Association of Circumscribed Subcortical Gray and White Matter Lesions With Apraxic Deficits in Patients With Left Hemisphere Stroke.

BACKGROUND AND OBJECTIVES: Apraxia is commonly attributed to left hemisphere (LH) lesions of the cortical fronto-temporo-parietal praxis networks or white matter lesions causing disconnections between cortical nodes. By contrast, the contribution of lesions to the subcortical gray matter, that is, basal ganglia or thalamus, to apraxic deficits remains controversial. Here, we investigate whether damage to these subcortical gray matter structures (i.e., caudate nucleus, putamen, globus pallidus, and thalamus) or the adjacent white matter tracts was associated with apraxic deficits. METHODS: We identified patients with distinct subcortical lesions with and without apraxia from a large retrospective sample of subacute LH ischemic stroke patients (n = 194). To test which subcortical structures (caudate nucleus, putamen, globus pallidus, thalamus, and adjacent white matter tracts), when lesioned, contributed to apraxic deficits, we statistically compared the proportion of lesioned voxels within subcortical gray and white matter structures between the apraxic and nonapraxic patients. RESULTS: Of the 194 stroke patients screened, 39 (median age = 65 years, range 30-82 years; median time poststroke at the apraxia assessment = 7 days, range 1-44 days) had lesions confined to subcortical regions (gray and white matter). Eleven patients showed apraxic deficits when imitating gestures or pantomiming object use. Region-wise statistical lesion comparison (controlled for lesion size) revealed a more significant proportion of damage ('lesion load') in the caudate nucleus in apraxic stroke patients (mean difference = 6.9%, 95% CI 0.4-13.3, p = 0.038, η p 2 = 0.11). By contrast, apraxic patients had lower lesion load in the globus pallidus (mean difference = 9.9%, 95% CI 0.1-19.8, p = 0.048, η p 2 = 0.10), whereas the lesion load in other subcortical structures (putamen, thalamus, and adjacent white matter tracts) did not differ significantly between the apraxic and nonapraxic patients. DISCUSSION: These findings provide new insights into the subcortical anatomy of apraxia after LH stroke, suggesting a specific contribution of caudate nucleus lesions to apraxic deficits.

Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke.

BACKGROUND: Previous studies on left hemisphere (LH) stroke patients reported effector-specific (hand, fingers, bucco-facial) differences in imitation performance. Furthermore, imitation performance differed between meaningless (ML) and meaningful (MF) gestures. Recent work suggests that a gesture's meaning impacts the body-part specificity of gesture imitation. METHODS: We tested the hypothesis that the gesture's meaning (ML vs MF) affects the lesion correlates of effector-specific imitation deficits (here: bucco-facial vs arm/hand gestures) using behavioural data and support vector regression-based lesion-symptom mapping (SVR-LSM) in a large sample of 194 sub-acute LH stroke patients. RESULTS: Behavioural data revealed a significant interaction between the effector used for imitation and the meaning of the imitated gesture. SVR-LSM analyses revealed shared lesion correlates for impaired imitation independent of effector or gesture meaning in the left supramarginal (SMG) and superior temporal gyri (STG). Besides, within the territory of the left middle cerebral artery, impaired imitation of bucco-facial gestures was associated with more anterior lesions, while arm/hand imitation deficits were associated with more posterior lesions. MF gestures were specifically associated with lesions in the left inferior frontal gyrus and the left insular region. Notably, an interaction of effector-specificity and gesture meaning was also present at the lesion level: A more pronounced difference in imitation performance between the effectors for ML (versus MF) gestures was associated with left-hemispheric lesions in the STG, SMG, putamen, precentral gyrus and white matter tracts. CONCLUSION: The current behavioural data show that ML gestures are particularly sensitive in assessing effector-specific imitation deficits in LH stroke patients. Moreover, a gesture's meaning modulated the effector-specific lesion correlates of bucco-facial and arm/hand gesture imitation. Hence, it is crucial to consider gesture meaning in apraxia assessments.

Different facets of object-use pantomime: online TMS evidence on the role of the supramarginal gyrus.

BACKGROUND: A key question in apraxia research is which specific cognitive processes in pantomiming the parietal cortex supports. The manipulation-based hypothesis and the technical-reasoning hypothesis ascribe different roles to the inferior parietal lobule (IPL). OBJECTIVE: We elucidated the role of the left supramarginal gyrus (SMG, i.e., part of IPL) during the processing of different aspects of object-use pantomime. METHODS: Thirty-one healthy participants matched pantomimes with the corresponding object (PO) or the corresponding situation (PS) during online transcranial magnetic stimulation (TMS) interference applied to left SMG, compared to a control stimulation (vertex). Notably, the object corresponding to a given pantomime was explicitly not shown in the PS task, excluding the possibility to analyse a physical object. Matching an object to the corresponding situation (OS) served as a control task. RESULTS: TMS interference with left SMG significantly affected response times for both investigated pantomime tasks (PO and PS); the effect in the PO task significantly correlated with that in the PS task. As expected, no TMS effect was observed in the control task (OS). CONCLUSION: Left SMG does not only establish a link between pantomime and a manipulable object but is also involved in pantomime recognition and comprehension. That TMS interfered with both pantomime tasks supports the manipulation-based hypothesis, assuming that the IPL recruits stored gesture engrams whenever pantomimes are processed.

Successful treatment of thromboses of major arteries after ChAdOx1 nCov-19 vaccination.

The ChAdOx1 nCoV-19 adenoviral vector vaccine to prevent contracting Covid-19 caused by infection with SARS-CoV-2 has been associated with vaccine-induced immune thrombotic thrombocytopenia (VITT) primarily leading to venous thromboses. Here, we report two cases of major arterial occlusions after ChAdOx1 nCov-19 vaccination, comprising a 42-year-old woman with thrombotic occlusion of the left carotid artery, and a 62-year-old man with occlusion of distal aorta and iliac arteries. Both were successfully treated with intravenous immunoglobulins and non-heparin anticoagulant agents leading to a beneficial short-term outcome of 6 weeks in case 1 and four months in case 2.

Neurological symptoms and complications in predominantly hospitalized COVID-19 patients: Results of the European multinational Lean European Open Survey on SARS-Infected Patients (LEOSS).

BACKGROUND AND PURPOSE: During acute coronavirus disease 2019 (COVID-19) infection, neurological signs, symptoms and complications occur. We aimed to assess their clinical relevance by evaluating real-world data from a multinational registry. METHODS: We analyzed COVID-19 patients from 127 centers, diagnosed between January 2020 and February 2021, and registered in the European multinational LEOSS (Lean European Open Survey on SARS-Infected Patients) registry. The effects of prior neurological diseases and the effect of neurological symptoms on outcome were studied using multivariate logistic regression. RESULTS: A total of 6537 COVID-19 patients (97.7% PCR-confirmed) were analyzed, of whom 92.1% were hospitalized and 14.7% died. Commonly, excessive tiredness (28.0%), headache (18.5%), nausea/emesis (16.6%), muscular weakness (17.0%), impaired sense of smell (9.0%) and taste (12.8%), and delirium (6.7%) were reported. In patients with a complicated or critical disease course (53%) the most frequent neurological complications were ischemic stroke (1.0%) and intracerebral bleeding (ICB; 2.2%). ICB peaked in the critical disease phase (5%) and was associated with the administration of anticoagulation and extracorporeal membrane oxygenation (ECMO). Excessive tiredness (odds ratio [OR] 1.42, 95% confidence interval [CI] 1.20-1.68) and prior neurodegenerative diseases (OR 1.32, 95% CI 1.07-1.63) were associated with an increased risk of an unfavorable outcome. Prior cerebrovascular and neuroimmunological diseases were not associated with an unfavorable short-term outcome of COVID-19. CONCLUSION: Our data on mostly hospitalized COVID-19 patients show that excessive tiredness or prior neurodegenerative disease at first presentation increase the risk of an unfavorable short-term outcome. ICB in critical COVID-19 was associated with therapeutic interventions, such as anticoagulation and ECMO, and thus may be an indirect complication of a life-threatening systemic viral infection.

Neuro-COVID-19 is more than anosmia: clinical presentation, neurodiagnostics, therapies, and prognosis.

PURPOSE OF REVIEW: To provide an overview on current knowledge of neurological symptoms and complications of COVID-19, and to suggest management concepts. RECENT FINDINGS: Headache, dizziness, excessive tiredness, myalgia, anosmia/hyposmia, and ageusia/dysgeusia are common nonspecific neurological manifestations during early COVID-19 disease found in the majority of patients. Less frequent but more severe and specific neurological manifestations include Guillain--Barré syndrome, encephalopathy, encephalitis/meningitis, epileptic seizures, and cerebrovascular events. Beyond standard neurological examination, these require a more extensive work-up, including cerebrospinal fluid assessment, neurophysiological evaluation, neuroimaging, and cognitive testing. Symptomatic treatment is advisable unless the neurological complication's immune pathogenesis is proven. SUMMARY: Neurological manifestations of COVID-19 occur during the acute, para-infectious, and 'recovery' phase. Therapeutic management depends on the clinical presentation and neurological work-up.

Status of clinical research in neurology in Germany-A national survey.

BACKGROUND AND PURPOSE: To provide an overview on the status of clinical research in neurology in Germany. METHODS: German university hospitals, nonuniversity hospitals, and neurological medical practices were surveyed regarding their clinical research activities during the period 2013 to 2017. RESULTS: Fifty percent of university hospitals, 10.6% of nonuniversity hospitals, and 5.2% of medical practices in Germany responded to our questionnaire. More than 80% of the clinical studies conducted have been phase III/IV and noninterventional trials (NISs), whereas <1% have been phase I and 3.5% investigator-initiated trials (IITs). University hospitals have conducted most of the phase II-IV trials. NISs have been predominantly performed by medical practices. Fifty-six percent of the university hospitals and less of the nonuniversity institutions confirmed the implementation of standard operating procedures (SOPs). In university hospitals, on average, 11 physicians had acquired a good clinical practice certificate. Overall, 43% of all trials have been performed in neuroimmunology. CONCLUSIONS: The status of clinical research in neurology in Germany is predominated by NISs and late-phase trials, potentially due to a general lack of easily accessible funding, which leads to a highly competitive environment and fewer opportunities to perform early-phase clinical trials as well as IITs. Our results indicate that there is substantial need for structured support for creating and implementing SOPs to maintain quality standards and guarantee uniformity of performance. This survey assessed many aspects of clinical research and serves as guidance for providing ideas for structured improvement of clinical research in neurology in Germany.

A systematic review of neurological symptoms and complications of COVID-19.

OBJECTIVE: To study the frequency of neurological symptoms and complications in COVID-19 patients in a systematic review of the literature. METHODS: Relevant studies were identified through electronic explorations of PubMed, medRxiv, and bioRxiv. Besides, three Chinese databases were searched. A snowballing method searching the bibliographies of the retrieved references was applied to identify potentially relevant articles. Articles published within 1 year prior to April 20th, 2020, were screened with no language restriction imposed. Databases were searched for terms related to SARS-CoV-2/COVID-19 and neurological manifestations, using a pre-established protocol registered on the International Prospective Register of Systematic Reviews database (ID: CRD42020187994). RESULTS: A total of 2441 articles were screened for relevant content, of which 92 full-text publications were included in the analyses of neurological manifestations of COVID-19. Headache, dizziness, taste and smell dysfunctions, and impaired consciousness were the most frequently described neurological symptoms, the latter more often among patients with a severe or critical disease course. To date, only smaller cohort studies or single cases have reported cerebrovascular events, seizures, meningoencephalitis, and immune-mediated neurological diseases, not suitable for quantitative analysis. CONCLUSION: The most frequent neurological symptoms reported in association with COVID-19 are non-specific for the infection with SARS-CoV-2. Although SARS-CoV-2 may have the potential to gain direct access to the nervous system, so far, SARS-CoV-2 was detected in the cerebrospinal fluid in two cases only. Standardized international registries are needed to clarify the clinical relevance of the neuropathogenicity of SARS-CoV-2 and to elucidate a possible impact of SARS-CoV-2 infection on common neurological disease, such as Alzheimer's, Parkinson's disease or multiple sclerosis.

Verum versus sham tDCS in the treatment of stroke-induced apraxia: study protocol of the randomized controlled trial RAdiCS -"Rehabilitating (stroke-induced) Apraxia with direct Current Stimulation".

INTRODUCTION: Stroke is the leading cause of acquired disability in western societies. (Motor) cognitive deficits like apraxia significantly contribute to disability after stroke, harming activities of daily living and rehabilitation outcome. To date, efficient therapeutic options for apraxia remain sparse. Thus, randomized controlled trials (RCTs) are warranted. METHODS: Based on promising results of a pilot study, the on-going RAdiCS (Rehabilitating stroke-induced Apraxia with direct Current Stimulation) study is a randomized controlled trial, which follows a double-blinded (investigator and patient), two-arm parallel interventional model. It is designed to include 110 apraxic patients (as diagnosed by the Cologne Apraxia Screening, KAS) in the subacute phase after a left hemisphere (LH) stroke. The University of Cologne initiated the trial, which is conducted in two German Neurorehabilitation Centers.The study aims to evaluate the effect of anodal (versus sham) transcranial direct current stimulation (tDCS) applied over the left posterior parietal cortex (PPC) with an intensity of 2 mA for 10 min on five consecutive days on apraxic deficits. In addition to anodal or sham tDCS, all LH stroke patients undergo a motor (cognitive) training that is performed before and after the stimulation (off-line stimulation).The primary outcome measure is the (differential) change in the overall KAS score after five daily sessions of anodal versus sham tDCS when compared to the baseline assessment before tDCS. Secondary study outcomes include further apraxia scores, aphasia severity, and measures of motor performance and disability after stroke. All outcome measures are obtained in the post-stimulation assessment as well as during follow-up (3-4 months after tDCS). PERSPECTIVE: The RCT RAdiCS shall evaluate in a large number of LH stroke patients whether anodal tDCS (compared to sham tDCS) expedites the rehabilitation of apraxia - over and above additional motor (cognitive) training and standard care. A positive study outcome would provide a new strategy for the treatment of apraxia, which hopefully ameliorates the negative impact of apraxia on daily living and long-term outcome. TRIAL REGISTRATION: Clinical Trials Gov: NCT03185234, registered 14 June 2017 ; Deutsches Register für Klinische Studien: DRKS00012292, registered 01 June 2017. TRIAL STATUS: Participant enrollment began on 22 June 2017. The trial is expected to be completed on 30 June 2022.

COVID-19 and neurological training in Europe: from early challenges to future perspectives.

The worldwide SARS-CoV-2 pandemic is dramatically affecting health systems with consequences also for neurological residency training. Here we report early experiences and challenges that European neurologists and residents faced. The breadth of the pandemic and the social restrictions induced substantial modifications in both inpatient and outpatient clinical care and academic activities as well, adversely affecting our residency training. On the other hand we see also opportunities, such as gaining more clinical and professional skills. All these drastic and sudden changes lead us to reconsider some educational aspects of our training program that need to be improved in order to better prepare the neurologists of the future to manage unexpected and large emergency situations like the one we are living in these days. A reconsideration of the neurological training program could be beneficial to guarantee high standard level of the residency training in this period and beyond.

Action and semantic tool knowledge - Effective connectivity in the underlying neural networks.

Evidence from neuropsychological and imaging studies indicate that action and semantic knowledge about tools draw upon distinct neural substrates, but little is known about the underlying interregional effective connectivity. With fMRI and dynamic causal modeling (DCM) we investigated effective connectivity in the left-hemisphere (LH) while subjects performed (i) a function knowledge and (ii) a value knowledge task, both addressing semantic tool knowledge, and (iii) a manipulation (action) knowledge task. Overall, the results indicate crosstalk between action nodes and semantic nodes. Interestingly, effective connectivity was weakened between semantic nodes and action nodes during the manipulation task. Furthermore, pronounced modulations of effective connectivity within the fronto-parietal action system of the LH (comprising lateral occipito-temporal cortex, intraparietal sulcus, supramarginal gyrus, inferior frontal gyrus) were observed in a bidirectional manner during the processing of action knowledge. In contrast, the function and value knowledge tasks resulted in a significant strengthening of the effective connectivity between visual cortex and fusiform gyrus. Importantly, this modulation was present in both semantic tasks, indicating that processing different aspects of semantic knowledge about tools evokes similar effective connectivity patterns. Data revealed that interregional effective connectivity during the processing of tool knowledge occurred in a bidirectional manner with a weakening of connectivity between areas engaged in action and semantic knowledge about tools during the processing of action knowledge. Moreover, different semantic tool knowledge tasks elicited similar effective connectivity patterns.