Frontal nonconvulsive status epilepticus associated with high-dose tiagabine therapy in a child with familial bilateral perisylvian polymicrogyria

Tiagabine-related status epilepticus: a case report and systematic literature review

Tiagabine-related status epilepticus (SE) is an uncommon complication of tiagabine use. We aimed to detail the features and outcomes in a patient with tiagabine poisoning and review the relevant literature. We describe a case of tiagabine-related SE and literature review based on a 1995-2019 PubMed search. We report the case of a 30-year-old man with super-refractory SE after tiagabine poisoning. He fully recovered after 72 h of general anesthesia and was discharged from the ICU on day 16. A literature review showed distinct features among patients with tiagabine-related SE. Tiagabine side effects were characterized by non-convulsive SE after a slight increase in tiagabine dose and a rapid favorable evolution after benzodiazepine and early tiagabine withdrawal. Generalized convulsive SE was a complication of voluntary or involuntary tiagabine poisoning and was particularly refractory. Both presentations are characterized by a return to baseline after prompt and adequate management. Tiagabine-related SE electroclinical features vary according to the underlying pathophysiological mechanism and can be life threatening. Recovery is the rule after tiagabine withdrawal and SE management with progressive therapeutic escalation guided by response to prior anticonvulsant treatments.

Tiagabine in clinical practice: effects on seizure control and behavior

OBJECTIVE

Preapproval randomized controlled trials of antiepileptic drugs provide data in limited patient groups. We assessed the side effect and seizure reduction profile of tiagabine (TGB) in typical clinical practice.

METHODS

Investigators recorded adverse effect (AE), seizure, and assessment-of-benefit data prospectively in sequential patients treated open label with TGB.

RESULTS

Two hundred ninety-two patients (39 children) were enrolled to be treated long term with TGB. Seizure types were focal-onset (86%), generalized-onset (12%), both focal- and generalized-onset (0.3%), and multiple associated with Lennox-Gastaut Syndrome (2%). Two hundred thirty-one received at least one dose of TGB (median = 28 mg/day) and had follow-up seizure or AE data reported. Common AEs were fatigue, dizziness, psychomotor slowing, ataxia, gastrointestinal upset, weight change, insomnia, and "others" (mostly behavioral). Serious AEs occurred in 19 patients: behavioral effects (n = 12), status epilepticus (n = 3), others (n = 3), and sudden unexplained death (n = 1). No patients experienced suicidal ideation/behavior, rash, nephrolithiasis, or organ failure. Seizure outcomes were seizure freedom (5%), ≥75% reduction (12%), ≥50% reduction (23%), and increased number of seizures (17%), or new seizure type (1%).

CONCLUSIONS

Behavioral AEs occurred in a larger proportion of patients compared to those reported in TGB preapproval randomized controlled trials. A moderate percentage of patients had a meaningful reduction in seizure frequency. In clinical practice, TGB remains a useful antiepileptic drug.

Electroencephalographic criteria for nonconvulsive status epilepticus: synopsis and comprehensive survey

There have been many attempts at defining the electroencephalography (EEG) characteristics of nonconvulsive status epilepticus (NCSE) without a universally accepted definition. This lack of consensus arises because the EEG expression of NCSE does not exist in isolation, but reflects status epilepticus under the variety of pathologic conditions that occur with age, cerebral development, encephalopathy, and epilepsy syndrome. Current NCSE definitions include "boundary conditions," in which electroencephalographic seizure activity occurs without apparent clinical seizures. Furthermore, what appears to one interpreter as status epilepticus, is not to another reader, reflecting the "art" of EEG interpretation. Seizures and epilepsy syndromes have undergone an evolution that has moved beyond a classification of focal or generalized conditions into a syndromic approach. It seems appropriate to make similar changes in the EEG analysis of the syndromes of NCSE. In effect, the literature on epilepsy classification has progressed to incorporate the different NCSE types with clinical descriptions, but the specific EEG evidence for these types is found largely in individual reports, and often by description only. NCSE classification of EEG patterns should derive from the aggregate of published EEG patterns in the respective clinical subtype, supported by an analysis of these EEG studies. The analysis that follows presents clinical descriptions and EEG patterns of NCSE in the neonatal period, infancy, childhood, adulthood, and late adulthood from a syndromic perspective based on age, encephalopathy, cerebral development, etiology, and syndrome. Proceeding from the proposed classification of status epilepticus syndromes in "Status epilepticus: its clinical features and treatment in children and adults" (published in 1994 by Cambridge University Press, New York), we have performed a systematic search for reports presenting EEG patterns of NCSE using the online medical search engine PubMed for 22 different search strategies. EEG patterns were reviewed by two board-certified epileptologists who reached consensus regarding presence of NCSE. From a total of 4,328 search results, 123 cases with corresponding EEG patterns could be allocated to underlying epilepsy syndromes. Typical characteristic, prominent electrographic patterns, and sequential arrangements are elucidated for the different NCSE syndromes. This compendium of patterns by NCSE syndrome classification with illustration of EEGs, and delineation of electroencephalographic features helps define the characteristics and semiologic borderlines among the types of NCSE.

Non-convulsive status epilepticus of frontal origin in mucopolysaccharidosis type II successfully treated with ethosuximide

At 7 years of age, a female with mucopolysaccharidosis type II (MPS II) showed a sudden deterioration in neurological function, a sleep disorder, and progressive behavioural impairment. Electroencephalography was performed 1 year and 8 months after the onset of the neurological regression and revealed continuous ictal activity in the frontal regions. The female was diagnosed as having frontal non-convulsive status epilepticus. After 5 weeks of therapy with ethosuximide, the ictal electroencephalographic activity disappeared. At the same time, her sleep and cognitive and behavioural functions were observed to improve. This is the first case of MPS type II reported in an individual with non-convulsive status epilepticus. Two main forms of MPS II can be recognized: attenuated and severe. Severe MPS II is characterized by neurodegeneration. No study has explored the relationship between epilepsy and neurological deterioration in MPS II. Our observation shows that epilepsy may be a treatable cause of neurological regression in individuals with MPS II.

Update on the newer antiepileptic drugs in child neurology: advances in treatment of pediatric epilepsy

The goal of epilepsy treatment is the prevention of recurrent seizures, and antiepileptic drugs (AEDs) are the mainstay. Uncontrolled seizures may cause medical, developmental, and psychologic disturbances. Treatment advances include 1) identification of the basic mechanisms of epilepsy and action of AEDs, 2) the introduction of many new AEDs, and 3) the use of neurostimulation, starting with vagus nerve stimulation. We must balance the efficacy of an AED versus its side effects, which if persistent, lead to patient discontinuation of the AED. Although all AEDs have a proven efficacy, they are differentiated by their efficacy for a given seizure type or epilepsy syndrome versus the side effects or tolerability. The many new AEDs give us a larger armamentarium for epilepsy treatment. We refer to studies and expert opinion consensus.

Use of second-generation antiepileptic drugs in the pediatric population

Epilepsy is common in the pediatric population. Nine second-generation antiepileptic drugs have been approved in the US for use in epilepsy over the past 15 years: felbamate, gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, oxcarbazepine, zonisamide, and pregabalin. Their use in pediatric patients is fairly widespread, despite most of these agents not having US FDA indications for use. Felbamate and gabapentin were the first two second-generation antiepileptic drugs to be approved in the US. Felbamate use has been limited because of the occurrence of hepatotoxicity and aplastic anemia. Although gabapentin is a fairly well tolerated antiepileptic drug, its use has also been limited as a result of inconsistent efficacy and concern about seizure exacerbation. Lamotrigine and topiramate are broad-spectrum antiepileptic drugs with efficacy in a wide variety of seizure types. Both agents have some tolerability concerns: rash with lamotrigine and neuropsychiatric events with topiramate. There are very little data on tiagabine use in children, but this agent appears to be effective and to have a good tolerability profile. Levetiracetam is a second-generation antiepileptic agent that is available intravenously. Considering its good efficacy, fast onset of action, and low incidence of serious adverse effects, its use in the acute setting could potentially increase. Oxcarbazepine and zonisamide have been relatively well studied in pediatric seizure patients, including use as monotherapy. Both agents have demonstrated good efficacy and tolerability for patients as young as 1 month old. Vigabatrin and rufinamide are currently not available in the US, but have been shown to have some success in other countries. Pregabalin is the newest antiepileptic agent, but lacks pediatric data currently.

Retrospective evaluation of tiagabine overdose

BACKGROUND

Tiagabine is an anticonvulsant that blocks reuptake of the inhibitory neurotransmitter GABA. There are no published studies or case series of tiagabine overdoses.

METHODS

The records of six poison centers and one statewide poison center network were searched for all exposures to tiagabine for the years 2000-2002. Inclusion criterion was a human tiagabine exposure with follow-up to a known outcome; exclusion criterion was multiple drug ingestion.

RESULTS

57 cases met the inclusion criterion. Thirty-seven patients were female (67%). Mean and median ages were 30.5 years (S.D. +/- 18.5) and 31 years, respectively, with a range of 2 to 80 years. Seven patients were < or = 6 years. Neurologic symptoms were common: lethargy, seizures (multiple), status epilepticus, seizure (single), coma, confusion, agitation, tremors, dizziness, dystonias/abnormal posturing, and hallucinations. Other symptoms included respiratory depression, tachycardia, hypertension, and hypotension. Therapies included benzodiazepines, mechanical ventilation, phenytoin, phenobarbital, diphenhydramine, and dopamine. The mean onset and duration of symptoms were 1.3 hours (+/- 0.5, range 1-2 hours) and 9.1 hours (+/- 3.8, range 4-24 hours), respectively. Dose ingested by history was known for 38 patients (67%). The lowest dose with the development of multiple seizures and coma was 96 mg. This occurred in a 36-year-old female with a history of epilepsy. The lowest dose with symptoms in a child was 8 mg, in a 6-year-old with drowsiness. Mean dose of those with and without symptoms was 102 mg and 10 mg, respectively. The mean dose for patients experiencing seizures was 224 mg (+/- 172, range 96 to 680 mg). The mean dose for patients experiencing coma and respiratory depression was 270 mg (+/- 204, range 96 to 680 mg). Fifty-two patients (91%) were evaluated in the ED of whom 43 were admitted for medical care.

CONCLUSION

Seizures and altered mental status were common with tiagabine overdose, with rapid onset and resolution of symptoms. In this series, seizures did not occur until the ingestion was greater than three times the maximum recommended daily dose.

Aggravation of epilepsy by antiepileptic drugs

Antiepileptic drugs may paradoxically worsen seizure frequency or induce new seizure types in some patients with epilepsy. The mechanisms of seizure aggravation by antiepileptic drugs are mostly unknown and may be related to specific pharmacodynamic properties of these drugs. This article provides a review of the various clinical circumstances of seizure exacerbation and aggravation of epilepsy by antiepileptic drugs as well as a discussion of possible mechanisms underlying the occasional paradoxical effect of these drugs. Antiepileptic drug-induced seizure aggravation can occur virtually with all antiepileptic medications. Drugs that aggravate seizures are more likely to have only one or two mechanisms of action, either enhanced gamma-aminobutyric acid-mediated transmission or blockade of voltage-gated sodium channels. Antiepileptic drug-induced seizure exacerbation should be considered and the accuracy of diagnosis of the seizure type should be questioned whenever there is seizure worsening or the appearance of new seizure types after the introduction of any antiepileptic medication.

Status Epilepticus and Tiagabine Therapy Revisited

PURPOSE

To determine whether antiepileptic treatment with tiagabine (TGB) is associated with an increased frequency of nonconvulsive status epilepticus (NCSE) in patients with refractory epilepsy.

METHODS

We reviewed retrospectively the medical and EEG records of all inpatients with refractory localization-related epilepsy at the National Society for Epilepsy treated with TGB between January 1997 and December 2000. Clinical and electroencephalographic (EEG) data before, during, and after TGB therapy were evaluated in those patients who experienced a deterioration in seizure control suggestive of NCSE. Frequency of NCSE was determined in a comparable, non-TGB-treated patient population.

RESULTS

Seven (7.8%) of 90 TGB-treated patients were identified who experienced episodes of electroclinically confirmed NCSE. Serial EEGs showed deterioration during TGB treatment, with resolution of abnormality on discontinuation of TGB in all seven patients. During the same observation period, 32 (2.7%) of 1,165 non-TGB-treated patients developed electroclinically defined NCSE.

CONCLUSIONS

Treatment with TGB is associated with an increased frequency of NCSE in patients with refractory localization-related epilepsy.

Tiagabine-induced generalised non convulsive status epilepticus in patients with lesional focal epilepsy

PURPOSE

To report 3 cases with focal lesional epilepsy that had non-convulsive status epilepticus (NCSE) induced by treatment with tiagabine (TGB) and review the previously published cases. Drugs that enhance GABAnergic transmission are recognised to promote absence seizures in patients with generalised epilepsy syndromes and may on occasions even induce NCSE. However, that TGB can also induce NCSE in focal lesional epilepsy is not widely recognised in clinical practice.

METHOD

The clinical history, EEG and MRI findings were reviewed in 3 patients with lesional focal epilepsy who presented to our epilepsy programs over a 12 month period with TGB-induced NCSE. All previously reported cases in the English medical literature were reviewed.

RESULTS

The three patients had longstanding complex partial and secondarily generalised seizures refractory to multiple different anti-epileptic drugs. In two cases, MRI demonstrated a focal malformation of cortical development in the left parieto-occipital region and in the third left mesial temporal sclerosis. Following commencement of TGB in one patient and dose escalation in two, prolonged episodes of confusion and poor responsiveness were noted. Prolonged EEG monitoring demonstrated continuous high amplitude, generalised, 2-4 Hz delta activity with intermingled spikes during the episodes of unresponsiveness, consistent with NCSE. The clinical and EEG activity normalised following the administration of IV clonazepam followed by dose reduction or withdrawal of the TGB. Eleven previously reported cases of patients with partial epilepsy and a focal underlying lesion on MRI were identified, all of whom had similar features to that seen in our cases.

CONCLUSIONS

These cases illustrate that TGB may induce generalised NCSE in patients with focal lesional epilepsy, in addition to those with generalised syndromes. We hypothesise that patients may have developed an acquired alteration in the sensitivity of their thalamocortical circuitry that renders them more sensitive to the effects of drugs that enhance GABAnergic activity.

Management of epilepsy in mentally retarded children using the newer antiepileptic drugs, vagus nerve stimulation, and surgery

Clusters of seizures, prolonged seizures, and status epilepticus occur more frequently in children with multiple disabilities, and chronic seizures are more likely to be refractory to treatment. In many patients, the seizures appear to contribute to the mental retardation. Thus, if the lives of these children are to improve, seizure control is essential. However, medical treatment can interfere with cognition and cause behavioral disturbances, making life very difficult for the child and the child's family. With the introduction of 10 new antiepileptic drugs in the last decade, the treatment of epilepsy in multiply handicapped children has significantly advanced. These new antiepileptic drugs may improve seizure control, medication tolerance, or both. Although the ultimate therapeutic goal is to keep children seizure free and alert, compromises regarding medication choice and dosage are still necessary in many cases. Novel treatment options, such as the vagus nerve stimulator, may decrease seizure frequency without behavioral or cognitive side effects. In carefully selected children with specific epilepsy syndromes, epilepsy surgery can provide partial or complete relief from seizures.

Non-convulsive status epilepticus associated with tiagabine therapy in children

A case of a 7-year-old male with epilepsy who developed non-convulsive status epilepticus (NCSE) with electroclinical features consistent with those of atypical absence seizures after adjunctive antiepileptic therapy of tiagabine (TGB) is reported. The patient had frequent generalised and rare partial seizures with generalised epileptic discharges on prior electroencephalogram (EEG) recordings. NCSE was developed when rapid dosage increase and high dose of TGB was given. This case emphasises the need for close monitoring of children with epilepsy taking TGB for exacerbation of seizures or development of NCSE.

Non-convulsive status epilepticus associated with tiagabine in a pediatric patient

We report a 4-year-old patient who developed non-convulsive status epilepticus (NCSE) following tiagabine (TGB) as add-on treatment for refractory partial seizures. NCSE occurred while the patient received TGB 0.83 mg/kg/day. In our case, the TGB reduction led to a significant improvement of electroclinical features. The mechanisms of this abnormal effect are not clear. GABA-ergic hyperfunction and/or multiplicity of interlinked brain GABA systems associated with individual specific sensitivity could play a critical role in the pathogenesis of NCSE. This is the first report of NCSE documented by electroencephalogram (EEG) in a child under 12 years of age on TGB treatment.

Nonconvulsive status epilepticus due to a de novo contralateral focus during tiagabine adjunctive therapy

We describe a 30-year-old woman with an infantile-onset epilepsy due to a left temporal gliotic area who developed a nonconvulsive status epilepticus (NCSE) during tiagabine (TGB) adjunctive therapy. The ictal EEG recording showed a de novo right temporal focus not previously evident. After the i.v. administration of 4 mg lorazepam, the NCSE episode rapidly resolved and her usual left temporal EEG abnormalities reappeared. To our knowledge this is the first case of paradoxical seizure exacerbation associated with TGB therapy in which the clinical and EEG features are congruous with a new contralateral focus.

Clinical and EEG findings in six patients with altered mental status receiving tiagabine therapy

Tiagabine (TGB), a novel GABA reuptake inhibitor antiepileptic drug, has been reported to induce nonconvulsive status epilepticus (NCSE) in patients with generalized or partial onset seizures. We describe six patients with refractory partial epilepsy treated with add-on TGB. They developed acute intermittent or progressive chronic confusion associated with diffuse slowing of the electroencephalogram (EEG), shortly after an increase in dose of TGB. This remitted in each situation after reduction of the daily dose. The possibility of nonconvulsive status epilepticus or toxic encephalopathy is discussed.

Tiagabine-related non-convulsive status epilepticus in partial epilepsy: three case reports and a review of the literature

There have been several recent reports of non-convulsive status epilepticus during tiagabine therapy in patients with partial epilepsy. We report three cases where elevation of tiagabine dosage was followed by electroclinical features, or electroencephalographic features without clinical signs, of non-convulsive status epilepticus. Administration of clonazepam and/or discontinuation to tiagabine lead to complete remission. In one case after re-exhibition of tiagabine the EEG again showed rhythmic delta waves. We review the other cases reported so far and discuss the different pathophysiological hypotheses about the association in the light of new experimental data.

Newer antiepileptic drugs: advantages and disadvantages

The choice of an antiepileptic drug depends firstly on its efficacy in specific seizure types and epilepsies. However, it is imperative to consider whether possible adverse events will outweigh any benefits. The advantages and disadvantages of vigabatrin, lamotrigine, gabapentin, topiramate, tiagabine and felbamate are considered in some detail, and oxcarbazepine, stiripentol, remacemide, zonisamide and levetiracetam more briefly. Vigabatrin is effective for partial seizures and infantile spasms, but visual field defects are limiting its use. Lamotrigine has a wide spectrum, needs to be prescribed with care. Gabapentin is unlikely to cause adverse effects, but has relatively poor efficacy. Topiramate is widely effective, but can be poorly tolerated. Tiagabine is relatively untried in childhood epilepsies. The use of felbamate is restricted to severe refractory epilepsies. Stiripentol can be effective in severe myoclonic epilepsy in infancy. Zonisamide has a special place in the progressive myoclonus epilepsies. Levetiracetam, remacemide and oxcarbazepine have been used mainly for partial seizures: further studies of their roles in other circumstances are required.