Cognitive side effects of valproic acid-induced hyperammonemia in children with epilepsy

Valproate-induced hyperammonemic encephalopathy treated by L-ornithine-L-aspartate: a case report

A 63-year-old man developed reduced consciousness and dysphagia progressively. Examination and parameters were normal, except for a Glasgow Coma Scale score of seven, and his grading on the swallow water test increased from grade 1 to grade 5. Brain imaging and blood tests were unexplainable except by high plasma ammonia. His past medical history included cerebral infarction, hypertension and epilepsy induced by cerebral hyperperfusion syndrome. He was rceiving antiepileptic treatment of continuously intravenously pumped sodium valproate of 64 mg/h for 4 days, which overlapped for 12 hours with taking 500 mg sustained release tablets. Sodium valproate was stopped; testing demonstrated normal plasma concentrations of sodium valproate and elevated concentrations of ammonia. Ornithine aspartate was administrated. The patient's level of responsiveness and ammonia levels gradually improved. The patient was also being treated with ceftriaxone sodium for a hypostatic pneumonia and with desmopressin for diabetes insipidus. There is an association between sodium valproate and hyperammonaemia and encephalopathy. Immediate recognition of the serious but uncommon adverse effects is essential. To our knowledge this is the first report of ornithine aspartate being used in this disorder.

Valproic Acid-Associated Hyperammonemia: A Systematic Review

BACKGROUND

Hyperammonemia is an adverse effect that poses clinical uncertainty around valproic acid (VPA) use. The prevalence of symptomatic and asymptomatic hyperammonemia and its relationship to VPA concentration is not well established. There is also no clear guidance regarding its management. This results in variability in the monitoring and treatment of VPA-induced hyperammonemia. To inform clinical practice, this systematic review aims to summarize evidence available around VPA-associated hyperammonemia and its prevalence, clinical outcomes, and management.

METHODS

An electronic search was performed through Ovid MEDLINE, Ovid Embase, Web of Science, and PsycINFO using search terms that identified hyperammonemia in patients receiving VPA. Two reviewers independently performed primary title and abstract screening with a third reviewer resolving conflicting screening results. This process was repeated during the full-text review process.

RESULTS

A total of 240 articles were included. Prevalence of asymptomatic hyperammonemia (5%-73%) was higher than symptomatic hyperammonemia (0.7%-22.2%) and occurred within the therapeutic range of VPA serum concentration. Various risk factors were identified, including concomitant medications, liver injury, and defects in carnitine metabolism. With VPA discontinued, most symptomatic patients returned to baseline mental status with normalized ammonia level. There was insufficient data to support routine monitoring of ammonia level for VPA-associated hyperammonemia.

CONCLUSIONS

Valproic acid-associated hyperammonemia is a common adverse effect that may occur within therapeutic range of VPA. Further studies are required to determine the benefit of routine ammonia level monitoring and to guide the management of VPA-associated hyperammonemia.

A comprehensive review on pharmacological applications and drug-induced toxicity of valproic acid

Valproic acid, a branching short chain fatty acid, is a popular drug to treat epilepsy and acts as a mood-stabilizing drug. The obstruction of ion channels and Gamma Amino Butyrate transamino butyrate GABA has been linked to antiepileptic effects. Valproic acid has been characterized as a Histone deacetylase inhibitor, functioning directly transcription of gene levels by blocking the deacetylation of histones and increasing the accessibility of transcription sites. Study has been extensively focused on pharmaceutical activity of valproic acid through various pharmacodynamics activity from absorption, distribution and excretion particularly in patients who are resistant to or intolerant of lithium or carbamazepine, as well as those with mixed mania or rapid cycling.

Valproic acid-induced encephalopathy: A review of clinical features, risk factors, diagnosis, and treatment

Valproic acid (VPA), or sodium valproate, is a commonly used medication for seizure disorders, migraines, and mental illness. Although VPA is relatively safe, it still has several adverse effects; among these, VPA-induced encephalopathy is the most serious. Valproic acid-induced encephalopathy mainly manifests as acute or subacute encephalopathy and has been associated with hyperammonemia, L-carnitine deficiency, and urea cycle enzyme dysfunction. Delayed identification of VPA-induced encephalopathy could be potentially fatal. Here, we perform an extensive review of relevant literature pertaining to VPA-induced encephalopathy, including its epidemiology, clinical features, possible pathophysiology, risk factors, diagnosis, and treatment.

Point-of-Care Analysis of Blood Ammonia with a Gas-Phase Sensor

Elevated blood ammonia (hyperammonemia) may cause delirium, brain damage, and even death. Effective treatments exist, but preventing permanent neurological sequelae requires rapid, accurate, and serial measurements of blood ammonia. Standard methods require volumes of 1 to 3 mL, centrifugation to isolate plasma, and a turn-around time of 2 h. Collection, handling, and processing requirements mean that community clinics, particularly those in low resource settings, cannot provide reliable measurements. We describe a method to measure ammonia from small-volume whole blood samples in 2 min. The method alkalizes blood to release gas-phase ammonia for detection by a fuel cell. When an inexpensive first-generation instrument designed for 100 μL of blood was tested on adults and children in a clinical study, the method showed a strong correlation (R² = 0.97) with an academic clinical laboratory for plasma ammonia concentrations up to 500 μM (16 times higher than the upper limit of normal). A second-generation hand-held instrument designed for 10-20 μL of blood showed a near-perfect correlation (R² = 0.99) with healthy donor blood samples containing known amounts of added ammonium chloride up to 1000 μM. Our method can enable rapid and inexpensive measurement of blood ammonia, transforming diagnosis and management of hyperammonemia.

Effect of sleep quality on memory, executive function, and language performance in patients with refractory focal epilepsy and controlled epilepsy versus healthy controls - A prospective study

We aimed to evaluate the effect of sleep quality on memory, executive function, and language performance in patients with refractory focal epilepsy and controlled epilepsy and compare these with healthy individuals. We prospectively enrolled 37 adolescent and adult patients with refractory focal epilepsy (Group 1) and controlled epilepsy (Group 2) in each group. History pertaining to epilepsy and sleep were recorded, and all patients underwent overnight polysomnography. Language, memory, and executive function assessments were done using Western Aphasia Battery, Post Graduate Institute (PGI) memory scale, and battery of four executive function tests (Trail Making Test A & B, Digit symbol test, Stroop Task, and Verbal Fluency Test), respectively. Forty age- and sex-matched controls were also included in the study. Significant differences were noted in both objective and subjective sleep parameters among all the groups. On polysomnography, parameters like total sleep time, sleep efficiency, sleep latency, and rapid eye movement (REM) latency were found to be significantly worse in Group 1 as compared with Group 2. Cognitive and executive parameters were significantly impaired in Group 1. Shorter total sleep time, poorer sleep efficiency, and prolonged sleep latencies were observed to be associated with poor memory and executive function in patients with refractory epilepsy. Our study strongly suggests that sleep disturbances, mainly shorter total sleep time, poor sleep efficiency, and prolonged sleep latencies, are associated with impaired memory and executive function in patients with refractory focal epilepsy and to a lesser extent, among those with medically controlled epilepsy.

GABAergic inhibitory neurons as therapeutic targets for cognitive impairment in schizophrenia

Schizophrenia is considered primarily as a cognitive disorder. However, functional outcomes in schizophrenia are limited by the lack of effective pharmacological and psychosocial interventions for cognitive impairment. GABA (gamma-aminobutyric acid) interneurons are the main inhibitory neurons in the central nervous system (CNS), and they play a critical role in a variety of pathophysiological processes including modulation of cortical and hippocampal neural circuitry and activity, cognitive function-related neural oscillations (eg, gamma oscillations) and information integration and processing. Dysfunctional GABA interneuron activity can disrupt the excitatory/inhibitory (E/I) balance in the cortex, which could represent a core pathophysiological mechanism underlying cognitive dysfunction in schizophrenia. Recent research suggests that selective modulation of the GABAergic system is a promising intervention for the treatment of schizophrenia-associated cognitive defects. In this review, we summarized evidence from postmortem and animal studies for abnormal GABAergic neurotransmission in schizophrenia, and how altered GABA interneurons could disrupt neuronal oscillations. Next, we systemically reviewed a variety of up-to-date subtype-selective agonists, antagonists, positive and negative allosteric modulators (including dual allosteric modulators) for α5/α3/α2 GABA_A and GABA_B receptors, and summarized their pro-cognitive effects in animal behavioral tests and clinical trials. Finally, we also discuss various representative histone deacetylases (HDAC) inhibitors that target GABA system through epigenetic modulations, GABA prodrug and presynaptic GABA transporter inhibitors. This review provides important information on current potential GABA-associated therapies and future insights for development of more effective treatments.

The importance of assessing behaviour and cognition in antiepileptic drug trials in children and adolescents

It has long been recognised that uncontrolled childhood epilepsy is detrimental to cognition and behaviour, impacting on a patient's ability to succeed academically. Patients who experience more frequent and serious seizures are at greater risk for cognitive decline, emphasising the need for more effective epilepsy treatments to bring seizures under control. That said, although more effective antiepileptic drugs (AEDs) have the potential to limit the impact of uncontrolled seizures on cognitive and behavioural function, recently it has been acknowledged that deficits in these functions may be caused by AEDs themselves. The cognitive and behavioural effects of older-generation AEDs have been determined largely from AE reporting rather than from specific assessment. Recently, clinical trials of newer-generation AEDs, such as topiramate, levetiracetam and perampanel, have included standardised neuropsychological tests as outcome measures to assess their impact on cognition and behaviour in children and adolescents. However, to understand how we may limit the cognitive and behavioural side effects of AEDs, it is necessary for us to gain a fuller, more accurate, characterisation of their true impact. Such insight will depend on sophisticated and standardised approaches to the design of AED clinical trials. This review provides a general overview of our current understanding of the impact of both epilepsy and AEDs on cognition and behaviour, before focusing on the AEDs for which more detailed assessment, using standardised cognitive and behavioural measures, has been undertaken. We will then go on to discuss the key elements in the design of future AED clinical trials to address current unmet needs.

Protective effect of rutin on impairment of cognitive functions of due to antiepileptic drugs on zebrafish model

Aim:

The severity of adverse reactions due to antiepileptics is observed during initiation and early treatment in which impairment of cognitive effects are common. Since long time, herbal medicine is a natural remedy to treat neural symptoms. Phytochemicals have been proven to be potent neuro-protective agents. Rutin, a bioflavonoid is established to be nootropic in many studies. In this study, we aimed to determine the protective effect of rutin in zebrafish against the side effects produced by AEDs.

Materials and Methods:

Seizures were induced in zebrafish by phenylenetetrazole. Rutin pretreatment (50 mg/kg, single injection, i.p.) was done before commencement of the study. Behavioral studies were performed as: latency to move high in the tank, locomotion effects, color effect, shoal cohesion, light/dark test on Zebrafish.

Results:

Treatment with rutin reverted the locomotor behavior to normal. Treatment with AEDs caused fishes to move in all regions while, in case of treatment with rutin, the response reverted to normal. Treatment with AEDs altered swimming behavior of zebrafish, however, rutin showed a positive effect over this behavior. Treatment with AEDs resulted in restricted movement of zebrafish to the dark zone. Treatment with rutin caused increased latency of zebrafish to move in the light compartment. Similarly, time spent in the light compartment by zebrafish treated with rutin was significantly (P < 0.01) higher as compared to zebrafish treated with AEDs.

Conclusion:

The results suggest a protective role of rutin on cognition impaired by AEDs.

Attention-deficit/hyperactivity disorder and attention impairment in children with benign childhood epilepsy with centrotemporal spikes

Attention-deficit/hyperactivity disorder (ADHD) is a common comorbidity in children with epilepsy and has a negative impact on behavior and learning. The purposes of this study were to quantify the prevalence of ADHD in benign childhood epilepsy with centrotemporal spikes (BCECTS) and to identify clinical factors that affect ADHD or attention impairment in patients with BCECTS. The medical records of 74 children (44 males) with neuropsychological examination from a total of 198 children diagnosed with BCECTS at Asan Medical Center were retrospectively reviewed. Electroclinical factors were compared across patients with ADHD and those without ADHD. Mean T-scores of the continuous performance test were compared across patients grouped according to various epilepsy characteristics. Forty-eight (64.9%) patients had ADHD. A history of febrile convulsion was more common in patients with ADHD than in patients without ADHD (p=0.049). Bilateral centrotemporal spikes on electroencephalogram were more common in patients receiving ADHD medication than in patients with untreated ADHD (p=0.004). Male patients, patients with frequent seizures prior to diagnosis, and patients with a high spike index (≥40/min) on sleep EEG at diagnosis had significantly lower visual selective attention (p<0.05). Children with BCECTS had a high prevalence of ADHD, and frequent seizures or interictal epileptiform abnormalities were closely related to impairment of visual selective attention in children with BCECTS, indicating the need for ADHD or attention impairment screening in children with BCECTS.

Initial anticonvulsant monotherapy in routine care of children and adolescents: levetiracetam fails more frequently than valproate and oxcarbazepine due to a lack of effectiveness

Since anticonvulsants such as valproate or oxcarbazepine have quite a disadvantageous profile of possible adverse drug events (ADEs), safer alternatives are being sought. The newer anticonvulsant levetiracetam is often considered advantageous. We performed a chart review of children and adolescents aged from 0.5 to 16.9 years, who had been started on an initial monotherapy with levetiracetam, valproate, or oxcarbazepine between 2007 and 2011, in order to analyze the therapy's failure rate during the first year. We differentiated failure of monotherapy due to a lack of effectiveness and due to ADEs. No psychometric tests were performed. Lack of effectiveness and inacceptable ADEs were assumed according to the judgment of physicians and families. Anticonvulsive monotherapy failed in 29/61 (48 %) levetiracetam patients and in 18/49 (37 %) valproate patients (for focal and generalized epilepsies; n.s.). This was caused by a lack of effectiveness in 25/61 (41 %) levetiracetam patients and in 11/49 (22 %) valproate patients (p ≤ 0.05). A modification of therapy due to ADEs was performed in 4/61 (7 %) levetiracetam patients and in 7/49 (14 %) valproate patients (n.s.). An anticonvulsive monotherapy failed in 21/42 (50 %) patients treated with levetiracetam and in 10/34 (29 %) patients treated with oxcarbazepine (for focal epilepsies; n.s.). Changes of monotherapy were caused by a lack of effectiveness in 17/42 (40 %) of levetiracetam patients and in 6/34 (18 %) of oxcarbazepine patients (p ≤ 0.05). ADEs leading to changes in therapy were reported for 4/42 (10 %) of levetiracetam and 4/34 (12 %) of oxcarbazepine patients (n.s.). An initial monotherapy of levetiracetam failed more frequently due to a lack of effectiveness than a monotherapy with valproate or oxcarbazepine. We found no significant difference in therapy failure due to ADEs.

Cognitive side-effects of antiepileptic drugs in children

Although the causes of cognitive impairment in patients with epilepsy have not been completely elucidated, three factors are clearly involved: the underlying etiology of epilepsy, the effects of seizures or the epileptiform EEG discharges themselves, and the central nervous system effects of antiepileptic drugs (AEDs). All commonly used AEDs have some effect on cognitive function, and the effect may be substantial when crucial functions are involved, such as learning in children. With phenobarbital, there is a high risk for serious cognitive effects impacting attention and memory. Phenytoin may affect mental speed, mainly in higher dosing and polytherapy. Moderate monotherapy doses do not seem to induce much effect. Valproate does not seem to impair cognition if sufficiently controlled for hyperammonemia. For carbamazepine, there are conflicting reports, which may be due to selection bias or dosing. For oxcarbazepine, there is no evidence for any detrimental change compared to valproate but mild improvements on attentional tests. For topiramate, there is clear evidence for topiramate-induced cognitive impairment (attention, memory, and language function) in adults and children. Although data is sketchy, levetiracetam does not seem to have a negative impact on cognition. For lamotrigine, there is evidence of a cognitive-enhancing effect on attention. No evidence for cognitive side-effects has been found for vigabatrin. Ethosuximide is not associated with cognitive impairment although the evidence is sketchy. For gabapentin, tiagabine, zonisamide, and rufinamide no studies in children are available.

Benign childhood epilepsy with centrotemporal spikes and the multicomponent model of attention: a matched control study

Although the high risk of cognitive impairments in benign childhood epilepsy with centrotemporal spikes (BCECTS) is now well established, there is no clear definition of a uniform neurocognitive profile. This study was based on a neuropsychological model of attention that assessed various components of attention in 21 children with BCECTS and 21 healthy children. All participants were tested with a computerized test battery using the multicomponent model of attention performance. In comparison with healthy participants, the children with BCECTS showed significant impairment in the measure of selectivity and in one measure of intensity of attention (arousal). Our results did not correlate with the electroclinical variables of age at onset of seizures and spike index on sleep EEGs. To the best of our knowledge, this is the first study in which the multicomponent model of attentional function has been used in children with BCECTS to provide a clearer neuropsychological profile of these patients.

Molecular and therapeutic potential and toxicity of valproic acid

Valproic acid (VPA), a branched short-chain fatty acid, is widely used as an antiepileptic drug and a mood stabilizer. Antiepileptic properties have been attributed to inhibition of Gamma Amino Butyrate (GABA) transaminobutyrate and of ion channels. VPA was recently classified among the Histone Deacetylase Inhibitors, acting directly at the level of gene transcription by inhibiting histone deacetylation and making transcription sites more accessible. VPA is a widely used drug, particularly for children suffering from epilepsy. Due to the increasing number of clinical trials involving VPA, and interesting results obtained, this molecule will be implicated in an increasing number of therapies. However side effects of VPA are substantially described in the literature whereas they are poorly discussed in articles focusing on its therapeutic use. This paper aims to give an overview of the different clinical-trials involving VPA and its side effects encountered during treatment as well as its molecular properties.

Attention impairment in rolandic epilepsy: systematic review

PURPOSE

Conflicting evidence about impairment of attention systems and the absence of a working model of attention has contributed to lack of clarity about comorbidity of attention problems in rolandic epilepsy (RE). Impairments in distributed attention systems may inform a disease model for RE, as well as direct interventions.

METHODS

We used a systematic review of the relevant literature published in English from 1990 to 2006 to evaluate impairment in attention in RE. The Mirsky and Posner models of attention were evaluated for applicability, and studies were reviewed for design, instrumentation, and congruence with the Posner model of attention.

RESULTS

Fourteen studies were identified: seven using a cross-sectional design (six active EEG abnormalities; one EEG remission) and seven longitudinal studies (abnormal EEGs and follow-up until normalized). According to the Posner model of attention, 12 studies employed measures that tapped the alerting network, 11 studies the orienting network, and eight the executive network. Nearly all controlled studies demonstrated impairments in all tested attention networks. In contrast, uncontrolled studies uniformly did not demonstrate impairments. Follow-up studies demonstrated complete or near complete resolution of attention impairments.

DISCUSSION

The weight of evidence, defined as the majority of studies evaluated, suggests that all three attention systems are impaired in children with active centrotemporal spikes (CTS), implying a more widespread functional cortical disturbance in RE than previously held. These impairments resolve upon EEG remission, suggesting a common pathological basis to the autosomal dominant CTS trait. Sources of methodological variation are discussed with recommendations for future investigations.