations from complex therapies have not been studied. We describe the rationale and concept of developing a Patient-Reported Outcome (PR...
Background:
Dopaminergic drugs are the primary risk factor for Impulse Control Behaviours (ICB) in Parkinson's disease (PD), others being early-onset disease and gender.
Objective:
This report further explores ICB symptom relationships with motor and mood phenotypes, the complex relationship with dopaminergic medications, and hypothesizes a mode...
The beneficial effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) for the motor symptoms in advanced Parkinson's disease (PD) are well established. Early in PD, mild cognitive impairment is present in a proportion of patients. Hence, it can also be present in PD patients considered for DBS. The potential impact of even a modes...
Myoclonus Dystonia Syndrome (MDS) is a childhood onset, alcohol responsive movement disorder caused by mutations in the SGCE gene in a proportion of cases. Single family and case series have suggested co-morbid psychiatric disease but have not compared cases to a control group.
To establish a cohort of MDS patients with SGCE mutations and a control...
Deep brain stimulation (DBS) has emerged as an effective neurosurgical tool to treat a range of conditions. Its use in movement disorders such as Parkinson's disease, tremor and dystonia is now well established and has been approved by the National Institute of Clinical Excellence (NICE). The NICE does, however, emphasise the need for a multidiscip...
The aim of this study was to investigate the clinical, neuropsychological, and self-awareness correlates of impulse-control disorder (ICD) in a group of 17 Parkinson's disease (PD) subjects with an active ICD and a comparison group of 17 PD subjects without ICD. Self-awareness was assessed with the Beck Cognitive Insight Scale and patient-caregiver...
Myoclonus dystonia syndrome is a childhood onset hyperkinetic movement disorder characterized by predominant alcohol responsive upper body myoclonus and dystonia. A proportion of cases are due to mutations in the maternally imprinted SGCE gene. Previous studies have suggested that patients with SGCE mutations may have an increased rate of psychiatr...
Objective:
To test the effects of a novel cognitive-behavioral therapy (CBT)-based intervention delivered by a nurse therapist to patients with Parkinson disease (PD) with clinically significant impulse control behaviors (ICB).
Methods:
This was a randomized controlled trial comparing up to 12 sessions of a CBT-based intervention compared to a w...
Motor complications in Parkinson's disease (PD) result from the short half-life and irregular plasma fluctuations of oral levodopa. When strategies of providing more continuous dopaminergic stimulation by adjusting oral medication fail, patients may be candidates for one of three device-aided therapies: deep brain stimulation (DBS), continuous subc...
Deep brain stimulation (DBS) is a well-established therapy for patients with advanced Parkinson's disease (PD) with clear benefits on many of the motor symptoms. The effects of DBS on the nonmotor symptoms are less well examined. Emergence of tools to measure the nonmotor burden in PD is now allowing a more objective assessment of impact of DBS on...
Cognitive impairment is a recognized feature of Parkinson's disease (PD), which, even if mild, can impact some aspects of a patient's ability to deal with everyday life. The current study examined the ability to solve social problems in three groups of participants: PD patients with mild cognitive impairment (PD-MCI); PD patients with no evidence o...
Deep brain stimulation hardware is constantly advancing. The last few years have seen the introduction of rechargeable cell technology into the implanted pulse generator design, allowing for longer battery life and fewer replacement operations. The Medtronic® system requires an additional pocket adaptor when revising a non-rechargeable battery such...
Parkinson's disease is heterogeneous, both in terms of motor symptoms and mood. Identifying associations between phenotypic variants of motor and mood subtypes may provide clues to understand mechanisms underlying mood disorder and symptoms in Parkinson's disease. A total of 513 patients were assessed using the Hospital Anxiety and Depression Scale...
Evidence suggests that both motor and nonmotor symptoms contribute to health status in Parkinson's disease. Less clear is how much change in health status can be expected if these clinical variables change. In addition, anxiety, separate from depression, has rarely been examined as a predictor of health status. We used hierarchical multiple regress...
Cognitive deficits increase with disease duration in Parkinson’s disease (PD). Patients referred for deep brain stimulation (DBS) usually have advanced disease, and some cognitive deficits are expected pre-operatively. Improved prediction of cognitive risk is one goal for DBS services. As a first step, the detailed cognitive profiles of patients re...
Objective
The availability of the newly-validated non-motor symptoms scale (NMSS) for Parkinson’s disease (PD) allowed an exploration of the effect of STN-DBS on non-motor symptoms (NMS).Background
In PD, NMS can dominate the clinical picture and cause disability. In PD, motor symptoms may warrant DBS, but NMS may co-exist. Unlike motor symptoms, t...
Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting.
MR imag...
