Olanzapine-Induced Clinical Seizure: A Case Report

Activation of the basal ganglia and indirect pathway neurons during frontal lobe seizures

There are no detailed descriptions of neuronal circuit active during frontal lobe motor seizures. Using activity reporter mice, local field potential recordings, tissue clearing, viral tracing, and super-resolution microscopy, we found neuronal activation after focal motor to bilateral tonic-clonic seizures in the striatum, globus pallidus externus, subthalamic nucleus, substantia nigra pars reticulata and neurons of the indirect pathway. Seizures preferentially activated dopamine D2 receptor-expressing neurons over D1 in the striatum, which have different projections. Furthermore, the D2 receptor agonist infused into the striatum exerted an anticonvulsant effect. Seizures activate structures via short and long latency loops, and anatomical connections of the seizure focus determine the seizure circuit. These studies, for the first time, show activation of neurons in the striatum, globus pallidus, subthalamic nucleus, and substantia nigra during frontal lobe motor seizures on the cellular level, revealing a complex neuronal activation circuit subject to modulation by the basal ganglia.

Modulatory Effect of Serotonergic System in Pentylenetetrazole-Induced Seizures and Associated Memory Deficit: Role of 5-HT1A and 5-HT2A/2C

Background and Purpose

Recent studies have recognised the memory deficit as one of the most common psychiatric issues in the patients with epilepsy, which severely affects the quality of life. Our previous studies have demonstrated the possible involvement of serotonergic system in the pathogenesis of epilepsy and associated memory deficit. The possible involvement of 5-HT_1A and 5-HT_2A/2C receptor has not been explored yet. Therefore, this study has been envisaged to explore the effect of 5-HT_1A and 5-HT_2A/2C receptor modulation on epilepsy and memory deficit in pentylenetetrazole-kindled mice.

Methods

In the present experimental approach, we examined the efficacy of modulation of 5-HT_1A and 5-HT_2A/2C receptor in pentylenetetrazole-induced kindling in male Swiss mice (n=75). Mice were kindled by sub-convulsive dose of pentylenetetrazole (35 mg/kg, intraperitoneal injection), at the interval of 48±2 hours). Successfully kindled animals were treated with 5-HT_1A and 5-HT_2A/2C receptor modulators. The effect of different treatments on seizure severity score and memory impairment was analysed.

Results

5-HT_1A receptor agonist improved the memory functions while seizure severity was not improved, and the opposite effect was observed with 5-HT_1A receptor antagonist. On the other hand, 5-HT_2A/2C receptor agonist significantly improved memory deficit as well as seizure severity in the kindled animals.

Conclusions

The outcome of the study indicates the possible involvement of 5-HT_2A/2C receptor in the pathogenesis of epilepsy and associated memory deficit, which can be further explored for its management.

Generalised tonic–clonic seizures on the subtherapeutic dose of olanzapine

Olanzapine is a second-generation antipsychotic. Incidence of olanzapine-induced seizures (OIS) is low with monotherapy. Combination therapy with another antipsychotic, drug metabolism and old age are risk factors for OIS. Our patient was a 71-year-old man, admitted to the psychiatry unit. He was managed on the lines of bipolar affective disorder current episode depression and dementia. He was started on olanzapine 1.25 mg two times/day. The patient developed generalised tonic–clonic seizure that lasted for around two and a half minutes within 24 hours of olanzapine treatment. His electroencephalogram showed findings that were suggestive of mild slowing. Our case discusses the incidence of OIS on the subtherapeutic dose. This presentation involves multiple risk factors for OIS: a history of stroke, poststroke seizure, old age and cognitive impairment. Due to scarcity of evidence of OIS; mostly with recommended therapeutic dose range physicians may underestimate seizure risk at subtherapeutic doses.

Circuits generating secondarily generalized seizures

Mapping the circuits underlying the generation and propagation of seizures is critically important for understanding their pathophysiology. We review evidence to suggest that circuits engaged in secondarily generalized seizures are likely to be more complex than those currently proposed. Focal seizures have been proposed to engage canonical thalamocortical circuits that mediate primarily generalized absence seizures, leading to secondarily generalized tonic-clonic seizures. In addition to traveling through the canonical thalamocortical circuits, secondarily generalized seizures could also travel through the striatum, globus pallidus, substantia nigra reticulata, and corpus callosum to the contralateral hemisphere. Recruitment of principal neurons in superficial layers 2/3 of the cortex can play a critical role in corticocortical seizure spread. Understanding the neuronal structures engaged in generating secondarily generalized seizures could provide novel targets for neuromodulation for the treatment of seizures. Furthermore, these sites may be loci of neuronal plasticity facilitating epileptogenesis. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Safety of Transcranial Magnetic Stimulation in Children: A Systematic Review of the Literature

BACKGROUND

Data and best practice recommendations for transcranial magnetic stimulation (TMS) use in adults are largely available. Although there are fewer data in pediatric populations and no published guidelines, its practice in children continues to grow.

METHODS

We performed a literature search through PubMed to review all TMS studies from 1985 to 2016 involving children and documented any adverse events. Crude risks were calculated per session.

RESULTS

Following data screening we identified 42 single-pulse and/or paired-pulse TMS studies involving 639 healthy children, 482 children with central nervous system disorders, and 84 children with epilepsy. Adverse events occurred at rates of 3.42%, 5.97%, and 4.55% respective to population and number of sessions. We also report 23 repetitive TMS studies involving 230 central nervous system and 24 children with epilepsy with adverse event rates of 3.78% and 0.0%, respectively. We finally identified three theta-burst stimulation studies involving 90 healthy children, 40 children with central nervous system disorder, and no epileptic children, with adverse event rates of 9.78% and 10.11%, respectively. Three seizures were found to have occurred in central nervous system disorder individuals during repetitive TMS, with a risk of 0.14% per session. There was no significant difference in frequency of adverse events by group (P = 0.988) or modality (P = 0.928).

CONCLUSIONS

Available data suggest that risk from TMS/theta-burst stimulation in children is similar to adults. We recommend that TMS users in this population follow the most recent adult safety guidelines until sufficient data are available for pediatric specific guidelines. We also encourage continued surveillance through surveys and assessments on a session basis.

Psychogenic polydipsia: the result, or cause of, deteriorating psychotic symptoms? A case report of the consequences of water intoxication

Water intoxication is a rare condition characterised by overconsumption of water. It can occur in athletes engaging in endurance sports, users of MDMA (ecstasy), and patients receiving total parenteral nutrition. This case outlines water intoxication in a patient with psychogenic polydipsia. When the kidney's capacity to compensate for exaggerated water intake is exceeded, hypotonic hyperhydration results. Consequences can involve headaches, behavioural changes, muscular weakness, twitching, vomiting, confusion, irritability, drowsiness, and seizures. Cerebral oedema can lead to brain damage and eventual death. In this case, psychogenic polydipsia led to significant hyponatraemia, cerebral oedema, and tonic-clonic seizures. Differential diagnoses for hyponatraemia are outlined. The aetiology of psychogenic polydipsia is uncertain, but postulated hypotheses are explored. Psychogenic polydipsia occurs in up 20% of psychiatric patients and this case serves to remind us to be cognizant of water overconsumption.

Do antipsychotic drugs increase seizure frequency in epilepsy patients?

To investigate whether addition of antipsychotic drugs (APD) would increase seizure frequency in epilepsy patients who were already treated with anti-epileptic drugs (AED), we compared a one-year seizure control outcome in 150 epilepsy patients with APD treatment for psychiatric conditions and 309 epilepsy patients without APD treatment matched for ages at epilepsy onset and the baseline evaluation and types of epilepsy. The seizure frequency was recorded at the baseline (immediately before the start of APD) and after the 1st, 3rd, 6th and 12th months. The seizure outcome at each of the four follow-up points was compared with the baseline. The seizure outcome was compared between the two groups as a whole and according to the types of epilepsy (idiopathic generalized and partial epilepsies). In the APD group, the seizure outcome was also analyzed according to the types of APD (first and second generation APD and combination of first and second generation APD) and the types of psychiatric conditions (psychosis and non-psychosis). The seizure outcome was significantly better in the APD group than control group at all the four follow-up points. According to the epilepsy types, the improvement in the seizure outcome was only observed in the patients with partial epilepsy. Of the APD group, there was no significant difference in the seizure outcome according to the types of APD or the psychiatric conditions. In epilepsy patients who are already treated with AED, APD treatment seems safe in seizure control outcome for treatment of psychiatric conditions.