scholarly journals Optically Pumped Magnetoencephalography in Epilepsy

2019 ◽  
Author(s):  
Umesh Vivekananda ◽  
Stephanie Mellor ◽  
Tim M Tierney ◽  
Niall Holmes ◽  
Elena Boto ◽  
...  
Keyword(s):  
Brain Region ◽  
Head Movement ◽  
Room Temperature ◽  
Focal Epilepsy ◽  
Epilepsy Patient ◽  
Optically Pumped ◽  
Future Directions ◽  
Scalp Eeg ◽  
Human Epilepsy ◽  
Squid System

AbstractOur aim was to demonstrate the first use of Optically Pumped Magnetoencephalography (OP-MEG) in an epilepsy patient with unrestricted head movement. Current clinical MEG uses a traditional SQUID system for recording MEG signal, where sensors are cryogenically cooled and housed in a helmet in which the patient’s head is fixed. Here we use a different type of sensor (OPM), which operates at room temperature and can be placed directly on the patient’s scalp, permitting free head movement. We performed two 30 minute OP-MEG recording sessions in a patient with refractory focal epilepsy and compared these with clinical scalp EEG performed earlier. OP-MEG was able to identify analogous interictal activity to scalp EEG, and source localise this activity to an appropriate brain region. This is the first application of OP-MEG in human epilepsy. Future directions include simultaneous EEG/OP-MEG recording and prolonged OP-MEG telemetry.

Neurophysiological seizure-onset predictors of epilepsy surgery outcome: a multivariable analysis

2020 ◽  
Vol 133 (6) ◽  
pp. 1863-1872 ◽  
Author(s):  
Hideaki Tanaka ◽  
Jean Gotman ◽  
Hui Ming Khoo ◽  
André Olivier ◽  
Jeffery Hall ◽  
...  
Keyword(s):  
Surgical Outcome ◽  
Focal Epilepsy ◽  
Univariate Analysis ◽  
Multivariable Analysis ◽  
Postoperative Outcome ◽  
Seizure Onset ◽  
Resective Surgery ◽  
Scalp Eeg ◽  
Surgery Outcome ◽  
Intracerebral Eeg

OBJECTIVEThe authors sought to determine which neurophysiological seizure-onset features seen during scalp electroencephalography (EEG) and intracerebral EEG (iEEG) monitoring are predictors of postoperative outcome in a large series of patients with drug-resistant focal epilepsy who underwent resective surgery.METHODSThe authors retrospectively analyzed the records of 75 consecutive patients with focal epilepsy, who first underwent scalp EEG and then iEEG (stereo-EEG) for presurgical assessment and who went on to undergo resective surgery between 2004 and 2015. To determine the independent prognostic factors from the neurophysiological scalp EEG and iEEG seizure-onset information, univariate and standard multivariable logistic regression analyses were used. Since scalp EEG and iEEG data were recorded at different times, the authors matched scalp seizures with intracerebral seizures for each patient using strict criteria.RESULTSA total of 3057 seizures were assessed. Forty-eight percent (36/75) of patients had a favorable outcome (Engel class I–II) after a minimum follow-up of at least 1 year. According to univariate analysis, a localized scalp EEG seizure onset (p < 0.001), a multilobar intracerebral seizure-onset zone (SOZ) (p < 0.001), and an extended SOZ (p = 0.001) were significantly associated with surgical outcome. According to multivariable analysis, the following two independent factors were found: 1) the ability of scalp EEG to localize the seizure onset was a predictor of a favorable postoperative outcome (OR 6.073, 95% CI 2.011–18.339, p = 0.001), and 2) a multilobar SOZ was a predictor of an unfavorable outcome (OR 0.076, 95% CI 0.009–0.663, p = 0.020).CONCLUSIONSThe study findings show that localization at scalp seizure onset and a multilobar SOZ were strong predictors of surgical outcome. These predictors can help to select the better candidates for resective surgery.

scholarly journals Detection of epileptic activity in presumably normal EEG

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Sara Baldini ◽  
Francesca Pittau ◽  
Gwenael Birot ◽  
Vincent Rochas ◽  
Miralena I Tomescu ◽  
...  
Keyword(s):  
Focal Epilepsy ◽  
Epileptic Activity ◽  
Scalp Eeg ◽  
Vigilance State ◽  
Explained Variance ◽  
Long Term Monitoring ◽  
Interictal Discharges ◽  
The Individual ◽  
Term Monitoring

Abstract Monitoring epileptic activity in the absence of interictal discharges is a major need given the well-established lack of reliability of patients’ reports of their seizures. Up to now, there are no other tools than reviewing the seizure diary; however, seizures may not be remembered or dismissed voluntarily. In the present study, we set out to determine if EEG voltage maps of epileptogenic activity in individual patients can help to identify disease activity, even if their scalp EEG appears normal. Twenty-five patients with pharmacoresistant focal epilepsy were included. For each patient, 6 min of EEG with spikes (yes-spike) and without visually detectable epileptogenic discharges (no-spike) were selected from long-term monitoring recordings (EEG 31–37 channels). For each patient, we identified typical discharges, calculated their average and the corresponding scalp voltage map (‘spike-map’). We then fitted the spike-map for each patient on their (i) EEG epochs with visible spikes, (ii) epochs without any visible spike and (iii) EEGs of 48 controls. The global explained variance was used to estimate the presence of the spike-maps. The individual spike-map occurred more often in the spike-free EEGs of patients compared to EEGs of healthy controls (P = 0.001). Not surprisingly, this difference was higher if the EEGs contained spikes (P &lt; 0.001). In patients, spike-maps were more frequent per second (P &lt; 0.001) but with a shorter mean duration (P &lt; 0.001) than in controls, for both no-spike and yes-spike EEGs. The amount of spike-maps was unrelated to clinical variables, like epilepsy severity, drug load or vigilance state. Voltage maps of spike activity are present very frequently in the scalp EEG of patients, even in presumably normal EEG. We conclude that spike-maps are a robust and potentially powerful marker to monitor subtle epileptogenic activity.

Low threshold, room temperature pulsed and quasi-continuous lasing in optically pumped CdZnTe/ZnTe quantum wells

1993 ◽  
Vol 22 (5) ◽  
pp. 479-484 ◽  
Author(s):  
R. D. Feldman ◽  
T. D. Harris ◽  
J. E. Zucker ◽  
D. Lee ◽  
R. F. Austin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Optically Pumped ◽  
Low Threshold

Physiological Activity and Artefacts in Epileptic Brain in Subdural EEG

2018 ◽  
pp. 84-97
Author(s):  
Beate Diehl ◽  
Catherine A. Scott
Keyword(s):  
Motor Cortex ◽  
Brain Region ◽  
Physiological Activity ◽  
Brain Oscillations ◽  
Intracranial Eeg ◽  
Scalp Eeg ◽  
Focal Pattern ◽  
Mu Rhythms ◽  
Eeg Recordings ◽  
Central Pacemaker

‘Physiological activity and artefacts in epileptic brain in subdural EEG’ reviews intracranial appearances of physiological brain rhythms in each brain region, many of which are also seen on scalp EEG. The alpha rhythm has been described as originating from multiple occipital and extra-occipital cortical generators variously overlapping and influencing each other, probably under the relative control of a central pacemaker. Another more focal pattern has been described in intracranial EEG recordings in the calcarine region, with a third rhythm arising in midtemporal regions, not detectable in scalp EEG, with a frequency in the alpha or theta range. Lambda waves, sleep structures, and mu rhythms over motor cortex can also be detected on subdural electrodes. On a region-by-region basis, intracranial EEG appearances are summarized, including brain oscillations in hippocampus and motor cortex and their modifiers, as well as ongoing rhythms in cingulum. Common sources of physiological and non-physiological artefacts are reviewed.

Molecular Beam Epitaxy of Znl-x Cdx Se/ZnSe Heterostructures And Their Optical Properties

1991 ◽  
Vol 228 ◽  
Author(s):  
H. Luo ◽  
N. Samarth ◽  
J. K. Furdyna ◽  
H. Jeon ◽  
J. Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stimulated Emission ◽  
Optically Pumped ◽  
Absorption Coefficients ◽  
Excitonic Absorption ◽  
Lasing Mechanism

ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe, and heterostructures based on ZnSe/CdSe digital alloys have been grown by molecular beam epitaxy (MBE). Their optical properties were studied with particular emphasis on excitonic absorption and photopumped stimulated emission. Excitonic absorption is easily observable up to 400 K, and is characterized by extremely large absorption coefficients (α = 2×105cm−1). Optically pumped lasing action is obtained at room temperature with a typical threshold intensity of 100 kW/cm2. The lasing mechanism in these II-VI quantum wells appears to be quite different from that in the better studied III-V materials: in our case, the onset of stimulated emission occurs before the saturation of the excitonic absorption, and the stimulated emission occurs at an energy lower than that of the excitonic absorption.

scholarly journals High-frequency oscillations in scalp EEG mirror seizure frequency in pediatric focal epilepsy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ece Boran ◽  
Johannes Sarnthein ◽  
Niklaus Krayenbühl ◽  
Georgia Ramantani ◽  
Tommaso Fedele
Keyword(s):  
Seizure Frequency ◽  
Epilepsy Surgery ◽  
High Frequency ◽  
Focal Epilepsy ◽  
Low Noise ◽  
Drug Resistant ◽  
Scalp Eeg ◽  
High Frequency Oscillations ◽  
Custom Made ◽  
Active Epilepsy

Abstract High-frequency oscillations (HFO) are promising EEG biomarkers of epileptogenicity. While the evidence supporting their significance derives mainly from invasive recordings, recent studies have extended these observations to HFO recorded in the widely accessible scalp EEG. Here, we investigated whether scalp HFO in drug-resistant focal epilepsy correspond to epilepsy severity and how they are affected by surgical therapy. In eleven children with drug-resistant focal epilepsy that underwent epilepsy surgery, we prospectively recorded pre- and postsurgical scalp EEG with a custom-made low-noise amplifier (LNA). In four of these children, we also recorded intraoperative electrocorticography (ECoG). To detect clinically relevant HFO, we applied a previously validated automated detector. Scalp HFO rates showed a significant positive correlation with seizure frequency (R2 = 0.80, p < 0.001). Overall, scalp HFO rates were higher in patients with active epilepsy (19 recordings, p = 0.0066, PPV = 86%, NPV = 80%, accuracy = 84% CI [62% 94%]) and decreased following successful epilepsy surgery. The location of the highest HFO rates in scalp EEG matched the location of the highest HFO rates in ECoG. This study is the first step towards using non-invasively recorded scalp HFO to monitor disease severity in patients affected by epilepsy.

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