Seizures anesthesia

If phenobaibiial fails, per ibatbital can be 0ven as needed to ooiRrol seizures. Anesthesia should be as light as possible. 

Male, Sprague-Dawley rats were implanted under pentobarbital anesthesia with a bipolar electrode in the right dorsal hippocampus for hippocampal stimulation and recording. Stainless steel screws were also placed over the contralateral frontal and parietal cortices for recording cortical seizure activity. The electrodes... 

Benzodiazepines. The benzodiazepines were developed in the 1950s and introduced into the U.S. market in the 1960s. They have found a variety of uses including the treatment of several anxiety disorders, insomnia, seizure disorders, alcohol withdrawal, surgical anesthesia, and others. The benzodiazepines have also been used to calm agitated patients and are therefore useful during the acute treatment phase of bipolar mania. 

Deep anesthesia with enflurane is associated with the appearance of seizurelike electroencephalographic (EEG) changes. Occasionally frank tonic-clonic seizures are observed. Consequently, other inhalational agents are usually given to patients with preexisting seizure disorders. 

Benzodiazepines are usually given orally and are well absorbed by this route. Since the benzodiazepines are weak bases, they are less ionized in the relatively alkaline environment of the small intestine, and therefore, most of their absorption takes place at this site. For emergency treatment of seizures or when used in anesthesia, the benzodiazepines also can be given parenter-ally. Diazepam and lorazepam are available for intravenous administration. 

CNS toxicity may occur, especially with regional anesthesia use, progressing rapidly from mild side effects to tremors, somnolence, seizures, vomiting, and respiratory depression,... 

Most BZs are completely absorbed from the gastrointestinal (GI) tract. The one exception is clorazepate, a pro-drug that undergoes acid hydrolysis in the stomach and is decarboxylated to form N-desmethyl-diazepam, which is then completely absorbed into the bloodstream (Bellantuono et ak, 1980 Hobbs et ak, 1996 Chouinard et ak, 1999). In contrast, most BZs, with the exception of lorazepam and midazolam, are not consistently absorbed from intramuscular injection (Chouinard et ak, 1999). Lorazepam is available as a sublingual form that reaches clinical effect at the same rate as an oral dose. In general, intravenous administration is used only for anesthesia or for the acute management of seizures. When BZs are given via this route, the onset of action is almost immediate (Chouinard et ak, 1999). 

Anesthetic techniques that have minimized adverse effects include the use of muscle relaxants and, more recently, nerve stimulators to assess adequacy of relaxation, the introduction of very rapid acting, short-duration barbiturates, and the use of atropinic agents to minimize the cardiovascular response to a combination of a seizure and anesthesia (93). In addition, 100% oxygenation (adequacy monitored by a pulse oximeter) with positive-pressure ventilation can minimize related cardiac events and memory disruption. 

Although the use of ketamine for anesthesia induction when seizure duration is insufficient has also been recommended, recent studies did not find this agent to be helpful (100, 101, 102 and 103). Disadvantages of ketamine include the following ... 

Memory disturbances typically include anterograde amnesia (i.e., the inability to recall newly learned material) and retrograde amnesia (i.e., the inability to recall previously learned material). Both types can present as deficits in either the dominant or nondominant cerebral hemispheres (i.e., verbal and nonverbal anterograde and retrograde amnesia). Some patients also complain of loss of autobiographical memories. It is often difficult, however, to sort out the relative contributions to memory disturbances from the induced seizures, the anesthesia, or the depressive illness itself. 

Table 22-2 summarizes several other important clinical uses of drugs in the sedative-hypnotic class. Drugs used in the management of seizure disorders and as intravenous agents in anesthesia are discussed in Chapters 24 and 25. 

Acute anxiety states panic attacks generalized anxiety disorder insomnia and other sleep disorders relaxation of skeletal muscle anesthesia (adjunctive) seizure disorders... 

Halothane, isoflurane, and enflurane have similar depressant effects on the EEG up to doses of 1-1.5 MAC. At higher doses, the cerebral irritant effects of enflurane may lead to development of a spike-and-wave pattern and mild generalized muscle twitching (ie, myoclonic activity). However, this seizure-like activity has not been found to have any adverse clinical consequences. Seizure-like EEG activity has also been described after sevoflurane, but not desflurane. Although nitrous oxide has a much lower anesthetic potency than the volatile agents, it does possess both analgesic and amnesic properties when used alone or in combination with other agents as part of a balanced anesthesia technique. 

Barbiturates are classified according to their duration of action (Figure 9.7). For example, thiopental [thye oh PEN tal], which acts within seconds and has a duration of action of about 30 minutes, is used in the intravenous induction of anesthesia. By contrast, phenobarbital [fee noe BAR bi tal], which has a duration of action greater than a day, is useful in the treatment of seizures (see p. 148). Pentobarbital [pen toe BAR bi tal], secobarbital [see koe BAR bi tal] and amobarbital [am oh BAR bi tal] are short-acting barbiturates, which are effective as sedative and hypnotic (but not antianxiety) agents. 

The prospects of more modern ECT being safe are nil. The newer methods add the risk of anesthesia, often complicated by multiple psychiatric drugs administered simultaneously. The electrical trauma must be sufficient to cause a grand mal seizure. Grand mal seizures, when repeated and especially when as severe as those caused by ECT, are in themselves harmful to the brain. Nor are modern variations in current intensity necessarily more benign because, in order to cause a seizure with the weaker currents, exposure time is often increased by 10-fold or more over earlier ECT methods. Also, in order to overcome the anticon-vulsive effects of the sedatives administered to put the patients to sleep, modern ECT often inflicts more intense electrical energy on the brain than the older animal studies and older forms of ECT (see the section Modified ECT ). Perhaps most obvious and important, the study by Sackeim et al. (2007) shows that the effects of modern ECT continue to be devastating. 

Flumazenil is used as a benzodiazepine antagonist in the treatment of poisoning or the reversal of benzodiazepine effects in anesthesia 1,2) or in neonates (3). Guidelines for its use have been summarized (4). The problems in its use are those of dose adjustment, the risks of panic anxiety, seizures, or other signs of excessively rapid benzodiazepine withdrawal, and pharmacokinetic problems due to the short half-life of flumazenil (about 1 hour) compared with the longer half-lives of most benzodiazepines (5). Its use is also commonly associated with vomiting and headache, and rarely with psychosis or sudden cardiac death (SEDA-17,... 

A 15-month-old infant developed seizures (132). Her heart rate was 200/minute, here peripheries were cya-nosed, and she had labored breathing, dilated pupils reacting sluggishly to light, and a temperature of 37.3° C. There was a rash over the right iliac fossa. Her neck and back were arched. Her liver was enlarged. There was no response to rectal diazepam, rectal paraldehyde, or intravenous lorazepam, but she responded to phenytoin and anesthesia with thiopental and suxamethonium. Amphetamine was detected in her urine. 

Once the electrical stimulus is delivered, a generalized brain seizure follows, of a variable duration of 30-90 seconds. Scientists believe that this seizure activity is the variable responsible for ECT s therapeutic benefits. The patient gradually awakens from anesthesia a few minutes later. There is some cognitive confusion, which usually clears over the next... 

Simultaneous scalp and depth electrode recordings were performed on five patients with complex partial epilepsy who underwent alfentanil anesthesia induction before depth electrode removal (7). Five equal bolus doses of alfentanil 100 gg were given to each patient at 60-second intervals (total dose 500 gg). Epileptiform activity was increased in three of the five, but without clinical evidence of seizure activity. 

Smith AR, Hur D, Resano F. Grand mal seizures after 2-chloroprocaine epidural anesthesia in a patient with plasma cholinesterase deficiency. Anesth Analg 1987 66(7) 677-8. 

Etomidate produced activation of epileptiform activity, and electrographic seizures during craniotomy in epileptic patients (8). Generalized seizures were noted after etomidate induction in 20% of 30 patients without a history of epilepsy (9). Cerebral excitation can also occur after recovery from etomidate anesthesia, with potential respiratory disturbance (10,11). Caution should be exercised when giving etomidate to patients with a history of seizures (SEDA-18,113). 

When etomidate was given to 12 patients who had seizures of short duration during electroconvulsive therapy conducted previously under propofol anesthesia, mean seizure duration was significantly increased with etomidate anesthesia (12). However, there is no evidence that this observation is associated with an improved psychiatric outcome. 

Krieger W, Koerner M. Generalized grand mal seizure after recovery from uncomplicated fentanyl-etomidate anesthesia. Anesth Analg 1987 66(3) 284-5. 

An 8-year-old girl with a history of seizures and cerebral ischemic strokes secondary to moyamoya disease underwent anesthetic induction with halothane and 70% nitrous oxide. She had had three previous uneventful anesthetics. Hiccups started within seconds of induction of anesthesia and did not cease until 20 minutes later, when she was paralysed, intubated, and ventilated. During the next 20 minutes a period of hemodynamic instability ensued, with increasing oxygen requirements. The procedure was stopped and pulmonary edema was confirmed on chest X-ray. The child was transferred to the intensive care unit and ventilated overnight. Further recovery was uneventful. 

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