Use of midazolam for refractory status epilepticus in pediatric patients

Efficacy of a combined anti-seizure treatment against cholinergic established status epilepticus following a sarin nerve agent insult in rats

The development of refractory status epilepticus (SE) following sarin intoxication presents a therapeutic challenge. Here, we evaluated the efficacy of delayed combined double or triple treatment in reducing abnormal epileptiform seizure activity (ESA) and the ensuing long-term neuronal insult. SE was induced in rats by exposure to 1.2 LD50 sarin followed by treatment with atropine and TMB4 (TA) 1 min later. Double treatment with ketamine and midazolam or triple treatment with ketamine, midazolam and levetiracetam was administered 30 min post-exposure, and the results were compared to those of single treatment with midazolam alone or triple treatment with ketamine, midazolam, and valproate, which was previously shown to ameliorate this neurological insult. Toxicity and electrocorticogram activity were monitored during the first week, and behavioral evaluations were performed 2 weeks post-exposure, followed by biochemical and immunohistopathological analyses. Both double and triple treatment reduced mortality and enhanced weight recovery compared to TA-only treatment. Triple treatment and, to a lesser extent, double treatment significantly ameliorated the ESA duration. Compared to the TA-only or the TA+ midazolam treatment, both double and triple treatment reduced the sarin-induced increase in the neuroinflammatory marker PGE2 and the brain damage marker TSPO and decreased gliosis, astrocytosis and neuronal damage. Finally, both double and triple treatment prevented a change in behavior, as measured in the open field test. No significant difference was observed between the efficacies of the two triple treatments, and both triple combinations completely prevented brain injury (no differences from the naïve rats). Delayed double and, to a greater extent, triple treatment may serve as an efficacious delayed therapy, preventing brain insult propagation following sarin-induced refractory SE.

Neuroprotection by delayed triple therapy following sarin nerve agent insult in the rat

The development of refractory status epilepticus (SE) induced by sarin intoxication presents a therapeutic challenge. In our current research we evaluate the efficacy of a delayed combined triple treatment in ending the abnormal epileptiform seizure activity (ESA) and the ensuing of long-term neuronal insult. SE was induced in male Sprague-Dawley rats by exposure to 1.2LD50 sarin insufficiently treated by atropine and TMB4 (TA) 1 min later. Triple treatment of ketamine, midazolam and valproic acid was administered 30 min or 1 h post exposure and was compared to a delayed single treatment with midazolam alone. Toxicity and electrocorticogram activity were monitored during the first week and behavioral evaluation performed 3 weeks post exposure followed by brain biochemical and immunohistopathological analyses. The addition of both single and triple treatments reduced mortality and enhanced weight recovery compared to the TA-only treated group. The triple treatment also significantly minimized the duration of the ESA, reduced the sarin-induced increase in the neuroinflammatory marker PGE2, the brain damage marker TSPO, decreased the gliosis, astrocytosis and neuronal damage compared to the TA+ midazolam or only TA treated groups. Finally, the triple treatment eliminated the sarin exposed increased open field activity, as well as impairing recognition memory as seen in the other experimental groups. The delayed triple treatment may serve as an efficient therapy, which prevents brain insult propagation following sarin-induced refractory SE, even if treatment is postponed for up to 1 h.

Intramuscular Midazolam for treatment of Status Epilepticus

INTRODUCTION

Status epilepticus (SE) is a common neurological and medical emergency. It has high mortality and morbidity rates, which typically correlate with seizure semiology and duration; therefore, prompt and proper pharmacological intervention is paramount. In a pre-hospital setting, establishing venous access can be difficult, so other routes of drug administration should be considered.

AREAS COVERED

The paper summarizes the data from the literature and provides an evaluation of the efficacy and safety of intramuscular midazolam (IM MDZ) as it pertains to the management of acute seizures and SE.

EXPERT OPINION

The cascade of events involved in the genesis and sustenance of seizures, if not promptly stopped, lead to the perpetuation of the condition and may contribute to the refractoriness of pharmacological treatment. Hence, non-venous routes for drug administration were developed to allow untrained personnel to rapidly stop seizures. Among benzodiazepines (BDZs), IM MDZ is at least as effective and safe as other intravenously administered BDZs. Moreover, thanks to IM MDZ's favorable pharmacodynamic and pharmacokinetic profile, it is a promising alternative to other non-venous drugs such as intranasal-MDZ, buccal-MDZ, and rectal-diazepam in the pre-hospital management of SE cases with motor features.

Efficacy of retigabine in ameliorating the brain insult following sarin exposure in the rat

BACKGROUND

Sarin is an irreversible organophosphate cholinesterase inhibitor. Following toxic signs, an extensive long-term brain damage is often reported. Thus, we evaluated the efficacy of a novel anticonvulsant drug retigabine, a modulator of neuronal voltage gated K⁺ channels, as a neuroprotective agent following sarin exposure.

METHODS

Rats were exposed to 1 LD₅₀ or 1.2 LD₅₀ sarin and treated at onset of convulsions with retigabine (5 mg/kg, i.p.) alone or in combination with 5 mg/kg atropine and 7.5 mg/kg TMB-4 (TA) respectively. Brain biochemical and immunohistopathological analyses were processed 24 h and 1 week following 1 LD₅₀ sarin exposure and at 4 weeks following exposure to 1.2 LD₅₀ sarin. EEG activity in freely moving rats was also monitored by telemetry during the first week following exposure to 1.2 LD₅₀ and behavior in the Open Field was evaluated 3 weeks post exposure.

RESULTS

Treatment with retigabine following 1 LD₅₀ sarin exposure or in combination with TA following 1.2 LD₅₀ exposure significantly reduced mortality rate compared to the non-treated groups. In both experiments, the retigabine treatment significantly reduced gliosis, astrocytosis and brain damage as measured by translocator protein (TSPO). Following sarin exposure the combined treatment (retigabine+ TA) significantly minimized epileptiform seizure activity. Finally, in the Open Field behavioral test the non-treated sarin group showed an increased mobility which was reversed by the combined treatment.

CONCLUSIONS

The M current modulator retigabine has been shown to be an effective adjunct therapy following OP induced convulsion, minimizing epileptiform seizure activity and attenuating the ensuing brain damage.

Review of a Large Clinical Series: Outcome of Pediatric Status Epilepticus Admitted to Intensive Care

The authors determine the relationship between seizure duration, etiology, and outcome in a modern intensive care setting and assess the usefulness of computed tomography (CT) and the empiric use of antimicrobial therapy. The design was a retrospective chart review. The setting was a tertiary pediatric critical care unit. Patients included 161 consecutive admissions to the critical care unit at the Hospital for Sick Children, Toronto, with status epilepticus over a 3-year period. There were no interventions. The overall mortality was 5.6%. A further 11% experienced an adverse neurological outcome as determined on hospital discharge. Mean seizure duration was 1.5 ± 2.8 hours in those children with a normal outcome, 1.7 ± 1.2 hours in those survivors with an abnormal neurological outcome ( P > 0.05), and 6.8 ± 12 hours in those who died ( P < 0.05). The CT scan was abnormal in 41% of cases. New findings that directly affected immediate management decisions were found in 20% of CT scans. Both the duration and etiology of status epilepticus affect the outcome. CT scanning should be done without delay, once the patient is stable. Antiviral therapy should be started empirically now that encephalitis is far more common than bacterial meningitis in this group of patients. Studies are lacking that compare the efficacy of drugs available to treat status epilepticus. These studies need to be done, as the findings could affect the duration of status.

Pharmacokinetics, pharmacodynamics, and safety of USL261, a midazolam formulation optimized for intranasal delivery, in a randomized study with healthy volunteers

OBJECTIVE

To compare the pharmacokinetics, pharmacodynamics, and tolerability of USL261, a midazolam formulation optimized for intranasal delivery, versus midazolam intravenous (IV) solution administered intranasally (MDZ-inj IN) or intravenously (MDZ-inj IV) in healthy adults.

METHODS

In this phase 1, five-way crossover, open-label study, 25 healthy adults (aged 18-42 years) were randomly assigned to receive 2.5, 5.0, and 7.5 mg USL261; 2.5 mg MDZ-inj IV; and 5.0 mg MDZ-inj IN. Blood samples were collected for 12 h post dose to determine pharmacokinetic profiles. Pharmacodynamic assessments of sedation and psychomotor impairment also were conducted. Adverse events, oxygen saturation, and vital signs were recorded.

RESULTS

Increasing USL261 dose corresponded with increases in midazolam area under the concentration time curve (AUC) and maximum observed plasma concentration (Cmax ), with all doses demonstrating rapid median time to Cmax (Tmax ; 10-12 min). USL261 also demonstrated increased absorption, with a 134% relative bioavailability, compared with the same MDZ-inj IN dose. USL261 was associated with dose-dependent increases in sedation and psychomotor impairment (p < 0.05); however, these effects lasted <4 h and generally did not differ from MDZ-inj IN or MDZ-inj IV at comparable doses. No serious adverse events (SAEs) or deaths were reported, and no treatment-emergent adverse events (TEAEs) led to study discontinuation.

SIGNIFICANCE

Compared with intranasal delivery of a midazolam formulation intended for IV delivery, USL261, optimized for intranasal administration demonstrated improved bioavailability with similar pharmacodynamic effects. Therefore, USL261 may be a preferable alternative to the currently approved rectal diazepam treatment for intermittent bouts of increased seizure activity.

Midazolam as an anticonvulsant antidote for organophosphate intoxication--A pharmacotherapeutic appraisal

OBJECTIVE

This review summarizes the therapeutic potential of midazolam as an anticonvulsant antidote for organophosphate (OP) intoxication.

METHODS

Benzodiazepines are widely used to treat acute seizures and status epilepticus (SE), a neurologic emergency of persistent seizures that can lead to severe neuronal damage or death. Midazolam is a benzodiazepine hypnotic with a rapid onset and short duration of action.

RESULTS

Midazolam is considered the new drug of choice for persistent acute seizures and SE, including those caused by neurotoxic OPs and nerve agents. Midazolam is a positive allosteric modulator of synaptic γ-aminobutyric acid (GABA)A receptors in the brain. It potentiates GABAergic inhibition and thereby controls hyperexcitability and seizures. Midazolam is administered intravenously or intramuscularly to control acute seizures and SE. Due to its favorable pharmacokinetic features, midazolam is being considered as a replacement anticonvulsant for diazepam in the antidote kit for nerve agents. Clinical studies such as the recent Rapid Anticonvulsant Medication Prior to Arrival Trial (RAMPART) trial have confirmed the anticonvulsant efficacy of midazolam in SE in prehospital settings.

SIGNIFICANCE

In experimental models, midazolam is effective when given at the onset of seizures caused by nerve agents. However, benzodiazepines are less effective at terminating seizures when given 30 min or later after OP exposure or seizure onset, likely because of internalization or downregulation of synaptic, but not extrasynaptic, GABAA receptors, which can lead to diminished potency and seizure recurrence.

Efficacy and safety of intramuscular midazolam versus rectal diazepam in controlling status epilepticus in children

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of intramuscular midazolam in controlling convulsive status epilepticus in children, by comparing it with rectal diazepam.

METHODS

In this randomized trial, 100 children (50 in each group) with convulsive status epilepticus aged 1 month to 16 years were enrolled and randomly assigned into two groups to receive either 0.3 mg/kg intramuscular midazolam or 0.5 mg/kg rectal diazepam. Main outcome measure was stopping of all motor activity after drug administration. Another measures were times between patient's arrival to emergency department till drug administration, between drug administration to seizure cessation, and between patient's arrival to seizure cessation.

RESULTS

Both medication were effective for seizure control and no significant difference was found between successful treatments after administering the medication (P = 0.061). In the midazolam group, in 96% (48/50) of cases treatment was successful and in the diazepam group, in 94% (47/50) of cases treatment was successful. Time from arrival to administering the medication was significantly shorter in midazolam group (P = 0.017). The majority of seizures in midazolam group were stopped in less than 66 s (median) compared to 130 s (median) for diazepam group, (P < 0.001). No serious adverse effects were seen in both groups.

CONCLUSION

IM midazolam is not superior but may be at least as effective as rectal diazepam for controlling of status epilepticus in children. Midazolam via IM route could be one of the choices in children with convulsive status seizures who have difficult IV access.

Risk factors for apnea in children presenting with out-of-hospital seizure

OBJECTIVE

This study aimed to quantify risk factors for apnea in children 0 to 5 years of age with out-of-hospital seizure.

METHODS

This is a retrospective study of pediatric patients with seizure transported by paramedics to the pediatric emergency department (PED) of a tertiary center from July 2008 to June 2009. Patients with traumatic injury and those with another diagnosis after PED evaluation were excluded. We evaluated the effect of field diazepam and other potential risk factors on the occurrence of apnea, defined as the need for airway management, that is, bag-mask ventilation by paramedics or bag-mask ventilation or intubation by PED staff within 30 minutes of arrival.

RESULTS

There were 336 pediatric patients meeting inclusion criteria. The median age was 1.9 years (interquartile range,1.3-3.0 years); 193 patients (57%) were male. Fifty-four patients (16%) were treated with diazepam before PED arrival. There were 28 apneic events (8.3%). The adjusted relative risk for apnea given diazepam in the field by any route was 10.2 (95% confidence interval, 3.9-21.8; P < 0.0001), adjusted for age and seizure on arrival. Persistent seizure on PED arrival was also highly associated with apnea, with an adjusted relative risk of 15.8 (95% confidence interval, 6.5-28.9; P < 0.0001).

CONCLUSIONS

Field treatment with diazepam and seizing at the time of PED arrival are associated with the occurrence of apnea in children 0 to 5 years of age with out-of-hospital seizure. Larger studies are needed to determine what other factors may contribute to this risk.

Risk factors for apnea in pediatric patients transported by paramedics for out-of-hospital seizure

STUDY OBJECTIVE

Apnea is a known complication of pediatric seizures, but patient factors that predispose children are unclear. We seek to quantify the risk of apnea attributable to midazolam and identify additional risk factors for apnea in children transported by paramedics for out-of-hospital seizure.

METHODS

This is a 2-year retrospective study of pediatric patients transported by paramedics to 2 tertiary care centers. Patients were younger than 15 years and transported by paramedics to the pediatric emergency department (ED) for seizure. Patients with trauma and those with another pediatric ED diagnosis were excluded. Investigators abstracted charts for patient characteristics and predefined risk factors: developmental delay, treatment with antiepileptic medications, and seizure on pediatric ED arrival. Primary outcome was apnea defined as bag-mask ventilation or intubation for apnea by paramedics or by pediatric ED staff within 30 minutes of arrival.

RESULTS

There were 1,584 patients who met inclusion criteria, with a median age of 2.3 years (Interquartile range 1.4 to 5.2 years). Paramedics treated 214 patients (13%) with midazolam. Seventy-one patients had apnea (4.5%): 44 patients were treated with midazolam and 27 patients were not treated with midazolam. After simultaneous evaluation of midazolam administration, age, fever, developmental delay, antiepileptic medication use, and seizure on pediatric ED arrival, 2 independent risk factors for apnea were identified: persistent seizure on arrival (odds ratio [OR]=15; 95% confidence interval [CI] 8 to 27) and administration of field midazolam (OR=4; 95% CI 2 to 7).

CONCLUSION

We identified 2 risk factors for apnea in children transported for seizure: seizure on arrival to the pediatric ED and out-of-hospital administration of midazolam.

Convulsive status epilepticus in children: etiology, treatment protocol and outcome

This study aimed to determine the etiology, treatment protocol and outcome of convulsive status epilepticus (SE) in children. An institutional treatment protocol using benzodiazepines (diazepam and midazolam) was assessed in a retrospective case study. The treatment protocol (Ege Pediatric Status Epilepticus Protocol or EPSEP) was developed based on an operational definition of pediatric SE according to the duration of seizure activity. Pediatric SE is divided into three categories: initial SE (20-30 min), established SE (30-60 min) and refractory SE (>60 min). Eight (30%) of the studied episodes were initial SE, 10 (37%) were established SE, and 9 (33%) were refractory SE. With respect to the etiological spectrum of SE, 11 (40%) children had meningitis or encephalitis. Febrile SE was identified in 7 (26%) patients. Only 2 episodes of initial SE (7.5%) were controlled with first step of the protocol (two concomitant-doses of rectal diazepam). Midazolam bolus and infusions (up to 1.2 μg/kg/min) were used to treat 22 episodes of SE (9 refractory SE, 10 established SE and 3 initial SE). Complete arrest of convulsive SE was achieved in 21 of 22 (95%) episodes with midazolam infusion. We concluded that the combined use of benzodiazepines (diazepam+midazolam) was safe and effective in the treatment of convulsive SE in children.

Seizure duration following sarin exposure affects neuro-inflammatory markers in the rat brain

The current study was aimed to characterize for the first time the alterations in the characteristic neuro-inflammatory markers triggered by sarin exposure in the rat's brain, and to investigate its dependency on seizure duration. Centrally mediated seizures are a common consequence of exposure to organophosphates (OP) despite conventional treatment with atropine and an oxime. In the present study midazolam, was used to control duration and intensity of seizures. The levels of the pro-inflammatory cytokine peptides IL-1beta, IL-6, TNF-alpha and prostaglandin E2 (PGE2) were monitored at various times after sarin exposure in the hippocampus and cortex of rats treated with midazolam following 5 or 30 min of seizure activity. Biochemical evaluation of brain tissues revealed a significant increase in the level of the pro-inflammatory peptides starting at 2 h and peaking at 2-24 h following sarin. Hippocampal values of IL1-beta increased from 1.2+/-0.1 pg/mg tissue (control), to 2.4+/-0.3 at 2 h (5 min seizure) and to 9.3+/-2.5 at 8h (30 min seizure). PGE2 level in the hippocampus increased up to 24 h following exposure (from 56+/-3 to 175+/-26 and 277+/-28 pg/mg tissue) following 5 and 30 min of seizure activity respectively. Thus, unlike limitation of seizures to 5 min by midazolam, delayed treatment (30 min) resulted in prolonged seizures and pronounced increase in cytokines and PGE2. In addition, a second increase in inflammatory markers was observed 30 days following sarin exposure only in rats treated following 30 min of seizure activity. Histological evaluation of the rat brain, conducted in this study, revealed lack of damage in the hippocampus and piriform cortex with minor lateral ventricles enlargement in few animals following 5 min of sarin-induced seizure activity. In contrast, marked histological damage to the brain was demonstrated following 30 min of seizure activity, consisting severe damage to the hippocampus, piriform cortex and some thalamic nuclei. In summary, a novel characterization of the prolonged central neuro-inflammatory process that accompanies sarin exposure is presented. The timing of the anticonvulsive treatment was shown to be crucial in modulation of the neuro-inflammatory response, and may implicate the consequent long-term brain damage.

Anticonvulsant treatment of sarin-induced seizures with nasal midazolam: An electrographic, behavioral, and histological study in freely moving rats

Centrally mediated seizures and convulsions are common consequences of exposure to organophosphates (OPs). These seizures rapidly progress to status epilepticus (SE) and contribute to profound brain injury. Effective management of these seizures is critical for minimization of brain damage. Nasal application of midazolam (1.5 mg/kg) after 5 min of sarin-induced electrographic seizure activity (EGSA) ameliorated EGSA and convulsive behavior (238 +/- 90 s). Identical treatment after 30 min was not sufficient to ameliorate ECoG paradoxical activity and convulsive behavior. Nasal midazolam (1.5 mg/kg), together with scopolamine (1 mg/kg, im) after 5 min of EGSA, exerted a powerful and rapid anticonvulsant effect (53 +/- 10 s). Delaying the same treatment to 30 min of EGSA leads to attenuation of paroxysmal ECoG activity in all cases but total cessation of paroxysmal activity was not observed in most animals tested. Cognitive tests utilizing the Morris Water Maze demonstrated that nasal midazolam alone or together with scopolamine (im), administered after 5 min of convulsions, abolished the effect of sarin on learning. Both these treatments, when given after 30 min of convulsions, only decreased the sarin-induced learning impairments. Whereas rats which were not subject to the anticonvulsant agents did not show any memory for the platform location, both treatments (at 5 min as well as at 30 min) completely abolished the memory deficits. Both treatments equally blocked the impairment of reversal learning when given at 5 min. However, when administered after 30 min, midazolam alone reversed the impairments in reversal learning, while midazolam with scopolamine did not. Rats exposed to sarin and treated with the therapeutic regimen with the exclusion of midazolam exhibited severe brain lesions that encountered the hippocampus, pyriform cortex, and thalamus. Nasal midazolam at 5 min prevented brain damage, while delaying the midazolam treatment to 30 min of EGSA resulted in brain damage. The addition of scopolamine to midazolam did not alter the above observation. In summary, nasal midazolam treatment briefly after initiation of OP-induced seizure leads to cessation of EGSA and prevented brain lesions and behavioral deficiencies in the rat model.

Determination of midazolam and its major metabolite 1'-hydroxymidazolam by high-performance liquid chromatography-electrospray mass spectrometry in plasma from children

We have developed a sensitive, selective and reproducible reversed-phase high-performance liquid chromatography method coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) for the simultaneous quantification of midazolam (MDZ) and its major metabolite, 1'-hydroxymidazolam (1'-OHM) in a small volume (200 microl) of human plasma. Midazolam, 1'-OHM and 1'-chlordiazepoxide (internal standard) were extracted from alkalinised (pH 9.5) spiked and clinical plasma samples using a single step liquid-liquid extraction with 1-chlorobutane. The chromatographic separation was performed on a reversed-phase HyPURITY Elite C18 (5 microm particle size; 100 mm x 2.1mm i.d.) analytical column using an acidic (pH 2.8) mobile phase (water-acetonitrile; 75:25% (v/v) containing formic acid (0.1%, v/v)) delivered at a flow-rate of 200 microl/min. The mass spectrometer was operated in the positive ion mode at the protonated-molecular ions [M+l]+ of parent drug and metabolite. Calibration curves in spiked plasma were linear (r2 > or = 0.99) from 15 to 600 ng/ml (MDZ) and 5-200 ng/ml (1'-OHM). The limits of detection and quantification were 2 and 5 ng/ml, respectively, for both MDZ and 1'-OHM. The mean relative recoveries at 40 and 600 ng/ml (MDZ) were 79.4+/-3.1% (n = 6) and 84.2+/-4.7% (n = 8), respectively; for 1'-OHM at 30 and 200 ng/ml the values were 89.9+/-7.2% (n = 6) and 86.9+/-5.6% (n = 8), respectively. The intra-assay and inter-assay coefficients of variation (CVs) for MDZ were less than 8%, and for 1'-OHM were less than 13%. There was no interference from other commonly used antimalarials, antipyretic drugs and antibiotics. The method was successfully applied to a pharmacokinetic study of MDZ and 1'-OHM in children with severe malaria and convulsions following administration of MDZ either intravenously (i.v.) or intramuscularly (i.m.).

Status epilepticus: clinical analysis of a treatment protocol based on midazolam and phenytoin

The efficacy of a combination of midazolam and phenytoin in treating generalized convulsive status epilepticus in children was studied retrospectively. The patient group comprised all patients admitted for generalized convulsive status epilepticus to the pediatric intensive care unit over 7 years. Patients treated according to the protocol were included (N = 122). These patients were treated with the following regimen; each subsequent step was taken if clinical evidence of epileptic activity persisted: midazolam 0.5 mg/kg rectally or 0.1 mg/kg intravenously. After 10 minutes: midazolam 0.1 mg/kg intravenously. After 10 minutes: phenytoin 20 mg/kg intravenously in 20 minutes. After phenytoin load: midazolam 0.2 mg/kg intravenously followed by midazolam 0.1 mg/kg/hour continuously, increased by 0.1 mg/kg/hour every 10 minutes to maximum 1 mg/kg/hour. Phenobarbital 20 mg/kg intravenously or pentobarbital 2 to 5 mg/kg intravenous load, 1 to 2 mg/kg/hour continuously intravenously. Patients who received initial rectal diazepam were included. Patients were categorized according to the cause of generalized convulsive status epilepticus. These categories were then related to the level of antiepileptic therapy needed. Patients' ages ranged from 0.5 to 197.4 months. The cause of generalized convulsive status epilepticus was idiopathic or febrile convulsions in two thirds of cases. Most (89%) patients were managed on midazolam and phenytoin. Generalized convulsive status epilepticus was terminated with midazolam alone in 58 patients, with the addition of phenytoin in 19 patients and with continuous midazolam in 32 patients. Thirteen patients needed additional barbiturates. The relationship between the level of antiepileptic therapy and etiology was not significant. Fifty-two patients needed artificial ventilation. Seven patients died; no deaths were directly attributable to generalized convulsive status epilepticus itself. With the use of the proposed protocol, combining midazolam and phenytoin, 89% of the cases of generalized convulsive status epilepticus could be successfully managed.

Pediatric refractory partial status epilepticus responsive to topiramate

Topiramate was safely administered to two young children with refractory partial status epilepticus via nasogastric tube in rapid titration up to a very high total daily dose. An excellent clinical response occurred in both cases. Reaching high daily doses of topiramate within days allowed for safe discontinuation of other antiepileptic drugs in both patients. Given the high efficacy of rapidly titrated topiramate in our patients, this medication may be useful in some cases of pediatric refractory partial status epilepticus. However, more clinical studies on this therapeutic approach are needed to establish the precise role of topiramate in status epilepticus in children.

Nerve agent attacks on children: diagnosis and management

Nerve agents (NAs) are the most lethal chemical weapons. We review the pathophysiology and management of NA poisoning of children. NAs cause cholinergic crisis. Children may manifest signs of cholinergic poisoning differently than adults. Children may be less likely to manifest miosis and glandular secretions. They may present with neurologic derangements alone. The goals of treatment should be to limit additional exposure, to provide respiratory support, and to prevent neurologic morbidity. Autoinjectors are optimal delivery vehicles for intramuscular antidotes and are likely to be used in civilian prehospital care. Antidotes include anticholinergics, oximes, and benzodiazepines. Several medications may be available within each class of antidotes. Clinicians will select an antidote based on the status of the individual victim, the accessibility of supportive care, and the availability of the drug. Atropine is well-tolerated and high doses may be required. The oxime pralidoxime chloride has a longer half-life in children. Currently, diazepam is the standard NA anticonvulsant. Midazolam may be the most effective intramuscular anticonvulsant after NA exposure, but, despite its efficacy, it is not an approved agent for seizures. Supportive care and long-term complications are summarized.

Nasal midazolam as a novel anticonvulsive treatment against organophosphate-induced seizure activity in the guinea pig

Seizures and status epilepticus, which may contribute to brain injury, are common consequences of exposure to organophosphorus (OP) cholinesterase inhibitors. Effective management of these seizures is critical. To investigate the efficacy of nasal midazolam as an anticonvulsive treatment for OP exposure, as compared to intramuscular midazolam, guinea pigs were connected to a recording swivel for electrocorticograph (ECoG) monitoring and clinical observation. The experimental paradigm consisted of pyridostigmine pretreatment (0.1 mg/kg i.m.) 20 min prior to sarin exposure (1.2x LD(50,) 56 micro g/kg i.m.). One minute post-exposure, atropine (3 mg/kg i.m.) and TMB-4 (1 mg/kg im) were administered. Within 3-8 min after sarin exposure all animals developed electrographic seizure activity (EGSA), with convulsive behavior. Treatment with midazolam (1 mg/kg i.m.) 10 min after the onset of EGSA abolished EGSA within 389+/-181 s. The same dose was not effective, in most cases, when given 30 min after onset. However, a higher dose (2 mg/kg) was found efficacious after 30 min (949+/-466 s). In contrast, nasal application of midazolam (1 mg/kg) was found most effective, with significant advantages, in amelioration of EGSA and convulsive behavior, when given 10 min (216+/-185 s) or 30 min (308+/-122 s) following the onset of EGSA ( P<0.001). Thus, nasal midazolam could be used as a novel, rapid and convenient route of application against seizure activity induced by nerve agent poisoning.

Controlling seizures in the prehospital setting: diazepam or midazolam?

OBJECTIVE

To determine which is the most effective and safe treatment for controlling seizures in children out-of-hospital: diazepam or midazolam.

METHODS

A retrospective review of the medical records of children presenting to the Emergency Department of the Children's Hospital at Westmead (CHW-ED) with seizures requiring treatment in the field by paramedics was carried out over a 4-year period (April 1996 to March 2000). In New South Wales, children with seizures in the prehospital setting received 0.5 mg/kg per rectum (p.r.) or 0.1 mg/kg i.v. diazepam until March 1998 and from March 1997 onwards they received 0.15 mg/kg i.m. or 0.1 mg/kg i.v. midazolam. The main outcome measured was cessation of seizure in the prehospital setting. Secondary outcomes were time taken to initiate treatment and the frequency of cardiorespiratory compromise.

RESULTS

Over the 4-year period, 2566 children presented to CHW-ED with a seizure; 107 children were eligible for entry into the present study. Of these 107 patients, 62 received diazepam and 45 received midazolam. Thirty-one (50.0%) in the diazepam group and 15 (33.3%) in the midazolam group were febrile seizures. Both groups were similar in terms of demographics and seizure type. A comparison of diazepam with midazolam showed that both drugs were effective in stopping seizures within 5 min of drug administration (37.1% cf. 51.1%). Fewer patients in the midazolam group suffered apnoea (20.0% cf. 29.0%; P < 0.05).

CONCLUSION

Midazolam controls seizures as effectively as diazepam in the prehospital setting. Furthermore, midazolam potentially reduces respiratory depression and time to treatment.

Continuous midazolam versus diazepam infusion for refractory convulsive status epilepticus

The objective of this study was to compare the efficacy of continuous midazolam and diazepam infusion for the control of refractory status epilepticus. An open-label, randomized control study was undertaken at the Pediatric Emergency and Intensive Care Service of a multidisciplinary teaching and referral hospital. Subjects included 40 children, 2 to 12 years of age, with refractory status epilepticus (motor seizures uncontrolled after two doses of diazepam, 0.3 mg/kg per dose, and phenytoin infusion, 20 mg/kg). Either continuous midazolam (n = 21) or diazepam infusion (n = 19) in incremental doses was administered. The primary outcome measure was the proportion of children in each group with successful control of refractory status epilepticus. The secondary outcome measure was the time to control seizure activity, recurrence of seizure after initial control, if any, the frequency of hypotension, and the need for ventilation. The two groups were similar in age (mean +/- SD = 4.9 +/- 43.6 months) and etiology. Twenty-three (57.5%) patients had acute central nervous system infection. Refractory status epilepticus was controlled in 18 (86%) and 17 (89%) patients in the midazolam and diazepam groups, respectively (P = not significant). The median time to seizure control was 16 minutes in both groups, but in the midazolam group, seizures recurred in more children (57% versus 16% in diazepam group; P < .05). The maximum dose (mean +/- SD) of midazolam and diazepam required was 5.3 +/- 2.6 microg/kg/min and 0.04 +/- 0.02 mg/kg/min, respectively. About half of the patients needed mechanical ventilation and 40% had hypotension in both groups, but the mortality was higher in the midazolam group (38%) as compared to the diazepam group (10.5%, P < .1 > .05). Continuous midazolam and diazepam infusions were equally effective for control of refractory status epilepticus. However, midazolam was associated with more seizure recurrence and higher mortality in refractory status epilepticus predominantly caused by central nervous system infections.

Treatment of epilepsy in the multiply handicapped

The medical management of epilepsy in the multi-handicapped patient requires careful evaluation, classification, and pharmacologic treatment. It is estimated that 20-40% of patients with mental retardation and cerebral palsy have epilepsy. This review reports the clinical trial data and personal experience related to the use of newer AEDs in the chronic management of epilepsy syndromes in children and adults, as well as information available on the treatment of seizures in individuals with mental retardation and associated handicaps. Furthermore, clusters of seizures, prolonged seizures and status epilepticus are more commonly seen in the multiply handicapped and mentally retarded population and require special attention. The new antiepileptic drugs felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide show specific advantage in some multiply handicapped patients, be it for seizure control or medication tolerance. Furthermore, new modalities of treatment for prolonged seizures allow better efficacy both outside of hospital and within hospital facilities. The treatment of epilepsy in multi-handicapped and retarded adults and children has significantly advanced in the past few years, and much of this improvement can be attributed to improved knowledge and monitoring of new antiepileptic drugs. Conventional anticonvulsants remain first line therapy for most clinicians, but newer AEDs must broaden the therapeutic option and do allow improved therapy for some multiply handicapped patients.

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.