Publications by authors named "Yee Leng Tan"

Background: Epilepsy is associated with increased risk for dementia, which adversely impacts the quality of life for patients and their families. Mild cognitive impairment (MCI) is the prodromal stage of dementia offering an important window for intervention. However, the epilepsy related risk factors for MCI are not well understood.

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Objective: Status epilepticus (SE) in the neurology intensive care unit (ICU) is associated with significant morbidity. We aimed to evaluate the utility of existing prognostic scores, namely the Status Epilepticus Severity Score (STESS), Epidemiology Based Mortality Score in Status Epilepticus (EMSE)-EACE and Encephalitis-Nonconvulsive Status Epilepticus-Diazepam Resistance-Image Abnormalities-Tracheal Intubation (END-IT), among SE patients in the neurology ICU.

Methods: Neurology ICU patients with SE requiring continuous electroencephalography (cEEG) monitoring over a 10 year period were included.

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Introduction: Noninvasive brain imaging tests play a major role in guiding decision-making and the usage of invasive, costly intracranial electroencephalogram (ICEEG) in the presurgical epilepsy evaluation. This study prospectively examined the concordance in localization between ictal EEG source imaging (ESI) and ICEEG as a reference standard.

Methods: Between August 2014 and April 2019, patients during video monitoring with scalp EEG were screened for those with intractable focal epilepsy believed to be amenable to surgical treatment.

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Article Synopsis
  • The study assessed the cost-effectiveness of a mobile app for detecting seizures in people with epilepsy in Singapore, aiming to improve safety and reduce anxiety. !* -
  • Using a Markov cohort model over ten years, the app showed an incremental cost-effectiveness ratio of $1,096 per quality-adjusted life year (QALY) and a high probability of being cost-effective. !* -
  • The findings suggest that the app is a promising alternative to current care methods, but further research is necessary to validate its real-world effectiveness and impact on quality of life.!*
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Objective: Drug-resistant epilepsy (DRE) can have devastating consequences for patients and families. Vagal nerve stimulation (VNS) is used as a surgical adjunct for treating DRE not amenable to surgical resection. Although VNS is generally safe, it has its inherent complications.

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Neurologists typically identify epileptic seizures from electroencephalograms (EEGs) by visual inspection. This process is often time-consuming, especially for EEG recordings that last hours or days. To expedite the process, a reliable, automated, and patient-independent seizure detector is essential.

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Article Synopsis
  • Clinical diagnosis of epilepsy is complicated by the reliance on identifying interictal epileptiform discharges (IEDs) in EEGs, a process that can be biased and time-consuming.
  • There is a lack of automated methods to differentiate between epileptic EEGs, even those without IEDs, and normal EEGs, indicating a need for improved automated systems for EEG interpretation.
  • This study investigates various EEG features and background characteristics to enhance diagnosis accuracy and reports promising results with improved classification metrics for both IEDs and IED-independent EEG features.
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Predictive models provide estimates on an individual's probability of having a disease or developing a disease/disease outcome. Clinicians often use them to support clinical decision-making. Many prediction models are published annually; online versions of models (such as MDCalc and QxMD) facilitate their use at the point of care.

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Article Synopsis
  • The study aimed to evaluate the postsurgical seizure outcomes in temporal lobe epilepsy (TLE) patients with normal or subtle, nonspecific MRI findings and identify factors affecting seizure control after surgery.
  • A retrospective analysis involved 73 patients who underwent surgery at two epilepsy centers between 1999 and 2014, assessing various clinical and surgical factors to predict seizure outcomes using logistic regression.
  • Results showed that 44% of patients achieved favorable seizure control (Engel class I), with positive indicators including focal nonmotor aware seizures and unilateral or no spikes on interictal EEG, suggesting that favorable outcomes are possible even in patients with minimal MRI abnormalities.
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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.

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Article Synopsis
  • The study focuses on improving predictions for seizure freedom after surgery for drug-resistant temporal lobe epilepsy (TLE) using multidimensional Bayesian network classifiers (MBCs), which are advanced probabilistic models.
  • Data from 231 TLE patients across two institutions were analyzed, and the MBC model showed modest predictive performance, achieving an area under the curve (AUC) of 0.67 to 0.72 at various post-surgery time points, outperforming traditional methods like logistic regression.
  • The MBC's ability to capture complex relationships between clinical data and surgical outcomes suggests it may enhance pre-operative counseling for TLE surgery, with potential for further improvement using additional data.
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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).

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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.

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Objective: Focal cortical dysplasias (FCDs) often cause pharmacoresistant epilepsy, and surgical resection can lead to seizure-freedom. Magnetic resonance imaging (MRI) and positron emission tomography (PET) play complementary roles in FCD identification/localization; nevertheless, many FCDs are small or subtle, and difficult to find on routine radiological inspection. We aimed to automatically detect subtle or visually-unidentifiable FCDs by building a classifier based on an optimized cortical surface sampling of combined MRI and PET features.

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Background: Interictal epileptiform discharges are an important biomarker for localization of focal epilepsy, especially in patients who undergo chronic intracranial monitoring. Manual detection of these pathophysiological events is cumbersome, but is still superior to current rule-based approaches in most automated algorithms.

Objective: To develop an unsupervised machine-learning algorithm for the improved, automated detection and localization of interictal epileptiform discharges based on spatiotemporal pattern recognition.

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Whether occurring before or after an epilepsy surgery, psychogenic nonepileptic seizures (PNES) impact treatment options and quality of life of patients with epilepsy. We investigated the frequency of pre- and postsurgical PNES, and the postsurgical Engel and psychiatric outcomes in patients with drug-resistant temporal lobe epilepsy (TLE). We reviewed 278 patients with mean age at surgery of 37.

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Temporal lobe epilepsy (TLE) is the most common focal epilepsy in adults. TLE has a high chance of becoming medically refractory, and as such, is frequently considered for further evaluation and surgical intervention. Up to 30% of TLE cases, however, can have normal ("nonlesional" or negative) magnetic resonance imaging (MRI) results, which complicates the presurgical workup and has been associated with worse surgical outcomes.

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Background: The clinical profile of frontotemporal dementia (FTD) in Southeast Asia is not known. We characterized and compared the demographic and clinical characteristics of FTD patients in Southeast Asia with North Asian and Western patients.

Methods: The study included Southeast Asian FTD patients presenting to a tertiary neurology institute.

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Background: In clinical heart failure (HF), inefficient propagation of blood through the left ventricle (LV) may result from suboptimal vortex formation (VF) ability of the LV during early diastole. We aim to (i) validate echocardiographic-derived vortex formation time (adapted) (VFTa) in control subjects and (ii) examine its utility in both systolic and diastolic HF.

Methods: Transthoracic echocardiography was performed in 32 normal subjects and in 130 patients who were hospitalized with HF [91, reduced ejection fraction (rEF) and 39, preserved ejection fraction (pEF)].

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Introduction: Studies have suggested that women who present with non-ST-segment elevation myocardial infarction (NSTEMI) may differ in their clinical response to early invasive strategy compared to male patients. We examined the impact of gender difference in NSTEMI patients on outcomes following invasive versus conservative treatment.

Materials And Methods: Patients enrolled in our national myocardial infarction (MI) registry between January 2000 and September 2005 with diagnosis of NSTEMI were retrospectively analysed.

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