Propofol and convulsions--the evidence mounts

Intravenous methylprednisolone reduces the risk of propofol-induced adverse effects during Wada testing

The adverse effects and risks associated with intracarotid propofol injection during Wada testing were retrospectively compared in two groups of patients with (n = 75) and without (n = 58) intravenous methylprednisolone administered before intracarotid propofol injection. The incidences of all adverse effects were decreased in the methylprednisolone group. In particular, severe adverse effects such as increased muscle tone with twitching and rhythmic movements or tonic posture, which could adversely affect Wada test results, were seen in one patient in the methylprednisolone group and seven patients in the control group, indicating 92% risk reduction. This study suggests that Wada testing using intravenous methylprednisolone administration prior to propofol injection is a safe approach to the preoperative evaluation of brain tumors, epilepsy, and arteriovenous malformations.

Wada test using secobarbital sodium (Ional) to determine language dominance

The intracarotid sodium amobarbital (Amytal) test, the Wada test, remains an efficient test for evaluation of language and memory function. However, due to a world shortage of amobarbital, it has become necessary to investigate the use of alternatives. We report the efficacy of the Wada test using secobarbital sodium (Ional) in determining language dominance. An accurate determination of language dominance was required in 43 patients preoperatively at our institution. Patients underwent the Wada test using secobarbital sodium, effectiveness and safety were assessed. Patients were monitored for vital signs (blood pressure, respiratory rates, heart rates and saturation of oxygen). Ten patients were further monitored for continuous intra-arterial blood pressure and monitored with scalp electroencephalography (EEG). Language dominance was determined by the Wada test with secobarbital sodium in all patients. Total volume of secobarbital sodium injected was 10-25 mg (mean 16.5 ± 3.2 mg). Changes in vital signs were minimal and any induced neurological deficits completely disappeared within 8 min. On EEG records, induced theta waves immediately appeared on the ipsilateral side of the intra-arterial injection and disappeared within 6 min. One patient described a scintillating scotoma (sensation of shimmering light in his eyes) at the moment of injection; another experienced an epileptic episode during the test and recovered after 6 min. No adverse events were observed in the remaining 41 cases. We propose secobarbital sodium as a safe and reliable alternative to sodium amobarbital used in the Wada test to determine language dominance.

Clinical evaluation of a new formulation of propofol in a medium-chain and long-chain triglycerides emulsion in dogs

Propofol formulated in a mixed medium-chain and long-chain triglycerides emulsion has been recently introduced for clinical use as an alternative to the conventional long-chain triglycerides formulation. This prospective multicentric study evaluated the clinical effectiveness and the complications associated with the use of this new formulation of propofol in dogs. Forty-six Spanish veterinary clinics participated in this study. A total of 541 anaesthesias (118 ASA I, 290 ASA II, 101 ASA III and 32 ASA IV) performed for various diagnostic and therapeutic purposes were evaluated. The anaesthetic protocol was not controlled, with the exception that propofol had to be used at least for induction of anaesthesia. The induction dose of propofol and the incidence of anaesthetic complications throughout the procedure were recorded. A chi-square test compared the incidence of complications according to the maintenance agent used (propofol vs. inhalatory anaesthesia), anaesthetic risk (ASA classification) and the reason for the anaesthesia. The patients premedicated with alpha2 agonists needed lower doses (mean +/- SD, 2.9 +/- 1.3 mg/kg i.v.) than the animals premedicated with phenothiazines (3.9 +/- 1.4 mg/kg i.v.) or benzodiazepines (4.0 +/- 1.4 mg/kg i.v.). The most frequent complications were difficult endotracheal intubation (1.3%), postinduction apnoea (11.3%), cyanosis (0.6%), bradypnoea (2.6%), tachypnoea (2.8%), bradycardia (2%), tachycardia (2.6%), hypotension (0.2%), shock (0.2%), vomiting (4.6%), epileptiform seizures (2.8%), premature awakening (7.4%) and delayed recovery (0.9%). There were no cases of pain on injection or aspiration pneumonia. Three dogs died (0.55%), one during induction and two during recovery from anaesthesia. This study demonstrates that the new formulation of propofol is an useful and effective drug to induce general anaesthesia in dogs.

A Retrospective Analysis of the Effect of General Anesthetics on the Successful Detection of Interictal Epileptiform Activity in Magnetoencephalography

BACKGROUND

A magnetoencephalography (MEG) study requires the patient to lie still for a prolonged period of time. In children and uncooperative adults with epilepsy, general anesthesia or sedation may be required to insure a good quality study. As general anesthetics have anticonvulsant and proconvulsant properties, we investigated whether the use of anesthesia reduced the successful detection of interictal epilepsy activity.

METHODS

MEG testing was performed on 41 epilepsy patients (10 women, 31 men; 1-48 yr) while anesthetized. To determine the impact of anesthesia on the identification of epileptiform activity, the anesthesia group of patients was compared with all other patients with epilepsy who were recorded in our laboratory without anesthesia, as well as with a subgroup of children with epilepsy who were able to be recorded without the need for anesthesia.

RESULTS

Propofol was used in 38 patients, etomidate in two, and one received sevoflurane. Twenty-nine (71%) were found to have interictal epileptiform activity in their MEG results. The percentage of MEG studies with a positive yield for interictal epileptiform activity is comparable with the percentage (63%) found in the patients with epilepsy undergoing MEG without anesthesia. In the 38 children younger than 18 yr, 28 (74%) had interictal epileptiform activity compared with 80% done without anesthesia.

CONCLUSION

We conclude that levels of anesthesia needed to provide unconsciousness and immobility during MEG studies do not significantly alter the likelihood of recording interictal epileptiform spike activity with MEG.

Delayed onset refractory dystonic movements following propofol anesthesia

Neuroexcitation is an uncommon but well recognized side effect of propofol anesthesia and sedation. We present a patient who, despite an intact mental status and without any preexisting movement disorder, experienced delayed onset of involuntary dystonic movements involving head, neck and shoulder for 11 h following emergence from propofol/nitrous oxide anesthesia.

Clinical review: severe asthma

Severe asthma, although difficult to define, includes all cases of difficult/therapy-resistant disease of all age groups and bears the largest part of morbidity and mortality from asthma. Acute, severe asthma, status asthmaticus, is the more or less rapid but severe asthmatic exacerbation that may not respond to the usual medical treatment. The narrowing of airways causes ventilation perfusion imbalance, lung hyperinflation, and increased work of breathing that may lead to ventilatory muscle fatigue and life-threatening respiratory failure. Treatment for acute, severe asthma includes the administration of oxygen, beta2-agonists (by continuous or repetitive nebulisation), and systemic corticosteroids. Subcutaneous administration of epinephrine or terbutaline should be considered in patients not responding adequately to continuous nebulisation, in those unable to cooperate, and in intubated patients not responding to inhaled therapy. The exact time to intubate a patient in status asthmaticus is based mainly on clinical judgment, but intubation should not be delayed once it is deemed necessary. Mechanical ventilation in status asthmaticus supports gas-exchange and unloads ventilatory muscles until aggressive medical treatment improves the functional status of the patient. Patients intubated and mechanically ventilated should be appropriately sedated, but paralytic agents should be avoided. Permissive hypercapnia, increase in expiratory time, and promotion of patient-ventilator synchronism are the mainstay in mechanical ventilation of status asthmaticus. Close monitoring of the patient's condition is necessary to obviate complications and to identify the appropriate time for weaning. Finally, after successful treatment and prior to discharge, a careful strategy for prevention of subsequent asthma attacks is imperative.

Activation of interictal spiking in mesiotemporal lobe epilepsy by propofol-induced sleep

The objective of this study was to test whether low-dose propofol increases the number of interictal spikes in patients with mesiotemporal lobe epilepsy, and to determine whether this is the result of intrinsic properties and is restricted to the primary epileptogenic focus. Controlled infusion of propofol in step-up/-down target concentrations of 0, 0.3, 0.6, and 0.8 mg/L was administered to 10 patients during a 3.5-hour daytime EEG registration. The number of spikes were counted and related to propofol concentration and sleep level. Results were compared with a spontaneous, nocturnal first sleep cycle in 9 of 10 patients. All patients entered nonrapid eye movement 1 sleep during propofol administration, and 8 reached nonrapid eye movement 2 sleep. In 7 patients who showed spikes, spikes were related to sleep (P < 0.05) and not to increasing (P = 0.1) or decreasing (P = 0.5) propofol concentration. Six of nine patients showed more spikes during spontaneous (nocturnal) sleep than during propofol-induced sleep. Contralateral spiking was not suppressed selectively. Low-dose propofol is a safe means of increasing spiking in these patients because it induces sleep. There were no signs of an intrinsic epileptogenicity of propofol or a selective effect on ipsilateral spikes. Controlled sleep induction will increase the yield of interictal spikes during short interictal recordings such as in magnetoencephalography.

[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.

Anesthetic care for the child with congenital central alveolar hypoventilation syndrome (Ondine's curse)

Idiopathic congenital central alveolar hypoventilation syndrome, otherwise known as Ondine's curse, is a rare neuropathologic syndrome characterized by an inadequate respiratory drive with hypoventilation and periods of prolonged apnea resulting in hypercarbia and hypoxemia. Although no definite pathologic abnormality has been identified to account for the disorder, it is thought to represent a primary defect related to altered function of central chemoreceptors resulting in defective control of minute ventilation. Associated problems related to neural crest cell migration, including neuroblastoma formation and Hirschsprung's disease, suggest that the primary defect is defective neural crest cell migration and function. Problems that may impact on perioperative care include the defective central control of ventilation and defective control of upper respiratory musculature, which may lead to upper airway obstruction. Although many patients will have previously undergone tracheostomy and chronic mechanical ventilation, problems in other organ systems can impact on perioperative care. Cardiovascular issues include the possible presence of cor pulmonale and autonomic nervous system dysfunction. Central nervous system issues include the frequent occurrence of seizures and mental retardation. The preoperative work-up, premedication, and the intraoperative/postoperative care and monitoring of these patients is reviewed.

Sedation and analgesia in paediatric intensive care units: a guide to drug selection and use

The indications for sedation in the paediatric intensive care unit (PICU) patient are varied ranging from short term use for various procedures to prolonged administration to provide comfort during mechanical ventilation. When faced with the decision to institute sedation, the healthcare provider must make three decisions: the agent to be used, the route of delivery, and the mode of administration (intermittent versus continuous). There are several agents that have been used to provide sedation in the PICU patient including the inhalational anaesthetic agents, benzodiazepines, opioids, ketamine, propofol, chloral hydrate, phenothiazines, and the barbiturates. This review describes the various agents for sedation and discusses their advantages and disadvantages as they pertain to the PICU. Consequences of and treatment strategies for long term problems with prolonged sedation including tolerance, physical dependency, and withdrawal are reviewed.

Propofol: application in veterinary sedation and anesthesia

Propofol can be used for sedation, induction of anesthesia, and maintenance of anesthesia in small animal patients. In all these situations recovery from its effects is typically rapid and smooth. The drug should be administered slowly, intravenously, to minimize the negative cardiac and respiratory effects seen after rapid bolus administration. The currently available formulations do not contain preservatives, and sterile technique should be strictly followed during its use. Propofol can be used for induction of anesthesia in patients with preexisting disease with minimal delays in recovery. It does not cause excitement at low doses so is also useful for sedation of patients undergoing nonpainful procedures such as radiological examination. This review focuses on the diverse clinical applications for propofol in a small animal practice including indications, recommendations, and contraindications as well as a discussion of the controversies that surround its use.

Convulsions, ataxia and hallucinations following propofol

A 6-year-old fit girl experienced convulsions 44 h after an otherwise uneventful anaesthesia with propofol, alfentanil and nitrous oxide. As an underlying pathology was suspected, the child was kept sedated for 6.5 h for further investigations. During this period she received a continuous infusion of propofol amounting in total to 1600 mg. After having regained consciousness, she was strikingly ataxic and remained so for 5 days. During this period she also experienced two episodes of hallucinations lasting about 2 h. Investigations including lumbar puncture, EEG, cerebral CT and MR scan could not explain the neurological symptoms. She recovered without long-term sequelae.

Propofol: pro- or anticonvulsant?

The pro- or anticonvulsant properties of propofol remain a matter of controversy. Although numerous case reports describe the appearance of abnormal movements, posturing and seizure-like activity related to the use of propofol, systematic studies in both humans and animals strongly suggest that it possesses antiepileptic properties. Propofol consistently reduces the seizure duration during electroconvulsive therapy, its use has been successful in controlling refractory status epilepticus and in animals it offers a strong protection against lignocaine- or pentylene-tetrazol-induced epilepsy. The beneficial effects of propofol may be related to its uniform depressant action on the central nervous system, to a potentialization of GABA-mediated pre- and postsynaptic inhibition, and by decreasing the release of excitatory transmitters, glutamate and aspartate.

Propofol inhibits epileptiform activity in rat hippocampal slices

Propofol (2,6 di-isopropylphenol) is an intravenous general anesthetic used widely in neuroanesthesia, as a sedative in intensive care units, and has successfully aborted refractory status epilepticus. We investigated the effects of propofol on epileptiform activity in rat hippocampal slices. Interictal epileptiform activity was produced by bath applying one of the following: picrotoxin (PTX; 10 and 50 microM), bicucculine methiodide (BMI; 10 and 50 microM), 4-aminopyridine (4-AP; 50 microM), 8.5 mM [K+]o or 0 [Mg2+]o artificial cerebrospinal fluid. Propofol was then added in increasing concentrations and the effect on the rate of extracellular field epileptiform discharges was measured. Ictal-like discharges (> 2 Hz for > 2 s) were produced by 7.5 mM [K+]o and pilocarpine (10 microM). Propofol (30 micrograms/ml, 168 microM) completely abolished discharges induced by 8.5 mM [K+]o and at 60 micrograms/ml (337 mM) completely suppressed discharges induced by 4-AP and 0 [Mg2+]o. Propofol was less effective in reducing discharges produced by GABAA/Cl- receptor complex antagonists. Propofol at a concentration of 300 micrograms/ml (1.7 mM) was needed to reduce BMI-induced (50 microM) discharges by 77% and only reduced PTX-induced (50 microM) discharges by 20%. Ictal-like discharges produced by pilocarpine were disrupted by low concentrations of propofol (3-10 micrograms/ml, 16.9-56.2 microM) and the duration of the ictal-like discharge period was significantly reduced. We found that propofol has significant in vitro antiepileptic effects. Additionally, propofol was less effective against GABAA antagonists suggesting that the GABAA receptor complex is the site of its action.

A method to produce sedation in critically ill patients

OBJECTIVE

To evaluate a protocol based on continuous infusion of a benzodiazepine and morphine to produce apnea/decreased respiratory effort as an adjunct to complex mechanical ventilation in patients with respiratory failure.

DESIGN

Observational report of consecutive patients.

SETTING

University medical intensive care unit.

PATIENTS

Seventeen consecutive patients with acute respiratory failure requiring high levels of sedation and/or paralysis to facilitate mechanical ventilation were studied.

INTERVENTIONS

Patients were started on a continuous infusion of a benzodiazepine and morphine soon after mechanical ventilation was instituted. The dosages of the benzodiazepine and morphine were increased to the end point of diminished respiratory effort or apnea depending on the clinical status of the patient and ventilatory mode. This regimen was supplemented with single doses of neuromuscular blocking agents (NMBAs) only as the dosages of benzodiazepine/narcotic were being titrated. The benzodiazepine/narcotic agents were then gradually reduced as the patient's condition improved, often using an oral route of administration.

MEASUREMENTS AND RESULTS

The benzodiazepine/morphine combination produced apnea and diminished respiratory effort in patients requiring sedation from 2 to 50 days, including those with hemodynamic instability, hepatic dysfunction, renal dysfunction, and sepsis. The combination allowed the use of NMBAs to be minimized. There was no evidence of worsened hemodynamic instability as a result of the administration of these agents. The gastrointestinal tract could be used for nutrition in 8 of the 17 patients.

CONCLUSIONS

Continuous infusion of a benzodiazepine and morphine controlled the respiratory rate in patients with severe respiratory failure requiring complex mechanical ventilatory support.

Continuous propofol infusion for the relief of treatment-resistant discomfort in a terminally ill pediatric patient with cancer

PURPOSE

To determine the effectiveness of propofol as adjunctive therapy in the treatment of drug-resistant discomfort in a terminally ill pediatric patient.

PATIENT AND METHODS

A 3-year-old child with advanced rhabdomyosarcoma and severe drug-resistant discomfort was studied. Propofol was administered as adjunctive therapy to provide relief from severe discomfort.

RESULTS

Propofol was initiated with a loading dose of 1.2 mg/kg followed by a continuous intravenous infusion of 1.2 mg/kg/h. Over the next 10 days, additional loading doses were administered and the infusion rate was increased to a maximum of 32 mg/kg/h. After the addition of propofol, our patient's discomfort improved greatly without the occurrence of propofol-associated adverse events.

CONCLUSIONS

Propofol appears to be an effective adjunct to opioids and a promising alternative to barbiturate therapy in the treatment of drug-resistant discomfort in terminally ill pediatric patients.

Sedation and Analgesia for Children in the Pediatric Intensive Care Unit

Several situations arise in the Pediatric Intensive Care Unit (PICU) patient which may require the pharmacologic control of pain and anxiety. The author discusses the various pharmacologic agents available for sedation and analgesia including the inhalational anesthetic agents, nitrous oxide, benzodiasepines, opioids, ketamine, propofol, and the barbiturates. While intravenous administration is generally chosen for the PICU patient, certain situations may arise which preclude this route. The available information concerning alternative routes of delivery for the various agents including subcutaneous and transmucosal administration is presented. The role of various regional anesthetic techniques to control pain in the PICU patient are reviewed.

Propofol. An overview of its pharmacology and a review of its clinical efficacy in intensive care sedation

Propofol is a phenolic derivative that is structurally unrelated to other sedative hypnotic agents. It has been used extensively as an anaesthetic agent, particularly in procedures of short duration. More recently it has been investigated as a sedative in the intensive care unit (ICU) where it produces sedation and hypnosis in a dose-dependent manner. Propofol also provides control of stress responses and has anticonvulsant and amnesic properties. Importantly, its pharmacokinetic properties are characterised by a rapid onset and short duration of action. Noncomparative and comparative trials have evaluated the use of propofol for the sedation of mechanically ventilated patients in the ICU (postsurgical, general medical, trauma). Overall, propofol provides satisfactory sedation and is associated with good haemodynamic stability. It produces results similar to or better than those seen with midazolam or other comparator agents when the quality of sedation and/or the amount of time that patients were at adequate levels of sedation are measured. Patients sedated with propofol also tend to have a faster recovery (time to spontaneous ventilation or extubation) than patients sedated with midazolam. Although most studies did not measure time to discharge from the ICU, propofol tended to be superior to midazolam in this respect. In a few small trials in patients with head trauma or following neurosurgery, propofol was associated with adequate sedation and control of cerebral haemodynamics. The rapid recovery of patients after stopping propofol makes it an attractive option in the ICU, particularly for patients requiring only short term sedation. In short term sedation, propofol, despite its generally higher acquisition costs, has the potential to reduce overall medical costs if patients are able to be extubated and discharged from the ICU sooner. Because of the potential for hyperlipidaemia and the development of tolerance to its sedative effects, and because of the reduced need for rapid reversal of drug effects in long term sedation, the usefulness of propofol in long term situations is less well established. While experience with propofol for the sedation of patients in the ICU is extensive, there are still areas requiring further investigation. These include studies in children, trials examining cerebral and haemodynamic outcomes following long term administration and in patients with head trauma and, importantly, pharmacoeconomic investigations to determine those situations where propofol is cost effective. In the meantime, propofol is a well established treatment native to benzodiazepines and/or other hypnotics or analgesics when sedation of patients in the ICU is required. In particular, propofol possesses unique advantages over these agents in patients requiring only short term sedation.

Propofol and seizures

It is now clear that "seizure activity", excitatory phenomena, and/or a disorder of muscle tone are potential complications of the use of propofol. Whether this "seizure activity" is primarily, secondarily, or not at all a cerebral cortical event is still to be elucidated. Clearly propofol does have anticonvulsant activity, and also clearly it can produce an involuntary movement disorder, in certain patients, under certain conditions. Propofol is not the first anaesthetic drug to be implicated in the causation of seizures or abnormal movements nor indeed the first to appear to have anti-convulsant and proconvulsant activity (e.g. Althesin). While propofol has undoubtedly proved a very useful drug, the problem of convulsive phenomena creates a degree of background concern about its use. More needs to be known about the mechanism of this complication and any risk factors involved in determining who may have a seizure after propofol. In the clinical setting, the reporting of seizures possibly related to propofol should include--medical history, including personal or family history of epilepsy and movement disorders; a history of previous anaesthetics and whether propofol was used; regular medications; use of drugs or alcohol; history of chemical dependency; emotional state prior to induction; presence of hyperventilation or fever; a description of the alleged seizure, including rate of administration of propofol and amount given, time of onset of seizure in relation to time of drug administration, speed of onset of signs, quality of the abnormal movements, part of body involved, duration, any indication of a postictal state, any cardiovascular changes which may have accompanied the seizure, and any other possible triggers for the reaction such as other drugs used, including premedication; post seizure investigations including temperature, blood sugar, electrolytes, arterial gas analysis, neurological examination, EEG and CT scan. These actions and these investigations concerning propofol should not be delayed. It would appear appropriate to recommend to patients who experience apparent convulsive phenomena after propofol that they not be re-exposed to the drug.

The laryngeal mask airway: its features, effects and role

The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anaesthetic practice. Numerous articles and letters about the device have been published in the last decade, but few large controlled trials have been performed. Despite widespread use, the definitive role of the laryngeal mask has yet to be established. In some situations, such as after failed tracheal intubation or in anaesthesia for patients undergoing laparoscopic or oral surgery, its use is controversial. There are a number of unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoid pressure prevents placement of the mask. We review the techniques of insertion, details of misplacement, and complications associated with the use of the laryngeal mask. We discuss the features and physiological effects of the device, including the changes in intra-cuff pressure during anaesthesia and effects on blood pressure, heart rate and intra-ocular pressure. We then attempt to clarify the role of the laryngeal mask in airway management during anaesthesia, based on the current knowledge, by discussing the advantages and disadvantages as well as the indications and contraindications of its use. Lastly we describe the use of the laryngeal mask in circumstances other than airway maintenance during anaesthesia: fibreoptic bronchoscopy, tracheal intubation through the mask and its use in cardiopulmonary resuscitation.

Propofol, seizures and generalized paroxysmal fast activity in the EEG

Propofol is a relatively new anesthetic agent used in outpatient surgery. Some investigators use it in the treatment of status epilepticus and in epilepsy surgery and have concluded that propofol has an anticonvulsant effect. Cases of seizure-like behaviors, myoclonus and opisthotonus following propofol anesthesia have been reported. Although rare, official warnings about this association have been issued. Different EEG abnormalities, and no abnormality, have been associated with propofol. We report a case of a healthy man who developed nonconvulsive seizures and generalized paroxysmal fast activity in his EEG following use of propofol for anesthesia.

Opisthotonos following propofol: a nonepileptic perspective and treatment strategy

In this report of opisthotonos during recovery from propofol anaesthesia, we relate clinical observations with scientific considerations, and propose a strategy for treatment of this rare side effect. Following a brief operative procedure, a healthy 29-yr-old woman developed recurrent opisthotonos while recovering from anaesthesia with alfentanil, propofol, and nitrous oxide. In contrast to accumulating reports, the patient remained conscious during each episode of back extension and retrocollis. The preservation of consciousness and similarities to strychnine-induced opisthotonos suggest to us that the mechanism may have a brainstem and spinal origin. Recent investigations show that propofol potentiates the inhibitory transmitters glycine and gamma-aminobutyric acid (GABA) which would enhance spinal inhibition during anaesthesia. Postanaesthetic opisthotonos, however, may be due to a propofol-induced tolerance to inhibitory transmitters. This rebound phenomenon would lead to an acute, enduring refractoriness in inhibitory pathways of the brainstem and spinal cord, resulting in increased activity of extensor motoneurons. We recommend a therapeutic strategy that restores inhibition by glycine and GABA at multiple sites; the preferred therapeutic agents would be diazepam and physostigmine. The episodes are usually short-lived, but two of the reviewed 17 patients developed recurrent retrocollis for four and 23 days following antiepileptic drug therapy. Since high doses of phenytoin and carbamazepine can result in opisthotonos, we recommend that anticonvulsants be reserved for postanaesthetic patients with electroencephalographic evidence of seizure activity.

Propofol--contrasting effects in movement disorders

We report two patients presenting for thalamotomy in whom tremor was abolished for 8 h after propofol anaesthesia. Propofol has two contrasting actions. It may have an anti-Parkinsonion effect, abolishing abnormal limb movements. On other occasions, propofol is known to induce spontaneous abnormal limb movements, as well as epileptiform activity. Propofol is probably best avoided for stereotactic procedures. It is difficult to reconcile these two opposing actions.

[Diprivan and epilepsy]

Propofol can be used safely in patients with a history of epilepsy. In the known epileptic patient, propofol is not contra-indicated, provided that the anaesthetist ensures that the anti-epileptic treatment is correctly maintained.

Delayed seizures following sedation with propofol

Seizures occurred in two adolescents approximately six hours after sedation with propofol for bone marrow biopsy. Case #1 was a patient with chronic renal failure, hypertension, and anaemia. Case #2 had just been diagnosed with acute lymphocytic leukaemia. Neither child had experienced seizures before, and both recovered without neurological sequelae. Although other factors may have caused the seizures, the episodes have raised concerns about the safety of propofol for patients travelling home after out-patient surgery. Further study is required to explain the cause of this complication or, at least, to identify risk factors.

Anesthetic considerations in the child with Gaucher disease

We present the case of a 7-month-old girl with Gaucher disease who required anesthetic care during laryngoscopy, bronchoscopy, and central line placement. Gaucher disease is a familial disorder of lipid catabolism with autosomal recessive inheritance. Due to the defective function of the enzyme glucosylceramide beta-glucosidase, glycosphingolipids accumulate, leading to end-organ dysfunction. Three clinical variants of the disease, which differ in age of onset, degree of central nervous system (CNS) involvement, and frequency in the population, have been described. Of concern to the anesthesiologist is the occurrence of significant CNS dysfunction in types II and III, with seizures, gastroesophageal reflux, and chronic aspiration. Bulbar involvement and infiltration of the upper airway with glycolipids may lead to upper airway obstruction. Additionally, hepatosplenomegaly, present in all three variants, may lead to hypersplenism with thrombocytopenia and anemia. Preoperative identification of the associated end-organ dysfunction will allow the safe provision of anesthetic care for these children.

Anaesthetic considerations in the child with Menkes' syndrome

The author presents and discusses the anaesthetic implications of a four-month-old infant with Menkes' syndrome who required tracheostomy. Menkes' syndrome is an X-linked recessive disorder of copper absorption and metabolism. Defective processing of copper results in abnormalities of several enzyme systems leading to severe dysfunction of multiple organ systems. Due to the progressive nature of this disorder and its severe effects on several different organ systems, most importantly the central nervous system, these children frequently require anaesthetic care during imaging procedures such as MRI or during various surgical operations. The high prevalence of seizure disorders, gastroesophageal reflux with the risk of aspiration, and airway complications related to poor pharyngeal muscle control are of concern to the anaesthetist. In addition, defective collagen formation, similar to that seen in Ehlers-Danlos syndrome, may be present. Identification of these associated conditions during the preoperative examination will guide the selection of appropriate, safe anaesthetic care for these children.