Intraoperative DBS targeting of the globus pallidus internus by using motor evoked potentials.

Objectives: Target localization for deep brain stimulation (DBS) is a crucial step that influences the clinical benefit of the DBS procedure together with the reduction of side effects. In this work, we address the feasibility of DBS target localization in the globus pallidus internus (GPi) aided by intraoperative motor evoked potentials (MEP) with emphasis on the reduction of capsular side effects.

Material And Methods: Micro-macroelectrode recordings were performed intraoperatively on 20 patients that underwent DBS treatment of the GPi (GPi-DBS).

The importance of pyramidal tract integrity for cortical plasticity and related functionality in patients with multiple sclerosis.

Background: Cortical plasticity induced by quadripulse stimulation (QPS) has been shown to correlate with cognitive functions in patients with relapsing-remitting multiple sclerosis (RRMS) and to not be reduced compared to healthy controls (HCs).

Objective: This study aimed to compare the degree of QPS-induced plasticity between different subtypes of multiple sclerosis (MS) and HCs and to investigate the association of the degree of plasticity with motor and cognitive functions. We expected lower levels of plasticity in patients with progressive MS (PMS) but not RRMS compared to HCs.

Long-term potentiation-like plasticity is retained during relapse in patients with Multiple Sclerosis.

Objective: To investigate the degree of synaptic plasticity in Multiple Sclerosis (MS) patients during acute relapses compared to stable MS patients and healthy controls (HCs) and to analyze its functional relevance.

Methods: Facilitatory quadripulse stimulation (QPS) was applied to the primary motor cortex in 18 acute relapsing and 18 stable MS patients, as well as 18 HCs. The degree of synaptic plasticity was measured by the change in motor evoked potential amplitude following QPS.

Anesthesia for deep brain stimulation system implantation: adapted protocol for awake and asleep surgery using microelectrode recordings.

Purpose: Deep brain stimulation (DBS), an effective treatment for movement disorders, usually involves lead implantation while the patient is awake and sedated. Recently, there has been interest in performing the procedure under general anesthesia (asleep). This report of a consecutive cohort of DBS patients describes anesthesia protocols for both awake and asleep procedures.

The degree of cortical plasticity correlates with cognitive performance in patients with Multiple Sclerosis.

Background: Cortical reorganization and plasticity may compensate for structural damage in Multiple Sclerosis (MS). It is important to establish sensitive methods to measure these compensatory mechanisms, as they may be of prognostic value.

Objective: To investigate the association between the degree of cortical plasticity and cognitive performance and to compare plasticity between MS patients and healthy controls (HCs).

Altered motor cortical plasticity in patients with hepatic encephalopathy: A paired associative stimulation study.

Objective: Hepatic encephalopathy (HE) is a potentially reversible brain dysfunction caused by liver failure. Altered synaptic plasticity is supposed to play a major role in the pathophysiology of HE. Here, we used paired associative stimulation with an inter-stimulus interval of 25 ms (PAS25), a transcranial magnetic stimulation (TMS) protocol, to test synaptic plasticity of the motor cortex in patients with manifest HE.

Directional Deep Brain Stimulation for Parkinson's Disease: Results of an International Crossover Study With Randomized, Double-Blind Primary Endpoint.

Objective: Published reports on directional deep brain stimulation (DBS) have been limited to small, single-center investigations. Therapeutic window (TW) is used to describe the range of stimulation amplitudes achieving symptom relief without side effects. This crossover study performed a randomized double-blind assessment of TW for directional and omnidirectional DBS in a large cohort of patients implanted with a DBS system in the subthalamic nucleus for Parkinson's disease.

Influence of High Pass Filter Settings on Motor Evoked Potentials.

Objective: Motor evoked potentials (MEP), obtained by transcranial magnetic stimulation (TMS) are a common tool in clinical research and diagnostic. Nevertheless, reports regarding the influence of filter settings on MEP are sparse. Here, we compared MEP amplitudes and signal to noise ratio (SNR) using multiple high pass filter (HPF) and notch filter settings.

Motor Evoked Potentials Improve Targeting in Deep Brain Stimulation Surgery.

Objectives: One of the main challenges posed by the surgical deep brain stimulation (DBS) procedure is the successful targeting of the structures of interest and avoidance of side effects, especially in asleep surgery. Here, intraoperative motor evoked potentials (MEPs) might serve as tool to identify the pyramidal tract. We hypothesized that intraoperative MEPs are useful to define the distance to the pyramidal tract and reduce the occurrence of postoperative capsular side effects.

[Deep brain stimulation for Parkinson's disease].

Deep brain stimulation is an established and evidence-based therapeutic option for the treatment of advanced Parkinson's disease. Main indication and inclusion criteria are the presence of idiopathic Parkinsonism with motor fluctuations and / or dyskinesias and / or with medication refractory tremor, a significant improvement of akinesia / rigidity in response to dopaminergic medication, the absence of relevant cognitive deficits and other significant comorbidities. DBS neurosurgery has a low risk of complications.

Impact of the number of conditioning pulses on motor cortex excitability: a transcranial magnetic stimulation study.

Conditioning transcranial magnetic stimulation (TMS) with subthreshold conditioning stimulus followed by supra-threshold test stimulus at inter-stimulus intervals (ISI) of 1-5 ms results in inhibition (SICI), while ISI at 10-15 ms results in facilitation (ICF). One concerning issue, applying ICF/SICI protocols on patients is the substantial protocol variability. Here, we hypothesized that increasing the number of CS could result in more robust ICF/SICI protocols.

Occipital repetitive transcranial magnetic stimulation does not affect multifocal visual evoked potentials.

Background: To identify mechanisms of cortical plasticity of the visual cortex and to quantify their significance, sensitive parameters are warranted. In this context, multifocal visual evoked potentials (mfVEPs) can make a valuable contribution as they are not associated with cancellation artifacts and include also the peripheral visual field.

Objective: To investigate if occipital repetitive transcranial magnetic stimulation (rTMS) can induce mfVEP changes.

Prolonged Neuropsychological Deficits, Central Nervous System Involvement, and Brain Stem Affection After COVID-19-A Case Series.

The affection of both the peripheral (PNS) and central nervous system (CNS) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been assumed to play a direct role in the respiratory failure of patients with Corona virus disease 2019 (COVID-19) through affection of medullary cardiorespiratory centers resulting in neurological complications and sequelae. We used a multimodal electrophysiological approach combined with neuropsychological investigations to study functional alteration of both the PNS and CNS in four patients with severe COVID-19. We found electrophysiological evidence for affection of both the PNS and CNS, and particularly affection of brain stem function.

Directional Deep Brain Stimulation of the Thalamic Ventral Intermediate Area for Essential Tremor Increases Therapeutic Window.

Objectives: Deep brain stimulation (DBS) of the posterior subthalamic area (PSA) and the ventral intermediate thalamic nucleus (VIM) is a well-established therapy for essential tremor (ET), but it is frequently associated with side effects like dysarthria or gait ataxia. Directional DBS (dDBS) may be a way to activate fiber tracts more selectively. Is dDBS for ET superior to omnidirectional DBS (oDBS) regarding therapeutic window and clinically as effective as oDBS?

Materials And Methods: Ten patients with ET treated with PSA/VIM-DBS were recruited.

Asleep Surgery May Improve the Therapeutic Window for Deep Brain Stimulation of the Subthalamic Nucleus.

Objective: The effect of anesthesia type in terms of asleep vs. awake deep brain stimulation (DBS) surgery on therapeutic window (TW) has not been investigated so far. The objective of the study was to investigate whether asleep DBS surgery of the subthalamic nucleus (STN) improves TW for both directional (dDBS) and omnidirectional (oDBS) stimulation in a large single-center population.

Effect of conditioning and test stimulus intensity on cortical excitability using triad-conditioning transcranial magnetic stimulation.

Cortical facilitation assessed with triad conditioning transcranial magnetic stimulation has been termed triad-conditioned facilitation (TCF). TCF has been supposed to reflect increased intracortical facilitation (ICF) at short interstimulus intervals (ISI) around 10 ms and an intrinsic rhythm of the motor cortex at longer ISI around 25 ms. To gain further insight into the pathophysiological mechanism of TCF, we systematically studied the effect of suprathreshold conditioning stimulus (CS) and test stimulus (TS) intensity on TCF.

Cerebellar Involvement in DYT-THAP1 Dystonia.

DYT-THAP1 dystonia is known to present a variety of clinical symptoms. To the best of our knowledge, this is the first case with DYT-THAP 1 dystonia and clinical signs of cerebellar involvement studied with transcranial magnetic stimulation in vivo. We report a case of a 51-year-old male DYT-THAP1 mutation carrier with dystonia, who additionally developed ataxia 1.

GABA-ergic tone hypothesis in hepatic encephalopathy - Revisited.

Objective: The GABA hypothesis of hepatic encephalopathy (HE) proposes an increased cerebral GABA-ergic tone in HE but has not been investigated in vivo in HE-patients yet. Cortical GABA-ergic and glutamatergic neurotransmission in HE-patients were evaluated using transcranial magnetic stimulation.

Methods: Twenty-one patients with HE grade 1 and 2 and age matched controls participated in the study.

Cerebellar inhibition in hepatic encephalopathy.

Objective: Previous animal work reported that hyperammonemia leads to opposing changes of GABAergic neurotransmission in terms of increase in the cerebellum and decrease in the cerebral cortex. In this study, we investigate GABAergic tone in the cerebellum in patients with hepatic encephalopathy (HE) at different stages of the disease and its relation to critical flicker frequency (CFF) and ataxia.

Methods: Cerebellar inhibition using transcranial magnetic stimulation was investigated in 15 patients with different stages of HE and 15 healthy controls.

An update on best practice of deep brain stimulation in Parkinson's disease.

During the last 30 years, deep brain stimulation (DBS) has evolved into the clinical standard of care as a highly effective treatment for advanced Parkinson's disease. Careful patient selection, an individualized anatomical target localization and meticulous evaluation of stimulation parameters for chronic DBS are crucial requirements to achieve optimal results. Current hardware-related advances allow for a more focused, individualized stimulation and hence may help to achieve optimal clinical results.

Less is more - Pulse width dependent therapeutic window in deep brain stimulation for essential tremor.

Background: Shorter pulse widths than conventional pulse width settings may lead to reduction of side effects and therefore be a valuable therapeutic option for deep brain stimulation (DBS) in patients with essential tremor (ET).

Objective: To compare the DBS effect of shorter pulse width at 40 μs (DBS-40 μs) to conventional pulse width at 60 μs (DBS-60 μs) on the therapeutic window in ET patients.

Methods: For this prospective, randomized, double-blind, crossover study 9 ET patients with chronic DBS of the ventral intermediate nucleus (VIM)/posterior subthalamic area (PSA) were recruited.