[Epileptogenic drugs in anesthesia]

Epilepsy and anesthesia

BACKGROUND AND OBJECTIVES

Epilepsy is one of the most frequent chronic neurological diseases. Although anesthesia for epilepsy patients is more common in neurosurgery, this group of patients needs, just as the general population, anesthesia for different diagnostic and therapeutic procedures. This article aims to address the issues of greatest interest to the anesthesiologist in the perioperative management of epileptic patients undergoing anesthesia for non-neurosurgical procedures.

CONTENT

We discuss relevant aspects of pathophysiology, classification and diagnosis of epilepsy; anticonvulsant therapy and interactions with anesthetic drugs; surgery and the ketogenic diet; pro-and anticonvulsant effects of drugs used in anesthesia; preoperative evaluation, intra- and postoperative conduct in epileptic patients, as well as the diagnosis and treatment of perioperative seizures.

CONCLUSIONS

In the perioperative management of epileptic patients is important for anesthesiologists to identify the type of epilepsy, the frequency, severity and the factors triggering the epileptogenic crises; the use of anticonvulsant drugs and possible interactions with drugs used in anesthesia; the presence of ketogenic diet and stimulatory of the vagus nerve, and its implications in anesthetic techniques. It is essential the understanding of pro- and anticonvulsant properties of drugs used in anesthesia, minimizing the risk of seizure activity in the intra- and postoperative. Finally, it is important to outline the diagnosis and initiate treatment of seizures, perioperative, which offers lower both morbidity and mortality.

[Perioperative anaesthetic management of an epileptic patient treated with a vagus nerve stimulation]

The vagal nerve stimulation is approved for medically refractory epilepsy and major depression. We report the perioperative management of an epileptic patient with this indwelling device. This observation summarizes the physiologic implications and the specific anaesthetic considerations for procedures with this pre-existing device.

Unexpected neurological sequelae following propofol anesthesia in infants: Three case reports

Propofol is a widely used hypnotic agent for induction and maintenance of pediatric anesthesia with a well known safety profile. Experimental in vitro studies suggest that propofol may be toxic to developing neurons. We report the cases of three infants who underwent surgery before 2 months of age for different benign pathologies. Propofol was used for induction and maintenance of anesthesia in all cases. The three patients developed convulsions with similar clinical characteristics (cluster of recurrent clinical and subclinical seizures) between the 23th and 30th hours following anesthesia. Clinical and electroencephalographic improvement was obtained between the third and fourth day of management in pediatric intensive care unit. The seizures never recurred, and the three patients underwent further uneventful general anesthesia without propofol. Follow-up of the three patients disclosed unexpected neurological dysfunction: progressive microcephaly (head circumferences were normal at birth), developmental impairment with cognitive and behavioural disturbances in two cases, and bilateral symmetrical white-matter abnormalities on cerebral magnetic resonance imaging.

CONCLUSION

The causal relationship between propofol anesthesia and the neurological symptoms of our patients remains difficult to ascertain, but we believe that pediatricians, anesthetists and intensive care-givers should be aware of this possible adverse reaction that has never been described before.

[Anesthesia for procedures other than neurosurgery in the adult with epilepsy]

Epilepsy is a common disease affecting between 1% and 2% of the general population. The incidence increases with age. Given the complicated etiology and pathogenesis of this disease, epileptic patients of all ages may require anesthesia. The perioperative care of these patients involves a number of special considerations, although the main issues to deal with are pharmacologic. This review gives an overview of the etiopathogenesis and pathophysiology of epilepsy and describes the general characteristics of antiepileptic drug therapy. The anesthetic implications of chronic treatment with antiepileptic agents and the interactions between these drugs and common anesthetics are discussed in more detail.

Conduite à tenir concernant le traitement médicamenteux des patients adressés pour chirurgie programmée

This review focuses on potential drug interactions between anaesthetic drugs or techniques and chronic medications in patients scheduled for surgery. The vast majority of therapeutics can be continued until the morning of surgery. However, for some drugs such as ACE inhibitors, there is strong evidence to recommend their discontinuation prior to surgery. When juged necessary, interruption of chronic therapeutic needs to be anticipated and planned. In the other hand, for other drugs such as beta-blockers or L-Dopa, acute withdrawal is associated with documented adverse outcome. As a result, such drugs have to be continuing throughout the operative period. Although a general consensus exists for many medications, there are still controverses as to the management of antithrombotic drugs and some central nervous system agents. Advances in anaesthesia include knowledge on the mechanisms involved in drug interactions, which allows us to improve the preoperative management of chronic therapeutics.

Tolerance and analgesic efficacy of a new i.v. paracetamol solution in children after inguinal hernia repair

BACKGROUND

A new intravenous (i.v.) formulation of paracetamol and propacetamol (prodrug of paracetamol) were compared to determine tolerance and relative analgesic efficacy during the first 6 h after inguinal hernia repair performed under general anesthesia combined with ilioinguinal block in children.

METHODS

A total of 183 ASA I or II in-patients, aged 1-12 years, admitted for unilateral inguinal hernia repair were randomized to receive in a double-blind design either i.v. paracetamol 15 mg.kg(-1) (n = 95) or propacetamol 30 mg.kg(-1) (n = 88) for postoperative pain relief as soon as pain intensity was greater than 30 on a 100 mm visual analog scale. All patients were evaluated for efficacy and tolerance. Efficacy was evaluated between 15 min and 6 h after the start of the 15 min infusion.

RESULTS

The most frequently reported adverse event was injection site pain, which was significantly reduced in the new formulation group (i.v. paracetamol 14.7% vs propacetamol 33.0% of children, P = 0.005). No significant difference was obtained between treatments on pain relief (PR), pain intensity difference (PAID) from baseline, and objective pain scale intensity difference (OPSD). Also, treatment effects did not differ significantly for maximum values and weighted sums of PR, PAID (investigator and child rated), OPSD, time to first request for rescue medication, proportion of children requesting rescue medication, and investigators' global treatment satisfaction.

CONCLUSION

A single infusion of i.v. paracetamol 15 mg.kg(-1) produced analgesia similar to a single infusion of propacetamol 30 mg.kg(-1) following inguinal hernia repair in children. Paracetamol i.v. 15 mg.kg(-1) was better tolerated at the injection site than propacetamol.

Le propofol et l'AIVOC en neuro-anesthésie

Propofol is an intravenous anaesthetic agent, which presents interesting features for its use in neuro-anaesthesia: it is a powerful hypnotic that does not increase the intracranial pressure. The delay of recovery is short even after several hours of continuous infusion. This is essential for a fast neurologic examination. Continuous infusion should be preferred to bolus in order to prevent hypotension and decrease of the cerebral perfusion pressure. Target-controlled infusion models based on effect site concentrations are now available through several softwares. This technique appears especially useful for awake craniotomy and functional neurosurgery. The level of consciousness is easily fixed between deep anaesthesia and light sedation permitting to ask the patient to move following orders. A sedation controlled by the patient himself is even possible.

Long-term amygdalohippocampal stimulation for refractory temporal lobe epilepsy

Short-term deep brain stimulation (DBS) recently has been shown to be efficacious in refractory temporal lobe epilepsy. We (1) evaluated long-term DBS in medial temporal lobe structures in patients with normal magnetic resonance imaging (MRI) findings and (2) investigated the use of chronic DBS electrodes for the localization of the ictal onset zone before DBS. In three patients with complex partial seizures (CPSs), DBS electrodes were implanted in the amygdalohippocampal region to identify and subsequently stimulate the ictal onset zone. CPSs were compared before and after chronic DBS. Side effects were carefully monitored. DBS electrodes yielded high-quality electroencephalogram recordings showing unilateral seizure onset in medial temporal lobe structures. For all patients, unilateral amygdalohippocampal stimulation was performed. After a mean follow-up of 5 months (range, 3-6 months), all patients had a greater than 50% reduction in seizure frequency. In two patients, antiepileptic drugs could be tapered. None of the patients reported side effects. This open study demonstrates the feasibility of consecutive electroencephalographic recordings and DBS in medial temporal lobe structures using DBS electrodes. These results prompt further studies in a larger patient population to establish the efficacy and safety of chronic DBS as an alternative treatment for refractory temporal lobe epilepsy.

An introduction to contingent (closed-loop) brain electrical stimulation for seizure blockage, to ultra-short-term clinical trials, and to multidimensional statistical analysis of therapeutic efficacy

Automated seizure blockage is a top research priority of the American Epilepsy Society. This delivery modality (referred to herein as contingent or closed loop) requires for implementation a seizure detection algorithm for control of delivery of therapy via a suitable device. The authors address the many potential advantages of this modality over conventional alternatives (periodic or continuous), and the challenges it poses in the design and analysis of trials to assess efficacy and safety-in the particular context of direct delivery of electrical stimulation to brain tissue. The experimental designs of closed-loop therapies are currently limited by ethical, technical, medical, and practical considerations. One type of design that has been used successfully in an in-hospital "closed-loop" trial using subjects undergoing epilepsy surgery evaluation as their own controls is discussed in detail. This design performs a two-way comparison of seizure intensity, duration, and extent of spread between the control (surgery evaluation) versus the experimental phase, and, within the experimental phase, between treated versus untreated seizures. The proposed statistical analysis is based on a linear model that accounts for possible circadian effects, changes in treatment protocols, and other important factors such as change in seizure probability. The analysis is illustrated using seizure intensity as one of several possible end points from one of the subjects who participated in this trial. In-hospital ultra-short-term trials to assess safety and efficacy of closed-loop delivery of electrical stimulation for seizure blockage are both feasible and valuable.