Browsing by Author "Leal, Alberto"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
- A custom-built single-channel in-ear electroencephalography sensor for sleep phase detection: an interdependent solution for at-home sleep studiesPublication . Borges, Daniel Filipe; Soares, Joana Isabel; Silva, Heloísa; Felgueiras, João; Batista, Carla; Ferreira, Simão; Rocha, Nuno; Leal, AlbertoSleep is vital for health. It has regenerative and protective functions. Its disruption reduces the quality of life and increases susceptibility to disease. During sleep, there is a cyclicity of distinct phases that are studied for clinical purposes using polysomnography (PSG), a costly and technically demanding method that compromises the quality of natural sleep. The search for simpler devices for recording biological signals at home addresses some of these issues. We have reworked a single-channel in-ear electroencephalography (EEG) sensor grounded to a commercially available memory foam earplug with conductive tape. A total of 14 healthy volunteers underwent a full night of simultaneous PSG, in-ear EEG and actigraphy recordings. We analysed the performance of the methods in terms of sleep metrics and staging. In another group of 14 patients evaluated for sleep-related pathologies, PSG and in-ear EEG were recorded simultaneously, the latter in two different configurations (with and without a contralateral reference on the scalp). In both groups, the in-ear EEG sensor showed a strong correlation, agreement and reliability with the ‘gold standard’ of PSG and thus supported accurate sleep classification, which is not feasible with actigraphy. Single-channel in-ear EEG offers compelling prospects for simplifying sleep parameterisation in both healthy individuals and clinical patients and paves the way for reliable assessments in a broader range of clinical situations, namely by integrating Level 3 polysomnography devices. In addition, addressing the recognised overestimation of the apnea-hypopnea index, due to the lack of an EEG signal, and the sparse information on sleep metrics could prove fundamental for optimised clinical decision making.
- Ictal and interictal source connectivity during gelastic seizures in a focal cortical dysplasia of the cingulate gyrusPublication . Borges, Daniel Filipe; Dias, Daniela; Cordeiro, Helena; Leal, AlbertoGelastic seizures are rare manifestations of epilepsy often associated with hypothalamic hamartomas (HH). In the absence of HH, localization of the origin is more difficult and there are several less well-established possibilities. Non-invasive assessment is often complicated by the deep localization of the epileptogenic area and the complex dynamics of spike activity. Robust neurophysiologic methods and careful validation of intrinsically epileptogenic lesions detected by RM can improve the validity of scalp EEG analysis. To analyze the dynamics of epileptic activity in gelastic seizures associated with cortical dysplasia. A 26-year-old girl with daily refractory gelastic seizures since the age of 6 underwent a neurophysiological assessment with long-term EEG recordings (24h, 31 channels) and an MRI of the brain. She had previously been rejected in an epilepsy surgery program because no structural brain lesion had been found and the EEG information was not informative enough. A recent 3T MRI showed cortical dysplasia in the cingulate gyrus, which was highly suspicious as an epileptogenic focus. We analyzed the 31-channel EEG (ictal and interictal) using source and functional connectivity methods to obtain a solid computer model of the origin and dynamics of epileptic activity and correlate it with the anatomical information of the MRI. Source analysis of interictal activity revealed multiple sources that dominated at different time points, indicating considerable dynamics that prevented clear source identification. The ictal recordings demonstrated barely late rhythmic activity over the frontal areas, but no early focalization. Connectivity analysis, which revealed the flow of information between cortical sources, showed a consistent origin of epileptic activity in the vicinity of cortical dysplasia for both interictal and ictal activity. EEG connectivity analysis significantly improves the performance of non-invasive methods for determining intracranial dynamics of epileptic activity and correlation with structural lesions.
- Is a hypothalamic hamartoma always a suspect in gelastic seizures? A source functional connectivity studyPublication . Borges, Daniel Filipe; Leal, AlbertoGelastic seizures are rare manifestations of epilepsy that are often associated with hypothalamic hamartomas (HH). In the absence of HH, location of the origin is more difficult and there are several less well-established possibilities. Non-invasive assessment is often complicated by the deep localization of the epileptogenic area and the complex dynamics of spike activity. Robust neurophysiological methods and careful validation of intrinsically epileptogenic lesions detected by RM can improve the validity of scalp EEG analysis. This presentation will discuss a case report analysing the dynamics of epileptic activity in gelastic seizures associated with cortical dysplasia. The clinical case was a 26-year-old girl with daily refractory gelastic seizures since the age of 6 who underwent neurophysiological examination with long-term EEG recordings and MRI of the brain. She had previously been rejected in an epilepsy surgery programme because no structural brain lesion had been found and the EEG information was not conclusive enough. A recent 3T MRI showed cortical dysplasia in the cingulate gyrus, which was highly suspicious as an epileptogenic focus. We analysed the 31-channel EEG (ictal and interictal) using source and functional connectivity methods to obtain a solid computer model of the origin and dynamics of the epileptic activity and correlate it with the anatomical information of the MRI. Source analysis of the interictal activity revealed multiple sources that dominated at different time points, suggesting considerable dynamics that prevented clear identification of the source. The ictal recordings showed little late rhythmic activity over the frontal areas, but no early focalization. Connectivity analysis, which revealed the flow of information between cortical sources, showed a consistent origin of epileptic activity near the cortical dysplasia for both interictal and ictal activity. EEG connectivity analysis significantly improves the performance of non-invasive methods for determining the intracranial dynamics of epileptic activity and correlation with structural lesions.
- Neurophysiology in the WildPublication . Borges, Daniel Filipe; Leal, AlbertoIntroduction: The acquisition of bioelectrical signals from the nervous system is traditionally complex, prone to artifacts and technically demanding. Currently, there are signs that research in this field is saturated and confined to institutional walls due to the cost-effectiveness profile of the methods used. Therefore, the demand for portable technology has grown exponentially to significantly increase the amount of data collected. Therefore, epilepsy, specifically regarding long-term electroencephalography (EEG), and sleep medicine are two of the best examples of the clinical utility of wearables for real-world (Level IV) studies. Objective: Development of clinical and translational research based on the development, application and clinical validation of neurophysiological wearable technology to study neural networks in different clinical contexts. Methods: Using a tailor-made 2-channel EEG wearable device and a customized single-channel EEG sensor inserted into the external auditory canal, we conducted three clinical validation studies in patients' homes. We detected and sonified typical absence seizures in pediatric epilepsy patients, studied patients with clinically suspected temporal lobe epilepsy, and recorded and staged 30-second epochs from sleep studies of healthy and pathological subjects. Results: The wearable devices employed showed neurophysiological data with consistently strong positive correlations, consistent performance and high reliability compared to gold standard methods, as well as near perfect inter-observer agreement. Conclusions: Clinical neuroscientists require large amounts of data, so these developments, driven largely by the influx of gadgets in the consumer market, are enabling more do-it-yourself and quantified-self methods. These neurophysiological signals from wearables hold great promise for advancing neuroscience through real-world data.
- Reading epilepsy and hyperexcitability of the visual word form areaPublication . Borges, Daniel Filipe; Leal, AlbertoReading epilepsy recruits critical language-related areas, with synchronization and subsequent spreading of excitation in response to the epileptogenic stimulus. The mechanism by which possible generalized discharges result in the expression of bilateral or unilateral clinical symptoms remains controversial. The cortical and subcortical areas involved may constitute part of the normal reading network, such as the visual word form area (VWFA). A right-handed, 59-year-old man was diagnosed with epilepsy at the age of 15 after tonic-clonic seizures. Later, the patient described myoclonic jerks of the masticatory and perioral muscles while reading. A multimodal approach with magnetic resonance imaging and ambulatory and video-electroencephalogram was used for seizure characterization and source analysis. A left hemisphere spontaneous occipitotemporal epileptic focus, activated by reading, was observed, spreading broadly throughout frontal and temporal language networks. There was an abnormally increased cortical response to visual word presentation in comparison to pseudowords. Spatial localization of spike sources suggested a close association between the primary epileptic focus and the VWFA. This epileptiform activity seems to be selectively triggered at an early stage of lexical processing, with a functional connection between the epileptic network and the VWFA. This multimodal and functional connectivity approach could be helpful in determining the epileptic network in reading epilepsy.
- Sleep stage detection: a clinical validation study of a custom-built single-channel in-ear EEG sensorPublication . Borges, Daniel Filipe; Soares, Joana I.; Silva, Heloísa; Felgueiras, João; Batista, Carla; Ferreira, Simão; Rocha, Nuno; Leal, AlbertoIntroduction:Sleep is vital for health. It has regenerative and protective functions, and its disruption reduces the quality of life and increases susceptibility to disease. During sleep, there is a cyclicity of distinct phases that are studied using polysomnography (PSG), a costly and technically demanding method that compromises the quality of natural sleep. The search for simpler devices for recording biological signals at home addresses some of these issues. Objective: To clinically validate a custom-built single-channel in-ear EEG sensor for sleep classification by assessing various sleep metrics and staging decisions with simultaneously recorded PSG. Methods: Prospective cross-sectional study with 28 participants, divided into two groups: healthy volunteers and clinical patients. In both groups, PSG, individual in-ear EEG- with two different electrode configurations- and actigraphic recordings (only in the healthy group) were performed simultaneously for a whole night. Statistical analysis focussed on the four main sleep metrics: TRT (total recording time), TST (total sleep time), SE (sleep efficiency), SL (sleep latency) and the 5-class classifications (wakefulness, N1, N2, N3 and REM sleep). This included correlation analyses between methods and Bland-Altman plots, Cohen’s K coefficient, and confusion matrices aiming 30-second epoch-wise agreement with an automatic sleep classification algorithm using visual sleep classification by an ERSR-certified human expert as the gold standard according to current AASM guidelines. Results: The analysed sleep data comprised 30960 epochs. The correlation analysis revealed strong positive correlations (0.90) for all variables for the in-ear sensor. The Bland-Altman plots show a high level of agreement and consistency (+- 1.87 SD), with minimal bias between methods. The average kappa values (0.75) and the confusion matrices with each method's sensitivity and specificity also show a very high level of concordance.Conclusions: In both groups, the in-ear EEG sensor showed strong correlation, agreement and reliability with the gold standard, supporting accurate sleep classification.
- Spike detection in the wild: Screening of suspected temporal lobe epilepsy cases using a tailored 2-channel wearable EEGPublication . Borges, Daniel Filipe; Soares, Joana Isabel; Dias, Daniela; Cordeiro, Helena; Leal, Alberto; Borges, Daniel FilipeTo clinically validate the contribution of a custom-built-wearable device (waEEG) compared to a full 10–20 electrode array ambulatory EEG (aEEG) for screening epilepsy cases in patients with suspected temporal lobe epilepsy (TLE) but negative routine EEGs. Patients (aged 16–91 years) with clinically suspected TLE who were referred for a 24 h aEEG were fitted with an additional 2-channel bipolar waEEG device and prospectively enrolled in the study until 20 TLE diagnoses were confirmed by aEEG. 41 patients were included and their waEEG was blindly reviewed by two experienced clinical neurophysiologists and a semi-automated spike detection software to categorize patients into TLE (spikes present) and non-TLE (no spikes) groups. The experts achieved good sensitivity (95%–100%) and accuracy (98%–93%) with excellent interrater agreement (kappa>0.80) in patient labelling. The semi-automated software performed poorly (40% sensitivity, 68% accuracy) and failed to classify TLE in more than half the cases. Classification was not affected by restricting spike detection to the evening and night time, which reduced the average length of the analyzed EEG from 23.4 to 10.4 h. Three false-positive spike detections were thoroughly analyzed and reclassified as artifacts due to eye and body movements and electrocardiographic contamination. To better control cardiac artifacts, the addition of an ECG channel to the waEEG is recommended. Detection of spikes with waEEG allows accurate detection of epilepsy in suspected TLE cases, with less technical and professional effort and improved acceptance. This screening tool could improve the yield of follow-up with a conventional aEEG and provide an accessible method for monitoring interictal epileptiform activity in TLE. Epilepsy is a chronic short circuit in the brain. In adults, it most often affects the temporal lobes, resulting in temporal lobe epilepsy (TLE). Seizures are infrequent but difficult to treat. Electroencephalography (EEG) is the best method to detect the electrical disturbances and is crucial to distinguish epilepsy from other non-epileptic disorders. Developing simple, inexpensive and easily accessible portable EEG methods that complement in-hospital assessment could significantly impact patient care. Our study aims to clinically validate a wearable epilepsy screening device to aid in TLE management, reduce delays in diagnosis and enable straightforward assessment of epileptic activity.
- The sound of silence: Quantification of typical absence seizures by sonifying EEG signals from a custom‐built wearable devicePublication . Borges, Daniel Filipe; Fernandes, João; Soares, Joana Isabel; Casalta‐Lopes, João; Carvalho, Daniel; Beniczky, Sándor; Leal, AlbertoObjective: To develop and validate a method for long- term (24- h) objective quantification of absence seizures in the EEG of patients with childhood absence epilepsy (CAE) in their real home environment using a wearable device (waEEG), comparing automatic detection methods with auditory recognition after seizure sonification. Methods: The waEEG recording was acquired with two scalp electrodes. Automatic analysis was performed using previously validated software (Persyst® 14) and then fully reviewed by an experienced clinical neurophysiologist. The EEG data were converted into an audio file in waveform format with a 60- fold time compression factor. The sonified EEG was listened to by three inexperienced observers and the number of seizures and the processing time required for each data set were recorded blind to other data. Quantification of seizures from the patient diary was also assessed. Results: Eleven waEEG recordings from seven CAE patients with an average age of 8.18 ± 1.60 years were included. No differences in the number of seizures were found between the recordings using automated methods and expert audio assessment, with significant correlations between methods (ρ > .89, p < .001) and between observers (ρ > .96, p < .001). For the entire data set, the audio assessment yielded a sensitivity of .830 and a precision of .841, resulting in an F1 score of .835. Significance: Auditory waEEG seizure detection by lay medical personnel provided similar accuracy to post- processed automatic detection by an experienced clinical neurophysiologist, but in a less time- consuming procedure and without the need for specialized resources. Sonification of long- term EEG recordings in CAE provides a user- friendly and cost- effective clinical workflow for quantifying seizures in clinical practice, minimizing human and technical constraints.
- The sound of silence: Quantification of typical absence seizures by sonifying EEG signals from a custom‐built wearable devicePublication . Borges, Daniel Filipe; Fernandes, João; Soares, Joana Isabel; Casalta‐Lopes, João; Carvalho, Daniel; Beniczky, Sándor; Leal, AlbertoTo develop and validate a method for long-term (24-h) objective quantification of absence seizures in the EEG of patients with childhood absence epilepsy (CAE) in their real home environment using a wearable device (waEEG), comparing automatic detection methods with auditory recognition after seizure sonification. The waEEG recording was acquired with two scalp electrodes. Automatic analysis was performed using previously validated software (Persyst® 14) and then fully reviewed by an experienced clinical neurophysiologist. The EEG data were converted into an audio file in waveform format with a 60-fold time compression factor. The sonified EEG was listened to by three inexperienced observers and the number of seizures and the processing time required for each data set were recorded blind to other data. Quantification of seizures from the patient diary was also assessed. Eleven waEEG recordings from seven CAE patients with an average age of 8.18 ± 1.60 years were included. No differences in the number of seizures were found between the recordings using automated methods and expert audio assessment, with significant correlations between methods (ρ > .89, p < .001) and between observers (ρ > .96, p < .001). For the entire data set, the audio assessment yielded a sensitivity of .830 and a precision of .841, resulting in an F1 score of .835. Auditory waEEG seizure detection by lay medical personnel provided similar accuracy to post-processed automatic detection by an experienced clinical neurophysiologist, but in a less time-consuming procedure and without the need for specialized resources. Sonification of long-term EEG recordings in CAE provides a user-friendly and cost-effective clinical workflow for quantifying seizures in clinical practice, minimizing human and technical constraints.