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For algorithm developers, this review details recent approaches to the problem, compares the accuracy of various algorithms, identifies common testing issues and proposes some solutions. For the algorithm user, e.g. electroencephalograph (EEG) technician or neurologist, this review provides an estimate of algorithm accuracy and comparison to that of human experts. Manuscripts dated from 1975 are reviewed. Progress since Frost's 1985 review of the state of the art is discussed. Twenty-fivedoi:10.1016/s1388-2457(02)00297-3 pmid:12464324 fatcat:nwly3illhjc2lexal2i5y2njwa
more »... ripts are reviewed. Many novel methods have been proposed including neural networks and high-resolution frequency methods. Algorithm accuracy is less than that of experts, but the accuracy of experts is probably less than what is commonly believed. Larger record sets will be required for expert-level detection algorithms. q
The high lipid solubility that permits rapid transfer across the blood-brain barrier makes propofol attractive for intracarotid injection. The authors hypothesized that intracarotid injection produces electrocerebral silence at a fraction of the intravenous dose and with less adverse systemic and cerebrovascular side effects. Methods: The authors compared the systemic and cerebrovascular effects of intracarotid and intravenous propofol during transient (10 s) and sustained (1 h) electrocerebraldoi:10.1097/00000542-200310000-00024 pmid:14508324 fatcat:ieworm67rfbahi56y5vmwdgm3e
more »... silence in anesthetized New Zealand White rabbits. Hemispheric electrocerebral activity, mean arterial blood pressure, ipsilateral and contralateral cerebral blood flow, tympanic temperature, and end-tidal carbon dioxide were continuously monitored in these animals. Changes in outcome variables were analyzed at four time points: at baseline, during electrical silence, during burst suppression, and after recovery of electrocerebral activity. Propofol (1%) was injected as intracarotid (0.1 ml) or intravenous (0.5 ml) boluses. Results: Intracarotid propofol produced electrocerebral silence at one fifth (sustained silence) to one tenth (transient silence) of the intravenous dose. Compared with baseline values, the mean arterial pressure and ipsilateral cerebral blood flow remained unchanged or decreased transiently during electrocerebral silence with intracarotid propofol. In contrast, intravenous propofol resulted in systemic hypotension and a decrease in ipsilateral cerebral blood flow. Conclusions: Intracarotid propofol resulted in electrocerebral silence at a fraction of the intravenous dose that was not associated with systemic hypotension or a sustained decrease in the cerebral blood flow. Intracarotid propofol could be potentially useful for providing electrocerebral silence when cerebral perfusion is at risk.
Somatosensory evoked potentials directly assess only a part of the spinal cord, the dorsal columns (Emerson, 1988) , and also the medial lemniscus, the thalamocortical radiations, and somatosensory cortex ... nervous system is usable if the other one is, or becomes, unusable due to preexisting neurologic compromise, anesthetic effects, NMB, excessively noisy data, or other technical problems (Legatt and Emerson ...doi:10.1097/wnp.0000000000000253 pmid:26756258 fatcat:zzbyfj3inzer5pwobgzhq6xpmi
doi:10.1016/s0022-5223(95)70290-3 pmid:7877320 fatcat:nxjbopr5ibdi3ikshfqvs6xd4a
doi:10.1038/ncomms2056 pmid:22968706 pmcid:PMC3658011 fatcat:yxhwaxl4ljcsrhvb5lo2wycdqy
Objectives: To determine the prevalence, predictors, and clinical significance of electrographic seizures (ESz) and other continuous electroencephalographic monitoring findings in critically ill patients with central nervous system infections.doi:10.1001/archneur.65.12.1612 pmid:19064748 fatcat:espfvpnpkbdo5epdjm2j5axj4u
Objective: To determine the incidence, predictors, and timing of nonconvulsive seizures (NCSz) during continuous electroencephalographic monitoring (cEEG) in critically ill children. Methods: We identified critically ill children who underwent cEEG during a 4-year period. Multivariate logistic regression analysis was performed to determine variables associated with NCSz. Results: Among 117 monitored children, 44% had seizures on cEEG and 39% had NCSz. The majority of patients with seizuresdoi:10.1001/archneur.63.12.1750 pmid:17172615 fatcat:7m3zg4kemja5hjgsxdy3b2cyc4
more »... had purely NCSz, and 23% of patients had status epilepticus, which was purely nonconvulsive in 89% of cases. Seizures occurred immediately on cEEG initiation in 15%, within 1 hour in 50%, and within 24 hours in 80%. Those with clinical sei-zures prior to cEEG were more likely to have NCSz on cEEG (83%) than those without prior seizures (17%). On multivariate analysis, NCSz were associated with periodic lateralized epileptiform discharges and absence of background reactivity. Conclusions: Seizures, the majority being NCSz, are common during cEEG in critically ill children (seen in 44% of patients). Half are detected in the first hour of recording, whereas 20% are not detected until after more than 24 hours of recording. Nonconvulsive seizures are associated with periodic lateralized epileptiform discharges and absence of reactivity on cEEG. This study confirms the importance of prolonged cEEG for critically ill children as a means to detect NCSz.
Sleep and Breathing
Objectives: This survey sought to determine whether self-professed sleep specialists in the State of Michigan show practice variations in the diagnosis and management of sleep-disordered breathing (SDB), and whether such variations occur between pulmonologists and neurologists. Methods: Questionnaires on practice volume and patterns during the prior 12 months were mailed to physician members of the Michigan Sleep Disorders Association (n = 119); 67 were completed and returned. Results:doi:10.1007/s11325-003-0095-7 pmid:14569520 fatcat:7tpu2pd7dvachmzxa7j42r5cr4
more »... ts reported that they personally saw a median of 8 new patients each week for suspected SDB; estimates were that 86% of these patients were eventually confirmed to have SDB. Most patients (82%) had laboratory-based polysomnography after an initial clinic evaluation, and most (69%) of those treated for SDB received continuous positive airway pressure. However, practice patterns differed substantially among respondents, even when the analysis was limited to the 42 who reported board certification by the American Board of Sleep Medicine. For example, among all surveyed practices the likelihood that suspected SDB would be evaluated with a split-night diagnostic and treatment polysomnogram varied from 0 to 90%. The likelihood of SDB treatment with bilevel positive airway pressure varied from 0 to 50%, with automatically titrating devices from 0 to 100%, with surgery from 0 to 100% (0 to 50% among certified practitioners), and with oral appliances from 0 to 20%. The practice patterns of pulmonologists and neurologists did not differ significantly. Conclusion: Approaches to SDB vary widely in Michigan, though not according to clinician background in pulmo-
Focal seizure propagation is classically thought to be spatially contiguous. However, propagation through the epileptic network, a collection of disparate epileptic nodes, has been theorized. Here, we used a multielectrode array, wide field calcium imaging, and two-photon calcium imaging to study focal seizure propagation pathways in an acute rodent neocortical 4-aminopyridine model. Although ictal neuronal bursts did not propagation beyond a 2-3 mm region, they were associated withdoi:10.1101/146407 fatcat:ul3mhwxwergexgjix225cj3rxa
more »... ide LFP fluctuations and parvalbumin-positive interneuron activity outside the seizure focus. Globally compromising this inhibitory response using bicuculline surface application resulted in classical contiguous propagation; whereas, focal bicuculline microinjection resulted in epileptic network formation with two physically disparate foci. Our study suggests both classical and epileptic network propagation could arise from inhibition defects without pre-existing pathological connectivity changes, and that preferred propagation pathways may result from variations in cortical topology.
., Robert Goodman, Ronald G. Emerson, Andrew Trevelyan, Marom Bikson, and Catherine A. ...doi:10.3389/fnhum.2013.00828 pmid:24367311 pmcid:PMC3851829 fatcat:577hl4exh5g7lpxqrygki66kfa
We developed a neural network model that can account for the major elements common to human focal seizures. These include the tonic-clonic transition, slow advance of clinical semiology and corresponding seizure territory expansion, widespread EEG synchronization, and slowing of the ictal rhythm as the seizure approaches termination. These were reproduced by incorporating usage-dependent exhaustion of inhibition in an adaptive neural network that receives global feedback inhibition in additiondoi:10.1101/724088 fatcat:d3vsv2xwonaw7ospweaoltdbae
more »... o local recurrent projections. Our model proposes mechanisms that may underline common EEG seizure onset patterns and status epilepticus and postulates a role for synaptic plasticity in emergence of epileptic foci. Complex patterns of seizure activity and bi-stable seizure evolution end-points arise when stochastic noise is included. With the rapid advancement of clinical and experimental tools, we believe that this can provide a roadmap and potentially a testbed for future explorations of seizure mechanisms and clinical therapies.
BACKGROUND: Lower socioeconomic status (SES) and environmental tobacco smoke (ETS) exposure are both associated with poorer disease outcomes in cystic fibrosis (CF), and children with low SES are disproportionately exposed to ETS. We analyzed a large cohort of young children with CF to distinguish the impact of SES and ETS on clinical outcomes. METHODS: The Early Pseudomonas Infection Control Observational study enrolled Pseudomonas-negative young children with CF <13 years of age. Andoi:10.1542/peds.2016-2730 pmid:28093464 pmcid:PMC5260155 fatcat:yl5fxvoujjgrdn4ary6jc7w4rm
more »... survey assessed SES and ETS exposures. Forced expiratory volume in 1 second (FEV 1 ), crackles and wheezes, and weight-for-age percentile were assessed at each clinical encounter over at least 4 years. Repeated measures analyses estimated the association of SES and ETS exposures with longitudinal clinical outcomes, adjusting for confounders. RESULTS: Of 1797 participants, 1375 were eligible for analysis. Maternal education was high school or less in 28.1%, 26.8% had household income <$40 000, and 43.8% had Medicaid or no insurance. Maternal smoking after birth was present in 24.8%, more prevalent in household with low SES. In separate models, lower SES and ETS exposure were significantly associated with lower FEV 1 % predicted, presence of crackles or wheezes, and lower weight percentile. In combined models, effect estimates for SES changed minimally after adjustment for ETS exposures, whereas estimates for ETS exposures were attenuated after adjusting for SES. CONCLUSIONS: ETS exposure was disproportionately high in low SES families in this cohort of children with CF. Lower SES and ETS exposure had independent adverse effects on pulmonary and nutritional outcomes. Estimated effect of SES on FEV 1 decreased minimally after ETS adjustment, suggesting health disparity risks independent of ETS exposure.
and Purpose-Although pathophysiological studies of focal cerebral ischemia in nonhuman primates can provide important information not obtainable in rodent models, primate experimentation is limited by considerations of cost, availability, effort, and ethics. A reproducible and quantitative model that minimizes the number of animals necessary to detect differences between treatment groups is therefore crucial. Methods-Eight male baboons (weight, 22Ϯ2 kg) underwent left transorbital craniectomydoi:10.1161/01.str.31.12.3054 pmid:11108772 fatcat:zphvx3ysrvgznoeydzdnwy4hhe
more »... llowed by 1 hour of temporary ipsilateral internal carotid artery occlusion at the level of the anterior choroidal artery together with bilateral temporary occlusion of both anterior cerebral arteries (A1) proximal to the anterior communicating artery. A tightly controlled nitrous oxide-narcotic anesthetic allowed for intraoperative motor evoked potential confirmation of middle cerebral artery (MCA) territory ischemia. Animals survived to 72 hours or 10 days if successfully self-caring. Outcomes were assessed with a 100-point neurological grading system, and infarct volume was quantified by planimetric analysis of both MRI and triphenyltetrazolium chloride-stained sections. Results-Infarction volumes (on T2-weighted images) were 32Ϯ7% (meanϮSEM) of the ipsilateral hemisphere, and neurological scores averaged 29Ϯ9. All animals demonstrated evidence of hemispheric infarction, with damage evident in both cortical and subcortical regions in the MCA vascular territory. Histologically determined infarction volumes differed by Ͻ3% and correlated with absolute neurological scores (rϭ0.9, Pϭ0.003). Conclusions-Transorbital temporary occlusion of the entire anterior cerebral circulation with strict control of physiological parameters can reliably produce reperfused MCA territory infarction. The magnitude of the resultant infarct with little interanimal variability diminishes the potential number of animals required to distinguish between 2 treatment regimens. The anatomic distribution of the infarct and associated functional deficits offer comparability to human hemispheric strokes. (Stroke. 2000;31:3054-3063.)
Objective: High frequency oscillations (HFOs) recorded from intracranial electrodes during epileptiform discharges have been proposed as a biomarker of epileptic brain sites and may also be a useful feature for seizure forecasting, with mixed results. Currently, pathological subclasses of HFOs have been defined primarily by frequency characteristics. Despite this, there has been limited investigation into the spatial context of HFOs with recruitment of local cortex into seizure discharging. Wedoi:10.1101/2020.01.09.20017053 fatcat:q7hlpjasxvcvxbrzvukuke3rwa
more »... ought to further understand the biophysical underpinnings of ictal HFOs. Methods: Here we examine ictal HFOs from multi-scale electrophysiological recordings during spontaneous human rhythmic onset seizures. We compare features of ictal discharges in both the seizure core and penumbra, as defined by multiunit activity patterns. Results: We show marked differences in spectral features, unit coupling, and information theoretic characteristics of HFOs during ictal discharges before and after local seizure invasion. Furthermore, we tie these timing-related differences to different spatial domains of seizures, showing that eccentric, penumbral discharges are widely distributed and less useful for seizure localization, which may explain the variable utility of HFOs in seizure localization and forecasting. Interpretation: We thus identify two distinct classes of ictal HFOs, implying two different mechanisms underlying pathological HFOs with contrasting significance for seizure localization.
Bispectral Index (BIS) has been used to monitor level of "sedation" based on the electroencephalogram (EEG). Patients evaluated for surgery to control a seizure disorder undergo Wada testing, during which one hemisphere is rendered functionally inactive after injecting a shortacting barbiturate. We surmised that the BIS values would reflect these functional changes. Eight epileptic patients were enrolled. A full array of 21 EEG electrodes and 2 BIS XP (Quatro) strips over each frontal region ofdoi:10.1213/01.ane.0000155957.48503.93 pmid:15976238 pmcid:PMC1413969 fatcat:muo3yu35ljai7anvhlvrdd7enm
more »... the scalp were applied. The EEG was continuously recorded. BIS values from each hemisphere were recorded every minute. Angiography was performed by advancing a catheter into each internal carotid artery. Amobarbital or methohexital was injected until the patient developed a hemiparesis. The EEG confirmed a significant lateralized cortical effect of the barbiturate. Repeated measures analysis of variance was used to analyze the differences between the BIS values from monitor electrode strips placed on the left (left BIS) and the right (right BIS) sides of the head as well as the differences in the left and right BIS values before and after each injection of the barbiturate. Injection of barbiturate into either the left or right internal carotid artery produced a significant change on the 21-electrode EEG. However, there was no difference between left BIS to right BIS values (P = 0.84). With repeated injections of barbiturates, some patients became sedated. At these times, both left BIS and right BIS values decreased together before and after injection of barbiturate. The BIS monitor was unable to distinguish significant hemispheric EEG and clinical functional changes except when the patient became sedated. The Bispectral Index (BIS) (Aspect Medical Systems Inc., Newton, MA) has been used to monitor the level of "sedation" and may be used to determine "awareness" during surgery (1). Because BIS values are derived from the electroencephalogram (EEG), it was surmised that BIS would reflect significant functional and EEG changes (2). We tested this hypothesis in patients being evaluated for surgery to control a seizure disorder. These patients undergo Wada testing (3). During this test, the patient is awake and not sedated so that an accurate Address correspondence and reprint requests to Eric functional assessment can be performed. A catheter is advanced from the femoral artery in the groin selectively into one and then the other internal carotid artery (ICA). To localize a patient's language and memory, a short-acting barbiturate, amobarbital (4) or methohexital (5), is injected through the catheter to produce transient focal neuronal dysfunction in the distribution of the middle cerebral artery of the ipsilateral hemisphere. To ensure that the barbiturate has actually been delivered to the brain regions under investigation, as well as to ensure that all language and memory testing takes place while the barbiturate is effective, the functional consequence of each injection is confirmed by real-time continuous EEG monitoring and realtime motor-strength testing. A standard 21-channel EEG will demonstrate transient, lateralized, and localized δ frequency slowing that is maximal in the frontotemporal regions and clears as the barbiturate loses its effect. Simultaneous motor-strength testing will demonstrate a transient contralateral hemiparesis that will precede the resolution of δ slowing on EEG. We hypothesized, that with two BIS monitors, one on each side of the forehead, we would see statistically significant changes in BIS values over time and as a function of which hemisphere had been affected by the injected barbiturate. Using standard 21-channel EEG and bilateral BIS monitoring from the left and right forehead, we evaluated 8 epileptic patients undergoing Wada testing with selective intracarotid injections of either amobarbital (4) or methohexital (5). Methods Eight patients gave informed and written consent for this IRB-approved prospective study. Age, sex, race, site of pathology, and medical history were recorded. All patients enrolled in the study were scheduled for Wada testing. This test is given to patients with uncontrolled seizures before planned resection of brain tissue containing epileptogenic foci. The Wada test determines if memory and/or language would be impaired after this operation (6). It has been suggested that this test may even be predictive of seizure outcome postoperatively (7) . Each patient was brought to the holding area where 21 gold-plated electrodes were placed on the head in the International 10-20 system of electrode placement and recorded digitally with an EEG machine (Xltek EP16, Oakville, Ontario, Canada). In addition, BIS monitor electrode strips (Quatro: part #186-0106) were placed on the forehead bilaterally and symmetrically except for electrode #1, for which 1 electrode was located just below the other as shown in Figure 1 . Two BIS A-2000 XP monitors (P/N 185-0070, host version 3.21) were used to record BIS values. BIS values were recorded both manually and electronically (by configuring the RS232 output from the BIS XP monitor) to a file using the program HyperTerminal (Hilgraeve, Monroe, MI). This file was subsequently read using Excel (Microsoft, Redmont, WA). The BIS monitors and the EEG machine were synchronized in time for proper data analysis. The patient was then brought into the angiography suite. No conscious sedation or other form of anesthesia was given for Wada testing in order that an accurate functional examination of language, memory, and motor strength could be obtained. Vital signs were taken as per usual protocol under the direction of the neuroradiologist. A catheter was inserted percutaneously into the femoral artery and then selectively advanced over a guidewire into the ICA. A cerebral angiogram was obtained before injection of the short-acting barbiturate. A selective injection of non-ionic iodinated contrast was performed to: 1) verify the position of the catheter, 2) determine the extent of cross-filling through the anterior communicating artery, and 3) verify the absence of vascular abnormalities which may impair the results of the study. In addition, this injection of contrast served as a control for the BIS values obtained subsequently, because the patient was fully awake during this part of the procedure. After the contrast injection, approximately 100-125 mg of amobarbital or 2-4 mg of methohexital was injected directly into the ICA over approximately 5 s. In each patient, the hemisphere thought to have the Heller et al. epileptogenic focus was injected first followed by the contralateral hemisphere. EEG monitoring occurred throughout the procedure and was used to confirm decreased cerebral cortex functioning. The duration of the barbiturate effect was monitored continuously by its EEG effect and motor testing and lasted approximately 5-12 min when amobarbital was injected and 4-7 min with methohexital. A few of the patients became sedated after the last injection of amobarbital. The motor examination was performed by having the patient raise his/her arms. Strength was measured on a scale of 0-5 with "0" as no muscle movement, "1" as very slight movement but not even in the plane of gravity, "2" movement in the plane of gravity, "3" movement against gravity, "4" movement and strength against some resistance, and "5" normal strength against normal resistance. The opposite hemisphere was injected only after the EEG had recovered to baseline. This took approximately 7-14 min depending on whether methohexital or amobarbital was used. The procedure took approximately 30-40 min for the evaluation of each hemisphere. The absence or presence of collateral circulation was recorded. EEG was used to confirm focal, localized suppression of cerebral activity. To test speech and language, patients were requested to follow two verbal commands (e.g., Point to your ear.), name two real (e.g., spoon) and four pictured (e.g., bicycle) objects, repeat phrases, and answer brief questions (e.g., Are 2 pounds of flour heavier than 1?). The verbal commands and object-naming stimuli also served as memory items. Patients were instructed to remember these items for later testing. Only items presented during a hemiparesis strength rating of <3/5 were considered valid for memory testing. After full neurologic recovery (typically 10 min from the initial injection), patients were requested to recall memory items, or, if necessary, to select the items presented previously from a series of multiple-choice arrays. Data from the BIS monitors were analyzed at 1-min intervals. Bilateral BIS scores were recorded before, during, and after injections to each side of the brain. BIS values are reported as mean ± 1 sd. All the data from the eight patients were combined into one database for statistical analysis. Repeated measures analysis of variance was used to analyze differences between the two BIS monitors as well as changes in BIS scores before and after left-and rightsided injections of barbiturate. A P value ≤ 0.05 was considered significant for all analyses. These data were compared with EEG monitoring and functional testing of motor strength, which were recorded by video and handwritten accounts.
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