Polymyxin-induced neuromuscular weakness: a case report

Polymyxin-induced neuromuscular blockade is a rare but potentially fatal condition, with majority of cases that were reported between 1962 and 1973. We describe a patient who developed hypercapnic respiratory failure after initiation of polymyxin for multi-drug resistant Escherichia Coli bacteremia, due to polymyxin-induced neuromuscular dysfunction. After cessation of polymyxin, he regained full strength, had complete resolution of ptosis, and was successfully extubated. In light of the renewed use of polymyxin in this era of antimicrobial-resistance, this case aims to raise awareness about this rare but life-threatening condition, which is easily reversible with early recognition and prompt discontinuation of the drug.

Bridging the Gap: Tailoring an Approach to Treatment in Febrile Infection-Related Epilepsy Syndrome

Cytokine profiling prior to immunotherapy is increasingly prevalent in Febrile infection-related epilepsy syndrome (FIRES). In this case, an 18-year-old boy presented with first-onset seizure after a nonspecific febrile illness. He developed super refractory status epilepticus requiring multiple anti-seizure medications and general anesthetic infusions. He was treated with pulsed methylprednisolone, plasma exchange and ketogenic diet. Contrast-enhanced MRI brain revealed post-ictal changes. EEG showed multifocal ictal runs and generalized periodic epileptiform discharges. Cerebrospinal fluid analysis, autoantibody testing and malignancy screen were unremarkable. Genetic testing revealed variants of uncertain significance (VUS) in the CNKSR2 and OPN1LW genes.Initial serum and CSF cytokine analyses performed on days 6 and 21 revealed that IL-6, IL-1RA, MCP1, MIP1β and IFNγ were elevated predominantly in the CNS, a profile consistent with cytokine release syndrome. Tofacitinib was initially trialed on day 30 of admission. There was no clinical improvement and IL-6 continued to rise. Tocilizumab was given on day 51 with significant clinical and electrographic response. Anakinra was subsequently trialed from days 99 to 103, as clinical ictal activity re-emerged on weaning anesthetics, but stopped due to poor response.Serial cytokine profiles showed improvement after 7 doses of tocilizumab. There was corresponding improved seizure control.This case illustrates how personalized immunomonitoring may be helpful in cases of FIRES, where proinflammatory cytokines are postulated to act in epileptogenesis. There is an emerging role for cytokine profiling and close collaboration with immunologists for the treatment of FIRES. The use of tocilizumab may be considered in FIRES patients with upregulated IL-6.

Combined balloon guide catheter, aspiration catheter, and stent retriever technique versus balloon guide catheter and stent retriever alone technique: a systematic review and meta-analysis

BACKGROUND

The use of a combination of balloon guide catheter (BGC), aspiration catheter, and stent retriever in acute ischemic stroke thrombectomy has not been shown to be better than a stent retriever and BGC alone, but this may be due to a lack of power in these studies. We therefore performed a meta-analysis on this subject.

METHODS

A systematic literature search was performed on PubMed, Scopus, Embase/Ovid, and the Cochrane Library from inception to October 20, 2021. Our primary outcomes were the rate of successful final reperfusion (Treatment in Cerebral Ischemia (TICI) 2c-3) and first pass effect (FPE, defined as TICI 2c-3 in a single pass). Secondary outcomes were 3 month functional independence (modified Rankin Scale score of 0-2), mortality, procedural complications, embolic complications, and symptomatic intracranial hemorrhage (SICH). A meta-analysis was performed using RevMan 5,4, and heterogeneity was assessed using the I² test.

RESULTS

Of 1629 studies identified, five articles with 2091 patients were included. For the primary outcomes, FPE (44.9% vs 45.4%, OR 1.04 (95% CI 0.90 to 1.22), I²=57%) or final successful reperfusion (64.5% vs 68.6%, OR 0.98 (95% CI 0.81% to 1.20%), I²=85%) was similar between the combination technique and stent retriever only groups. However, the combination technique had significantly less rescue treatment (18.8% vs 26.9%; OR 0.70 (95% CI 0.54 to 0.91), I²=0%). This did not translate into significant differences in secondary outcomes in functional outcomes, mortality, emboli, complications, or SICH.

CONCLUSION

There was no significant difference in successful reperfusion and FPE between the combined techniques and the stent retriever and BGC alone groups. Neither was there any difference in functional outcomes, complications, or mortality.

Improving automated diagnosis of epilepsy from EEGs beyond IEDs

Objective.Clinical diagnosis of epilepsy relies partially on identifying interictal epileptiform discharges (IEDs) in scalp electroencephalograms (EEGs). This process is expert-biased, tedious, and can delay the diagnosis procedure. Beyond automatically detecting IEDs, there are far fewer studies on automated methods to differentiate epileptic EEGs (potentially without IEDs) from normal EEGs. In addition, the diagnosis of epilepsy based on a single EEG tends to be low. Consequently, there is a strong need for automated systems for EEG interpretation. Traditionally, epilepsy diagnosis relies heavily on IEDs. However, since not all epileptic EEGs exhibit IEDs, it is essential to explore IED-independent EEG measures for epilepsy diagnosis. The main objective is to develop an automated system for detecting epileptic EEGs, both with or without IEDs. In order to detect epileptic EEGs without IEDs, it is crucial to include EEG features in the algorithm that are not directly related to IEDs.Approach.In this study, we explore the background characteristics of interictal EEG for automated and more reliable diagnosis of epilepsy. Specifically, we investigate features based on univariate temporal measures (UTMs), spectral, wavelet, Stockwell, connectivity, and graph metrics of EEGs, besides patient-related information (age and vigilance state). The evaluation is performed on a sizeable cohort of routine scalp EEGs (685 epileptic EEGs and 1229 normal EEGs) from five centers across Singapore, USA, and India.Main results.In comparison with the current literature, we obtained an improved Leave-One-Subject-Out (LOSO) cross-validation (CV) area under the curve (AUC) of 0.871 (Balanced Accuracy (BAC) of 80.9%) with a combination of three features (IED rate, and Daubechies and Morlet wavelets) for the classification of EEGs with IEDs vs. normal EEGs. The IED-independent feature UTM achieved a LOSO CV AUC of 0.809 (BAC of 74.4%). The inclusion of IED-independent features also helps to improve the EEG-level classification of epileptic EEGs with and without IEDs vs. normal EEGs, achieving an AUC of 0.822 (BAC of 77.6%) compared to 0.688 (BAC of 59.6%) for classification only based on the IED rate. Specifically, the addition of IED-independent features improved the BAC by 21% in detecting epileptic EEGs that do not contain IEDs.Significance.These results pave the way towards automated detection of epilepsy. We are one of the first to analyze epileptic EEGs without IEDs, thereby opening up an underexplored option in epilepsy diagnosis.

Effect of perioperative seizures on mortality and recurrence in patients with brain metastases

Objective

To identify the independent risk factors for 30-day perioperative seizures, as well as to evaluate the effect of perioperative seizures on overall mortality and tumor recurrence among patients who underwent surgical resection of brain metastases.

Methods

Patients who underwent surgical resection of brain metastases at our institution between 2011 and 2019 were included. 30-day perioperative seizures were defined as the presence of any preoperative or postoperative seizures diagnosed by a neurosurgeon or neurologist within 30 days of metastases resection. Independent risk factors for 30-day perioperative seizures were evaluated using multivariate logistic regression models. Kaplan-Meier plots and Cox regression models were constructed to evaluate the effects of 30-day perioperative seizures on overall mortality and tumor recurrence. Subgroup analyses were conducted for 30-day preoperative and 30-day postoperative seizures.

Results

A total of 158 patients were included in the analysis. The mean (SD) age was 59.3 (12.0) years, and 20 (12.7%) patients had 30-day perioperative seizures. The presence of 30-day preoperative seizures (OR=41.4; 95% CI=4.76, 924; p=0.002) was an independent risk factor for 30-day postoperative seizures. Multivariate Cox regression revealed that any 30-day perioperative seizure (HR=3.25; 95% CI=1.60, 6.62; p=0.001) was independently and significantly associated with overall mortality but not tumor recurrence (HR=1.95; 95% CI=0.78, 4.91; p=0.154).

Conclusions

Among patients with resected brain metastases, the presence of any 30-day perioperative seizure was independently associated with overall mortality. This suggests that 30-day perioperative seizures may be a prognostic marker of poor outcome. Further research evaluating this association as well as the effect of perioperative antiepileptic drugs in patients with resected brain metastases may be warranted.

Vagus nerve stimulation for treatment of drug-resistant epilepsy: a systematic review and meta-analysis

To analyze the efficacy and safety of high-frequency VNS versus control (low-frequency VNS or no VNS) in patients with DRE using data from randomized controlled trials (RCTs). An electronic literature search was conducted on PubMed, EMBASE, and Cochrane Controlled Register of Trials (CENTRAL); 12 RCTs reporting seizure frequency or treatment response in studies containing a high-frequency VNS treatment arm (conventional VNS or transcutaneous VNS [tVNS]) compared to control (low-frequency VNS or no VNS) were included. Seizure frequency, treatment response (number of patients with ≥ 50% reduction in seizure frequency), quality of life (QOL), and adverse effects were analyzed. Seizure frequency was reported in 9 studies (718 patients). Meta-analysis with random-effects models favored high-frequency VNS over control (standardized mean difference = 0.82, 95%-CI = 0.39-1.24, p < .001). This remained significant for subgroup analyses of low-frequency VNS as the control, VNS modality, and after removing studies with moderate-to-high risk of bias. Treatment response was reported in 8 studies (758 patients). Random-effects models favored high-frequency VNS over control (risk ratio = 1.57, 95%-CI = 1.19-2.07, p < .001). QOL outcomes were reported descriptively in 4 studies (363 patients), and adverse events were reported in 11 studies (875 patients). Major side effects and death were not observed to be more common in high-frequency VNS compared to control. High-frequency VNS results in reduced seizure frequency and improved treatment response compared to control (low-frequency VNS or no VNS) in patients with drug-resistant epilepsy. Greater consideration for VNS in patients with DRE may be warranted to decrease seizure frequency in the management of these patients.

Time-Frequency Decomposition of Scalp Electroencephalograms Improves Deep Learning-Based Epilepsy Diagnosis

Epilepsy diagnosis based on Interictal Epileptiform Discharges (IEDs) in scalp electroencephalograms (EEGs) is laborious and often subjective. Therefore, it is necessary to build an effective IED detector and an automatic method to classify IED-free versus IED EEGs. In this study, we evaluate features that may provide reliable IED detection and EEG classification. Specifically, we investigate the IED detector based on convolutional neural network (ConvNet) with different input features (temporal, spectral, and wavelet features). We explore different ConvNet architectures and types, including 1D (one-dimensional) ConvNet, 2D (two-dimensional) ConvNet, and noise injection at various layers. We evaluate the EEG classification performance on five independent datasets. The 1D ConvNet with preprocessed full-frequency EEG signal and frequency bands (delta, theta, alpha, beta) with Gaussian additive noise at the output layer achieved the best IED detection results with a false detection rate of 0.23/min at 90% sensitivity. The EEG classification system obtained a mean EEG classification Leave-One-Institution-Out (LOIO) cross-validation (CV) balanced accuracy (BAC) of 78.1% (area under the curve (AUC) of 0.839) and Leave-One-Subject-Out (LOSO) CV BAC of 79.5% (AUC of 0.856). Since the proposed classification system only takes a few seconds to analyze a 30-min routine EEG, it may help in reducing the human effort required for epilepsy diagnosis.

Multi-Center Validation Study of Automated Classification of Pathological Slowing in Adult Scalp Electroencephalograms Via Frequency Features

Pathological slowing in the electroencephalogram (EEG) is widely investigated for the diagnosis of neurological disorders. Currently, the gold standard for slowing detection is the visual inspection of the EEG by experts, which is time-consuming and subjective. To address those issues, we propose three automated approaches to detect slowing in EEG: Threshold-based Detection System (TDS), Shallow Learning-based Detection System (SLDS), and Deep Learning-based Detection System (DLDS). These systems are evaluated on channel-, segment-, and EEG-level. The three systems perform prediction via detecting slowing at individual channels, and those detections are arranged in histograms for detection of slowing at the segment- and EEG-level. We evaluate the systems through Leave-One-Subject-Out (LOSO) cross-validation (CV) and Leave-One-Institution-Out (LOIO) CV on four datasets from the US, Singapore, and India. The DLDS achieved the best overall results: LOIO CV mean balanced accuracy (BAC) of 71.9%, 75.5%, and 82.0% at channel-, segment- and EEG-level, and LOSO CV mean BAC of 73.6%, 77.2%, and 81.8% at channel-, segment-, and EEG-level. The channel- and segment-level performance is comparable to the intra-rater agreement (IRA) of an expert of 72.4% and 82%. The DLDS can process a 30 min EEG in 4 s and can be deployed to assist clinicians in interpreting EEGs.

Automated Adult Epilepsy Diagnostic Tool Based on Interictal Scalp Electroencephalogram Characteristics: A Six-Center Study

The diagnosis of epilepsy often relies on a reading of routine scalp electroencephalograms (EEGs). Since seizures are highly unlikely to be detected in a routine scalp EEG, the primary diagnosis depends heavily on the visual evaluation of Interictal Epileptiform Discharges (IEDs). This process is tedious, expert-centered, and delays the treatment plan. Consequently, the development of an automated, fast, and reliable epileptic EEG diagnostic system is essential. In this study, we propose a system to classify EEG as epileptic or normal based on multiple modalities extracted from the interictal EEG. The ensemble system consists of three components: a Convolutional Neural Network (CNN)-based IED detector, a Template Matching (TM)-based IED detector, and a spectral feature-based classifier. We evaluate the system on datasets from six centers from the USA, Singapore, and India. The system yields a mean Leave-One-Institution-Out (LOIO) cross-validation (CV) area under curve (AUC) of 0.826 (balanced accuracy (BAC) of 76.1%) and Leave-One-Subject-Out (LOSO) CV AUC of 0.812 (BAC of 74.8%). The LOIO results are found to be similar to the interrater agreement (IRA) reported in the literature for epileptic EEG classification. Moreover, as the proposed system can process routine EEGs in a few seconds, it may aid the clinicians in diagnosing epilepsy efficiently.

Automated Detection of Interictal Epileptiform Discharges from Scalp Electroencephalograms by Convolutional Neural Networks

Visual evaluation of electroencephalogram (EEG) for Interictal Epileptiform Discharges (IEDs) as distinctive biomarkers of epilepsy has various limitations, including time-consuming reviews, steep learning curves, interobserver variability, and the need for specialized experts. The development of an automated IED detector is necessary to provide a faster and reliable diagnosis of epilepsy. In this paper, we propose an automated IED detector based on Convolutional Neural Networks (CNNs). We have evaluated the proposed IED detector on a sizable database of 554 scalp EEG recordings (84 epileptic patients and 461 nonepileptic subjects) recorded at Massachusetts General Hospital (MGH), Boston. The proposed CNN IED detector has achieved superior performance in comparison with conventional methods with a mean cross-validation area under the precision-recall curve (AUPRC) of 0.838[Formula: see text]±[Formula: see text]0.040 and false detection rate of 0.2[Formula: see text]±[Formula: see text]0.11 per minute for a sensitivity of 80%. We demonstrated the proposed system to be noninferior to 30 neurologists on a dataset from the Medical University of South Carolina (MUSC). Further, we clinically validated the system at National University Hospital (NUH), Singapore, with an agreement accuracy of 81.41% with a clinical expert. Moreover, the proposed system can be applied to EEG recordings with any arbitrary number of channels.

Deep Learning for Interictal Epileptiform Spike Detection from scalp EEG frequency sub bands

Epilepsy diagnosis through visual examination of interictal epileptiform discharges (IEDs) in scalp electroencephalogram (EEG) signals is a challenging problem. Deep learning methods can be an automated way to perform this task. In this work, we present a new approach based on convolutional neural network (CNN) to detect IEDs from EEGs automatically. The input to CNN is a combination of raw EEG and frequency sub-bands, namely delta, theta, alpha and, beta arranged as a vector for one-dimensional (1D) CNN or matrix for two-dimensional (2D) CNN. The proposed method is evaluated on 554 scalp EEGs. The database consists of 18,164 IEDs marked by two neurologists. Five-fold cross-validation was performed to assess the IED detectors. The resulting 1D CNN based IED detector with multiple sub-bands achieved a false positive rate per minute of 0.23 and a precision of 0.79 at 90% sensitivity. Further, the proposed system is evaluated on datasets from three other clinics, and the features extracted from CNN outputs could significantly discriminate (p-values <; 0.05) the EEGs with and without IEDs. We have proposed an optimized method with better performance than the literature that could aid clinicians to diagnose epilepsy expeditiously, and thereby devise proper treatment.

Rationale and design of a randomized trial of early intensive blood pressure lowering on cerebral perfusion parameters in thrombolysed acute ischemic stroke patients

BACKGROUND AND RATIONALE

Uncertainty persists over the optimal management of blood pressure (BP) in the early phase of acute ischemic stroke (AIS). This study aims to determine the safety and effects of intensive BP lowering on cerebral blood flow (CBF) and functional in AIS patients treated with intravenous thrombolysis.

METHODS

In a randomized controlled trial, 54 thrombolysed AIS patients with a systolic BP of 160 to 180 mm Hg will be randomized to early intensive BP lowering (systolic target range 140-160 mm Hg) or guideline-based BP management (systolic range 160-180 mm Hg) during first 72-hours using primarily intravenous labetalol. We hypothesize that early intensive BP lowering will not reduce CBF by 20% and/or increase the volume of hypoperfused tissue by >20% on computed tomographic perfusion. Clinical outcome will be assessed using a dichotomized modified Rankin scale (scores 0-1 as excellent outcome vs scores 2-6 as dead or dependent) at 90 days. Other outcome would be symptomatic intracerebral hemorrhage. The trial is registered at ClinicalTrials.gov, NCT03443596.

CONCLUSION

This randomized study will provide important information about the physiological effects of BP reduction on cerebral perfusion after intravenous thrombolysis in AIS.

Good Intracranial Collaterals Trump Poor ASPECTS (Alberta Stroke Program Early CT Score) for Intravenous Thrombolysis in Anterior Circulation Acute Ischemic Stroke

BACKGROUND AND PURPOSE

In acute ischemic stroke, large early infarct size estimated by the Alberta Stroke Program Early CT Score (ASPECTS) is associated with poorer outcomes and is a relative contraindication for recanalization therapies. The state of the intracranial collateral circulation influences the functional outcome and may be a variable to consider before thrombolysis. We evaluated the prognostic effect of the collateral circulation in patients with thrombolyzed acute ischemic stroke who have large early infarct sizes as indicated by low ASPECTS.

MATERIALS AND METHODS

Patients with anterior circulation acute ischemic stroke who received a computed tomographic angiogram and subsequent treatment with intravenous tissue-type plasminogen activator from 2010 to 2013 were studied. Two independent neuroradiologists determined their ASPECTS. We stratified patients using ASPECTS into 2 groups: large volume infarcts (ASPECTS≤7 points) and small volume infarcts (ASPECTS 8-10). In addition, we evaluated a third group with very large volume infarcts (ASPECTS≤5 points). We then analyzed the 3 subgroups using the Maas, Tan, and ASPECTS-collaterals grading systems of the computed tomographic angiogram intracranial collaterals. Good outcomes were defined by modified Rankin Scale score of 0 to 2 at 3 months.

RESULTS

A total of 300 patients were included in the final analysis. For patients with very large volume infarcts (ASPECTS≤5 points), univariable analysis showed that younger age, male sex, lower National Institute of Health Stroke Scale (NIHSS), lower systolic blood pressure, and good collaterals by Maas, Tan, or ASPECTS-collaterals grading were predictors of good outcomes. On multivariate analysis, younger age (odds ratio, 0.93; 95% confidence interval, 0.89-0.97; P=0.002) and good collaterals by ASPECTS-collaterals system (odds ratio, 1.34; 95% confidence interval, 1.15-1.57; P<0.001) were associated with good outcomes.

CONCLUSIONS

In patients with large and very large volume infarcts, good collaterals as measured by the ASPECTS-collaterals system is associated with improved outcomes and can help select patients for intravenous thrombolysis.

Intravenous Thrombolysis for Acute Ischemic Stroke due to Cervical Internal Carotid Artery Occlusion

BACKGROUND

Internal carotid artery (ICA) occlusions are poorly responsive to intravenous thrombolysis with tissue plasminogen activator (IV-tPA) in acute ischemic stroke (AIS). Most study populations have combined intracranial and extracranial ICA occlusions for analysis; few have studied purely cervical ICA occlusions. We evaluated AIS patients with acute cervical ICA occlusion treated with IV-tPA to identify predictors of outcomes.

METHODS

We studied 550 consecutive patients with AIS who received IV-tPA and identified 100 with pure acute cervical ICA occlusion. We evaluated the associations of vascular risk factors, National Institutes of Health Stroke Scale (NIHSS) score, and leptomeningeal collateral vessel status via 3 different grading systems, with functional recovery at 90 days, mortality, recanalization of the primary occlusion, and symptomatic intracranial hemorrhage (SICH). Modified Rankin Scale score 0-1 was defined as an excellent outcome.

RESULTS

The 100 patients had mean age of 67.8 (range 32-96) and median NIHSS score of 19 (range 4-33). Excellent outcomes were observed in 27% of the patients, SICH in 8%, and mortality in 21%. Up to 54% of the patients achieved recanalization at 24 hours. On ordinal regression, good collaterals showed a significant shift in favorable outcomes by Maas, Tan, or ASPECTS collateral grading systems. On multivariate analysis, good collaterals also showed reduced mortality (OR .721, 95% CI .588-.888, P = .002) and a trend to less SICH (OR .81, 95% CI .65-1.007, P = .058). Interestingly, faster treatment was also associated with favorable functional recovery (OR 1.028 per minute, 95% CI 1.010-1.047, P = .001).

CONCLUSIONS

Improved outcomes are seen in patients with early acute cervical ICA occlusion and better collateral circulation. This could be a valuable biomarker for decision making.

Abstract 208: Non-gated Cardiac Ct Angiograms for Detection of Embolic Sources in Acute Ischemic Stroke

Background and Purpose: We assessed the diagnostic feasibility of using a 2-phase 64-slice non-gated cardiac computed tomographic angiography (CTA) in acute stroke patients, done in the same sitting as the brain CTA and using the same contrast dose, for the detection of a cardiac source of embolism. We expected to identify additional causes of stroke related to other unexpected pathology of heart or ascending aorta, which might be useful in therapeutic decision making and prognostication.

Methods: We recruited 20 consecutive patients with acute ischemic stroke within the 4.5hours of symptom-onset, activated for intravenous thrombolysis. In addition to our usual CTA protocol that spanned from the arch of aorta to the circle of Willis, we enlarged the field of scanning to include the heart. Radio-contrast load (Omipaque 350) remained unchanged (injected at 3-4ml/sec; total 60-80mls, triggered by bolus tracking). All scans were 0.5cm thick slices and were reviewed by a radiologist and cardiologist and the abnormal findings were conveyed to the treating neurologist. In patients with potential cardiac source of embolism, an urgent trans-thoracic or trans-esophageal echocardiogram was arranged.

Results: Of 20 patients, there were 3 abnormal findings, 1patient had a ventricular thrombus , 1 had a localized dissection in the ascending aorta and the third patient had a thrombus at the atrial appendage. Both were confirmed by trans-esophageal echocardiography and anticoagulation was started urgently the next day. None of our patients developed contrast nephropathy on follow up.

Conclusions: expanding the field of scanning to include the heart and ascending aorta ( a non-gated cardiac CTA) to the routinely performed CTA of cervico-cranial arterial tree is a noninvasive and useful modality for detecting high-risk cardiac and aortic sources of embolism in acute stroke patients.

Abstract 220: Neurovascular Uncoupling in Acute Ischemic Stroke Correlates Well With Clinical Fluctuations in Acute Ischemic Stroke

Background and aims: Fluctuations in neurological status are frequently seen during first few days in thrombolysed acute ischemic stroke (AIS) patients. Underlying mechanisms for these fluctuations often remain unclear. Cerebral homeostatic balance is regulated by autoregulation and neurovascular coupling (NVC). We hypothesized that neurovascular uncoupling in AIS contributes to the fluctuations in neurological status.

Methods: In this ongoing prospective study, consecutive and thrombolyzed AIS patients were recruited within 12 hours of symptom-onset. Serial CT perfusion (CTP) imaging (within 12 hours, at 24 and 72 hours after symptom-onset) were performed. Serial Quantitative EEG (QEEG) were performed, close to CTP imaging. Power within the alpha band (8-15Hz) was determined in each channel using epochs of 10-seconds % calculated for each hemisphere. Continuous transcranial Doppler (TCD) recording were obtained from both middle cerebral arteries, simultaneously with EEG. Neurological status was monitored with serial NIH stroke scale (NIHSS) scores. Neurovascular uncoupling was defined as a mismatch among CTP, QEEG and clinical findings. QEEG, CTP and TCD data were analysed independently by investigators blinded to the clinical findings.

Results: A total of 32 patients (19 male, median age 68 years (range 56-86) were included. Median NIHSS score at recruitment was 8 points (range 1-24). NIHSS fluctuations by 4 or more points (deterioration followed by improvement or deterioration following improvement in absence of re-occlusion) were noted in 13 (40%) cases. Increasing cerebral edema (2 cases) and regional hyperperfusion (4 cases) were seen on serial CTP. Remaining 7 cases showed serial improvement in CTP. QEEG showed significantly increased inter-hemispheric alpha band power ratio (unaffected hemisphere/affected hemisphere ratio more than 1.5), irrespective of the CTP and TCD results, suggestive of neurovascular uncoupling as the underlying mechanism for early neurological fluctuations.

Conclusion: Neurovascular uncoupling is a relatively frequent phenomenon during first few days of acute ischemic stroke. Multi-modal monitoring is useful in identifying these patients for appropriate therapeutic decision making.

Abstract TP54: Topographical Aspects Collateral Score is a Useful Prognostic Factor in Thrombolysed Anterior Circulation Acute Ischemic Stroke Patients

Background: the ASPECTS- collateral score on CT-angiograms was shown to be successful in prognosticating functional outcomes and complications during intravenous thrombolysis in acute ischemic stroke (AIS). We studied predetermined topological information to see if any specific region had more prognostic value.

Methods: consecutive patients from 2010-2014 with intracranial internal carotid artery, M1 or M2 middle carotid artery occlusions treated with intravenous thrombolysis were included. The primary outcome measure was good clinical outcome (3-month modified Rankin Scale score 0-1). We scored each region as 0= no collaterals, 1= poor compared to contralateral and 2= good collaterals. Prognostic value of the 6 cortical ASPECTS-collateral regions in predicting outcomes was determined by multivariable logistic regression.

Results: 310 patients were included (Median age, 66.1±14.5 years; median National Institutes of Health Stroke Scale (NIHSS)- 18 points (range 3-36). Inter-rater reliability for ASPECTS-collaterals was good (κ=0.78). There was no Statistical collinearity among ASPECTS-collateral regions. Using multivariable logistic regression, only the M5 region (odds ratio, 2.72, 95%CI 1.52-4.84, p =0.001), age (OR 0.957 per yr 95%CI 0.936-0.978, p <0.001), Diabetes (OR 0.367, 95%CI 0.193- 0.700, p =0.002) and NIHSSS (OR 0.878 per point, 95%CI 0.836-0.922, p=0.001) were significantly associated with good outcomes. When compared with NIHSS, the receiver operating characteristic curves for NIHSS+M5 (area under the curve, 0.749) correlated well with clinical severity scores. Addition of M5 collateral score showed a statistically significant additive effect to the NIHSS score for predicting good outcomes (Z score: -1.684, p=0.045).

Conclusions: Involvement of the parietal region (M5) regions is a reliable predictor of clinical outcome in anterior circulation large artery occlusion. This simple radiological marker can strengthen the clinical NIHSS score and may be considered during prognostication

How temporal evolution of intracranial collaterals in acute stroke affects clinical outcomes

OBJECTIVE

We compared intracranial collaterals on pretreatment and day 2 brain CT angiograms (CTA) to assess their evolution and relationship with functional outcomes in acute ischemic stroke (AIS) patients treated with IV tissue plasminogen activator (tPA).

METHODS

Consecutive AIS patients who underwent pretreatment and day 2 CTA and received IV tPA during 2010-2013 were included. Collaterals were evaluated by 2 independent neuroradiologists using 3 predefined criteria: the Miteff system, the Maas system, and 20-point collateral scale by the Alberta Stroke Program Early CT Score methodology. We stratified our cohort by baseline pre-tPA state of their collaterals and by recanalization status of the primary vessel for analysis. Good outcomes at 3 months were defined by a modified Rankin Scale score of 0-1.

RESULTS

This study included 209 patients. Delayed collateral recruitment by any grading system was not associated with good outcomes. All 3 scoring systems showed that collateral recruitment on the follow-up CTA from a baseline poor collateral state was significantly associated with poor outcome and increased bleeding risk. When the primary vessel remained persistently occluded, collateral recruitment was significantly associated with worse outcomes. Interestingly, collateral recruitment was significantly associated with increased mortality in 2 of the 3 grading systems.

CONCLUSIONS

Not all collateral recruitment is beneficial; delayed collateral recruitment may be different from early recruitment and can result in worse outcomes and higher mortality. Prethrombolysis collateral status and recanalization are determinants of how intracranial collateral evolution affects functional outcomes.

Assessment of intracranial collaterals on CT angiography in anterior circulation acute ischemic stroke

BACKGROUND AND PURPOSE

Intracranial collaterals influence the prognosis of patients treated with intravenous tissue plasminogen activator in acute anterior circulation ischemic stroke. We compared the methods of scoring collaterals on pre-tPA brain CT angiography for predicting functional outcomes in acute anterior circulation ischemic stroke.

MATERIALS AND METHODS

Two hundred consecutive patients with acute anterior circulation ischemic stroke treated with IV-tPA during 2010-2012 were included. Two independent neuroradiologists evaluated intracranial collaterals by using the Miteff system, Maas system, the modified Tan scale, and the Alberta Stroke Program Early CT Score 20-point methodology. Good and extremely poor outcomes at 3 months were defined by modified Rankin Scale scores of 0-1 and 5-6 points, respectively.

RESULTS

Factors associated with good outcome on univariable analysis were younger age, female sex, hypertension, diabetes mellitus, atrial fibrillation, small infarct core (ASPECTS ≥8), vessel recanalization, lower pre-tPA NIHSS scores, and good collaterals according to Tan methodology, ASPECTS methodology, and Miteff methodology. On multivariable logistic regression, only lower NIHSS scores (OR, 1.186 per point; 95% CI, 1.079-1.302; P = .001), recanalization (OR, 5.599; 95% CI, 1.560-20.010; P = .008), and good collaterals by the Miteff method (OR, 3.341; 95% CI, 1.203-5.099; P = .014) were independent predictors of good outcome. Poor collaterals by the Miteff system (OR, 2.592; 95% CI, 1.113-6.038; P = .027), Maas system (OR, 2.580; 95% CI, 1.075-6.187; P = .034), and ASPECTS method ≤5 points (OR, 2.685; 95% CI, 1.156-6.237; P = .022) were independent predictors of extremely poor outcomes.

CONCLUSIONS

Only the Miteff scoring system for intracranial collaterals is reliable for predicting favorable outcome in thrombolyzed acute anterior circulation ischemic stroke. However, poor outcomes can be predicted by most of the existing methods of scoring intracranial collaterals.

External validation of the Boston Acute Stroke Imaging Scale and M1-BASIS in thrombolyzed patients

BACKGROUND AND PURPOSE

Radiological findings play an essential role in therapeutic decision making and prognostication in acute ischemic stroke (AIS). The Boston Acute Stroke Imaging Scale (BASIS) and Middle Cerebral Artery-BASIS (M1-BASIS) methodologies are rapid purely radiological instruments and easily applicable for patients with AIS. We validated these methods in patients with AIS treated with intravenous tissue-type plasminogen activator.

METHODS

For BASIS, patients were labeled as having major stroke if there was occlusion of distal internal carotid artery, proximal (both M1 and M2 segments) of middle cerebral artery or the basilar artery, or an Alberta Stroke Program Early CT Score≤7. M1-BASIS differs from BASIS by classifying AIS patients with M2 occlusion as a minor stroke. We evaluated these classification systems for predicting functional outcomes (modified Rankin Scale score 0-1) at 3 months.

RESULTS

Two hundred sixty-five consecutive AIS patients treated with intravenous tissue-type plasminogen activator were included. On multivariate analysis, younger age (odds ratio, 1.039, 95% confidence interval, 1.009-1.070; P=0.011), lower National Institutes of Health Stroke Scale score (odds ratio, 1.140; 95% confidence interval, 1.073-1.210; P<0.001), and minor stroke by M1-BASIS (odds ratio, 2.376; 95% confidence interval, 1.047-5.393; P=0.039) were independent predictors of good functional outcome. When compared with National Institutes of Health Stroke Scale, the receiver operating characteristic curves for both BASIS (area under the curve, 0.721) and M1-BASIS (area under the curve, 0.795) correlated well with clinical severity scores. M1-BASIS has an additive effect with the National Institutes of Health Stroke Scale score to predict good outcomes.

CONCLUSIONS

The purely radiological M1-BASIS correlates well with the clinical severity of stroke and can be a reliable prognostication tool in thrombolyzed AIS patients. This system might find an important place in the current era of telestroke.

Should we treat patients with impaired consciousness and periodic patterns on EEG?

PURPOSE

The significance of periodic EEG patterns in patients with impaired consciousness is controversial. We aimed to determine if treating these patterns influences clinical outcome.

METHOD

We studied all patients who had periodic discharges on their EEG recordings from January 2007 to December 2009. Patients with clinical seizures within the preceding 24h, or with unequivocal electrographical seizure activity were excluded. Logistic regression was performed to analyze for factors associated with (a) mortality (b) functional status (c) resolution of EEG pattern.

RESULTS

Of the 4246 patients who had EEG, 111 (2.6%) had periodic EEG patterns. 64 met inclusion criteria. In adjusted analysis, higher mortality was associated with acute symptomatic etiology (OR 17.74, 95% CI 1.61-196.07, p=0.019), and presence of clinical seizures (OR 4.73, 95% CI 1.10-20.34, p=0.037). For each unit decrement of GCS, the odds of inpatient mortality and a poorer functional state on discharge increased by 23% (95% CI 7-37%, p=0.009) and 33% (95% CI 9-51%, p=0.011) respectively. Administration of abortive therapy was an independent risk factor for poorer functional status on discharge (adjusted OR 41.39, 95% CI 2.88-594.42, p=0.006), while patients with history of pre-existing cerebral disease appeared more likely to return to baseline functional status on discharge (unadjusted OR 5.00, 95% CI 1.40-17.86, p=0.013).

CONCLUSION

Treatment of periodic EEG patterns does not independently improve clinical outcome of patients with impaired conscious levels. Occurrence of seizures remote to the time of EEG and lower GCS scores independently predict poor prognoses.

Abstract W P35: Assessment of Collaterals on Day-2 CT Angiography Can Predict Functional Outcome in Thrombolyzed Anterior Circulation Acute Ischemic Stroke

Background: Several methods exist that assess the intracranial collaterals on CT-angiography (CTA) of the brain. We compared existing methods for quantification of collaterals on day-2 CTA in thrombolyzed AIS patients to assess their predictive value for functional outcome.

Methods: Consecutive AIS patients treated with intravenous tissue plasminogen activator (IV-tPA) during 2007-2012 were included. Data were collected for demographics, vascular risk factors, NIHSS scores and stroke subtypes. Intracranial collaterals were evaluated by 2 independent neuroradiologists using 4 existing methods- Miteff’s system (grades middle cerebral artery (MCA) collateral branches with respect to sylvian fissure); Maas system (compares collaterals in affected hemisphere against the contralateral side); Modified Tan’s scale (collaterals in 50% or more of MCA territory classified as good); and 20-point collateral grading scale by Alberta Stroke Program Early CT score (ASPECTS) methodology. Good functional outcome at 3-months was determined by modified Rankin scale (mRS) scores of 0-1.

Results: Day-2 CTA was performed in 150 patients with anterior circulation AIS treated with IV-tPA. Median age 66yrs (range 33-92), 47% males, median NIHSS 19 points (range 4-34) and median onset-to-treatment time 165 minutes (range 74-274). Overall, 67 (44.6%) patients achieved good functional outcome at 3-months. On univariable analysis- younger age, lower pre-tPA NIHSS scores, atrial fibrillation, good collaterals according to ASPECTS scoring and good collaterals by Maas methodology were significantly associated with good functional outcome. On multivariable analysis, lower NIHSS (OR 1.155 per NIHSS point; 95% CI 1.066-1.251, p=0.001), younger age (OR 1.052 per year; 95% CI 1.012-1.094, p=0.010), good collaterals by Maas methodology (OR 2.805 95% CI 1.122 -7.011, p =0.002) and good collaterals (score of 9 or more) by ASPECTS methodology (OR 3.769 ; 95%CI: 1.327- 10.708, p= 0.013 ) were found as independent predictors of good outcome.

Conclusion: Of the existing intracranial collaterals scoring systems, only the ASPECTS and Maas methods are reliable predictor of favourable outcome in thrombolyzed anterior circulation AIS patients.

Abstract T MP29: Impaired Vasodilatory Reserve on Acetazolamide-Challenged 99tc-hmpao-Spect is a Strong Predictor of Stroke Recurrence in Patients With Severe Steno-Occlusive Disease of Intracranial Carotid or Middle Cerebral Artery

Background: Intracranial stenosis carries an increased risk for cerebrovascular ischemia. In severe stenosis, cerebral autoregulation may be impaired due to inadequate cerebral vasodilatory reserve (CVR) & intracranial steal phenomenon (reversed-Robin Hood syndrome-RRHS). Identification of patients with inadequate CVR and RRHS may help in identifying high-risk patients.

Methods: In this prospective study, we included patients with symptomatic and severe stenosis of intracranial carotid (ICA) & middle cerebral artery (MCA). CVR was evaluated with transcranial Doppler (TCD) and breath-holding index (BHI) <0.69 determined inadequate CVR. RRHS was detected as transient velocity reduction in affected artery when flow increased in the reference artery. Patients with RRHS were further evaluated with acetazolamide-challenged 99Tc-HMPAO-SPECT.

Results: 126 patients (80 male, mean age 56yrs; range 23-78yrs) fulfilled our TCD criteria for inadequate CVR. HMPAO-SPECT showed impaired CVR in 84 (67%) patients. RRHS noted on TCD in 38 (45%) patients (median steal magnitude 14%; inter-quartile range, IQR 10) was confirmed by acetazolamide-challenged HMPAO-SPECT (median perfusion deficit 8%; IQR 13%) in 35 (92%) cases (sensitivity 82%, specificity 96% with positive predictive value 96%). A strong relationship between RRHS on TCD and SPECT was noted on ROC curve analysis (area under curve 0.93; 95% confidence interval 0.87-0.98;p<0.00001). Linear relationship was observed between impaired vasodilatory reserve and stroke recurrence during follow up (mean 35months; range 8 to 49months)- 56% in patients with RRHS versus 20% in patients with moderately impaired CVR versus 4% in patients with mildly impaired CVR (chi-square 18.42; df=2; p<0.001 for trend). RRHS on HMPAO-SPECT was an independent predictor of recurrent cerebral ischemic events (RR 1.9, 95%CI 1.2-4.2; p=0.03).

Conclusions: Among patients with severe intracranial stenosis, intracranial steal phenomenon is associated with high risk of cerebral ischemic events. Acetazolamide-challenged HMPAO-SPECT is reliable in the quantification of vasodilatory reserve for selecting a target group of patients for possible revascularization.

Abstract T MP26: Role of 99tc-hmpao Spect in the Assessment of Cerebral Hemodynamic Parameters After Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients With Severe Steno-Occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective: Although superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery in patients with symptomatic carotid occlusion failed to demonstrate any benefit, its role in symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated changes in hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) who underwent STA-MCA bypass for impaired cerebral vasodilatory reserve (CVR).

Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) evaluation and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (<0.69) were further evaluated with acetazolamide-challenged 99Tc-HMPAO-SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. TCD and SPECT were repeated in all patients at 4±1 months and they were followed-up for cerebral ischemic events.

Results: Of the 126 patients (80 male, mean age 56yrs; range 23-78yrs) that fulfilled our inclusion criteria, 84 (67%) showed impaired CVR HMPAO-SPECT. Fifty (60%) of them underwent STA-MCA bypass while 34(40%) received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1 months after surgery showed significant improvement in STA-MCA bypass group. TCD BHI improved from a median (IQR) of -0.05 to 1.1 (p<0.001). Compared to 98% patients with impaired CVR on pre-operative SPECT, only 20% showed abnormal results on post-operative imaging (p<0.001). During follow-up (mean 35 months; range 8 to 49months), only 6/50 (12%) patients in bypass group developed cerebral ischemic events as compared to15/34 (44%) cases on medical therapy (absolute risk reduction 32%, p=0.006).

Conclusion: 99Tc-HMPAO SPECT with acetazolamide challenge is a reliable tool for the assessment of cerebral vasodilatory reserve in patients with severe steno-occlusive disease of intracranial ICA or MCA. STA-MCA bypass surgery in carefully selected patients results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Abstract 2: Extensive Collateral Recruitment after Intravenous Thrombolysis in Acute Ischemic Stroke is Associated with Symptomatic Intracranial Haemorrhage

Background: Various collateral channels are recruited to provide alternative pathways in acute ischemic stroke (AIS), however the relationship with patient outcomes remain unclear. We compared various existing methods of scoring collaterals on the pre-treatment and day-2 computed tomographic angiogram (CTA) of the brain in thrombolyzed AIS patients.

Methods: We included 115 consecutive patients in whom CTA was performed both pre-tPA and on day-2. Intracranial collaterals were evaluated by 2 independent neuroradiologists using 4 existing and one modified method- Miteff’s system (grades middle cerebral artery (MCA) collateral branches with respect to sylvian fissure); Maas system (compares collaterals in affected hemisphere against the contralatral side); Modified Tan’s scale (collaterals in 50% or more of MCA territory classified as good); and 20-point collateral grading scale by Alberta Stroke Program Early CT score (ASPECTS) methodology. For the modified scoring system we adapted ASPECTS methodology into a 14 point score for cortical and internal cerebral veins (ICV) and removing basal ganglia area from scoring. Symptomatic intracranial hemorrhage (SICH) was defined by new bleeding on the CT scan and an increase in NIH stroke scale (NIHSS) by 4 points or more.

Results: On univariate analysis collateral recruitment via the Tan scoring system, ASPECTS method (improvement of ≥6 points), modified scoring system (improvement ≥7 points), hypertension and higher NIHSS score were associated with SICH. On multivariate analysis only collateral recruitment on the Tan scoring system (OR 3.286 95% CI 1.014-11.025, p =0.049), Collateral recruitment on ASPECTS ≥6 points (OR 2.839 95% CI 1.064- 7.576, p = 0.037) and collateral recruitment on the modified scoring system ≥ 7 (OR 4.174 95% CI 1.212-14.372, p = 0.023) were independent predictors of SICH. Interestingly, collateral failure on the day-2 CTA did not show any association with SICH.

Conclusion: Large recruitment of the collateral channels on the day-2 CTA is strongly associated with SICH after thrombolysis . Perhaps, an unregulated cerebral hyperperfusion contributed to SICH and close monitoring along with aggressive blood pressure control might prevent complications.

Abstract W P227: Cerebral Hyperperfusion Syndrome after Intravenous Thrombolysis for Acute Ischemic Stroke

Background: Cerebral hyperperfusion syndrome (CHS) is a recognized complication after surgical revascularization of a chronically atherosclerotic artery. However, this phenomenon is unexpected when an acutely occluded artery is recanalized by IV-TPA for acute ischemic stroke (AIS).In patients with discrepant neuroimaging and clinical findings, our multimodal evaluations revealed CHS in a series of 7 patientsmafter IV- TPA therapy.

Methods: Patients in whom the occluded ICA or MCA in pre-TPA CT-angiogram (CTA) showed recanalization in the day-2 CTA, were observed for any new unexpected neuropsychiatric symptoms/signs. If these were present they underwent multimodal evaluation including serial transcranial Doppler (TCD), quantitative electroencephalography (QEEG) and HMPAO-SPECT. Patients with considerable mismatch between clinical and neuroimaging findings were also included. CHS was deemed to have occurred if the unexpected neuropsychiatric signs corresponded with TCD flow velocity >100% of the contralateral vessel, EEG showed abnormal activity and HMPAO-SPECT scan showed markedly increased cerebral perfusion compared to the contralateral side.

Results: Out of 155 patients treated with IV-TPA, 7 (4.5%) patients fulfilled our definition of CHS. All 7 patients developed the symptoms 2-3 days after IV-TPA. Abnormalities on TCD, QEEG and HMPAO-SPECT were observed in all patients. The unexpected symptoms included generalized headache (4 cases), unexplained persistent drowsiness (3 cases), visual neglect (2 cases), aphasia (2 cases) and severe suicidal thoughts despite complete neurological recovery (1 case). All cases had hypertension prior to the index stroke. Upright posture, fluid restriction and aggressive blood pressure control resulted in rapid resolution of abnormal features in all cases within a week. All patients achieved modified Rankin score 0-1 with no intracranial hemorrhage.

Conclusion: CHS after intravenous thrombolysis in acute ischemic stroke should be suspected in patients that achieve arterial recanalization with unexplained new neuropsychiatric manifestations. Early diagnosis and appropriate management might prevent hemorrhage and achieve good functional outcomes.

Early and continuous neurologic improvements after intravenous thrombolysis are strong predictors of favorable long-term outcomes in acute ischemic stroke

BACKGROUND

Intravenously administered tissue plasminogen activator (IV tPA) remains the only approved therapeutic agent for arterial recanalization in acute ischemic stroke (AIS). Considerable proportion of AIS patients demonstrate changes in their neurologic status within the first 24 hours of intravenous thrombolysis with IV tPA. However, there are little available data on the course of clinical recovery in subacute 2- to 24-hour window and its impact. We evaluated whether neurologic improvement at 2 and 24 hours after IV tPA bolus can predict functional outcomes in AIS patients at 3 months.

METHODS

Data for consecutive AIS patients treated with IV tPA within 4.5 hours of symptom onset during 2007-2011 were prospectively entered in our thrombolyzed registry. National Institutes of Health Stroke Scale (NIHSS) scores were recorded before IV tPA bolus, at 2 and 24 hours. Early neurologic improvement (ENI) at 2 hours was defined as a reduction in NIHSS score by 10 or more points from baseline or an absolute score of 4 or less points at 2 hours. Continuous neurologic improvement (CNI) was defined as a reduction of NIHSS score by 8 or more points between 2 and 24 hours or an absolute score of 4 or less points at 24 hours. Favorable functional outcomes at 3 months were determined by modified Rankin Scale (mRS) score of 0-1.

RESULTS

Of 2460 AIS patients admitted during the study period, 263 (10.7%) received IV tPA within the time window; median age was 64 years (range 19-92), with 63.9% being men, a median NIHSS score of 17 points (range 5-35), and a median onset-to-treatment time of 145 minutes (range 57-270). Overall, 130 (49.4%) thrombolyzed patients achieved an mRS score of 0-1 at 3 months. The female gender, age, and baseline NIHSS score were found to be significantly associated with CNI on univariate analysis. On multivariate analysis, NIHSS score at onset and female gender (odds ratio [OR]: 2.218, 95% confidence interval [CI]: 1.140-4.285; P=.024) were found to be independent predictors of CNI. Factors associated with favorable outcomes at 3 months on univariate analysis were younger age, female gender, hypertension, NIHSS score at onset, recanalization on transcranial Doppler (TCD) monitoring or repeat computed tomography (CT) angiography, ENI at 2 hours, and CNI. On multivariate analysis, NIHSS score at onset (OR per 1-point increase: .835, 95% CI: .751-.929, P<.001), 2-hour TCD recanalization (OR: 3.048, 95% CI: 1.537-6.046; P=.001), 24-hour CT angiographic recanalization (OR: 4.329, 95% CI: 2.382-9.974; P=.001), ENI at 2 hours (OR: 2.536, 95% CI: 1.321-5.102; P=.004), and CNI (OR: 7.253, 95% CI: 3.682-15.115; P<.001) were independent predictors of favorable outcomes at 3 months.

CONCLUSIONS

Women are twice as likely to have CNI from the 2- to 24-hour period after IV tPA. ENI and CNI within the first 24 hours are strong predictors of favorable functional outcomes in thrombolyzed AIS patients.

Complex partial status epilepticus associated with adult H1N1 infection

In the wake of the worldwide H1N1 pandemic, there has been evidence that the H1N1 influenza virus is associated with neurological complications. This is the first report describing status epilepticus in an adult patient with H1N1 virus infection, to our knowledge. This patient had no prior history of epilepsy and presented with complex partial status epilepticus. This was further illustrated on electroencephalographs and MRI brain changes that corresponded with the patient's clinical state and which subsequently resolved on follow-up. Although uncommon, H1N1 infections may result in central nervous system complications in adults and it is crucial to treat such patients with urgency.

Using continuous electroencephalography in the management of delayed cerebral ischemia following subarachnoid hemorrhage

BACKGROUND

Using clinical parameters to identify and monitor treatment response in patients with delayed cerebral ischemia (DCI) following subarachnoid hemorrhage is challenging. We sought to determine whether continuous electroencephalography (CEEG) aids the prediction of the clinical course and response to treatment of DCI.

METHODS

Patients deemed high-risk for DCI based on the modified Fisher scale were prospectively monitored. A novel CEEG parameter measuring relative alpha power and variability in the anterior brain quadrants termed composite alpha index (CAI) was graphically displayed. Predictions of the status of patients for the ensuing day were made by an independent reviewer, first using clinical data then repeated following the addition of CAI trends. These were compared to the actual clinical state. The reviewer was blinded to the presence and treatment of DCI. Patients with DCI were further studied by trending the daily mean alpha power against the modulation of treatment and clinical evolution.

RESULTS

Fifty-nine predictions were made in 12 patients (mean age 54.3 years, range 35-70; nine females) with Hunt-Hess grades ranging I-V. Sensitivity of predicting clinical deterioration with CEEG improved from 40 to 67% and clinical improvement from 8 to 50%. In three patients, CEEG was predictive greater than 24 h prior to clinical change. Tracking the daily mean alpha power accurately identified DCI recurrence and poor responders to first-line therapy at pre-clinical stages.

CONCLUSION

CEEG is a useful non-invasive tool to supplement routine clinical parameters in the prediction of DCI. It can dynamically monitor the response to treatment and might aid pre-clinical management decisions.

The clinico-radiological spectrum of isolated cortical vein thrombosis

Isolated cortical vein thrombosis (ICVT) in the absence of sinus or great venous involvement is rare. Various MRI sequences have been proposed for diagnostic accuracy, although follow-up data are limited. The optimal management strategy remains uncertain. Patients with ICVT treated between 2006 and 2008 were retrospectively studied. Diagnostic and follow-up neuroimaging were reviewed independently, and we evaluated their treatment and outcomes. Five patients (mean age 41 years; range, 25-54 years) were included. All presented with seizures. Focal neurological deficits were noted in one patient only. T2 susceptibility-weighted MRI abnormalities were observed in all patients. T2-weighted parenchymal hyperintensities involving the cortical-subcortical regions around the ICVT had completely resolved on follow-up scans. Clinical outcomes were uniformly good, despite variable treatment strategies. We observed significant, yet reversible, parenchymal T2-weighted MRI lesions in our patients with ICVT. Follow-up clinical and radiological studies demonstrate recovery independent of treatment regimes. T2-weighted MRI was found to be a useful diagnostic tool and might improve diagnostic accuracy in carefully selected patients with new-onset seizures.

BOLD signal changes preceding negative responses in EEG-fMRI in patients with focal epilepsy

PURPOSE

In simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), increased neuronal activity from epileptiform spikes commonly elicits positive blood oxygenation level-dependent (BOLD) responses. Negative responses are also occasionally seen and have not been explained. Recent studies describe BOLD signal changes before focal EEG spikes. We aimed to systematically study if the undershoot of a preceding positive response might explain the negative BOLD seen in the focus.

METHODS

Eighty-two patients with focal epilepsy who underwent EEG-fMRI at 3T were retrospectively studied. Studies with a focal negative BOLD response in the region of the spike field were reanalyzed using models with hemodynamic response functions (HRFs) peaking from -9 to +9 s around the spike.

RESULTS

Eight patients met the inclusion criteria, showing negative BOLD responses in the spike field on standard analysis. None had positive BOLD responses immediately adjacent to the areas of deactivation. Regions of deactivation were found to have congruent preceding positive responses in two cases. These early activations were seen at the combined maps of -5 to -9 s.

DISCUSSION

This study indicates that in a small proportion of patients with focal epilepsy in whom the standard analysis reveals focal negative responses, an earlier positive BOLD response is probably the cause. The origin of negative BOLD signal changes in the focus as a result of an epileptic event remains, however, unexplained in most of the patients in whom it occurs.

Generalised convulsive status epilepticus in Singapore: clinical outcomes and potential prognostic markers

PURPOSE

To study the characteristics, outcomes and prognostic markers of convulsive status epilepticus (SE) in Singapore.

METHODS

62 adult admissions to the National University Hospital Singapore from 2002 to 2005 were studied. Ethnicity, history of epilepsy, educational subnormality, neuroimaging, seizure duration, length of stay, Modified Rankin Scale (MRS) pre and post discharge, blood glucose, creatine kinase, potassium, white cell and platelet count were recorded. An MRS> or =3 at discharge was defined as a poor outcome. ROCs of significant variables were plotted to identify the best test cut-offs.

RESULTS

Mean age was 59.2 years (range 20-94). 75.9% patients had epilepsy. Mean length of stay was 14 days (range 1-75). Univariate analyses revealed age (p=0.01, OR 1.075, 95% CI 1.030-1.122), length of stay in ICU (p=0.03, OR 1.299, 95% CI 1.014-1.665) and hospital (p=0.014, OR 1.203, 95% CI 1.038-1.393) and hyperglycemia (p=0.045, OR 1.327, 95% CI 1.007-1.750) associated with poor outcome. Test cut-off values for prognostic markers were established: age> or =55 years (ROC 0.790, sensitivity 72.3, specificity 85.7, PPV9 4.4%, NPV 48.8%) and serum glucose> or =7 mmol/L (ROC 0.737, sensitivity 72.3, specificity 80.0, PPV 93.5%, NPV 36.4%). A discriminant model using these variables was then constructed with probability scores for poor outcome.

DISCUSSION

Age, hyperglycemia and length of stay in hospital influenced outcome from convulsive SE in the local population with hyperglycemia being a novel prognostic marker. Some prognostic markers cited in the literature differed, highlighting the possibility that these indicators may vary across population groups.

Ultrasound Assisted Thrombolysis in Acute Ischaemic Stroke: Preliminary Experience in Singapore

Background and Aim: Intravenously-administered tissue plasminogen activator (IV-TPA) induces thrombolysis and remains the only FDA-approved therapy for acute ischaemic stroke. IV-TPA thrombolysis has been approved recently in Singapore for acute stroke. Continuous exposure of clot to 2-MHz pulsed-wave transcranial Doppler (TCD) ultrasound during IV-TPA infusion is known to augment thrombolysis. We aimed to determine the feasibility, safety and efficacy of ultrasound-assisted thrombolysis in acute ischaemic stroke in Singapore. Subjects and Methods: Consecutive patients with acute ischaemic stroke due to intracranial arterial-occlusions were treated with standard IV-tPA and continuously monitored with 2-MHz TCD according to the CLOTBUST-trial protocol. Arterial recanalisation was determined with Thrombolysis in Brain Ischemia (TIBI) flow-grading system. Safety and efficacy of ultrasoundassisted thrombolysis were assessed by rates of symptomatic intracranial haemorrhage (sICH) and functional recovery at 1 month, respectively. Results: Five consecutive patients (mean age 58 years, 3 men and 3 of Chinese ethnicity) were included. Mean time elapsed between symptom onset and presentation to emergency room was 98 minutes (range, 50 to 135 minutes) while the mean time interval between symptom onset to IV-TPA bolus was 144 minutes (range, 125 to 180 minutes). Partial or complete recanalisation with reduction in the stroke severity was noted in 4 out of the 5 patients during IV-TPA infusion (mean change in NIHSS = 4 points; range 2 to 8 points). None of our patients developed sICH while 4 patients demonstrated good functional outcome at 1 month. Conclusions: Our preliminary study demonstrates the feasibility, safety and efficacy of ultrasound-assisted thrombolysis in acute ischaemic stroke in Singapore. Continuous TCD-monitoring during IV-TPA infusion provides real-time information, enhances thrombolysis and improves functional outcomes in acute ischaemic stroke. Key words: Acute ischaemic stroke, Thrombolysis, Transcranial Doppler

Ultrasound assisted thrombolysis in acute ischaemic stroke: preliminary experience in Singapore

BACKGROUND AND AIM

Intravenously-administered tissue plasminogen activator (IV-TPA) induces thrombolysis and remains the only FDA-approved therapy for acute ischaemic stroke. IV-TPA thrombolysis has been approved recently in Singapore for acute stroke. Continuous exposure of clot to 2-MHz pulsed-wave transcranial Doppler (TCD) ultrasound during IV-TPA infusion is known to augment thrombolysis. We aimed to determine the feasibility, safety and efficacy of ultrasound-assisted thrombolysis in acute ischaemic stroke in Singapore.

SUBJECTS AND METHODS

Consecutive patients with acute ischaemic stroke due to intracranial arterial-occlusions were treated with standard IV-tPA and continuously monitored with 2-MHz TCD according to the CLOTBUST-trial protocol. Arterial recanalisation was determined with Thrombolysis in Brain Ischemia (TIBI) flow-grading system. Safety and efficacy of ultrasoundassisted thrombolysis were assessed by rates of symptomatic intracranial haemorrhage (sICH) and functional recovery at 1 month, respectively.

RESULTS

Five consecutive patients (mean age 58 years, 3 men and 3 of Chinese ethnicity) were included. Mean time elapsed between symptom onset and presentation to emergency room was 98 minutes (range, 50 to 135 minutes) while the mean time interval between symptom onset to IV-TPA bolus was 144 minutes (range, 125 to 180 minutes). Partial or complete recanalisation with reduction in the stroke severity was noted in 4 out of the 5 patients during IV-TPA infusion (mean change in NIHSS = 4 points; range 2 to 8 points). None of our patients developed sICH while 4 patients demonstrated good functional outcome at 1 month.

CONCLUSIONS

Our preliminary study demonstrates the feasibility, safety and efficacy of ultrasound-assisted thrombolysis in acute ischaemic stroke in Singapore. Continuous TCD-monitoring during IV-TPA infusion provides real-time information, enhances thrombolysis and improves functional outcomes in acute ischaemic stroke.

Outcome of Severe Head Injured Patients Admitted to Intensive Care During Weekday Shifts Compared to Nights and Weekends

Introduction: Some studies have demonstrated an increased risk of death for patients admitted at nights or during weekends. This study was undertaken to investigate the demographic profile, medical interventions and outcome of severe head injury patients stratified according to day and time of admission to a specialised neurosciences intensive care unit (NICU). Materials and Methods: A retrospective study using a prospectively maintained severe head injury database in a tertiary hospital. Admissions to the NICU were grouped into weekdays, weeknights and weekends. A comparison of patients admitted during the day and night hours were also made. Results: A total of 838 severe head injury patients admitted to NICU were included in the study, of which 263 were admitted on weekdays, 327 on weeknights and 248 on weekends. More patients were admitted during the night (496) compared to during the day (342). There were no significant differences in the demographic profile, mechanism of injury, severity of injury, need for neurosurgical intervention, and duration of mechanical ventilation, intensive care unit (ICU) stay and mortality associated with day and time of admission. In multivariate analyses controlling for confounding factors, no statistically significant difference in ICU mortality was found with the day and time of admission. Conclusions: There were more severe head injury patients admitted to ICU at night and on weekends, with no significant difference in demographic profile, types of injuries, need for neurosurgical interventions and duration of ICU stay and mortality in a specialised NICU with adequate staffing and requisite diagnostic and therapeutic modalities available. Key words: Cerebral ischaemia, CT angiography, Transcranial Doppler

Validation of Transcranial Doppler with CT Angiography in Cerebral Ischaemia: A Preliminary Pilot Study in Singapore

Introduction: Transcranial Doppler (TCD) is an established tool for the non-invasive assessment of cerebral blood flow. Since TCD results vary with the skills and experience of the sonographer, it requires validation against contrast angiography. We evaluated the diagnostic accuracy of TCD against computed tomography angiography (CTA) and the feasibility of the latter as an additional screening tool in our acute ischaemic stroke patients. Materials and Methods: Our stroke unit manages about 700 patients annually. Acute stroke patients undergo TCD for vascular assessment of major arteries of the circle of Willis. Randomly selected acute stroke patients with significant stenosis on TCD underwent high-resolution cranial CTA with multidetector helical scanner. CTA was performed within 24 hours of TCD and images were interpreted by a neuroradiologist blinded to TCD findings. An independent neurosonologist re-evaluated TCD if CTA findings were contradictory. Additional information by either modality was also noted. Results: Fifteen patients (12 men, mean age 61 ± 15years) with cerebral ischaemia and moderate (>50%) stenosis in ≥1 large intracranial arterial segment on routine TCD were evaluated by CTA. Compared with 21 segments of significant stenosis on CTA, TCD showed 16 true-positive, 3 false-positive and 5 false-negative results (sensitivity: 76.2%, positive predictive value: 84.2%). In 3 cases, TCD showed findings complementary to CTA (real-time embolisation, collateral flow patterns, evidence of distal M2 branch occlusion). Conclusion: TCD in our neurovascular laboratory shows a satisfactory agreement with cranial CTA in evaluating patients with cerebral ischaemia. TCD can provide additional real-time dynamic findings complementary to information provided by CTA. Key words: Cerebral ischaemia, CT angiography, Transcranial Doppler