Isoflurane for refractory status epilepticus: a clinical series

Anesthetic management of the patient with epilepsy or prior seizures

PURPOSE OF REVIEW

Epilepsy is a clinical disorder of paroxysmal recurring seizures, the diagnosis excluding alcohol or drug withdrawal seizures or such recurring exogenous events as repeated insulin-induced hypoglycemia. Epilepsy has a profound impact on each individual diagnosed with this disease.

RECENT FINDINGS

New antiepileptic drugs (AEDs) have been a major change in the approach to management of patients with epilepsy. These drugs tend to have fewer significant drug interactions and less severe side effects. Nonetheless, first-generation AEDs are still widely used. Propofol and desflurane have reliable anticonvulsant effects, whereas remifentanil in larger doses and sevoflurane appear to support epileptiform activity, although the clinical significance of these observations is unclear.

SUMMARY

The primary concerns for providing anesthesia to the patient with epilepsy are the capacity of anesthetics to modulate or potentiate seizure activity and the interaction of anesthetic drugs with AEDs. Proconvulsant and anticonvulsant properties have been reported for virtually every anesthetic such that these properties become elements of the anesthetic plan in the patient with epilepsy. Moreover, AEDs have many physiologic and pharmacologic effects that can have an impact on an anesthetic.

Cortical inhibition during burst suppression induced with isoflurane anesthesia

Isoflurane is a widely used anesthetic which safely and reversibly induces deep coma and associated burst suppression (BS) electroencephalographic patterns. Here we investigate possible underlying causes for the state of cortical hyperexcitability which was recently shown to be one of the characteristics of BS. Our hypothesis was that cortical inhibition is diminished during isoflurane-induced BS. Experiments were performed in vivo using intracellular recordings of cortical neurons to assess their responsiveness to stimulations of connected thalamic nuclei. We demonstrate that during BS EPSPs were diminished by 44%, whereas inhibitory potentials were completely suppressed. This finding was supported by additional results indicating that a decrease in neuronal input resistance normally found during inhibitory responses under low isoflurane conditions was abolished in the BS condition. Moreover, removal of inhibition occasionally revealed excitatory components which were absent during recordings before the induction of BS. We also show that the absence of inhibition during BS is not caused by a blockage of GABA receptors, since iontophoretically applied GABA shows receptor availability. Moreover, the concentration of extracellular chloride was increased during BS, as would be expected after reduced flow of chloride through GABA(A) receptors. Also inhibitory responses were reinstated by selective blockage of glial glutamate transporters with dihydrokainate. These results suggest that the lack of inhibition during BS is caused by reduced excitation, probably resulting from increased glial uptake of glutamate stimulated by isoflurane, which creates a diminished activation of cortical interneurons. Thus cortical hyperexcitability during BS is favored by suppressed inhibition.

Treatment of refractory status epilepticus: literature review and a proposed protocol

Refractory status epilepticus describes continuing seizures despite adequate initial pharmacologic treatment. This situation is common in children, but few data are available to guide management. We review the literature related to the pharmacologic treatment and overall management of refractory status epilepticus, including midazolam, pentobarbital, phenobarbital, propofol, inhaled anesthetics, ketamine, valproic acid, topiramate, levetiracetam, pyridoxine, corticosteroids, the ketogenic diet, and electroconvulsive therapy. Based on the available data, we present a sample treatment algorithm that emphasizes the need for rapid therapeutic intervention, employs consecutive medications with different mechanisms of action, and attempts to minimize the risk of hypotension. The initial steps suggest using benzodiazepines and phenytoin. Second steps suggest using levetiracetam or valproic acid, which exert few hemodynamic adverse effects and have multiple mechanisms of action. Additional management strategies that could be employed in tertiary-care settings, such as coma induction guided by continuous electroencephalogram monitoring and surgical options, are also discussed.

Therapeutic applications and uses of inhalational anesthesia in the pediatric intensive care unit

OBJECTIVE

To review the physical properties, end-organ effects, therapeutic applications, and delivery techniques of inhalational anesthetic agents in the pediatric intensive care unit.

DATA SOURCE

A computerized, bibliographic search regarding intensive care unit applications of inhalational anesthetic agents.

MAIN RESULTS

Although the end-organ effects of inhalational anesthetic agents vary depending on the agent, general effects include a dose-related depression of ventilatory and cardiovascular function. With increasing anesthetic depth, there is a decrease in alveolar ventilation with a reduction in tidal volume and an increase in PaCO2 in spontaneously breathing patients. The potent inhalational anesthetic agents decrease mean arterial pressure and myocardial contractility. The decrease in mean arterial pressure reduces renal and hepatic blood flow. Secondary effects on end-organ function may result from the metabolism of these agents and the release of inorganic fluoride. Beneficial effects include sedation, amnesia, and anxiolysis, making these agents effective for sedation during mechanical ventilation. Bronchodilatory and anticonvulsant properties have led to their use as therapeutic agents in patients with refractory status asthmaticus and epilepticus. Issues regarding their delivery in the intensive care unit include equipment for their delivery, scavenging, and monitoring.

CONCLUSIONS

The literature contains reports of the therapeutic use of the potent inhalational anesthetic agents in the pediatric intensive care unit. Potential applications include sedation during mechanical ventilation as well as therapeutic use for the treatment of status asthmaticus and epilepticus.

The anaesthesiologist in the intensive care unit

PURPOSE OF REVIEW

This review focuses on recent knowledge in areas of anaesthesia expertise which are indispensable to intensive care unit management, including airway management, vascular access, regional analgesia and the treatment of status asthmaticus and status epilepticus.

RECENT FINDINGS

Etomidate as the sole agent for intubation in the intensive care unit has a 90% success rate, while in a prehospital setting, the addition of succinylcholine to etomidate results in a 99% success rate. In determining successful intubation, capnography and laryngoscopic/fibreoptic visualization are superior to auscultation, while auscultation is as effective as the self-inflating bulb or transillumination with the lightwand. The dorsalis pedis artery is an effective alternative to radial artery cannulation, while arterial cannulation itself can result in major adverse effects if complications arise. Ultrasound guidance in the placement of central catheters results in an improved insertion success rate. Internal jugular and subclavian lines have similar risk of haemothorax or pneumothorax, while subclavian lines are associated with the lowest incidence of infection. Midazolam, thiopentone and propofol have all been found to be efficacious in terminating refractory status epilepticus, with thiopentone resulting in a lower incidence of breakthrough seizures or treatment failure but an increased incidence of hypotension. Inhalational anaesthesia using isoflurane or desflurane has also been found to be successful in refractory status epilepticus. In the management of status asthmaticus, limiting minute volume while tolerating hypercapnia and acidosis as well as the use of inhalational anesthesia have proven effective strategies in a number of refractory cases.

SUMMARY

The anaesthesiologist's unique knowledge and skills are ideally suited to the practical management of patients in a critical care setting as well as in the treatment of the critical phases of many illnesses.

Advances in the management of seizures and status epilepticus in critically ill patients

Seizures and status epilepticus are common in critically ill patients. They can be difficult to recognize because most are non-convulsive and require electroencephalogram monitoring to detect; hence, they are currently underdiagnosed. Early recognition and treatment are essential to obtain maximal response to first-line treatment and to prevent neurologic and systemic sequelae. Anti-seizure medication should be combined with management of the underlying cause and reversal of factors that can lower the seizure threshold, including many medications, fever, hypoxia, and metabolic imbalances. This article discusses specific treatments and specific situations, such as hepatic and renal failure patients and organ transplant patients.

Treatment of Status Epilepticus in Adults: Guidelines of the Italian League Against Epilepsy

Status epilepticus (SE) is a medical emergency which can lead to significant morbidity and mortality and requires prompt diagnosis and treatment. SE is differentiated into generalized or partial SE on the basis of its electro-clinical manifestations. The guidelines for the management of SE produced by the Italian League against Epilepsy also distinguish three different stages of SE (initial, established and refractory), based on time elapsed since the onset of the condition and responsiveness to previously administered drugs. Treatment should be started as soon as possible, particularly in generalized convulsive SE, and should include general support measures, drugs to suppress epileptic activity and, whenever possible, treatments aimed at relieving the underlying (causative) condition. Benzodiazepines are the first line antiepileptic agents, and i.v. lorazepam is generally preferred because it is associated with a lower risk of early relapses. If benzodiazepines fail to control seizures, i.v. phenytoin is usually indicated, though i.v. phenobarbital or i.v. valproate may also be considered. Refractory SE requires admission to an intensive care unit (ICU) to allow adequate monitoring and support of respiratory, metabolic and hemodynamic functions and cerebral electrical activity. In refractory SE, general anesthesia may be required. Propofol and thiopental represent first line agents in this setting, after careful assessment of potential risks and benefits.

[Refractory status epilepticus: diagnosis, therapy, course, and prognosis]

Status epilepticus (SE) is a frequent neurological emergency with an annual incidence of 10-20/100,000 individuals. The overall mortality is about 10-20%. Patients present with long-lasting fits or series of epileptic seizures or extended stupor and coma. Furthermore, patients with SE can suffer from a number of systemic complications possibly also due to side effects of the medical treatment. In the beginning, standardized treatment algorithms can successfully stop most SE. A minority of SE cases prove however to be refractory against the initial treatment and require intensified pharmacologic intervention with nonsedating anticonvulsive drugs or anesthetics. In some partial SE, nonpharmacological approaches (e.g., epilepsy surgery) have been used successfully. This paper reviews scientific evidence of the diagnostic approach, therapeutic options, and course of refractory SE, including nonpharmacological treatment.

Inhalational anaesthetics in the ICU: theory and practice of inhalational sedation in the ICU, economics, risk-benefit

ICU sedation poses many problems. The action and side-effects of intravenous drugs in the severely ill patient population of an ICU are difficult to control. The incidence of post-traumatic stress disorder after long-term sedation is high. The recent focus on propofol infusion syndrome entails restrictions in the use of this drug. On the other hand, volatile anaesthetics very selectively suppress consciousness but leave many autonomic functions intact. In the absence of perception and disturbed information processing the number of adverse experiences should be lower, leading to a better psychological outcome. Respiration and intestinal motility are not depressed, facilitating modern therapeutic concepts such as early enteral feeding and augmentation of spontaneous breathing. Awakening after inhalational ICU sedation is quick and predictable, extubation can be planned and organized, and the time during which the patient needs very close observation will be short. Technological advances have greatly simplified the application of inhalational anaesthetics. New anaesthesia ventilators offer ventilatory modes and high flow generation comparable to ICU ventilators. However, they are not yet licensed for stand-alone use. The introduction of a volatile anaesthetic reflection filter for the first time enables the concept of inhalational sedation to be performed with very little effort by many ICUs. This 'anaesthetic conserving device' (AnaConDa) is connected between the patient and a normal ICU ventilator, and it retains 90% of the volatile anaesthetic inside the patient just like a heat and moisture exchanger. In this chapter possible advantages of the new concept and the choice of the inhalational agent are discussed. The technical prerequisites are explained, and the practice and pitfalls of inhalational ICU sedation in general and when using the AnaConDa are described in detail.

Severe refractory status epilepticus owing to presumed encephalitis

The severe refractory type of status epilepticus is very rare in the pediatric population. Eight children with the severe refractory type of status epilepticus owing to presumed encephalitis are described. The age at the onset of status epilepticus of the eight study children ranged between 2.5 and 15 years. Seven of the eight children presented with fever several days prior to the onset of seizures. A comprehensive clinical and laboratory investigation failed to delineate a cause for their seizures. Burst suppression coma was induced by pentothal, midazolam, propofol, or ketamine in all of the children. The mean duration of anesthesia was 28 days (range 4-62 days), but the seizures persisted in spite of repeated burst suppression cycles in all of them. Two children died. Four of the surviving children continued to suffer from seizures, and cognitive sequelae were present throughout follow-up in four children. In summary, the severe refractory type of status epilepticus of the acute symptomatic type owing to relatively mild encephalitis carries a high mortality rate and poor morbidity in terms of seizures and cognition at follow-up.

Desflurane compared with propofol for postoperative sedation in the intensive care unit

BACKGROUND

We hypothesized that emergence from sedation in postoperative patients in the intensive care unit would be faster and more predictable after sedation with desflurane than with propofol.

METHODS

Sixty patients after major operations were allocated randomly to receive either desflurane or propofol. The target level of sedation was defined by a bispectral index(TM) (BIS(TM)) of 60. All patients were receiving mechanical ventilation of the lungs for 10.6 (SD 5.5) h depending on their clinical state. The study drugs were stopped abruptly in a calm atmosphere with the fresh gas flow set to 6 litres min(-1), and the time until the BIS increased above 75 was measured (t(BIS75), the main objective measure). After extubation of the trachea, when the patients could state their birth date, they were asked to memorize five words.

RESULTS

Emergence times were shorter (P<0.001) after desflurane than after propofol (25th, 50th and 75th percentiles): t(BIS75), 3.0, 4.5 and 5.8 vs 5.2, 7.7 and 10.3 min; time to first response, 3.7, 5.0 and 5.7 vs 6.9, 8.6 and 10.7 min; time to eyes open, 4.7, 5.7 and 8.0 vs 7.3, 10.5 and 20.8 min; time to squeeze hand, 5.1, 6.5 and 10.2 vs 9.2, 11.1 and 21.1 min; time to tracheal extubation, 5.8, 7.7 and 10.0 vs 9.7, 13.5 and 18.9 min; time to saying their birth date, 7.7, 10.5 and 15.5 vs 13.0, 19.4 and 31.8 min. Patients who received desflurane recalled significantly more of the five words. We did not observe major side-effects and there were no haemodynamic or laboratory changes except for a more marked increase in systolic blood pressure after stopping desflurane. Using a low fresh gas flow (air/oxygen 1 litre min(-1)), pure drug costs were lower for desflurane than for propofol (95 vs 171 Euros day(-1)).

CONCLUSIONS

We found shorter and more predictable emergence times and quicker mental recovery after short-term postoperative sedation with desflurane compared with propofol. Desflurane allows precise timing of extubation, shortening the time during which the patient needs very close attention.

Diagnosis and Treatment of Nonconvulsive Status Epilepticus in an Intensive Care Unit Setting

Nonconvulsive status epilepticus (NCSE) in adults is a heterogeneous epileptic emergency and includes absence status (AS), complex-partial status epilepticus (CPSE), and the status epilepticus of epileptic encephalopathy (SEEE). The latter seems to be strikingly frequent among patients in intensive care units (ICU). Diagnosis of NCSE is difficult, but has to be made quickly. It relies on clinical signs and a confirmation electroencephalography (EEG). According to the different etiologies and outcomes of AS, CPSE, and SEEE, treatment has to be individually adapted, but needs to follow some basic principles--treatment should take place in the ICU and be monitored by continuous EEG. With a few exceptions, the first drug is an intravenous benzodiazepine, mainly lorazepam. Intravenous fosphenytoin or phenytoin or valproate may follow next. If some forms of NCSE are resistant to first- and second-line treatments, single or combinations of anesthetics and enteral antiepileptic drugs (AEDs) may be added. This opinion is not evidence-based, and randomized controlled prospective trials to evaluate optimal treatment of NCSE are of first priority.

Progress in clinical neurosciences: Status epilepticus: a critical review of management options

Although generalized tonic-clonic status epilepticus (SE) is frequently seen, an evidence-based approach to management is limited by a lack of randomized clinical studies. Clinical practice, therefore, relies on a combination of expert recommendations, local hospital guidelines and dogma based on individual preference and past successes. This review explores selected and controversial aspects of SE in adults and provides a critical appraisal of currently recommended management strategies.

[Pseudoperiodic and paroxysmal electroencephalographic activities]

Periodic and paroxysmal EEG patterns are frequent and easily recognized. They often correlate with particular neurological or systemic conditions. We propose a reclassification and critical examination of these periodic EEG patterns by reviewing the original work presented by J. Gaches in this journal some thirty years ago. Periodic EEG activity is still classified by its localisation--generalised or focal--and by its periodicity--long or short. Periodic long-interval diffuse paroxysmal patterns are reported with rare pathologies such as SSPE, trypanosomiasis or intoxication with phencyclidine. Suppression bursts (SB) may be found in two main situations post-anoxic encephalopathies and drug-induced comas. Ohtahara syndrome is a very rare childhood epileptic syndrome with SB. Periodic short-interval diffuse pattern have been reported in Creutzfeldt-Jakob disease but also in toxic encephalopathies, such as lithium intoxication or as recently reported in acute Cefepime intoxication as well as with metabolic encephalopathies and rarely during AIDS. Periodic lateralized epileptiform discharges (PLEDs) have been classified according to their morphology and the associated condition (epileptic seizures, subtle status, "vascular" seizure). The principal etiology is cerebro-vascular disease and herpes encephalitis but it has also been reported in several other neurological diseases.

[Epileptogenic drugs in anesthesia]

Most anaesthetics and analgesics have both pro- and anticonvulsant activity. The data in the literature should be analysed with respect to the patient population, the recording of epileptic activity and the method of EEG analysis. Among inhaled anaesthetics, isoflurane has strong anticonvulsant properties. In some circumstances, sevoflurane may induce an epileptic activity. With the exception of ketamine and etomidate, all intravenous hypnotics may be used for anesthesia of the epileptic patient. Midazolam is a potent anticonvulsant. Among narcotics, fentanyl and alfentanil may induce clinical or electroencephalographic seizures. Considering the large number of patients treated with these agents without any neurological adverse effect, the clinical relevance of these data is unclear. Neuromuscular blocking agents do not possess pro- or anticonvulsant properties.

The treatment of convulsive status epilepticus in children. The Status Epilepticus Working Party, Members of the Status Epilepticus Working Party

There is currently little agreement between hospital protocols when treating convulsive status epilepticus in children, and a working party has been set up to produce a national evidence based guideline for treating this condition. This four step guideline is presented in this paper. Its effectiveness will be highlighted and its use audited in a number of centres.

The anticonvulsant effects of volatile anesthetics on penicillin-induced status epilepticus in cats

Volatile anesthetics may be used to treat status epilepticus when conventional drugs are ineffective. We studied 30 cats to compare the inhibitory effects of sevoflurane, isoflurane, and halothane on penicillin-induced status epilepticus. Anesthesia was induced and maintained with one of the three volatile anesthetics in oxygen. Penicillin G was injected into the cisterna magna, and the volatile anesthetic discontinued. Once status epilepticus was induced (convulsive period), the animal was reanesthetized with 0.6 minimum alveolar anesthetic concentration (MAC) of the volatile anesthetic for 30 min, then with 1.5 MAC for the next 30 min. Electroencephalogram and multiunit activity in the midbrain reticular formation were recorded. At 0.6 MAC, all anesthetics showed anticonvulsant effects. Isoflurane and halothane each abolished the repetitive spike phase in one cat; isoflurane reduced the occupancy of the repetitive spike phase (to 27%+/-22% of the convulsive period (mean +/- SD) significantly more than sevoflurane (60%+/-29%; P < 0.05) and halothane (61%+/-24%; P < 0.05), and the increase of midbrain reticular formation with repetitive spikes was reduced by all volatile anesthetics. The repetitive spikes were abolished by 1.5 MAC of the anesthetics: in 9 of 10 cats by sevoflurane, in 9 of 9 cats by isoflurane, and in 9 of 11 cats by halothane. In conclusion, isoflurane, sevoflurane, and halothane inhibited penicillin-induced status epilepticus, but isoflurane was the most potent.

IMPLICATIONS

Convulsive status epilepticus is an emergency state and requires immediate suppression of clinical and electrical seizures, but conventional drugs may be ineffective. In such cases, general anesthesia may be effective. In the present study, we suggest that isoflurane is preferable to halothane and sevoflurane to suppress sustained seizure.

Efficacy and mortality in treatment of refractory generalized convulsive status epilepticus in children: a meta-analysis

There is no consensus on the choice of drug treatment for refractory generalized convulsive status epilepticus in children. The objective of this meta-analysis of the published literature was to determine the effects of drug treatments on efficacy (seizure cessation) and mortality in children with this condition, controlling for potential confounding factors. One hundred eleven children, treated with diazepam, midazolam, thiopental, pentobarbital, or isoflurane, met strict inclusion criteria. Diazepam was significantly less efficacious than other treatments (P = .006) stratifying for etiology. Overall mortality was 20% in symptomatic cases and 4% in idiopathic cases (P = .038). Mortality was less frequent in midazolam-treated patients (P = .021) stratifying for etiology. Midazolam appears to be a good choice for initial treatment of refractory generalized convulsive status epilepticus in children, but the attribution of differences in efficacy and mortality solely to drug effect is not possible based on the published literature.

Complications and costs of treatment of refractory generalized convulsive status epilepticus in children

Multiple case series in the literature suggest that benzodiazepines and barbiturates are highly efficacious at stopping seizures. Apparent differences in mortality might not be due solely to drug effect. In this systematic review of the medical literature, we assessed the complications and costs of treatment of refractory status epilepticus in 111 children who met strict inclusion criteria, as part of an effort to provide an evidenced-based recommendation for optimal therapy. All children treated with barbiturates required mechanical ventilation, versus 13% of patients treated with benzodiazepines. Benzodiazepine treatment was associated with pressor use in 3.5% of cases, versus 35% with barbiturate treatment. Midazolam treatment was for the shortest duration and allowed the most rapid return to consciousness. Differences in mean 24-hour drug costs were small compared to savings produced by shorter length of treatment and return to consciousness. Benzodiazepines appear to have higher drug costs but lower complications and overall costs than barbiturates.

Refractory status epilepticus in children: role of continuous diazepam infusion

To determine efficacy of continuous diazepam infusion in the treatment of refractory status epilepticus in a retrospective study, we analyzed data of 62 children admitted consecutively to our Pediatric Intensive Care Unit with a diagnosis of refractory status epilepticus. The unit followed a standard treatment protocol for diazepam infusion; if it failed, thiopental infusion was used. The mean age of patients was 2.80 years (range, 1.5 to 11.5 yr). Thirty-six patients (60%) had acute infections of the central nervous system and 10 (16%) had idiopathic epilepsy. Diazepam infusion was used in 57 patients. This treatment controlled seizures in 86% of patients (49/57), on average within 40 minutes (median, 30 min; range, 10-120 min), at a mean infusion rate of 0.017 mg/kg/min (range, 0.01-0.03 mg/kg/min). The mean total duration of infusion was 68 hours (range, 12-220 hr). Diazepam infusion was associated with hypotension in one patient, respiratory depression requiring ventilatory support in 12% of patients (6/49), and death in 14% of patients (7/49). Thiopental infusion was used in nine patients, including eight in whom diazepam infusion had failed. Thiopental infusion controlled seizures in all nine patients, but all of them needed mechanical ventilation, and seven needed vasopressor support for hypotension; four patients (44%) died. We conclude that continuous diazepam infusion is a reasonably effective modality to control refractory status epilepticus in children and is associated with reduced need for ventilatory and vasopressor support.

Intraoperative convulsions in a child with arthrogryposis

A case of intraoperative convulsions occurring in a child with arthrogryposis multiplex congenita is presented. Arthrogryposis and the anaesthetic management of children with this condition is discussed. Factors which may have contributed to the convulsions are considered.

Adaptive segmentation of burst-suppression pattern in isoflurane and enflurane anesthesia

In this paper a developed novel algorithm for adaptive segmentation of Burst-suppression EEG is presented. The algorithm can detect bursts, suppression and artifacts, dividing the signal into corresponding segments. A compact representation of burst-suppression EEG, useful in monitoring long-term recordings, is presented. In the second part of the paper the burst-suppression patterns of isoflurane and enflurane anesthesia are compared. It is found that bursts as well as suppression segments are shorter in enflurane anesthesia while the coefficient of variability of the segment lengths is similar for the two anesthetics.

The intensive care treatment of convulsive status epilepticus in the UK. Results of a national survey and recommendations

Six hundred and ninety-four members of the Intensive Care Society working in the UK were surveyed by postal questionnaire between May and November 1993 to determine their management of convulsive status epilepticus resistant to initial therapy with intravenous diazepam and phenytoin. Four hundred and eight forms were completed and returned (58.8%). The survey revealed that, following failure of initial management, a benzodiazepine infusion (35%) or anaesthetic induction agent (32%) were the preferred second lines of treatment in intensive care units. In paediatric intensive care units, phenobarbitone (31%) was the agent of choice. Most respondents (57%) gave anaesthetic induction agents within 60 min of the start of status epilepticus, the majority choosing thiopentone (82%). Patients were usually monitored using clinical assessment only (45%), except in paediatric intensive care units and specialist neurological or neurosurgical units where the majority used a cerebral function monitor. Only 12% of the respondents were aware of a protocol for status epilepticus in their intensive care units. The most frequently used therapeutic and monitoring strategies in the management of refractory status epilepticus in the UK are insufficient and need re-evaluation.

Management of generalized tonic-clonic status epilepticus

The steps to be taken in the management of GTC status are outlined in Table 2. Once the GTC status is brought under control, prevention of recurrent seizures must be considered. The specific etiology must be sought. Those patients who require long-term prophylactic anticonvulsant therapy include those with structural brain abnormalities, progressive neurological disorders, and patients with idiopathic epilepsy.

Hallucinations on withdrawal of isoflurane used as sedation

Hallucinations on withdrawal of midazolam have been noted in intensive care patients. Isoflurane is increasingly used as an alternative drug for sedation. We report a seven-year-old child with 15% burns who, on withdrawal of isoflurane, suffered hallucinations, a generalized seizure and disorientation. The adverse symptoms occurred within hours of stopping the isoflurane and lasted for five days.

Refractory status epilepticus in adults

The management of status epilepticus has improved over the past 20 years, resulting in a substantial decrease in the associated morbidity and mortality. Patients who have seizures that are refractory to initial pharmacologic interventions tend to have significant underlying toxic, metabolic, structural, or infectious disorders, and therefore management of refractory status epilepticus must focus on stabilization and on identification and correction of seizure etiology. Regardless of etiology, the faster the seizures are brought under control, the better the prognosis. Risk of central nervous system injury increases after 30 minutes of seizure activity, and therefore efforts should focus on controlling the abnormal electrical discharges at the earliest time possible, preferably within one hour. Benzodiazepines, phenytoin, and phenobarbital remain the most commonly used first- and second-line anticonvulsants, have proven effective in cases of status epilepticus, and should be administered within the first 45 minutes of management. For refractory status epilepticus, pentobarbital anesthesia is evolving as an effective and recommended treatment modality and should be instituted immediately after phenytoin and phenobarbital loading. The role of other anticonvulsants remains to be investigated in controlled clinical trials.

Generalized convulsive status epilepticus: pathophysiology and treatment

The treatment of generalized convulsive status epilepticus according to a protocol, including a time schedule, prevents unnecessary delay and improves outcome. Based on a literature study and our own clinical experiences a treatment protocol is discussed with special emphasis on medical complications, choice of antiepileptic drugs, route of administration and a proper time schedule.

Status epilepticus in children. The acute management

Status epilepticus is a common pediatric emergency that may result in significant morbidity and mortality. This article provides a clinical update on generalized tonic-clonic status epilepticus in children and a practical approach to their initial stabilization and pharmacologic management. Only an organized approach to the initial stabilization and management of the child in status epilepticus will help prevent unnecessary complications and death.

Control of epilepsia partialis continua and secondarily generalised status epilepticus with isoflurane

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Neurosurgical treatment of refractory status epilepticus

Refractory status epilepticus (RSE) is defined as status epilepticus that continues despite aggressive treatment. A 9.8-year-old boy with a past history of daily left focal motor seizures was transferred to University of California at Los Angeles (UCLA) Hospital in pentobarbital coma after 4 days in RSE. The RSE was treated with very high doses of all appropriate antiepileptic drugs (AEDs), alone and in combination. The pentobarbital was titrated to burst suppression on EEG, but whenever pentobarbital was decreased, the seizures recurred. An ictal positron tomography scan of glucose metabolism demonstrated a right frontal area of hypermetabolism corresponding to an epileptic focus on EEG and magnetic resonance lesion. Eight days after the boy was admitted to UCLA, the right frontal focus was surgically removed, with immediate control of the status epilepticus. Whereas before onset of RSE, he had daily focal seizures, the boy has been seizure-free postoperatively for greater than 1 year. Operative treatment should be considered in patients with RSE in whom a focus of seizure onset can be demonstrated and who are reasonably considered surgical candidates.

The effects of convective cooling and rewarming on systemic and central nervous system physiology in isoflurane-anesthetized dogs

Recent studies have demonstrated that small (i.e., 2-5 degrees C) reductions in temperature may protect the brain and spinal cord from ischemic injury. The present study evaluated the physiologic response of anesthetized animals to convective-based cooling and warming. Six shaved, isoflurane-anesthetized (1.50% end-expired; 1 MAC), pancuronium-paralyzed dogs were subjected to temperature manipulation. The flow of cool (13-14 degrees C) or warm (39-41 degrees C) air was uniformly applied to the the dorsal and lateral surfaces of the dog using an inflatable blanket with perforations in the interior surface. Convective cooling reduced pulmonary artery temperature (Tpa) from 37.0 +/- 0.2 degrees C (Mean +/- S.D.) to 33.0 +/- 0.0 degrees C over a 93 +/- 18 min period. Thereafter, the active cooling was discontinued and passive cooling resulted in a further reduction in Tpa to 32.4 +/- 0.3 degrees C over the next 60 min. Institution of convective warming resulted in an increase in Tpa from 32.4 +/- 0.3 to 33.0 +/- 0.0 degrees C in 23 +/- 14 min and from 33.0 to 37.0 +/- 0.0 in an additional 137 +/- 26 min. During the periods of active cooling, passive cooling and active warming, there were strong correlations between Tpa and temperature within the brain, cisterna magna, parietal epidural space, lumbar subarachnoid space and other commonly used temperature measurement sites non-invasively monitored (e.g. tympanic membrane, esophagus, rectum) r greater than or equal to 0.97; P less than 0.0001). The combination of isoflurane anesthesia (a potent EEG-suppressor) plus mild hypothermia (less than 34 degrees C) resulted in an EEG attenuation in five dogs, two of which progressed to burst suppression. The magnitude of EEG changes correlated with the degree of temperature reduction. Upon rewarming to 37 degrees C, all dogs had normal EEG activity and normal brain concentrations of high energy phosphates, glucose and lactate. Blood pressure and cardiac output did not change during the study and no dog exhibited acid-based anomalies or blood lactate accumulation. Whole body oxygen consumption and heart rate decreased in a temperature-dependent fashion. Cardiac rhythm disturbances were rare. The authors conclude that convection-based corporeal cooling and rewarming are efficacious methods for non-invasively and uniformly altering CNS temperatures without adversely affecting cerebral or systemic physiology.

Isoflurane in the management of status epilepticus after surgery for lesion around the motor area

When conventional treatment for status epilepticus fails, general anaesthesia is recommended. We present our experience with isoflurane, an inhalational anaesthetic, in the management of four patients with status epilepticus which occurred soon after surgery for motor area lesion. The seizures were controlled with relatively small concentrations of isoflurane. Hypotension, the only adverse effect of isoflurane, was managed easily with the use of dopamine in physiological saline. Although status epilepticus occurring soon after surgery is transient, it carries a risk of persistent brain damage if active treatment is not instituted promptly. Isoflurane general anaesthesia may be recommended to control it in the intensive neurosurgical care.

Variance of interburst intervals in burst suppression

Each EEG performed over a 3 year period at the University of Michigan with a diagnosis of generalized burst-suppression (BS) was reviewed. Ten EEGs from 10 patients with hypoxic-ischemic encephalopathy (HIE-BS) and 21 records from 8 patients with pentobarbital induced burst-suppression for treatment of status epilepticus (SE-BS) were reviewed. For each EEG, the mean duration of 40 interburst intervals (IBIs) as well as their coefficient of variability were calculated. We found that in the SE-BS group the coefficient of variability of IBI duration was highly correlated with the logarithm of mean IBI duration while in the HIE-BS group, there was no significant correlation between these 2 variables. This suggests that the underlying mechanism causing BS is different in the 2 groups and might be related to a uniform and progressive affection of similar brain structures in the SE-BS group and a more patchy and variable pathology in the HIE-BS group.