Computer-assisted analysis of routine EEG to identify hidden biomarkers of epilepsy: A systematic review

Background

Computational analysis of routine electroencephalogram (rEEG) could improve the accuracy of epilepsy diagnosis. We aim to systematically assess the diagnostic performances of computed biomarkers for epilepsy in individuals undergoing rEEG.

Methods

We searched MEDLINE, EMBASE, EBM reviews, IEEE Explore and the grey literature for studies published between January 1961 and December 2022. We included studies reporting a computational method to diagnose epilepsy based on rEEG without relying on the identification of interictal epileptiform discharges or seizures. Diagnosis of epilepsy as per a treating physician was the reference standard. We assessed the risk of bias using an adapted QUADAS-2 tool.

Results

We screened 10 166 studies, and 37 were included. The sample size ranged from 8 to 192 (mean=54). The computed biomarkers were based on linear (43%), non-linear (27%), connectivity (38%), and convolutional neural networks (10%) models. The risk of bias was high or unclear in all studies, more commonly from spectrum effect and data leakage. Diagnostic accuracy ranged between 64% and 100%. We observed high methodological heterogeneity, preventing pooling of accuracy measures.

Conclusion

The current literature provides insufficient evidence to reliably assess the diagnostic yield of computational analysis of rEEG.

Significance

We provide guidelines regarding patient selection, reference standard, algorithms, and performance validation.

Antithrombotic Treatment for Stroke Prevention in Cervical Artery Dissection: The STOP-CAD Study

Background: Small, randomized trials of cervical artery dissection (CAD) patients showed conflicting results regarding optimal stroke prevention strategies. We aimed to compare outcomes in patients with CAD treated with antiplatelets versus anticoagulation. Methods: This is a multi-center observational retrospective international study (16 countries, 63 sites) that included CAD patients without major trauma. The exposure was antithrombotic treatment type (anticoagulation vs. antiplatelets) and outcomes were subsequent ischemic stroke and major hemorrhage (intracranial or extracranial hemorrhage). We used adjusted Cox regression with Inverse Probability of Treatment Weighting (IPTW) to determine associations between anticoagulation and study outcomes within 30 and 180 days. The main analysis used an "as treated" cross-over approach and only included outcomes occurring on the above treatments. Results: The study included 3,636 patients [402 (11.1%) received exclusively anticoagulation and 2,453 (67.5%) received exclusively antiplatelets]. By day 180, there were 162 new ischemic strokes (4.4%) and 28 major hemorrhages (0.8%); 87.0% of ischemic strokes occurred by day 30. In adjusted Cox regression with IPTW, compared to antiplatelet therapy, anticoagulation was associated with a non-significantly lower risk of subsequent ischemic stroke by day 30 (adjusted HR 0.71 95% CI 0.45-1.12, p=0.145) and by day 180 (adjusted HR 0.80 95% CI 0.28-2.24, p=0.670). Anticoagulation therapy was not associated with a higher risk of major hemorrhage by day 30 (adjusted HR 1.39 95% CI 0.35-5.45, p=0.637) but was by day 180 (adjusted HR 5.56 95% CI 1.53-20.13, p=0.009). In interaction analyses, patients with occlusive dissection had significantly lower ischemic stroke risk with anticoagulation (adjusted HR 0.40 95% CI 0.18-0.88) (Pinteraction=0.009). Conclusions: Our study does not rule out a benefit of anticoagulation in reducing ischemic stroke risk, particularly in patients with occlusive dissection. If anticoagulation is chosen, it seems reasonable to switch to antiplatelet therapy before 180 days to lower the risk of major bleeding. Large prospective studies are needed to validate our findings.

Inter-rater reliability of risk of bias tools for non-randomized studies

PURPOSE

There is limited knowledge on the reliability of risk of bias (ROB) tools for assessing internal validity in systematic reviews of exposure and frequency studies. We aimed to identify and then compare the inter-rater reliability (IRR) of six commonly used tools for frequency (Loney scale, Gyorkos checklist, American Academy of Neurology [AAN] tool) and exposure (Newcastle-Ottawa scale, SIGN50 checklist, AAN tool) studies.

METHODS

Six raters independently assessed the ROB of 30 frequency and 30 exposure studies using the three respective ROB tools. Articles were rated as low, intermediate, or high ROB. We calculated an intraclass correlation coefficient (ICC) for each tool and category of ROB tool. We compared the IRR between ROB tools and tool type by inspection of overlapping ICC 95% CIs and by comparing their coefficients after transformation to Fisher's Z values. We assessed the criterion validity of the AAN ROB tools by calculating an ICC for each rater in comparison with the original ratings from the AAN.

RESULTS

All individual ROB tools had an IRR in the substantial range or higher (ICC point estimates between 0.61 and 0.80). The IRR was almost perfect (ICC point estimate > 0.80) for the AAN frequency tool and the SIGN50 checklist. All tools were comparable in IRR, except for the AAN frequency tool which had a significantly higher ICC than the Gyorkos checklist (p = 0.021) and trended towards a higher ICC when compared to the Loney scale (p = 0.085). When examined by category of ROB tool, scales, and checklists had a substantial IRR, whereas the AAN tools had an almost perfect IRR. For the criterion validity of the AAN ROB tools, the average agreement between our raters and the original AAN ratings was moderate.

CONCLUSION

All tools had substantial IRRs except for the AAN frequency tool and the SIGN50 checklist, which both had an almost perfect IRR. The AAN ROB tools were the only category of ROB tools to demonstrate an almost perfect IRR. This category of ROB tools had fewer and simpler criteria. Overall, parsimonious tools with clear instructions, such as those from the AAN, may provide more reliable ROB assessments.

NCCT Markers of Intracerebral Hemorrhage Expansion Using Revised Criteria: An External Validation of Their Predictive Accuracy

BACKGROUND AND PURPOSE

Several NCCT expansion markers have been proposed to improve the prediction of hematoma expansion. We retrospectively evaluated the predictive accuracy of 9 expansion markers.

MATERIALS AND METHODS

Patients admitted for intracerebral hemorrhage within 24 hours of last seen well were retrospectively included from April 2016 to April 2020. The primary outcome was revised hematoma expansion, defined as any of a ≥6-mL or ≥33% increase in intracerebral hemorrhage volume, a ≥ 1-mL increase in intraventricular hemorrhage volume, or de novo intraventricular hemorrhage. We assessed the predictive accuracy of expansion markers and determined their association with revised hematoma expansion.

RESULTS

We included 124 patients, of whom 51 (41%) developed revised hematoma expansion. The sensitivity of each marker for the prediction of revised hematoma expansion ranged from 4% to 78%; the specificity, 37%-97%; the positive likelihood ratio, 0.41-7.16; and the negative likelihood ratio, 0.49-1.06. By means of univariable logistic regressions, 5 markers were significantly associated with revised hematoma expansion: black hole (OR = 8.66; 95% CI, 2.15-58.14; P = .007), hypodensity (OR = 3.18; 95% CI, 1.49-6.93; P = .003), blend (OR = 2.90; 95% CI, 1.08-8.38; P = .04), satellite (OR = 2.84; 95% CI, 1.29-6.61; P = .01), and Barras shape (OR = 2.41, 95% CI; 1.17-5.10; P = .02). In multivariable models, only the black hole marker remained independently associated with revised hematoma expansion (adjusted OR = 5.62; 95% CI, 1.23-40.23; P = .03).

CONCLUSIONS

No single NCCT expansion marker had both high sensitivity and specificity for the prediction of revised hematoma expansion. Improved image-based analysis is needed to tackle limitations associated with current NCCT-based expansion markers.

Impact of bilingual face, arm, speech, time (FAST) public awareness campaigns on emergency medical services (EMS) activation in a large Canadian metropolitan area

BACKGROUND AND AIMS

Face, arm, speech, time (FAST) public awareness campaigns improve stroke recognition in the general population. Whether this translates into improved emergency medical services (EMS) activation remains unclear. We assessed the association of five consecutive FAST campaigns with EMS calls for suspected strokes in a large urban area of Quebec, Canada.

METHODS

We conducted an observational study to assess data collected between June 2015 and December 2019 by the public EMS agency covering the cities of Laval and Montreal (Quebec, Canada). Five FAST campaigns were held over this period (mean duration: 9 weeks). We compared daily EMS calls before and after all FAST campaigns (2015 vs 2019) with t tests and Mann-Whitney U tests. We used single-group, univariate interrupted time series to measure changes in daily EMS calls for suspected strokes following each FAST campaign (stroke categories: any, symptom onset < 5 h, Cincinnati Prehospital Stroke Scale [CPSS] 3/3). Calls for headache served as negative control.

RESULTS

After five FAST campaigns, mean daily EMS calls increased by 28% (p < 0.001) for any suspected stroke and by 61% (p < 0.001) for stroke with symptom onset < 5 h, compared to 10.1% for headache (p = 0.012). Significant increases in daily EMS calls were observed after three campaigns (highest OR = 1.26; 95% CI 1.11, 1.43; p < 0.001). There were no significant changes in calls after individual campaigns for suspected stroke with symptom onset < 5 h, or suspected stroke with CPSS 3/3.

CONCLUSIONS

We observed an inconsistent impact of individual FAST campaigns on EMS calls for any suspected stroke, and did not observe significant EMS call changes after individual campaigns for acute (< 5 h) and severe (CPSS 3/3) strokes. These results may help stakeholders identify potential benefits and limitations of public awareness campaigns using the FAST acronym.

Computer-assisted analysis of routine electroencephalogram to identify hidden biomarkers of epilepsy: protocol for a systematic review

INTRODUCTION

The diagnosis of epilepsy frequently relies on the visual interpretation of the electroencephalogram (EEG) by a neurologist. The hallmark of epilepsy on EEG is the interictal epileptiform discharge (IED). This marker lacks sensitivity: it is only captured in a small percentage of 30 min routine EEGs in patients with epilepsy. In the past three decades, there has been growing interest in the use of computational methods to analyse the EEG without relying on the detection of IEDs, but none have made it to the clinical practice. We aim to review the diagnostic accuracy of quantitative methods applied to ambulatory EEG analysis to guide the diagnosis and management of epilepsy.

METHODS AND ANALYSIS

The protocol complies with the recommendations for systematic reviews of diagnostic test accuracy by Cochrane. We will search MEDLINE, EMBASE, EBM reviews, IEEE Explore along with grey literature for articles, conference papers and conference abstracts published after 1961. We will include observational studies that present a computational method to analyse the EEG for the diagnosis of epilepsy in adults or children without relying on the identification of IEDs or seizures. The reference standard is the diagnosis of epilepsy by a physician. We will report the estimated pooled sensitivity and specificity, and receiver operating characteristic area under the curve (ROC AUC) for each marker. If possible, we will perform a meta-analysis of the sensitivity and specificity and ROC AUC for each individual marker. We will assess the risk of bias using an adapted QUADAS-2 tool. We will also describe the algorithms used for signal processing, feature extraction and predictive modelling, and comment on the reproducibility of the different studies.

ETHICS AND DISSEMINATION

Ethical approval was not required. Findings will be disseminated through peer-reviewed publication and presented at conferences related to this field.

PROSPERO REGISTRATION NUMBER

CRD42022292261.

Medical and surgical treatment of epilepsy in older adults: A national survey

OBJECTIVE

There are no clinical guidelines dedicated to the treatment of epilepsy in older adults. We investigated physician opinion and practice regarding the treatment of people with epilepsy aged 65 years or older. We also sought to study how our opinion and practice varied between geriatricians, general neurologists, and epilepsy neurologists (i.e., epileptologists).

METHODS

We initially piloted our survey to measure test-retest reliability. Once finalized, we disseminated the survey via two rounds of facsimiles, and then conventional mail, to eligible individuals listed in a national directory of Canadian physicians. We used descriptive statistics such as stacked bar charts and tables to illustrate our findings.

RESULTS

One hundred forty-four physicians (104 general neurologists, 25 geriatricians, and 15 epileptologists) answered our survey in its entirety (overall response rate of 13.2%). Levetiracetam and lamotrigine were the preferred antiseizure medications (ASMs) to treat older adults with epilepsy. Two thirds of epileptologists and almost half of general neurologists would consider prescribing lacosamide in >50% of people aged >65 years; only one geriatrician was of the same opinion. More than 40% of general neurologists and geriatricians erroneously believed that none of the ASMs mentioned in our survey was previously studied in randomized controlled trials specific to the treatment of epilepsy in older adults. Epileptologists were more likely as compared to general neurologists and geriatricians to recommend epilepsy surgery (e.g., 66.6% vs. 22.9%-37.5% among older adults).

SIGNIFICANCE

Therapeutic decisions for older adults with epilepsy are heterogeneous between physician groups and sometimes misalign with available clinical evidence. Our surveyed physicians differed in their approach to ASM choice as well as perception of surgery in older adults with epilepsy. These findings likely reflect the lack of clinical guidelines dedicated to this population and the deficient implementation of best practices.

Non-contrast CT markers of intracerebral hematoma expansion: a reliability study

OBJECTIVES

We evaluated whether clinicians agree in the detection of non-contrast CT markers of intracerebral hemorrhage (ICH) expansion.

METHODS

From our local dataset, we randomly sampled 60 patients diagnosed with spontaneous ICH. Fifteen physicians and trainees (Stroke Neurology, Interventional and Diagnostic Neuroradiology) were trained to identify six density (Barras density, black hole, blend, hypodensity, fluid level, swirl) and three shape (Barras shape, island, satellite) expansion markers, using standardized definitions. Thirteen raters performed a second assessment. Inter- and intra-rater agreement were measured using Gwet's AC₁, with a coefficient > 0.60 indicating substantial to almost perfect agreement.

RESULTS

Almost perfect inter-rater agreement was observed for the swirl (0.85, 95% CI: 0.78-0.90) and fluid level (0.84, 95% CI: 0.76-0.90) markers, while the hypodensity (0.67, 95% CI: 0.56-0.76) and blend (0.62, 95% CI: 0.51-0.71) markers showed substantial agreement. Inter-rater agreement was otherwise moderate, and comparable between density and shape markers. Inter-rater agreement was lower for the three markers that require the rater to identify one specific axial slice (Barras density, Barras shape, island: 0.46, 95% CI: 0.40-0.52 versus others: 0.60, 95% CI: 0.56-0.63). Inter-observer agreement did not differ when stratified for raters' experience, hematoma location, volume, or anticoagulation status. Intra-rater agreement was substantial to almost perfect for all but the black hole marker.

CONCLUSION

In a large sample of raters with different backgrounds and expertise levels, only four of nine non-contrast CT markers of ICH expansion showed substantial to almost perfect inter-rater agreement.

KEY POINTS

• In a sample of 15 raters and 60 patients, only four of nine non-contrast CT markers of ICH expansion showed substantial to almost perfect inter-rater agreement (Gwet's AC₁> 0.60). • Intra-rater agreement was substantial to almost perfect for eight of nine hematoma expansion markers. • Only the blend, fluid level, and swirl markers achieved substantial to almost perfect agreement across all three measures of reliability (inter-rater agreement, intra-rater agreement, agreement with the results of a reference reading).

Incidence and Prevalence of Drug-Resistant Epilepsy: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the incidence and prevalence of drug-resistant epilepsy (DRE) as well as its predictors and correlates, we conducted a systematic review and meta-analysis of observational studies.

METHODS

Our protocol was registered with PROSPERO, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-analysis of Observational Studies in Epidemiology reporting standards were followed. We searched MEDLINE, Embase, and Web of Science. We used a double arcsine transformation and random-effects models to perform our meta-analyses. We performed random-effects meta-regressions using study-level data.

RESULTS

Our search strategy identified 10,794 abstracts. Of these, 103 articles met our eligibility criteria. There was high interstudy heterogeneity and risk of bias. The cumulative incidence of DRE was 25.0% (95% confidence interval [CI]: 16.8-34.3) in child studies but 14.6% (95% CI: 8.8-21.6) in adult/mixed age studies. The prevalence of DRE was 13.7% (95% CI: 9.2-19.0) in population/community-based populations but 36.3% (95% CI: 30.4-42.4) in clinic-based cohorts. Meta-regression confirmed that the prevalence of DRE was higher in clinic-based populations and in focal epilepsy. Multiple predictors and correlates of DRE were identified. The most reported of these were having a neurologic deficit, an abnormal EEG, and symptomatic epilepsy. The most reported genetic predictors of DRE were polymorphisms of the ABCB1 gene.

CONCLUSIONS

Our observations provide a basis for estimating the incidence and prevalence of DRE, which vary between populations. We identified numerous putative DRE predictors and correlates. These findings are important to plan epilepsy services, including epilepsy surgery, a crucial treatment option for people with disabling seizures and DRE.

Abstract P608: Risk of Cancer Following an Ischemic Stroke: A Retrospective Cohort Study From the Canadian Longitudinal Study on Aging

Background: Cancer promotes thromboembolism through inflammation and hypercoagulability, and an ischemic stroke may be the first sign of an occult malignancy. Stroke survivors may be at higher risk of incident cancer diagnosis, although the magnitude and the period at risk remain unclear. We conducted a retrospective cohort study to compare the risk of cancer in stroke survivors to that of the general population.

Methods: The Canadian Longitudinal Study on Aging (CLSA) is a large, national population-based cohort of Canadian women and men aged 45-85 years when recruited between 2011 and 2015. Participants provided information on socio-demographics and prior diagnoses. We used data from the comprehensive sub-group (n=30,097) to build a retrospective cohort of participants with and without prior stroke by exact matching for age (1:4 ratio). We used log-binomial regression models to estimate the risk of cancer in people with versus without ischemic stroke while adjusting for shared risk factors.

Results: We included 920 individuals in the stroke group and 3,680 individuals in the control group, respectively followed for a median of 10 (interquartile range [IQR]: 4, 17) and 11 years (IQR: 5, 19). Most inclusion events in the stroke group were minor strokes or transient ischemic attacks (n=614, 66.7%). We observed a higher incidence of cancer in the first year after stroke that declined thereafter (p=0.030). The risk of new cancer diagnosis after stroke was significantly increased (relative risk: 2.38; 95% confidence interval: 1.18, 4.63; p-value=0.012) after adjustments. The most frequent primary cancers in the first year after stroke were prostate (n=8, 57.1%) and melanoma (n=2, 14.3%).

Conclusions: The risk of new cancer diagnosis in the first year after an ischemic stroke is about 2.4 times higher as compared to age-matched individuals from the general population without stroke after adjustments. Surveillance bias may explain a portion of post-stroke cancer diagnoses in the stroke group although a CLSA tendency to recruit healthier participants likely led to an underestimation of post-stroke cancer risk. Prospective experimental trials are needed to quantify the potentially pressing need to screen for post-stroke cancer.

Frequency and predictors of occult cancer in ischemic stroke: A systematic review and meta-analysis

BACKGROUND

The optimal approach for cancer screening after an ischemic stroke remains unclear.

AIMS

We sought to summarize the existing evidence regarding the frequency and predictors of cancer after an ischemic stroke.

SUMMARY OF REVIEW

We searched seven databases from January 1980 to September 2019 for articles reporting malignant tumors and myeloproliferative neoplasms diagnosed after an ischemic stroke (PROSPERO protocol: CRD42019132455). We screened 15,400 records and included 51 articles. The pooled cumulative incidence of cancer within one year after an ischemic stroke was 13.6 per thousand (95% confidence interval [CI], 5.6-24.8), higher in studies focusing on cryptogenic stroke (62.0 per thousand; 95% CI, 13.6-139.3 vs 9.6 per thousand; 95% CI, 4.0-17.3; p = 0.02) and those reporting cancer screening (39.2 per thousand; 95% CI, 16.4-70.6 vs 7.2 per thousand; 95% CI, 2.5-14.1; p = 0.003). Incidence of cancer after stroke was generally higher compared to people without stroke. Most cases were diagnosed within the first few months after stroke. Several predictors of cancer were identified, namely older age, smoking, and involvement of multiple vascular territories as well as elevated C-reactive protein and d-dimers.

CONCLUSIONS

The frequency of incident cancer after an ischemic stroke is low, but higher in cryptogenic stroke and after cancer screening. Several predictors may increase the yield of cancer screening after an ischemic stroke. The pooled incidence of post-stroke cancer is likely underestimated, and larger studies with systematic assessment of cancer after stroke are needed to produce more precise and valid estimates.

Acute carotid stenting in patients undergoing thrombectomy: a systematic review and meta-analysis

BACKGROUND

The benefit of acute carotid stenting compared with no acute stenting on clinical outcomes among patients with tandem lesions (TL) undergoing endovascular thrombectomy (EVT) remains unknown.

METHODS

We conducted a a systematic review and meta-analysis of studies comparing acute carotid stenting versus no stenting among TL patients undergoing EVT with regards to 90 day modified Rankin Scale (mRS) score, symptomatic intracerebral hemorrhage (sICH), and mortality. Four reviewers screened citations for eligibility and two assessed retained studies for risk of bias and data extraction. A random effects model was used for the synthesis of aggregated data.

RESULTS

21 studies (n=1635 patients) were identified for the systematic review; 19 were cohort studies, 1 was a post-hoc analysis of an EVT trial, and 1 was a pilot randomized controlled trial. 16 studies were included in the meta-analysis. Acute stenting was associated with a favorable 90 day mRS score: OR 1.43 (95% CI 1.07, 1.91). No significant heterogeneity between studies was found for this outcome (I²=17.0%; χ²=18.07, p=0.26). There were no statistically significant differences for 3 month mortality (OR 0.80 (95% CI 0.50, 1.28)) or sICH (OR 1.41 (95% CI 0.91, 2.19)).

CONCLUSIONS

This meta-analysis suggests that among TL patients undergoing EVT, acute carotid stenting is associated with a greater likelihood of favorable outcome at 90 days compared with no stenting.