scholarly journals Neurophysiological Characterization of Thalamic Nuclei in Epileptic Anaesthetized Patients

2019 ◽  
Vol 9 (11) ◽  
pp. 312 ◽  
Author(s):  
Vega-Zelaya ◽  
Torres ◽  
Navas ◽  
Pastor
Keyword(s):  
General Anesthesia ◽  
Interspike Interval ◽  
The Other ◽  
Electrode Placement ◽  
Thalamic Nuclei ◽  
Mean Frequency ◽  
The Mean ◽  
Tonic Pattern ◽  
Deep Brain

Deep brain stimulation (DBS) requires precise localization, which is especially difficult at the thalamus, and even more difficult in anesthetized patients. We aimed to characterize the neurophysiological properties of the ventral intermediate (V.im), ventral caudal (V.c), and centromedian parvo (Ce.pc) and the magnocellular (Ce.mc) thalamic nuclei. We obtained microelectrode recordings from five patients with refractory epilepsy under general anesthesia. Somatosensory evoked potentials recorded by microelectrodes were used to identify the V.c nucleus. Trajectories were reconstructed off-line to identify the nucleus recorded, and the amplitude of the action potential (AP) and the tonic (i.e., mean frequency, density, probability of interspike interval) and phasic (i.e., burst index, pause index, and pause ratio) properties of the pattern discharges were analyzed. The Mahalanobis metric was used to evaluate the similarity of the patterns. The mean AP amplitude was higher for the V.im nucleus (172.7 ± 7.6 µV) than for the other nuclei, and the mean frequency was lower for the Ce.pc nucleus (7.2 ± 0.8 Hz) and higher for the V.c nucleus (11.9 ± 0.8 Hz) than for the other nuclei. The phasic properties showed a bursting pattern for the V.c nucleus and a tonic pattern for the centromedian and V.im nuclei. The Mahalanobis distance was the shortest for the V.im/V.c and Ce.mp/Ce.pc pairs. Therefore, the different properties of the thalamic nuclei, even for patients under general anesthesia, can be used to positively define the recorded structure, improving the exactness of electrode placement in DBS.

Avoiding the ventricle: a simple step to improve accuracy of anatomical targeting during deep brain stimulation

2009 ◽  
Vol 110 (6) ◽  
pp. 1283-1290 ◽  
Author(s):  
Ludvic Zrinzo ◽  
Arjen L. J. van Hulzen ◽  
Alessandra A. Gorgulho ◽  
Patricia Limousin ◽  
Michiel J. Staal ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Electrode Placement ◽  
Neurosurgical Procedures ◽  
Electrode Implantation ◽  
Clinical Observations ◽  
Simple Step ◽  
The Mean ◽  
The Impact ◽  
Deep Brain

Object The authors examined the accuracy of anatomical targeting during electrode implantation for deep brain stimulation in functional neurosurgical procedures. Special attention was focused on the impact that ventricular involvement of the electrode trajectory had on targeting accuracy. Methods The targeting error during electrode placement was assessed in 162 electrodes implanted in 109 patients at 2 centers. The targeting error was calculated as the shortest distance from the intended stereotactic coordinates to the final electrode trajectory as defined on postoperative stereotactic imaging. The trajectory of these electrodes in relation to the lateral ventricles was also analyzed on postoperative images. Results The trajectory of 68 electrodes involved the ventricle. The targeting error for all electrodes was calculated: the mean ± SD and the 95% CI of the mean was 1.5 ± 1.0 and 0.1 mm, respectively. The same calculations for targeting error for electrode trajectories that did not involve the ventricle were 1.2 ± 0.7 and 0.1 mm. A significantly larger targeting error was seen in trajectories that involved the ventricle (1.9 ± 1.1 and 0.3 mm; p < 0.001). Thirty electrodes (19%) required multiple passes before final electrode implantation on the basis of physiological and/or clinical observations. There was a significant association between an increased requirement for multiple brain passes and ventricular involvement in the trajectory (p < 0.01). Conclusions Planning an electrode trajectory that avoids the ventricles is a simple precaution that significantly improves the accuracy of anatomical targeting during electrode placement for deep brain stimulation. Avoidance of the ventricles appears to reduce the need for multiple passes through the brain to reach the desired target as defined by clinical and physiological observations.

A European multicentric experience using the CardioSEAL® and Starflex double umbrella devices to close interatrial communications holes within the oval fossa

2000 ◽  
Vol 10 (5) ◽  
pp. 519-526 ◽  
Author(s):  
M. Carminati ◽  
S. Giusti ◽  
G. Hausdorf ◽  
S. Qureshi ◽  
M. Tynan ◽  
...  
Keyword(s):  
General Anesthesia ◽  
Surgical Repair ◽  
Clinical Success ◽  
The Other ◽  
Thromboembolic Events ◽  
Clinical Complications ◽  
The Mean ◽  
One Year ◽  
Flap Valve

AbstractIn this review, we describe the experience from 13 European centres using the CardioSEAL and Starflex double umbrella devices to close interatrial communications within the oval fossa (so-called ‘stcundum’ defects). Between October 1996 and April 1999, the procedure was attempted in 334 patients with a mean age of 12 years and a mean weight of 44kg. The mean measured stretched diameter of the defect was 15 mm. In the overall group, the defect was solitary in 245 patients (73%), multiple in 21 (6%), associated with an aneurysm of the flap valve in 15 (5%), was represented by patency of the oval foramen in 44 (13%), and was a fenestration in a Fontan repair in 9 (3%). In all patients, the devices were inserted under general anesthesia, using fluoroscopic and transesophageal echocardiographic control. Implantation was achieved in 325 (97,3%). The device embolized within either a few minutes or a few hours in 13 patients (4%). Of these, uncomplicated surgical repair was undertaken in 10, while the device was retrieved in 3 using catheters and a second device was successfully implanted. Residual shunting was detected immediately after the procedure in 41% of the patients, with the incidence decreasing to 31% at discharge, 24% at 1 month, 21% at 6 months, and 20.5% at one year. During the period of follow-up, elective surgical repair became necessary in two patients, due to malposition of the device in one, and late embolization in the other. Fractures of arms were seen in 6.1%, most commonly with the largest devices. All those with fractured arms of the device were asymptomatic, and no clinical complications related to the fractures were observed. There were no arrythmias, endocarditis, valvar distortion, thromboembolic events, or other complications. After one year of follow-up, clinical success, defined as complete closure of the defect or presence of only a trivial leak, had been obtained in 92.5% of the patients. We conclude, therefore, that these devices produce excellent results when used to close defects of small to moderate size. Results are less than optimal, or else complications ensure, when attempts are made to close very large defects.

scholarly journals Spatiotemporal characterization of Ensemble Prediction Systems – the Mean-Variance of Logarithms (MVL) diagram

2008 ◽  
Vol 15 (1) ◽  
pp. 109-114 ◽  
Author(s):  
J. M. Gutiérrez ◽  
C. Primo ◽  
M. A. Rodríguez ◽  
J. Fernández
Keyword(s):  
Weather Prediction ◽  
The Other ◽  
Ensemble Prediction ◽  
Spatiotemporal Evolution ◽  
Novel Approach ◽  
The Mean ◽  
The Ensemble Method ◽  
Prediction Systems ◽  
Mean Variance

Abstract. We present a novel approach to characterize and graphically represent the spatiotemporal evolution of ensembles using a simple diagram. To this aim we analyze the fluctuations obtained as differences between each member of the ensemble and the control. The lognormal character of these fluctuations suggests a characterization in terms of the first two moments of the logarithmic transformed values. On one hand, the mean is associated with the exponential growth in time. On the other hand, the variance accounts for the spatial correlation and localization of fluctuations. In this paper we introduce the MVL (Mean-Variance of Logarithms) diagram to intuitively represent the interplay and evolution of these two quantities. We show that this diagram uncovers useful information about the spatiotemporal dynamics of the ensemble. Some universal features of the diagram are also described, associated either with the nonlinear system or with the ensemble method and illustrated using both toy models and numerical weather prediction systems.

Electron Holographic Characterization of Nano-Hetero Interface Effect in Gold Catalysts

2004 ◽  
Vol 839 ◽  
Author(s):  
S. Ichikawa ◽  
T. Akita ◽  
K. Okazaki ◽  
K. Tanaka ◽  
M. Kohyama
Keyword(s):  
Gold Particle ◽  
Size Dependence ◽  
Critical Size ◽  
High Resolution Electron Microscopy ◽  
The Other ◽  
Electron Holography ◽  
Bulk State ◽  
Resolution Electron ◽  
The Mean

ABSTRACTWe investigated the atomic structure near the interface and the size dependence of the mean inner potential of gold in Au/TiO2 catalysts prepared by the deposition precipitation (DP) method and the vacuum evaporation (VE) method using high resolution electron microscopy (HREM) and electron holography. The TiO2 supports prepared by DP method and VE method are considered to have oxygen-rich surfaces and titanium-rich surfaces respectively. In case of the Au/TiO2 catalyst prepared by DP method, the mean inner potential of gold increased depending on the size of the particle. When the size of the gold particle is over 5nm, the mean inner potential of gold was the same as that of bulk Au. When the size is below 5nm, the mean inner potential became to increase. It increases suddenly over 40V, particularly in case of below 2nm. It indicates that the electronic state of gold on TiO2 changes from that of bulk state as the size decreases. On the other hand, the mean inner potential of gold in Au/TiO2 catalysts prepared by VE method also increased as the size decreased, but the behavior of the size dependence is different from that of DP method. The critical size of the mean inner potential change is around 3nm. The size of the gold particle was below 3nm, the mean inner potential of gold increased gradually. The mean inner potential of VE method is less than that of DP method with the same particle size in spite of the size below 3nm. The stoichiometry at the interface between Au and TiO2 should be one of the dominant reasons for the behavior difference of the size dependence of the mean inner potential between the preparations.

scholarly journals Features of Action Potentials from Identified Thalamic Nuclei in Anesthetized Patients

2020 ◽  
Vol 10 (12) ◽  
pp. 1002
Author(s):  
Jesús Pastor ◽  
Lorena Vega-Zelaya
Keyword(s):  
General Anesthesia ◽  
Action Potentials ◽  
Thalamic Nuclei ◽  
Capacitive Current ◽  
Electrophysiological Properties ◽  
First Derivative ◽  
Microelectrode Recordings ◽  
Different Types ◽  
The Relationship ◽  
Deep Brain

Our objective was to describe the electrophysiological properties of the extracellular action potential (AP) picked up through microelectrode recordings (MERs). Five patients were operated under general anesthesia for centromedian deep brain stimulation (DBS). APs from the same cell were pooled to obtain a mean AP (mAP). The amplitudes and durations for all 2/3 phases were computed from the mAP, together with the maximum (dVmax) and minimum (dVmin) values of the first derivative, as well as the slopes of different phases during repolarization. The mAPs are denominated according to the phase polarity (P/N for positive/negative). We obtained a total of 1109 mAPs, most of the positive (98.47%) and triphasic (93.69%) with a small P/N deflection (Vphase1) before depolarization. The percentage of the different types of mAPs was different for the nuclei addressed. The relationship between dVmax and the depolarizing phase is specific. The descending phase of the first derivative identified different phases during the repolarizing period. We observed a high correlation between Vphase1 and the amplitudes of either depolarization or repolarization phases. Human thalamic nuclei differ in their electrophysiological properties of APs, even under general anesthesia. Capacitive current, which is probably responsible for Vphase1, is very common in thalamic APs. Moreover, subtle differences during repolarization are neuron-specific.

THE GEOMETRICAL CHARACTERIZATION OF NEURAL ACTIVITY DISPLAYS A SENSITIVITY TO CONVULSANTS

1991 ◽  
Vol 01 (01) ◽  
pp. 253-259 ◽  
Author(s):  
I. D. ZIMMERMAN ◽  
P. E. RAPP ◽  
A. I. MEES
Keyword(s):  
Interspike Interval ◽  
Three Dimensional ◽  
Interval Data ◽  
Time Intervals ◽  
Geometrical Characterization ◽  
Single Nerve ◽  
Before And After ◽  
The Mean ◽  
Standard Techniques

Direct application of a drop of penicillin to the brain's surface can elicit brain electrical activity similar to that seen in some forms of epilepsy. The procedure has therefore become one of the standard techniques in the experimental investigation of epilepsy. The time intervals between action potentials, called the interspike intervals, were measured from single nerve cells in the cerebral cortex of the rat before and after local administration of penicillin. The resulting interspike interval data were examined by elementary statistical procedures and by embedding the data in two- and three-dimensional spaces. The mean interspike interval did not change significantly in response to penicillin. In contrast, the geometrical characterization displayed a dramatic sensitivity to the drug.

scholarly journals Neurophysiological Characterization of Posteromedial Hypothalamus in Anaesthetized Patients

2021 ◽  
Vol 12 (1) ◽  
pp. 43
Author(s):  
Jesús Pastor ◽  
Lorena Vega-Zelaya ◽  
Elena Martín-Abad
Keyword(s):  
General Anesthesia ◽  
Action Potentials ◽  
Mass Function ◽  
Probability Mass Function ◽  
Pooled Data ◽  
Potential Map ◽  
Probability Mass ◽  
First Time ◽  
Deep Brain

Deep brain stimulation (DBS) requires a precise localization, which is especially difficult at the hypothalamus, because it is usually performed in anesthetized patients. We aimed to characterize the neurophysiological properties posteromedial hypothalamus (PMH), identified by the best neurophysiological response to electrical stimulation. We obtained microelectrode recordings from four patients with intractable aggressivity operated under general anesthesia. We pooled data from 1.5 mm at PMH, 1.5 mm upper (uPMH) and 1.5 mm lower (lPMH). We analyzed 178 units, characterized by the mean action potential (mAP). Only 11% were negative. We identified the next types of units: P1N1 (30.9%), N1P1N2 (29.8%), P1P2N1 (16.3%), N1P1 and N1N2P1 (6.2%) and P1N1P2 (5.0%). Besides, atypical action potentials (amAP) were recorded in 11.8%. PMH was highly different in cell composition from uPMH and lPMH, exhibiting also a higher percentage of amAP. Different kinds of cells shared similar features for the three hypothalamic regions. Although features for discharge pattern did not show region specificity, the probability mass function of inter-spike interval were different for all the three regions. Comparison of the same kind of mAP with thalamic neurons previously published demonstrate that most of cells are different for derivatives, amplitude and/or duration of repolarization and depolarization phases and also for the first phase, demonstrating a highly specificity for both brain centers. Therefore, the different properties described for PMH can be used to positively refine targeting, even under general anesthesia. Besides, we describe by first time the presence of atypical extracellular action potentials.

Occurrence and Molecular Characterization of Acetolactate Synthase (ALS) Inhibitor–Resistant Kochia (Kochia scoparia) in Western Canada

2011 ◽  
Vol 25 (1) ◽  
pp. 170-175 ◽  
Author(s):  
Hugh J. Beckie ◽  
Suzanne I. Warwick ◽  
Connie A. Sauder ◽  
Chris Lozinski ◽  
Scott Shirriff
Keyword(s):  
Molecular Characterization ◽  
Sequence Data ◽  
Acetolactate Synthase ◽  
Western Canada ◽  
Kochia Scoparia ◽  
Mean Frequency ◽  
Auxin Resistance ◽  
The Mean ◽  
Als Inhibitor

A survey of 109 fields was conducted across western Canada in spring 2007 to determine the extent of ALS-inhibitor and dicamba (synthetic auxin) resistance in kochia. Weed seedlings were collected from fields in three provinces of western Canada and transplanted into the greenhouse. Seeds were harvested from selfed plants, and the F1progeny were screened for resistance to the ALS-inhibitor mixture thifensulfuron–tribenuron or dicamba. All kochia populations were susceptible to dicamba. ALS inhibitor–resistant kochia was found in 85% of the fields surveyed in western Canada: 80 of 95 fields in Alberta, six of seven fields in Saskatchewan, and all seven fields in Manitoba. For the 93 ALS inhibitor–resistant populations, the mean frequency (±SE) of parental plants classified as resistant was 61 ± 3%. Most of the resistant populations (87%) were heterogeneous and contained both resistant and susceptible individuals.ALSsequence data (Pro197and Asp376mutations) and genotyping data (Trp574mutation) obtained for 87 kochia parental (i.e., field-collected) plants confirmed the presence of all three target-site mutations as well as two mutational combinations (Pro197+ Trp574, Asp376+ Trp574) in resistant individuals.

Intraoperative Computed Tomography for Registration of Stereotactic Frame in Frame-Based Deep Brain Stimulation

2020 ◽  
Author(s):  
Michael R Jones ◽  
Archit B Baskaran ◽  
Mark J Nolt ◽  
Joshua M Rosenow
Keyword(s):  
Computed Tomography ◽  
Deep Brain Stimulation ◽  
Electrode Placement ◽  
Absolute Difference ◽  
Ct Scanner ◽  
Intraoperative Ct ◽  
Stereotactic Frame ◽  
The Mean ◽  
Conventional Ct ◽  
Deep Brain

Abstract BACKGROUND Deep brain stimulation (DBS) electrode placement utilizing a frame-based technique requires registration of the stereotactic frame with computed tomography (CT) or magnetic resonance (MR) imaging. This traditionally has been accomplished with a conventional CT scanner. In recent years, intraoperative CT has become more prevalent. OBJECTIVE To compare the coordinates obtained with intraoperative CT and conventional CT for registration of the stereotactic frame for DBS. METHODS Patients undergoing DBS electrode placement between 2015 and 2017, who underwent both conventional and intraoperative CT for registration of the stereotactic frame, were included for analysis. The coordinates for the stereotactic target, anterior commissure, and posterior commissure for each CT method were recorded. The mean, maximum, minimum, and standard deviation of the absolute difference for each of the paired coordinates was calculated. Paired t-tests were performed to test for statistical significance of the difference. The directional difference as well as the vector error between the paired coordinates was also calculated. RESULTS The mean absolute difference between conventional and intraoperative CT for the coordinate pairs was less than 0.279 mm or 0.211 degrees for all coordinate pairs analyzed. This was not statistically significant for any of the coordinate pairs. Moreover, the maximum absolute difference between all coordinate pairs was 1.04 mm. CONCLUSION Intraoperative CT imaging provides stereotactic frame registration coordinates that are similar to those obtained by a standard CT scanner. This may save time and hospital resources by obviating the need for the patient to go to the radiology department for a CT scan.

Motor Evoked Potential Recordings During Segmented Deep Brain Stimulation—A Feasibility Study

2021 ◽  
Vol 20 (4) ◽  
pp. 419-425
Author(s):  
Jay Shils ◽  
Ryan B Kochanski ◽  
Alireza Borghei ◽  
Alexander Candocia ◽  
Gian D Pal ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
General Anesthesia ◽  
Brain Stimulation ◽  
Pulse Generator ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Therapeutic Window ◽  
The Mean ◽  
Deep Brain ◽  
Stimulation Of

Abstract BACKGROUND Segmented deep brain stimulation (DBS) leads, which are capable of steering current in the direction of any 1 of 3 segments, can result in a wider therapeutic window by directing current away from unintended structures, particularly, the corticospinal tract (CST). It is unclear whether the use of motor evoked potentials (MEPs) is feasible during DBS surgery via stimulation of individual contacts/segments in order to quantify CST activation thresholds and optimal contacts/segments intraoperatively. OBJECTIVE To assess the feasibility of using MEP to identify CST thresholds for ring and individual segments of the DBS lead under general anesthesia. METHODS MEP testing was performed during pulse generator implantation under general anesthesia on subjects who underwent DBS lead implantation into the subthalamic nucleus (STN). Stimulation of each ring and segmented contacts of the directional DBS lead was performed until CST threshold was reached. Stereotactic coordinates and thresholds for each contact/segment were recorded along with the initially activated muscle group. RESULTS A total of 34 hemispheres were included for analysis. MEP thresholds were recorded from 268 total contacts/segments. For segmented contacts (2 and 3, respectively), the mean highest CST thresholds were 2.33 and 2.62 mA, while the mean lowest CST thresholds were 1.7 and 1.89 mA, suggesting differential thresholds in relation to CST. First dorsal interosseous and abductor pollicis brevis (34% each) were the most commonly activated muscle groups. CONCLUSION MEP threshold recording from segmented DBS leads is feasible. MEP recordings can identify segments with highest CST thresholds and may identify segment orientation in relation to CST.

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