PubMed · 8789629
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1995. Electrosurgical active electrode shielding systems.. https://pubmed.ncbi.nlm.nih.gov/8789629/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
STUDY OBJECTIVES: Recognizing epileptic seizures during video polysomnography (VPSG) can be challenging, particularly when using standard, limited EEG montages and paper speed. Few sleep laboratories have PSG equipment that allows for the recording of 18 channels of EEG without compromising the ability to detect sleep apnea, periodic limb movements, and parasomnias. We studied the ability of sleep medicine- and EEG-trained polysomnographers to correctly identify epileptic seizures during PSG using 4, 7, and 18 channels of simultaneous EEG, recording at conventional PSG and EEG paper speeds. The purpose of this study was to determine the value of limited EEG montages viewed with EEG reformatting capability in the identification of seizures during PSG. DESIGN: Blinded EEG analysis of seizures and arousals during VPSG. SETTING: Tertiary care hospital with sleep laboratory and epilepsy monitoring unit. PATIENTS: Subjects with focal (partial) epilepsy that underwent video-EEG monitoring. INTERVENTIONS: We designed two 7-channel EEG montages that might facilitate the identification of seizures arising from the frontal and temporal lobes. Sleep medicine- and EEG-trained polysomnographers were asked to review tracings containing frontal or temporal lobe epileptic seizures and arousals from sleep. Utilizing the capability of our digital recording equipment to reformat EEG channels and change paper speeds, we asked the readers to classify events recorded with 4, 7, and 18 channels of simultaneous EEG, at paper speeds of 10 and 30 mm/sec. MEASUREMENTS AND RESULTS: 6 readers viewed 32 sleep-related events (13 frontal lobe seizures, 11 temporal lobe seizures, and 8 arousals). The following factors were analyzed for their influence on accuracy of event detection: 1) the type of training of the reader (EEG vs. sleep medicine); 2) the number of EEG channels (4, 7, or 18); and 3) paper speed (10 vs. 30 mm/sec). Pair-wise comparisons and generalized estimating equations were used to identify factors leading to more accurate detection of seizures and arousals. 77% of events were correctly identified: 74% of seizures and 88% of arousals. Seizure detection was better using 7 and 18 channels (sensitivity of 82% and 86%, respectively) than 4 EEG channels (sensitivity of 67%) for temporal lobe seizures only. The number of EEG channels did not affect the accuracy of frontal lobe seizure detection. For EEG-trained readers, accuracy was greater using 30 mm/sec than 10 mm/sec paper speed (85% vs. 78% correct, respectively). CONCLUSIONS: Adding EEG channels and EEG reformatting capabilities to PSG interpretation improves the detection of some types of epileptic seizures. Accuracy of temporal lobe seizure detection using an abbreviated 7-channel montage approximates that of an 18-channel EEG recording. However, the same is not true of frontal lobe seizures in which accuracy was similar regardless of the number of EEG channel available. Further studies are needed to identify specific EEG montages that would best detect epileptiform activity during VPSG.
STUDY OBJECTIVES: The role of arousal from sleep in promoting epileptic seizures is controversial. To examine the question of whether seizures precede or follow arousals from sleep, we defined the timing of temporal lobe seizures in relation to sleep and arousal using combined scalp-intracranial electrodes. DESIGN: Retrospective review of 67 sleep-related mesial temporal lobe seizures in 14 subjects. SETTING: Inpatient epilepsy monitoring laboratory. PATIENTS: Subjects with medically refractory mesial temporal lobe seizures undergoing epilepsy surgery evaluations. INTERVENTIONS: None MEASUREMENTS AND RESULTS: Electroencephalographic (EEG) and/or polygraphic recordings and videotapes were independently reviewed to determine intracranial electrode seizure onset times and time of initial arousal from sleep. In 60 seizures in 13 subjects, intracranial ictal onsets always preceded clinical arousals from sleep. Electrographic signs of arousal in the scalp EEG, defined by the presence of sustained alpha or theta activity, either coincided with or followed, but never preceded, intracranial ictal onsets. In seven seizures in one subject with known seizures upon awakening, intracranial ictal onsets always followed clinical arousals and electrographic signs of arousal from sleep. Seven of the 14 subjects had electrooculogram and chin electromyogram monitoring; in these subjects, no seizures occurred during REM sleep with the majority occurring during NREM stage 2 sleep. CONCLUSIONS: Most sleep-related temporal lobe seizures occurred during NREM sleep and preceded arousals, supporting the premise that processes involved in the initiation and maintenance of NREM sleep play a greater role in facilitating temporal seizures than those involved in promoting REM sleep and arousal. However, arousal from sleep may provoke seizures in exceptional cases.
A new low-power, small-scale 2.45 GHz microwave plasma source at atmospheric pressure for atomic emission spectrometry based on microstrip technology is described. The MicroStrip Plasma (MSP) source was produced in microstrip technology on a fused-silica wafer and designed as an element-selective detector for miniaturized analytical applications. The electrodeless microwave-induced plasma (MIP) operates at microwave input power of 10-40 W and gas flows of 50-1000 mL.min-1 of Ar. Rotational (OH) and excitation (Fe) temperatures were found to be 650 and 8000 K, respectively. Spatially resolved measurements of the Hg I 253.7-nm atomic emission line with an electronic slitless spectrograph (ESS) showed that a cylindrically symmetric plasma with a diameter of about 1 mm is obtained. With the MSP, Hg could be determined by applying the flow injection cold vapor (FI-CV) technique with a detection limit of 50 pg.ml-1. In terms of the relative standard deviation, a time stability of < 1.4% for 45 replicates within 80 min can be realized at a concentration level of 10 ng.ml-1 of Hg. Hg could be determined in the leachate of a certified standard reference soil (STSD-4) obtained by treatment with aqua regia at the 930 +/- 76 ng.g-1 level. Results obtained by calibration with aqueous solutions of Hg and with standard addition were found to be in good agreement with those of cold-vapor atomic absorption spectrometry.