Epileptic manifestations induced by midazolam in the neonatal period

Midazolam-Induced Seizure-Like Activity in Five Neonates: A case series

An intravenous (IV) administration of midazolam may result in seizure-like activity or movement. This report describes 5 neonates who developed seizure-like movements after IV midazolam injection. The patients presented between 2019 and 2022 and were admitted to a neonatal intensive care unit located within an academic centre in Muscat, Oman. The abnormal movements occurred shortly after IV bolus administration of midazolam. None of the patients experienced seizure-like movements after receiving midazolam infusions. The seizure-like movements were aborted either spontaneously or by antiseizure medications. In addition, seizure recurrence was not observed in any of the infants during the later stages of their treatment. Since this adverse effect might be related to the speed of the bolus administration, IV midazolam must be given as a slow bolus over 2-3 minutes followed by a slow flush of normal saline. To prevent midazolam's potential adverse effect on newborns, neonatal caregivers must be aware of it.

Lennox-Gastaut syndrome characterized by super-refractory status epilepticus treated with high-dose anesthetics: A case report

RATIONALE

Super-refractory status epilepticus is a serious illness with high morbidity and mortality, which is defined as an SE that continues or recurs 24 hours or more after the onset of anesthesia. Anesthetic agents can be either pro-convulsant or anticonvulsant or both.

PATIENT CONCERNS

Epilepsy occurred at the age of 3 years. At the age of 4 years, generalized tonic-clonic seizure occurred for the first time. The patient was hospitalized at the age of 27 and 28 years for treating status epilepticus. At the age of 33 years, antiepileptic drugs were stopped due to poor appetite. In an early morning, the patient was found delirious with reduced speech.

DIAGNOSIS

Occasionally, the patient blinked his eyelids, or deflected his eyeballs to 1 side. When propofol was lowered to 10 mL/H, the epileptic wave reduced obviously. Afterwards, the patient opened his eyes autonomously and his consciousness gradually recovered. The patient could answer questions, and the limbs had voluntary movements. The patient breathing also gradually recovered, and his urine gradually returned to pale yellow from green. After anesthetic was stopped for 10 days, the patient lost his consciousness again. The patient eyes turned upward frequently, which was relieved in 1 to 2 seconds with an attack once every 2 to 5 minutes.

INTERVENTIONS

Clonazepam was gradually reduced to 2 mg qn, and the patient gradually woke up during this process. The patient was also treated with levetiracetam 1.5 g bid, oxcarbazepine 0.6 g bid, topiramate 50 mg bid and valproate 0.4 g tid.

OUTCOMES

After 1 month follow-up, status epilepticus did not appear again.

LESSONS

Propofol aggravated the tonic seizures. As tonic seizures occur during natural sleep and after sleep induced by various narcotic drugs, the decrease of consciousness level induced by excessive sedation of narcotic drugs has been suggested as the reason for poor seizure control.

The Critical Modulatory Role of Spiny Stellate Cells in Seizure Onset Based on Dynamic Analysis of a Neural Mass Model

Growing evidence suggests that excitatory neurons in the brain play a significant role in seizure generation. Nonetheless, spiny stellate cells are cortical excitatory non-pyramidal neurons in the brain, whose basic role in seizure occurrence is not well understood. In the present research, we study the critical role of spiny stellate cells or the excitatory interneurons (EI), for the first time, in epileptic seizure generation using an extended neural mass model inspired by a thalamocortical model originally introduced by another research group. Applying bifurcation analysis on this modified model, we investigated the rich dynamics corresponding to the epileptic seizure onset and transition between interictal and ictal states caused by EI connectivity to other cell types. Our results indicate that the transition between interictal and ictal states (preictal signal) corresponds to a supercritical Hopf bifurcation, and thus, the extended model suggests that before seizure onset, the amplitude and frequency of neural activities gradually increase. Moreover, we showed that (1) the altered function of GABAergic and glutamatergic receptors of EI can cause seizure, and (2) the pathway between the thalamic relay nucleus and EI facilitates the transition from interictal to ictal activity by decreasing the preictal period. Thereafter, we considered both sensory and cortical periodic inputs to study model responses to various harmonic stimulations. Bifurcation analysis of the model, in this case, suggests that the initial state of the model might be the main cause for the transition between interictal and ictal states as the stimulus frequency changes. The extended thalamocortical model shows also that the amplitude jump phenomenon and non-linear resonance behavior result from the preictal state of the modified model. These results can be considered as a step forward to a deeper understanding of the mechanisms underlying the transition from normal activities to epileptic activities.

Pharmacokinetic-Pharmacodynamic Modeling in Pediatric Drug Development, and the Importance of Standardized Scaling of Clearance

Pharmacokinetic/pharmacodynamic (PKPD) modeling is important in the design and conduct of clinical pharmacology research in children. During drug development, PKPD modeling and simulation should underpin rational trial design and facilitate extrapolation to investigate efficacy and safety. The application of PKPD modeling to optimize dosing recommendations and therapeutic drug monitoring is also increasing, and PKPD model-based dose individualization will become a core feature of personalized medicine. Following extensive progress on pediatric PK modeling, a greater emphasis now needs to be placed on PD modeling to understand age-related changes in drug effects. This paper discusses the principles of PKPD modeling in the context of pediatric drug development, summarizing how important PK parameters, such as clearance (CL), are scaled with size and age, and highlights a standardized method for CL scaling in children. One standard scaling method would facilitate comparison of PK parameters across multiple studies, thus increasing the utility of existing PK models and facilitating optimal design of new studies.

Premature birth, homeostatic plasticity and respiratory consequences of inflammation

Infants who are born premature can have persistent apnea beyond term gestation, reemergence of apnea associated with inflammation during infancy, increased risk of sudden unexplained death, and sleep disorder breathing during infancy and childhood. The autonomic nervous system, particularly the central neural networks that control breathing and peripheral and central chemoreceptors and mechanoreceptors that modulate the activity of the central respiratory network, are rapidly developing during the last trimester (22-37 weeks gestation) of fetal life. With advances in neonatology, in well-resourced, developed countries, infants born as young as 23 weeks gestation can survive. Thus, a substantial part of maturation of central and peripheral systems that control breathing occurs ex-utero in infants born at the limit of viability. The balance of excitatory and inhibitory influences dictates the ultimate output from the central respiratory network. We propose in this review that simply being born early in the last trimester can trigger homeostatic plasticity within the respiratory network tipping the balance toward inhibition that persists in infancy. We discuss the intersection of premature birth, homeostatic plasticity and biological mechanisms leading to respiratory depression during inflammation in former premature infants.

Paradoxical Reaction to Midazolam in Preterm Neonates: A Case Series

Midazolam is a drug belonging to the benzodiazepine group and is used commonly for seizure control as well as preoperative and procedure-related sedation in neonates. Many adverse effects of midazolam have been reported in the past. Paradoxical stimulation of the central nervous system such as restlessness, nightmare, and hallucinations as well as hypomanic behavior has been reported in adults and children. Seizure is a rare adverse effect of midazolam. Cases of myoclonic movements associated with midazolam have been published worldwide; however, none so far have been reported from India. We report two newborns in our Neonatal Unit, who developed myoclonic seizure after the administration of midazolam. Both of these neonates were preterm, require multiple invasive and noninvasive investigations also leads to parent and clinician stress.

Altered GABA signaling in early life epilepsies

The incidence of seizures is particularly high in the early ages of life. The immaturity of inhibitory systems, such as GABA, during normal brain development and its further dysregulation under pathological conditions that predispose to seizures have been speculated to play a major role in facilitating seizures. Seizures can further impair or disrupt GABA_A signaling by reshuffling the subunit composition of its receptors or causing aberrant reappearance of depolarizing or hyperpolarizing GABA_A receptor currents. Such effects may not result in epileptogenesis as frequently as they do in adults. Given the central role of GABA_A signaling in brain function and development, perturbation of its physiological role may interfere with neuronal morphology, differentiation, and connectivity, manifesting as cognitive or neurodevelopmental deficits. The current GABAergic antiepileptic drugs, while often effective for adults, are not always capable of stopping seizures and preventing their sequelae in neonates. Recent studies have explored the therapeutic potential of chloride cotransporter inhibitors, such as bumetanide, as adjunctive therapies of neonatal seizures. However, more needs to be known so as to develop therapies capable of stopping seizures while preserving the age- and sex-appropriate development of the brain.

Sexually dimorphic expression of KCC2 and GABA function

GABA(A) receptors have an age-adapted function in the brain. During early development, they mediate depolarizing effects, which result in activation of calcium-sensitive signaling processes that are important for the differentiation of the brain. In more mature stages of development and in adults, GABA(A) receptors acquire their classical hyperpolarizing signaling. The switch from depolarizing to hyperpolarizing GABA(A)-ergic signaling is triggered through the developmental shift in the balance of chloride cotransporters that either increase (i.e. NKCC1) or decrease (i.e. KCC2) intracellular chloride. The maturation of GABA(A) signaling follows sex-specific patterns, which correlate with the developmental expression profiles of chloride cotransporters. This has first been demonstrated in the substantia nigra, where the switch occurs earlier in females than in males. As a result, there are sensitive periods during development when drugs or conditions that activate GABA(A) receptors mediate different transcriptional effects in males and females. Furthermore, neurons with depolarizing or hyperpolarizing GABA(A)-ergic signaling respond differently to neurotrophic factors like estrogens. Consequently, during sensitive developmental periods, GABA(A) receptors may act as broadcasters of sexually differentiating signals, promoting gender-appropriate brain development. This has particular implications in epilepsy, where both the pathophysiology and treatment of epileptic seizures involve GABA(A) receptor activation. It is important therefore to study separately the effects of these factors not only on the course of epilepsy but also design new treatments that may not necessarily disturb the gender-appropriate brain development.

GABA(A) receptors in normal development and seizures: friends or foes?

GABA(A) receptors have an age-adapted function in the brain. During early development, they mediate excitatory effects resulting in activation of calcium sensitive signaling processes that are important for the differentiation of the brain. In more mature stages of development and in adults, GABA(A) receptors transmit inhibitory signals. The maturation of GABA(A) signaling follows sex-specific patterns, which appear to also be important for the sexual differentiation of the brain. The inhibitory effects of GABA(A) receptor activation have been widely exploited in the treatment of conditions where neuronal silencing is necessary. For instance, drugs that target GABA(A) receptors are the mainstay of treatment of seizures. Recent evidence suggests however that the physiology and function of GABA(A) receptors changes in the brain of a subject that has epilepsy or status epilepticus.This review will summarize the physiology of and the developmental factors regulating the signaling and function of GABA(A) receptors; how these may change in the brain that has experienced prior seizures; what are the implications for the age and sex specific treatment of seizures and status epilepticus. Finally, the implications of these changes for the treatment of certain forms of medically refractory epilepsies and status epilepticus will be discussed.

Response to neonatal anesthesia: effect of sex on anatomical and behavioral outcome

Numerous studies have documented the consequences of exposure to anesthesia in models of term and post-term infants, evaluating the incidence of cell loss, physiological alterations and cognitive dysfunction. However, surprisingly few studies have investigated the effect of anesthetic exposure on outcomes in newborn rodents, the developmental equivalent of premature human infants. This is critical given that one out of every eight babies born in the United States is premature, with an increased prevalence of surgical procedures required in these individuals. Also, no studies have investigated if the genetic sex of the individual influences the response to neonatal anesthesia. Using the newborn rat as the developmental equivalent of the premature human, we documented the effect of a single bout of exposure to either the inhalant isoflurane or the injectable barbiturate phenobarbital on hippocampal anatomy, hippocampal dependent behavioral performance and normal developmental endpoints in male and female rats. While both forms of anesthesia led to significant decrements in cognitive abilities, along with a significant reduction in volume and neuron number in the hippocampus in adulthood, the decrements were significantly greater in males than in females. Interestingly, the deleterious effects of anesthesia were manifest on developmental measures including surface righting and forelimb grasp, but were not evident on basic physiological parameters including body weight or suckling. These findings point to the hazardous effects of exposure to anesthesia on the developing CNS and the particular sensitivity of males to deficits.

Comparison of continuous drip of midazolam or lidocaine in the treatment of intractable neonatal seizures

Seizures constitute the most common neurological symptom in the neonatal period. Treatment usually involves the administration of intravenous benzodiazepines followed by either phenobarbital or phenytoin. For nonresponsive cases, continuous intravenous drip of either midazolam or lidocaine has been suggested for seizure control. Some reports suggest that seizures themselves may have a deleterious effect on long-term neurological outcome. Therefore, there is a need to find treatment regimens with better efficacy to provide maximum seizure control. The authors compared the effectiveness of lidocaine and midazolam in the treatment of intractable seizures in newborn infants born at or after 36 weeks of gestation who suffered from hypoxic-ischemic encephalopathy and who had their cerebral activity monitored. Thirty infants were included in the study: 22 received lidocaine, and 8 received midazolam. Seventeen (77%) infants had a good or partial response to lidocaine, and 4 (50%) had a partial response to midazolam. Of 20 infants diagnosed with hypoxic-ischemic encephalopathy grade 2, 18 (90%) responded to second-line treatment (14 [93%] of 15 to lidocaine and 4 [80%] of 5 to midazolam). Among 10 infants with hypoxic-ischemic encephalopathy grade 3, only 3 (30%) responded to second-line treatment (all 3 to lidocaine, none to midazolam). The findings suggest that lidocaine may be more effective than midazolam in reducing or controlling refractory neonatal seizures. The lower response rate to midazolam was more evident in infants with severe hypoxic-ischemic encephalopathy (grade 3).

Long-term effects of diazepam and phenobarbital treatment during development on GABA receptors, transporters and glutamic acid decarboxylase

Diazepam (DZ) and phenobarbital (PH) are commonly used to treat early-life seizures and act on GABAA receptors (GABAR). The developing GABAergic system is highly plastic, and the long-term effects of postnatal treatment with these drugs on the GABAergic system has not been extensively examined. In the present study, we investigated the effects of prolonged DZ and PH treatment during postnatal development and then discontinuation on expression of a variety of genes involved in GABAergic neurotransmission during adulthood. Rat pups were treated with DZ, PH or vehicle from postnatal day (P) 10-P40 and then the dose was tapered for 2 weeks and terminated at P55. Expression of GABAR subunits, GABAB receptor subunits, GABA transporters (GAT) and GABA synthesizing enzymes (glutamic acid decarboxylase: GAD) mRNAs in hippocampal dentate granule neurons (DGNs) were analyzed using antisense RNA amplification at P90. Protein levels for the alpha1 subunit of GABAR, GAD67, GAT1 and 3 were also assessed using Western blotting. At P90, mRNA expression for GAT-1, 3, 4, GABAR subunits alpha4, alpha6, beta3, delta and theta and GABAB receptor subunit R1 was increased and mRNA expression for GAD65, GAD67 and GABAR subunits alpha1 and alpha3 were decreased in DGNs of rats treated with DZ and PH. The current data suggest that prolonged DZ and PH treatment during postnatal development causes permanent alterations in the expression of hippocampal GABA receptor subunits, GATs and GAD long after therapy has ended.

Safety of benzodiazepines in newborns

BACKGROUND

Benzodiazepines are being used in neonatal intensive care units for sedation and control of seizures. However, anecdotal reports suggest that their use in infants may be associated with serious adverse effects (AEs).

OBJECTIVE

To determine the incidence of AEs from benzodiazepine use in preterm and full-term infants.

METHODS

Retrospective chart review of 63 infants who received benzodiazepines as a sedative or anticonvulsant over a 16-month period.

RESULTS

Mean +/- SD gestational age of the infants was 33.1 +/- 6.2 weeks, and birth weight was 2.3 +/- 1.2 kg. Median (range) postnatal age at commencement of drug administration was 19 (5-54) days. Forty-one infants received lorazepam, 8 received midazolam, and 14 received both. Ten (16%) of the infants had 14 documented adverse events: seizures (n = 6), hypotension (n = 5), and respiratory depression (n = 3). Using a validated adverse drug reaction probability scale, a probable association with benzodiazepine use was demonstrated in 12 of the AEs. Due to the retrospective nature of the data, a score for definite association was not attainable. Anticonvulsant administration was required for 4 of 6 infants and, in all cases of respiratory depression, ventilatory support was initiated or increased. Two cases of significant hypotension were treated with inotropes. There was no statistically significant correlation between AEs and benzodiazepine dose or concomitant use of inotropes or analgesics (morphine), although most infants had underlying medical conditions or received multiple drugs that may have predisposed them to experience AEs.

CONCLUSIONS

Administration of benzodiazepines was frequently associated with AEs in full-term and preterm infants. It is possible that underlying illnesses and concomitant drug use predisposed these effects. Until the benefit-to-risk ratio is determined by further studies, judicious use of benzodiazepines is recommended in this vulnerable population.