Nabeel Sheikh

Frontal EEG delta/alpha ratio and screening for post-stroke cognitive deficits: The power of four electrodes

This study analysed correlations between post-stroke, quantitative electroencephalographic (QEEG) indices, and cognition-specific, functional outcome measures. Results were compared between QEEG indices calculated from the standard 19 versus 4 frontal (or 4 posterior) electrodes to assess the feasibility and efficacy of employing a reduced electrode montage. Resting-state EEG was recorded at the bedside within 62-101 h after onset of symptoms of middle cerebral artery, ischaemic stroke (confirmed radiologically). Relative power for delta, theta, alpha and beta, delta/alpha ratio (DAR) and pairwise-derived brain symmetry index (pdBSI) were averaged; over all electrodes (global), over F3, F4, F7, F8 (frontal) and P3, P4, T5, T6 (posterior). The functional independence measure and functional assessment measure (FIM-FAM) was administered at mean 105 days post-stroke. Total (30 items) and cognition-specific (5 items) FIM-FAM scores were correlated with QEEG indices using Spearmans coefficient, with a Bonferroni correction. Twenty-five patients were recruited, 4 died within 3 months and 1 was lost to follow-up. Hence 20 cases (10 female; 9 left hemisphere; mean age 68 years, range 38-84) were analysed. Two QEEG indices demonstrated highly-significant correlations with cognitive outcomes: frontal DAR (ρ = -0.664, p ≤ 0.001) and global, relative alpha power (ρ = 0.67, p ≤ 0.001). After correction there were no other significant correlations. Alpha activity - particularly frontally - may index post-stroke attentional capacity, which appears to be a key determinant of functional and cognitive outcomes. Likewise frontal delta pathophysiology influences such outcomes. Pending further studies, DAR from 4 frontal electrodes may inform early screening for post-MCA stroke cognitive deficits, and thereby, clinical decisions.

Measurement of blood-brain barrier permeability in acute ischemic stroke using standard first-pass perfusion CT data

Background and purpose Increased blood–brain barrier permeability is believed to be associated with complications following acute ischemic stroke and with infarct expansion. Measurement of blood–brain barrier permeability requires a delayed image acquisition methodology, which prolongs examination time, increasing the likelihood of movement artefacts and radiation dose. Existing quantitative methods overestimate blood–brain barrier permeability when early phase CT perfusion data are used. The purpose of this study is to develop a method that yields the correct blood–brain barrier permeability value using first-pass perfusion CT data. Methods We acquired 43 CT perfusion datasets, comprising experimental (n = 30) and validation subject groups (n = 13). The Gjedde–Patlak method was used to estimate blood–brain barrier permeability using first-pass (30–60 s after contrast administration) and delayed phase (30–200 s) data. In the experimental group, linear regression was used to obtain a function predicting first-pass blood–brain barrier permeability estimates from delayed phase estimates in each stroke compartment. The reliability of prediction with this function was then tested using data from the validation group. Results The predicted delayed phase blood–brain barrier permeability was strongly correlated with the measured delayed phase value (r = 0.67 and 0.6 for experimental and validation group respectively; p < 0.01). Predicted and measured delayed phase blood–brain barrier permeability in each stroke compartment were not significantly different in both experimental and validation groups. Conclusion We have developed a method of estimating blood–brain barrier permeability using first-pass perfusion CT data. This predictive method allows reliable blood–brain barrier permeability estimation within standard acquisition time, minimizing the likelihood of motion artefacts thereby improving image quality and reducing radiation dose.

QEEG may uniquely inform and expedite decisions regarding intra-arterial clot retrieval in acute stroke.

A recent review highlights that QEEG can uniquely inform ischaemic stroke (IS) management and treatment (Finnigan and van Putten, 2013). IS produces abnormal, slow EEG activity (delta and theta) and attenuation of faster (alpha and beta) activity (Finnigan and van Putten, 2013). One key QEEG index is ‘‘power’’ (signal intensity; units microvolts squared) of frequency-specific activity. Numerous studies indicate that global delta and alpha power measures and the delta/alpha ratio (DAR) can uniquely inform IS management (e.g., Finnigan et al., 2006, 2007; Finnigan and van Putten, 2013). Broadly, DAR below 1 is normative whereas higher values are abnormal (Finnigan and van Putten, 2013). Several observations indicate that continuous EEG/QEEG can detect cerebral responses to reperfusion following recanalisation, immediately and before this is apparent clinically (de Vos et al., 2008; Finnigan et al., 2006; Finnigan and van Putten, 2013). For example a significant delta power reduction observed 25 min after IV alteplase preceded any notable symptomatic change by approximately 2 h (Finnigan et al., 2006). Such observations indicate that QEEG could inform and expedite decisions regarding further reperfusion therapies such as intra-arterial clot retrieval (Finnigan and van Putten, 2013). The current cases add novel evidence to support this proposal. Patients were enrolled into an observational study investigating the prognostic value of EEG in acute IS (www.anzctr.org.au; ACTRN12611000611921). Approval was obtained from the local University and Hospital Human Research Ethics Committees and written informed consent obtained. EEG was acquired using a NicOne ICU Brain Monitor (CareFusion Healthcare) and the standard trodes) were each computed from 2 min epochs of artefact-free EEG, and median times of these are noted below. DAR changes were assessed via repeated-measures t-tests and significant outcomes are reported. A 74 year old woman (Patient A), residing in low-level care (pre-morbid mRS = 1) with history of hypertension, dyslipidemia and non-anticoagulated atrial fibrillation, presented 2 h after acute onset symptoms. These were mild drowsiness, visuospatial and sensory inattention to the right, global aphasia, forced gaze deviation, moderate right facial weakness, severe dysarthria and mild right limb weakness (NIHSS = 15). CT Perfusion (CTP) showed a infarct core in the left frontal premotor region. EEG and IV alteplase commenced within 4.5 h. DAR was 12.83 immediately prior to bolus, decreased temporarily post-bolus yet remained abnormal (8.58) before rising and remaining above 12 for approximately 2 h. Symptoms marginally improved with NIHSS being 10 at 2 h post-bolus (alert, improved facial weakness, only left nasolabial fold flattening and improved dysarthria, recovered limb strength). While some initial NIHSS and DAR improvements occurred, both remained abnormally high. The DAR reduction also was transient and thereafter DAR constantly remained even more abnormal than baseline. Lower NIHSS primarily reflected an improved level of alertness evidently, and other deficits (dysphasia, persistent forced gaze deviation, neglect) persisted. Follow-up non-contrast CT (NCCT) revealed a hypodensity largely corresponding to the infarct core on acute CTP; and the patient remained functionally impaired at discharge (NIHSS = 11). After 3 months the modified Rankin Scale score was 4 (moderately severe disability). QEEG-DAR measures were consistent with the aforementioned outcomes and thus

Prognosticating post-stroke cognitive outcomes: Pre-discharge, frontal EEG markers are informative

Synopsis: Stroke patients with acute occlusions of the large proximal cerebral arteries and high thrombus load do not show an optimal response to i. v. thrombolysis alone. During the recent years mechanical neurointerventional revascularization techniques with clot retrievers and aspiration catheters have been developed in adjunct to systemic therapy. Today interventional thrombectomy is mainly based on a combination with stentretrievers and aspiration. Compared to prior approaches this technique is relatively easy to perform and to standardize and allows for recanalization rates of up to 90 %. Clinical success rates of more than 50 % of patients with mRS 0–2 could be achieved in experienced centers. Drawbacks of catheter based revascularization techniques are logistic demands and the descrepancy between high recanalization rates and lower rates of good clinical outcomes. The problem of futile recanalization was one of the influence factors for the failure of several randomized trials (RCTs) i. v.-lysis vs. thrombectomy. Improper patient selection, inefficient interventional techniques and late time windows were among the reasons why superiority of endovascular treatment could not be demonstrated with high levels of scientific evidence. Neurointerventional hypes and accelerated demands for RCTs at an early stage of development without proof of sufficient efficacy of a new technique led to negative or equivocal results. Hopefully better trials are on the way. To become successful the relationship between neurologists and neurointerventionists should be less competitive to work together with the aim to improve outcome of stroke patients and to keep neurointervenition in the neuro field instead of vascular medicine. Invited Speaker

QEEG may uniquely inform and expedite decisions regarding reperfusion therapies in acute stroke

Background: CT brain (CTB), CT perfusion (CTP) and CT angiography (CTA) of brain and neck are critical tools for acute stroke assessment. Post processing (PP) for CTP is traditionally time consuming. This study evaluated the impact PP tools had on workups times of CTP by utilising new semi-automated algorithms and advanced image reconstruction. Methods: Acute stroke assessment includes CTB, CTP and CTA of the brain and neck with dedicated PP of the CTP. The sample included 90 consecutive exams on patients that presented to the emergency department for assessment of acute stroke. The initial 45 exams used traditional PP workflow whilst the latter 45 exams utilised the new PP tools. All CTP workups included generation of cerebral blood volume, cerebral blood flow, mean transit time and time to peak maps. Data mining from the picture archiving and communication system (PACS) enabled quantification of CTP workup times by recording the time between scan end and last CTP PP image arriving at PACS for each exam. Comparative analysis was made between both methods of PP for the CTP workup time. Results: Average traditional CTP PP workup time = 24.98 minutes Average CTP PP workup time using the new PP tools = 14 minutes. Average total PP time for CTP workup improved by 10.98 minutes (44%). Conclusion: CTP images using the new PP tools were ready for review 44% faster than traditional PP methods. New PP tools have potential for expediting patient management decisions.

Pre-discharge EEG markers are informative of post-stroke cognitive outcomes

Background: A rural feedback survey, highlighted need for user friendly, accessible stroke education for generalist staff. Funded by a scholarship from Rural Division of CETI. Developed in partnership by Stroke Care Coordinators within the Hunter New England Area Health Service (HNEAHS), North Coast Area Health Service (NCAHS). Located on the National Stroke Foundation Web Site. Aims: eStroke was designed for clinicians working in Stroke, as well as generalist staff. The primary aim is to provide information to clinicians working within rural facilities. Methods: Built on the evidence-based guidelines and advice from expert multidisciplinary stroke clinicians. E-learning format, easily accessed, at no cost to metropolitan, rural and remote clinicians. Guidance and governance provided by HNEAHS and NCAHS. The Online Package has the ability to collect feedback data on site usage and comments. Results: Consultation with expert clinicians resulted in 10 packages covering pre hospital, acute stroke management, rehabilitation and beyond has been developed. This includes the utilisation of five case studies to demonstrate a practical approach to stroke management. The National Stroke Foundation has collated feedback from the go live date of the rural component of estroke. Conclusion: Provides easily accessible, practical Stroke information for beginner to intermediate in an e learning format. Opportunity to develop and build on existing skill base and develop more specialized skills. To date e Stroke Online package has attracted high volume of users with positive feedback.

CT perfusion and bilateral paramedian thalamic stroke due to Artery of Percheron occlusion

Hypothesis / aims of study Urinary incontinence following acute stroke is common, affecting between 40%-60% of people admitted to hospital [1]. It is related to poor outcome and is poorly managed in many cases. Our NIHR funded research programme aims to develop, implement and explore the potential effectiveness and costeffectiveness of a systematic voiding programme for the in-patient management of urinary incontinence after stroke. The systematic voiding programme includes bladder training and pelvic floor muscle training for patients who are cognitively able and prompted voiding for patients with cognitive impairments.