The role of neurophysiological tools in the evaluation of ischemic stroke evolution: a narrative review

Research progress of quantitative electroencephalography in post-ischemic stroke mental disorders

Quantitative electroencephalography (qEEG) has significantly advanced in the field of neuroscience as a highly sensitive tool for routine monitoring following a stroke. It holds promise in diagnosing post-stroke psychiatric disorders and evaluating treatment outcomes. This review systematically examined published papers and thoroughly analyzed research findings on using qEEG indicators to monitor mental abnormalities in patients with ischemic stroke. The review covers key time periods, including the early stage (within 72 h), subacute stage (72 h to 1 month), and chronic stage (over 1 month) post-onset. The current evidence suggests that correlation indicators from electroencephalography (EEG) monitoring vary across different time periods, with Power spectrum analysis is a current research hotspot. This review summarizes and analyzes specialized studies on utilizing these qEEG indicators for monitoring and evaluating mental disorders in ischemic stroke, identifying key monitoring indicators highlighted in current research.

A pictorial neuroradiological review of brain vascular abnormalities in patients with kidney disease

A well-known link exists between cerebrovascular disease and chronic kidney disease. Cerebrovascular pathology in patients with kidney disease may be asymptomatic and occasionally discovered through neuroradiological examinations or it may present with neurological symptoms. Covert cerebrovascular lesions represent the earliest injuries associated with chronic kidney disease and primarily result from small vessel damage. These conditions often manifest incidentally, appearing as structural changes (such as lacunes, white matter lesions, enlarged perivascular spaces, cerebral microbleeds, and atrophy) as well as microstructural and hemodynamic alterations, detectable through routine and advanced functional MRIs. These alterations may be associated with a higher risk of stroke, cognitive decline, and dementia. Patients with end-stage renal disease or chronic kidney disease undergoing dialysis may be at increased risk of large-artery atherosclerosis, cardio-embolism, or small-vessel occlusion, and they may experience symptomatic acute ischemic strokes as rare complications. Currently, there are no established guidelines or standardized diagnostic protocols for preventing cerebrovascular disease in patients with kidney disease. Clinical and radiological studies are warranted to evaluate the usefulness of incorporating neuroimaging into the diagnostic work-up of these patients in order to improve prognosis and reduce diagnostic delays.

Post-stroke changes in brain structure and function can both influence acute upper limb function and subsequent recovery

Improving outcomes after stroke depends on understanding both the causes of initial function/impairment and the mechanisms of recovery. Recovery in patients with initially low function/high impairment is variable, suggesting the factors relating to initial function/impairment are different to the factors important for subsequent recovery. Here we aimed to determine the contribution of altered brain structure and function to initial severity and subsequent recovery of the upper limb post-stroke. The Nine-Hole Peg Test was recorded in week 1 and one-month post-stroke and used to divide 36 stroke patients (18 females, age: M = 66.56 years) into those with high/low initial function and high/low subsequent recovery. We determined differences in week 1 brain structure (Magnetic Resonance Imaging) and function (Magnetoencephalography, tactile stimulation) between high/low patients for both initial function and subsequent recovery. Lastly, we examined the relative contribution of changes in brain structure and function to recovery in patients with low levels of initial function. Low initial function and low subsequent recovery are related to lower sensorimotor β power and greater lesion-induced disconnection of contralateral [ipsilesional] white-matter motor projection connections. Moreover, differences in intra-hemispheric connectivity (structural and functional) are unique to initial motor function, while differences in inter-hemispheric connectivity (structural and functional) are unique to subsequent motor recovery. Function-related and recovery-related differences in brain function and structure after stroke are related, yet not identical. Separating out the factors that contribute to each process is key to identifying potential therapeutic targets for improving outcomes.

Fluoxetine-induced downregulation of circMap2k1 signaling cascade to improve neurological function after ischemic stroke

BACKGROUND

Ischemic stroke (IS) is known for its high incidence, disability, and mortality, and there is an urgent need to investigate the pathophysiological mechanisms and develop novel treatment strategies.

OBJECTIVES

We aimed to investigate the mechanisms of the novel circMap2k1/miR-135b-5p/Pidd1 axis in the treatment of IS progression with fluoxetine.

METHODS

The middle cerebral artery occlusion (MCAO) model was done in adult male Sprague-Dawley (SD) rats and followed by fluoxetine treatment and the injection of adeno-associated virus (AAV)-sh-ctr and AAV-sh-circMap2k1 into the bilateral hippocampal tissues of rats. Dual-luciferase reporter gene assay was employed to confirm the binding between miR-135b-5p and Pidd1. Enzyme-linked immunosorbent assay was performed to measure the concentrations of the inflammatory factors TNF-α, IL-6, and IL-1β in the plasma. The role of circMap2k1 in cells was tested by overexpression of circMap2k1. Cell viability was assessed using Cell Counting Kit-8 assay, while apoptosis was measured by flow cytometry.

RESULTS

Knockdown of circMap2k1 enhanced the therapeutic and protective effect of fluoxetine on IS injury in rats. Dual-luciferase reporter gene assay confirmed the targeting of miR-135b-5p to Pidd1. Additionally, fluoxetine deactivated the adsorption of miR-135b-5p by downregulating circMap2k1, and miR-135b-5p further exerted its inhibitory effect on Pidd1 and finally attenuated the inflammatory response caused by microglial polarization after IS. Cell experiments revealed that overexpression of circMap2k1 repressed cell viability and promoted cell apoptosis.

CONCLUSIONS

Fluoxetine downregulated of circMap2k1 was associated ameliorate neurological injury and inflammatory responses induced by microglial polarization after IS. The manuscript is available as a preprint at this link: doi.org/10.21203/rs.3.rs-3209057/v1.

Aberrant neural oscillations in poststroke aphasia

Neural oscillations are electrophysiological indicators of synchronous neuronal activity in the brain. Recent work suggests aberrant patterns of neuronal activity in patients with poststroke aphasia. Yet, there is a lack of systematic explorations of neural oscillations in poststroke aphasia. Investigating changes in the dynamics of neuronal activity after stroke may be helpful to identify neural markers of aphasia and language recovery and increase the current understanding of successful language rehabilitation. This review summarizes research on neural oscillations in poststroke aphasia and evaluates their potential as biomarkers for specific linguistic processes. We searched the literature through PubMed, Web of Science, and EBSCO, and selected 31 studies that met the inclusion criteria. Our analyses focused on neural oscillation activity in each frequency band, brain connectivity, and therapy-induced changes during language recovery. Our review highlights potential neurophysiological markers; however, the literature remains confounded, casting doubt on the reliability of these findings. Future research must address these confounds to confirm the robustness of cross-study findings on neural oscillations in poststroke aphasia.

Clinical recommendations for non-invasive ultrasound neuromodulation

Non-invasive ultrasound neuromodulation has experienced exponential growth in the neuroscientific literature, recently also including clinical studies and applications. However, clinical recommendations for the secure and effective application of ultrasound neuromodulation in pathological brains are currently lacking. Here, clinical experts with neuroscientific expertise in clinical brain stimulation and ultrasound neuromodulation present initial clinical recommendations for ultrasound neuromodulation with relevance for all ultrasound neuromodulation techniques. The recommendations start with methodological safety issues focusing on technical issues to avoid harm to the brain. This is followed by clinical safety issues focusing on important factors concerning pathological situations.

Defining the concept of reserve in the motor domain: a systematic review

A reserve in the motor domain may underlie the capacity exhibited by some patients to maintain motor functionality in the face of a certain level of disease. This form of "motor reserve" (MR) could include cortical, cerebellar, and muscular processes. However, a systematic definition has not been provided yet. Clarifying this concept in healthy individuals and patients would be crucial for implementing prevention strategies and rehabilitation protocols. Due to its wide application in the assessment of motor system functioning, non-invasive brain stimulation (NIBS) may support such definition. Here, studies focusing on reserve in the motor domain and studies using NIBS were revised. Current literature highlights the ability of the motor system to create a reserve and a possible role for NIBS. MR could include several mechanisms occurring in the brain, cerebellum, and muscles, and NIBS may support the understanding of such mechanisms.

Spectral exponent assessment and neurofilament light chain: a comprehensive approach to describe recovery patterns in stroke

Introduction

Understanding the residual recovery potential in stroke patients is crucial for tailoring effective neurorehabilitation programs. We propose using EEG and plasmatic Neurofilament light chain (NfL) levels as a model to depict longitudinal patterns of stroke recovery.

Methods

We enrolled 13 patients (4 female, mean age 74.7 ± 8.8) who underwent stroke in the previous month and were hospitalized for 2-months rehabilitation. Patients underwent blood withdrawal, clinical evaluation and high-definition EEG at T1 (first week of rehabilitation) and at T2 (53 ± 10 days after). We assessed the levels of NfL and we analyzed the EEG signal extracting Spectral Exponent (SE) values. We compared our variables between the two timepoint and between cortical and non-cortical strokes.

Results

We found a significant difference in the symmetry of SE values between cortical and non-cortical stroke at both T1 (p = 0.005) and T2 (p = 0.01). SE in the affected hemisphere showed significantly steeper values at T1 when compared with T2 (p = 0.001). EEG measures were consistently related to clinical scores, while NfL at T1 was related to the volume of ischemic lesions (r = 0.75; p = 0.003). Additionally, the combined use of NfL and SE indicated varying trends in longitudinal clinical recovery.

Conclusion

We present proof of concept of a promising approach for the characterization of different recovery patterns in stroke patients.

Using TMS-EEG to assess the effects of neuromodulation techniques: a narrative review

Over the past decades, among all the non-invasive brain stimulation (NIBS) techniques, those aiming for neuromodulatory protocols have gained special attention. The traditional neurophysiological outcome to estimate the neuromodulatory effect is the motor evoked potential (MEP), the impact of NIBS techniques is commonly estimated as the change in MEP amplitude. This approach has several limitations: first, the use of MEP limits the evaluation of stimulation to the motor cortex excluding all the other brain areas. Second, MEP is an indirect measure of brain activity and is influenced by several factors. To overcome these limitations several studies have used new outcomes to measure brain changes after neuromodulation techniques with the concurrent use of transcranial magnetic stimulation (TMS) and electroencephalogram (EEG). In the present review, we examine studies that use TMS-EEG before and after a single session of neuromodulatory TMS. Then, we focused our literature research on the description of the different metrics derived from TMS-EEG to measure the effect of neuromodulation.