The role of intravenous valproic acid in status epilepticus

Pediatric Headache and Seizures

Headache and seizures are two of the most common complaints seen in the field of pediatric neurology with headache being number one. Both these conditions may coexist. Where the difficulty begins is when the symptoms are not clear cut in making a diagnosis, and conditions are possible as either an atypical seizure or migraine variant. What further complicates matters is the fact that there are many underlying neurologic conditions that carry with them a higher likelihood of developing both headaches and seizures, making each a distinct possibility when obtaining a history from a parent about unusual spells. Although differentiating between seizure and headache may not be easy, with a focused yet thorough history and appropriate use of investigative tools, it can be done. Coming to the correct diagnosis is only the start; once seizures and or headaches have been appropriately diagnosed then the real challenge begins and that is finding a way to successfully treat the headaches and seizures. Within pediatric neurology, the acute options tend to be more diagnosis specific whereas the prophylactic ones may overlap and treat both headaches and seizures. In the following review, we will discuss the epidemiology of pediatric headaches and seizures, the overlap between these 2 conditions in diagnosis, as well as how to tell them apart, and the treatment options and prognosis of both common neurologic disorders in children.

Pediatric seizures

Seizures are a commonly encountered condition within the emergency department and, because of this, can engender complacency on the part of the physicians and staff. Unfortunately, there is significant associated morbidity and mortality with seizures, and they should never be regarded as routine. This point is particularly important with respect to seizures in pediatric patients. The aim of this review is to provide a current view of the various issues that make pediatric seizures unique and to help elucidate emergent evaluation and management strategies.

Efficacy and safety of intravenous sodium valproate versus phenobarbital in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children: a randomised trial

Status epilepticus and acute prolonged seizures are the most commonly occurring neurological emergencies in children. Such events have high morbidity and mortality rates along with poor long-term outcomes, depending on their duration and causes. Therefore, such seizures warrant urgent treatment using appropriate doses of anticonvulsants. Benzodiazepines, phenobarbital, and phenytoin are the most commonly used anticonvulsants for controlling status epilepticus and acute prolonged seizures. However, these medications have several well-known adverse effects. Previous studies on both adults and children have shown the efficacy and safety of rapid infusion of valproate in controlling status epilepticus. However, few well-designed randomised trials have been carried out in children, and there remains a paucity of data regarding intravenous sodium valproate use in children. Therefore, our aim was to compare the efficacy and safety of rapid loading of valproate with those of intravenous phenobarbital in children with status epilepticus and acute prolonged seizures. Sixty children (30 in each group) with convulsive status epilepticus and acute prolonged seizures were enrolled and randomly assigned to receive either valproate or phenobarbital. The main outcome variable was termination of all convulsive activity within 20 min of starting anticonvulsant infusion. Intravenous rapid loading of valproate was successful in seizure termination in (27/30, 90%) of patients compared to phenobarbital (23/30, 77%) (p = 0.189). Clinically significant adverse effects occurred in 74% patients of the phenobarbital group and 24% patients of the valproate group (p < 0.001). In conclusion, rapid loading of valproate is effective and safe in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children. Intravenous valproate should be considered as a suitable choice for terminating status epilepticus and acute prolonged seizures in children.

Diagnostic work-up and therapeutic options in management of pediatric status epilepticus

BACKGROUND

Status epilepticus (SE) is a life-threatening neurologic disorder comprising prolonged and unremitting crisis, and two or more series of seizures without complete intercritical recovery.

DATA SOURCES

We reviewed the literature through a Pubmed/Medline research using key words including status epilepticus, antiepileptic drugs and children, in order to revise and compare international/national protocols and to examine pediatric guidelines in SE management.

RESULTS

Neurologic impairment and SE etiology seem to be the most independent risks for mortality. A deep semiologic evaluation is essential to addressing diagnostic work-up. Ematochemical parameters, plasma levels of antiepileptic drugs and clinically oriented toxic/metabolic screening should be mandatory for investigating both causes and effects of SE. Electroencephalography is clearly helpful to characterize focal from generalized SE and to distinguish epileptic events from pseudoseizures, and it is deal to find nonconvulsive SE. Neuroimaging techniques could detect epileptogenic lesions (such as cortical malformations, tumors, demyelinating disorders or strokes) but are common in practice to find negative or controversial results. Pharmacologic management can be essentially arranged in three stages: benzodiazepines for early SE (lasting less than 30 minutes), phenytoin/fosphenytoin, phenobarbital, valproate, levetiracetam or lacosamide for established SE (30-90 minutes), and anesthetics for refractory SE (more than 90 minutes).

CONCLUSIONS

Status epilepticus is the most common neurologic emergency in childhood. A systematic diagnostic work-up and a three steps based therapeutic approach is required at this age.

A systematic review of randomized controlled trials on the theraputic effect of intravenous sodium valproate in status epilepticus

We performed this systematic review to determine whether intravenous sodium valproate was more effective or safer than other drugs in patients with status epilepticus (SE). A literature search was performed using Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL). From 544 articles screened, 5 were identified as randomized controlled trials and were included for data extraction. The main outcomes were SE controlled and risk of seizure continuation. The meta-analysis was performed with the Random-effect model. The quality of the included studies was evaluated by GRADE (Grading of Recommendations Assessment, Development, and Evaluation). There was no significant statistics in SE controlled between intravenous sodium valproate and phenytoin. Compared with diazepam, sodium valproate had a statistically significant lower risk of time interval for control of refractory SE (RSE) after having drugs; however, there was no statistically significant difference in SE controlled within 30 min between the two groups. There was no statistically significant difference in cessation from status between intravenous sodium valproate and levetiracetam. Intravenous sodium valprate was as effective as intravenous phenytoin for SE controlled and risk of seizure continuation.

Emergency management of paediatric status epilepticus in Australia and New Zealand: practice patterns in the context of clinical practice guidelines

AIMS

To establish current acute seizure management through a review of clinical practice guidelines (CPGs) and reported physician management in the 11 largest paediatric emergency departments in Australia (n= 9) and New Zealand (n= 2) within the Paediatric Research in Emergency Departments International Collaborative (PREDICT) network, and to compare this with Advanced Paediatric Life Support (APLS) guidelines and existing evidence.

METHODS

(i) Review of CPGs for acute seizure management at PREDICT sites. (ii) A standardised anonymous survey of senior emergency doctors at PREDICT sites investigating management of status epilepticus (SE).

RESULTS

Ten sites used seven different seizure CPGs. One site had no seizure CPG. First line management was with benzodiazepines (10 sites). Second line and subsequent management included phenytoin (10), phenobarbitone (10), thiopentone (9), paraldehyde (6) and midazolam infusion (5). Of 83 available consultants, 78 (94%) responded. First line management of SE without intravenous (IV) access included diazepam per rectum (PR) (49%), and midazolam intramuscular (41%) and via the buccal route (9%). First line management of SE with IV access included midazolam IV (50%) and diazepam IV (44%). The second line agent was phenytoin (88%); third line agents were phenobarbitone (33%), thiopentone and intubation (32%), paraldehyde PR (22%) and midazolam infusion (6%). Fourth line agents were thiopentone and intubation (60%), phenobarbitone (16%), midazolam infusion (13%) and paraldehyde (9%).

CONCLUSIONS

Initial seizure management by CPG recommendations and reported physician practice was broadly similar across PREDICT sites and consistent with APLS guidelines. Practice was variable for second/third line SE management. Areas of controversy would benefit from multi-centred trials.

Status epilepticus: evidence and controversy

Status Epilepticus (SE) is a potential and relatively common complication of epileptic seizures. Traditionally, SE was defined as 30 minutes of continuous seizure activity or a series of seizures without return to full consciousness between the seizures. As a practical rule, it is admitted that all patients arriving at the emergency room suffering from epileptic seizures could have SE and should be treated accordingly. It is well known that the longer an attack has lasted, the more difficult it is to control in the next 5 to 10 minutes. On the other hand, once an attack has lasted for over 5 to 10 minutes, it is unlikely to cease spontaneously. Ambulatory intervention should focus on this "therapeutic interval" in acute attacks with the use of first-line drugs such as the intramuscular, rectal, oral, and/or intranasal application of benzodiazepines (BZD). Treatment of SE is a medical emergency, which should include 3 priority objectives: (1) to stop the seizures; (2) to maintain internal homeostasis; and (3) to treat possible complications. Current consensus is that a BZD, notably lorazepam or diazepam, is the initial class of drug for the treatment of SE. Phenytoin, fosphenytoin, or valproate generally is agreed upon as the next drugs to be administered. Failure to respond to optimal BZD and phenytoin loading operationally defines refractory SE.

Intravenous sodium valproate versus diazepam infusion for the control of refractory status epilepticus in children: a randomized controlled trial

An open-label, randomized controlled study was conducted at a tertiary care teaching hospital to compare efficacy and safety of intravenous sodium valproate versus diazepam infusion for control of refractory status epilepticus. Forty children with refractory status epilepticus were randomized to receive either intravenous sodium valproate or diazepam infusion. Refractory status epilepticus was controlled in 80% of the valproate and 85% of the diazepam patients. The median time to control refractory status epilepticus was less in the valproate group (5 minutes) than the diazepam group (17 minutes; P < .001). None of the patients in the valproate group required ventilation or developed hypotension, whereas in the diazepam group 60% required ventilation and 50% developed hypotension after starting diazepam infusion. No adverse effects on liver functions were seen with valproate. It is concluded that intravenous sodium valproate is an effective alternative to diazepam infusion in controlling refractory status epilepticus in children and is free of respiratory depression and hypotension.

Clinical Utility of a Continuous Intravenous Infusion of Valproic Acid in Pediatric Patients

STUDY OBJECTIVE

To describe the dose-concentration relationship of a continuous intravenous infusion of valproic acid (VPA) in pediatric patients when a dosing protocol is used.

DESIGN

Retrospective and concurrent chart review.

SETTING

Tertiary care, 473-bed, academic medical center with a 120-bed, dedicated children's hospital.

PATIENTS

Twenty-six pediatric patients (< 18 yrs old) who received VPA according to the protocol for continuous intravenous infusions between January 1, 2004, and March 31, 2006, identified by using a pharmacy order-entry system.

MEASUREMENTS AND MAIN RESULTS

Patient demographics, VPA treatment regimens, clinical responses, and safety data were recorded and analyzed. Median patient age was 8.5 years (range 1.4-16 yrs). Approximately two thirds received VPA for seizures, and one third for migraines. Patients were given a mean +/- SD VPA loading dose of 28.5 +/- 5.2 mg/kg followed by a continuous infusion rate of 1 +/- 0.2 mg/kg/hour. Mean +/- SD serum concentration measured 4.5 +/- 1.6 hours after the loading dose was 83.3 +/- 22.8 microg/ml. Steady-state concentration at 23.3 +/- 3.0 hours after the start of the continuous infusion was 80.0 +/- 26.0 microg/ml. Postload and steady-state serum concentrations were within the target concentration of 50-100 microg/ml in 77% and 69% of patients, respectively. On further analysis, when the target range was expanded to 50-125 microg/ml (125 microg/ml was deemed acceptable if no adverse effects were noted), 89% and 92% of patients, respectively, had postload and steady-state VPA serum concentrations within this range. The response rate was excellent, with nearly 85% of patients achieving a complete or partial response to therapy. Adverse effects were generally mild and uncommon.

CONCLUSIONS

The continuous-infusion protocol permitted rapid intravenous loading of VPA in pediatric patients while minimizing adverse events and achieving concentrations in the upper region of the therapeutic range.

New management strategies in the treatment of status epilepticus

Status epilepticus is a neurologic emergency associated with high mortality and long-term disability. Recent advances in our understanding of the pathophysiological mechanisms involved in the initiation and perpetuation of seizure activity have revealed that status epilepticus is a dynamic and evolving process. Alterations at the cellular level parallel physiological, physical, and electrical changes at the bedside. Loss of cerebral autoregulation and neuronal damage begin after 30 minutes of continuous seizure activity. This understanding has led to changes in treatments of status epilepticus, which must be multidisciplinary and occur simultaneously in many different areas. The goals of pharmacological therapy are to terminate seizures early and prevent recurrence. Two recent large clinical studies have shown the benefit of early administration of benzodiazepines to control status epilepticus. Pharmacological algorithms designed to focus medical management have trended toward earlier and more aggressive treatment. The hope is that continued exploration into the basic mechanisms involved in status epilepticus and future controlled clinical trials defining optimal medical management will produce further advances.

Population pharmacokinetics of intravenous valproic acid in Korean patients

OBJECTIVE

To determine population-based pharmacokinetic parameters for intravenous valproic acid, and the factors influencing these parameters, in Korean adults.

METHODS

Valproic acid concentrations were obtained using a peak and trough sampling scheme for 102 Korean epileptic patients who were not taking concurrent antiepileptic medication. Three hundred and fifty-four serum concentrations were analysed according to a one-compartment model with a mixed effect modelling method (NONMEM Ver 5.0). The influence of body-weight (kg), height, daily valproic acid dose (mg/day), body mass index (kg/m2), sex, and age on volume of distribution (Vd) and clearance (CL) was assessed in the course of analysis.

RESULTS

Vd and CL of valproic acid increased with body-weight. No significant influence of the other screened covariates was observed. The final regression model was: [equation: see text]. Interindividual variabilities (coefficient of variation) for CL and Vd were 32 and 18%, respectively. Residual error including intraindividual variability was 26.7%.

CONCLUSION

The current results may be used as a basic reference to optimize drug therapy with intravenous valproic acid. Further research on the paediatric population is necessary to confirm the non-linearity of the relation between body-weight and Vd.

New-onset absence status epilepsy presenting as altered mental status in a pediatric patient

Absence status epilepsy (ASE) is an uncommon seizure disorder in children. The primary presentation of new-onset ASE in a pediatric patient is an unusual cause of altered mental status in the emergency department. We describe a previously healthy 8-year-old child who presented with an acutely altered mental state. The patient was awake but confused, with a fluctuating level of alertness and an inability to perform simple routine tasks. The results of general physical and neurologic examination, with the exception of mental status, were normal. Head computed tomography and laboratory test results were normal. Electroencephalographic testing revealed seizure activity consistent with ASE. Administration of intravenous diazepam caused cessation of seizure activity and a return to the patient's baseline mental function. Although rare, ASE should be considered in the differential diagnosis of altered mental status in children.