The EEG, Evoked Potentials, and Single-unit Activity during Ketamine Anesthesia in Cats

Kayama, Yukihiko; Iwama, Kitsuya

doi:10.1097/00000542-197204000-00004

Cited by 106 publications

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“…TM However, as with barbiturates, the altered enflurane seizure pattern persisted for a period exceeding the EEG effects of ketamine alone. 29 One must differentiate between EEG seizure patterns and convulsive activity. Anticonvulsants may abolish motor expression yet leave EEG seizure patterns unaltered.…”

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confidence: 99%

The influence of intravenous anaesthetics on enflurane-induced central nervous system seizure activity

Darimont¹,

Jenkins

1977

Canad. Anaesth. Soc. J.

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ENFLUIaANE is a halogenated ether which has been recently introduced into clinical anaesthetic practice. Its attractive features include rapid induction and emergence, minimal gastro-intestina] disturbance and limited biotransformation. However, sufficient concern exists about its potential for eliciting excitation of the central nervous system (CNS) that the manufacturer considers a pre-existing seizure disorder a eontraindication to its use. 1 Recent reports indicate that enflurane-induced EEG seizures, sometimes accompanied by convulsive activity, may be seen in patients with no apparent pre-existing CNS disorder3 -5 Identical EEG seizure patterns can be reproduced in healthy animal preparations. ~9 High inspired concentrations of enflurane and/or low carbon dioxide tensions are well established as factors precipitating or augmenting abnormal EEG activity both in man and in laboratory animals.However, little information is available about the influence on enflurane seizure patterns of other anaesthetic agents used concomitantly. Virtue reported the abolition of enflurane-induced myoclonus in dogs with intravenous thiopentone. TM Dobkin and associates noted the absence of motor movements in patients given enflurane in combination with barbiturates and muscle relaxants but, in common with other early clinical evaluations, did not assess these patients for EEG evidence of cerebral irritability23The study reported here was undertaken, therefore, to assess the effects, if any, of several commonly employed intravenous induction agents on both the threshold for enflurane-indueed EEG seizures and on the continuation of established EEG seizure activity. METrIODS AND RESULTSEight adult female cats were used for a total of 28 experiments. These animals were chronic preparations with permanently implanted EEG recording electrodes.Each animal was provided with four stainless steel screws resting on the fi'ontal dura. Subcortical structures were implanted with four bipolar electrodes, corresponding to two bilateral sites. Each animal had two subcortical sites selected fi'om brain stem reticular formation, amygdala or hippocampal nuclei.Implantation was undertaken with intraperitoneal pentobarbitone anaesthesia (35 mg/kg). The animals were mounted in a David Kopf stereotaxie apparatus and the subcortical sites were implanted according to the coordinates of Jasper. la From the

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confidence: 99%

The influence of intravenous anaesthetics on enflurane-induced central nervous system seizure activity

Darimont¹,

Jenkins

1977

Canad. Anaesth. Soc. J.

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“…2D). The smallest signals recorded were spontaneous transient nonepileptiform discharges associated with ketamine anesthesia (Kayama and Iwama, 1972) ("ketamine spikes"; Fig. 2B, asterisk).…”

Section: Resultsmentioning

confidence: 99%

“…The use of fiber-optics and evacuated packaging (Mhaskar et al, 2012;Sander et al, 2012) enabled flexible positioning, low-power operation, and the ability to position the heated sensor within a few millimeters of living tissue. The sensor head contained a 87 Rb vapor cell within a vacuum package (Mescher et al, 2005) (Fig. 1D), keeping the outside of the sensor at room temperature while the cell was heated to 150°C.…”

Section: Methodsmentioning

confidence: 99%

Magnetoencephalography of Epilepsy with a Microfabricated Atomic Magnetrode

et al. 2014

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Magnetoencephalography has long held the promise of providing a noninvasive tool for localizing epileptic seizures in humans because of its high spatial resolution compared with the scalp EEG. Yet, this promise has been elusive, not because of a lack of sensitivity or spatial resolution but because the large size and immobility of present cryogenic (superconducting) technology prevent long-term telemetry required to capture these very infrequent epileptiform events. To circumvent this limitation, we used Micro-Electro-Mechanical Systems technology to construct a noncryogenic (room temperature) microfabricated atomic magnetometer ("magnetrode") based on laser spectroscopy of rubidium vapor and similar in size and flexibility to scalp EEG electrodes. We tested the magnetrode by measuring the magnetic signature of epileptiform discharges in a rat model of epilepsy. We were able to measure neuronal currents of single epileptic discharges and more subtle spontaneous brain activity with a high signal-to-noise ratio approaching that of present superconducting sensors. These measurements are a promising step toward the goal of high-resolution noninvasive telemetry of epileptic events in humans with seizure disorders.

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“…8 Ketamine increases CBF, has variable effects on CMRO2, 9 and increases the amplitude of somatosensory evoked potentials. 10 The effect of a-chloralose upon CMRO2, CBF, and baseline electrophysiologic parameters has not been well studied. Halothane increases CBF, decreases CMRO2, 11 decreases the amplitude, and increases the latency of somatosensory evoked potentials.…”

Section: A Lthough the Model Of Focal Cerebral Ischemiamentioning

confidence: 99%

Anesthetic modulation of cerebral hemodynamic and evoked responses to transient middle cerebral artery occlusion in cats.

Helfaer

Kirsch

Traystman

1990

Stroke

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We measured cerebral blood flow and somatosensory evoked potentials during transient focal cerebral ischemia in cats to compare the effects of four commonly used anesthetic regimens: ketamine/fentanyl/N 2 O (fentanyl), pentobarbital, ketamine/o^chloralose (cv-chloralose), and ketamine/halothane/N 2 O (halothane). Six cats in each group were subjected to 60 minutes of left middle cerebral artery occlusion followed by 120 minutes of reperfusion. Although the amplitude of the initial somatosensory evoked potential wave complex was highest in the tt-chloralose group (58.6±16.5 /iX) and smallest in the halothane group (27J±5.7 fiV), amplitude fell by 75% in all groups upon occlusion. Baseline cerebral blood flow varied substantially between groups (e.g., in the right intersylvian gyrus: fentanyl, 96 ±12; pentobarbital, 30±5; o-chloralose, 24±3; and halothane, 76±11 ml/min/100 g). Occlusion decreased cerebral blood flow to subcortical (e.g., left caudate) structures in all groups (fentanyl, 29±11%; pentobabital, 45±12%; o-chloralose, 27±13%; and halothane, 18±5% of baseline). Postischemic hyperemia occurred in the cortical regions of cats anesthetized with pentobarbital or «-chloralose that had reduced cerebral blood flows during occlusion but not in cats anesthetized with fentanyl (cerebral blood flow during occlusion not different from that of cats anesthetized with pentobarbital or . occlusion has been used by many laboratories, 1 -5 cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO 2 ), and histologic patterns have been difficult to compare among laboratories. This difficulty results in part from not knowing whether differences in results can be attributed to differences in anesthetics, species, or models.Anesthetics (e.g., pentobarbital, ketamine/achloralose, and ketamine/halothane/r^O), Received April 26, 1989; accepted January 11, 1990. evoked potentials. For example, pentobarbital decreases CBF, CMRO 2 , 7 and the amplitude of somatosensory evoked potentials.8 Ketamine increases CBF, has variable effects on CMRO2, 9 and increases the amplitude of somatosensory evoked potentials.10 The effect of a-chloralose upon CMRO2, CBF, and baseline electrophysiologic parameters has not been well studied. Halothane increases CBF, decreases CMRO2, 11 decreases the amplitude, and increases the latency of somatosensory evoked potentials.12 N 2 O increases CMRO 2 13 and C B F 4 and decreases the amplitude of soma...

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The EEG, Evoked Potentials, and Single-unit Activity during Ketamine Anesthesia in Cats

Cited by 106 publications

References 0 publications

The influence of intravenous anaesthetics on enflurane-induced central nervous system seizure activity

The influence of intravenous anaesthetics on enflurane-induced central nervous system seizure activity

Magnetoencephalography of Epilepsy with a Microfabricated Atomic Magnetrode

Anesthetic modulation of cerebral hemodynamic and evoked responses to transient middle cerebral artery occlusion in cats.

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