Treatment of infantile spasms: results of a population-based study with vigabatrin as the first drug for spasms

Prediction model for long-term seizure and developmental outcomes among children with infantile epileptic spasms syndrome

Introduction

Children with infantile epileptic spasms syndrome (IESS) are likely to experience poor outcomes. Researchers have investigated the factors related to its long-term prognosis; however, none of them developed a predictive model.

Objective

This study aimed to clarify the factors that influence the long-term prognosis of seizures and their development and to create a prediction model for IESS.

Materials and methods

We conducted a retrospective cohort study enrolling participants diagnosed with IESS at the Tottori University Hospital. We examined the seizure and developmental status at 3 and 7 years after the IESS onset and divided the participants into favorable and poor outcome groups. Subsequently, we analyzed the factors associated with the poor outcome group and developed a prediction model at 3 years by setting cutoff values using the receiver operating characteristic curve.

Results

Data were obtained from 44 patients with IESS (19 female patients and 25 male patients). Three years after epileptic spasms (ES) onset, seizure and development were the poor outcomes in 15 (34.9%) and 27 (61.4%) patients, respectively. The persistence of ES or tonic seizures (TS) after 90 days of onset, moderate or severe magnetic resonance imaging abnormalities, and developmental delay before IESS onset were significantly associated with poor outcomes. Seven years after the onset of ES, seizures and development were the poor outcomes in 9 (45.0%) and 13 (72.2%) patients, respectively. We found that no factor was significantly associated with poor seizure outcomes, and only developmental delay before IESS onset was significantly associated with poor developmental outcomes. Our prediction model demonstrated 86.7% sensitivity and 64.3% specificity for predicting poor seizure outcomes and 88.9% sensitivity and 100% specificity for predicting poor developmental outcomes.

Conclusion

Our prediction model may be useful for predicting the long-term prognosis of seizures and their development after 3 years. Understanding the long-term prognosis during the initial treatment may facilitate the selection of appropriate treatment.

Integration of multiscale entropy and BASED scale of electroencephalography after adrenocorticotropic hormone therapy predict relapse of infantile spasms

BACKGROUND

Even though adrenocorticotropic hormone (ACTH) demonstrated powerful efficacy in the initially successful treatment of infantile spasms (IS), nearly half of patients have experienced a relapse. We sought to investigate whether features of electroencephalogram (EEG) predict relapse in those IS patients without structural brain abnormalities.

METHODS

We retrospectively reviewed data from children with IS who achieved initial response after ACTH treatment, along with EEG recorded within the last two days of treatment. The recurrence of epileptic spasms following treatment was tracked for 12 months. Subjects were categorized as either non-relapse or relapse groups. General clinical and EEG recordings were collected, burden of amplitudes and epileptiform discharges (BASED) score and multiscale entropy (MSE) were carefully explored for cross-group comparisons.

RESULTS

Forty-one patients were enrolled in the study, of which 26 (63.4%) experienced a relapse. The BASED score was significantly higher in the relapse group. MSE in the non-relapse group was significantly lower than the relapse group in the γ band but higher in the lower frequency range (δ, θ, α). Sensitivity and specificity were 85.71% and 92.31%, respectively, when combining MSE in the δ/γ frequency of the occipital region, plus BASED score were used to distinguish relapse from non-relapse groups.

CONCLUSIONS

BASED score and MSE of EEG after ACTH treatment could be used to predict relapse for IS patients without brain structural abnormalities. Patients with BASED score ≥ 3, MSE increased in higher frequency, and decreased in lower frequency had a high risk of relapse.

Assessing Risk for Relapse among Children with Infantile Spasms Using the Based Score after ACTH Treatment: A Retrospective Study

Introduction

Even though adrenocorticotropic hormone (ACTH) demonstrated powerful efficacy in the initially successful treatment of infantile spasms (IS), nearly one-half of patients whose spasms were once suppressed experienced relapse. There is currently no validated method for the prediction of the risk of relapse. The Burden of Amplitudes and Epileptiform Discharges (BASED) score is an electroencephalogram (EEG) grading scale for children with infantile spasms. We sought to determine whether an association exists between the BASED score after ACTH treatment and relapse after initial response with ACTH.

Methods

Children with IS who achieved initial response after ACTH treatment were selected as the study subjects. Those who experienced relapse within 12 months after ACTH treatment were categorized as the relapse group, and those who did not were categorized as the non-relapse group. Their general clinical data and EEG data (using BASED scoring) after ACTH treatment were collected, and compared between groups. Cox proportional hazards models were fit to determine factors associated with relapse.

Results

A total of 64 children with IS were enrolled in the study, of which 37 (57.8%) experienced a relapse, and the median duration after ACTH treatment was 3 (1.5, 6) months. The BASED score was significantly higher in the relapse group than in the non-relapse group. Cox modeling demonstrated that BASED score was independently associated with relapse. The patients with a score greater than or equal to 3 showed a high rate (89.3%) of relapse. The relapse group had stronger, more stable EEG functional networks than the non-relapse group, and there were obvious correlations between BASED score and functional connectivity.

Conclusion

This study suggests the BASED score after ACTH treatment has potential value as a predictor for relapse after initial response. Children with IS who have a BASED score greater than or equal to 3 after the initial response of ACTH carry a high risk of relapse within 1 year.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00347-7.

Seizure semiology, localization, and the 2017 ILAE seizure classification

In the study of epilepsy, the term semiology is used to comprise the clinical characteristics of a seizure, both subjective symptoms and objective phenomena. It is produced by activation of the symptomagenic zone, and an accurate and comprehensive understanding of the localizing value of seizure semiology is crucial for presurgical evaluation and planning. Myriad publications in epilepsy journals detail correlations between various semiological features and activation of specific cortical regions. Traditionally these studies involved scalp EEG recorded in epilepsy monitoring units. The increasing use of invasive monitoring, and specifically the use of depth electrodes and stereo-electroencephalography, has advanced our understanding of the characteristics of seizures arising from ictal foci deep to the scalp, including the cingulate, insula and operculum. However, the distinction between seizure onset and symptomogenic zones is not always clear. In 2017 the International League Against Epilepsy (ILAE) published an operational classification of seizure types based heavily on seizure semiology. The current paper provides an updated review of the current body of knowledge relating to seizure semiology, incorporating both scalp EEG studies and more recent stereo-electroencephalography discoveries in the framework of the 2017 ILAE classification.

Preoperative evaluation and surgical strategy for epileptic spasms in children

Epileptic spasm (ES) is one of the most common types of seizures in children. It is primarily characterized by brief axial contractions lasting less than 2 s and recurring in short clusters. It usually occurs in children of 3 to 12 months of age, although it can also occur after the age of 1 year. In general, children with ES develop other symptoms of epilepsy, such as tonic, tonic‐clonic, or focal seizures, after 3 to 5 years of age. ES in children is often damaging and usually results in developmental regression. First‐line treatments for spasm seizures include adrenocorticotropic hormone (ACTH) and vigabatrin. However, many patients fail to respond to these medications, and continued to have spasms associated with progressive neurodevelopmental degeneration. Therefore, it is important to consider whether children with drug resistance meet surgical indications to consider surgical treatment in such conditions. In this study, we reviewed and summarized the importance of preoperative evaluation in order to provide surgical options for treatment of children with ES.

Isovaline efficacy in a rat pup model of infantile spasms

Infantile spasms, also known as epileptic spasms during infancy, is an epileptic disorder of infancy and early childhood that is associated with developmental delay or regression, high mortality rate and is difficult to treat with conventional antiseizure medication. Previously, we reported that a unique amino acid called isovaline had potent anticonvulsive efficacy in the 4-aminopyridine and pilocarpine rat models of seizures. In this study, we examined whether isovaline possess therapeutic utility in a well-established rat model of infantile spasms which involves the pretreatment of a pregnant dam with betamethasone and subsequent induction of spasms with N-methyl-D-asparate (NMDA), a glutamate receptor agonist, in 15-day old pups. We treated seven of these pups with saline prior to administering NMDA and eight of these pups with isovaline (300 mg/kg) intraperitoneal (i.p.) prior to NMDA. Isovaline significantly reduced the number of full-body jumps from 18.1 ± 5.0 to 6.3 ± 1.8 and leg/arm/tail strains from 4.4 ± 1.6 to 1.1 ± 0.5. A trend in a reduction of body twitch was noted in rat pups administered isovaline (P = 0.05), but no significant difference was seen in NMDA-induced head nods (P = 0.221). In conclusion, our data demonstrate a potential for isovaline to attenuate an aggressive form of epilepsy that typically requires highly toxic medications to treat in children.

Infantile Spasms: Outcome in Clinical Studies

Children with infantile spasms are likely to have a poor outcome. Outcome measures for infantile spasms include primary response to treatment, relapse of spasms, neurological development, death, and progression to another type of epilepsy (Consensus Statements of the WEST Delphi Group 2004). This review is based mainly on prospective studies and emphasizes data about the current first-line drugs, adrenocorticotropic hormone, vigabatrin, and prednisolone, taking into account the proportion of patients with known and unknown etiology, which has a very strong effect on seizure outcome. In most studies, hormonal treatment (adrenocorticotropic hormone or prednisolone) is the optimal monotherapy, except for patients with tuberous sclerosis complex, in whom vigabatrin appears superior. Combination therapy (hormones plus vigabatrin) may well be more effective than either agent alone. The underlying etiology is the most important prognostic factor. In studies with a long follow-up (up to 50 years), a favorable cognitive outcome has been observed in approximately one quarter of patients and complete seizure freedom in one-third. Autism is relatively frequent, and premature mortality is high throughout life. Modifiable prognostic factors include early recognition of the spasms with prompt treatment, short duration of hypsarrhythmia, prompt treatment of relapses of spasms and multifocal epileptic discharges, and early treatment of adverse effects. It is hoped that eventually advanced genetics and molecular data will allow an understanding of the pathogenetic mechanisms of many specific etiologies to allow disease-specific treatment such as is emerging for tuberous sclerosis.

Multimodal localization and surgery for epileptic spasms of focal origin: a review

Epileptic spasms (ES) are a common manifestation of intractable epilepsy in early life and can lead to devastating neurodevelopmental consequences. Epilepsy surgery for ES is challenging because of inherent difficulties in localizing the epileptogenic zone in affected infants and children. However, recent clinical series of resective neurosurgery for ES suggest that not only is surgery a viable option for appropriately selected patients, but postoperative seizure outcomes can be similar to those achieved in other types of focal epilepsy. Increased awareness of ES as a potentially focal epilepsy, along with advances in neuroimaging and invasive monitoring technologies, have led to the ability to surgically treat many patients with ES who were previously not considered surgical candidates. In this study, the authors review the current state of epilepsy surgery for ES. Specifically, they address how advances in neuroimaging and invasive monitoring have facilitated patient selection, presurgical evaluation, and ultimately, resection planning.

Effect of vigabatrin on seizure control and safety profile in different subgroups of children with epilepsy

OBJECTIVE

To evaluate the efficacy and safety of vigabatrin in pediatric epilepsy.

METHODS

We retrospectively reviewed patients with epilepsy treated with vigabatrin over a 2-year period at a pediatric tertiary center. We assessed the relationship between seizure frequency, etiology, vigabatrin dose, adverse events, medication discontinuation reasons, and electroencephalography (EEG) characteristics.

RESULTS

One hundred three patients followed at Boston Children's Hospital were treated with vigabatrin and had complete medical records. Within the follow-up interval, 69 (67%) of 103 patients had discontinued vigabatrin therapy. Two patients (1.9%) died during therapy for unknown reasons. Median age at vigabatrin initiation was 8 months (interquartile range [IQR] 5-15). Median starting dose was 48.1 mg/kg per day (IQR 29.8-52.3) with a median target of 100 mg/kg (IQR 81.9-107.9). Median treatment duration was 12.1 months (n = 89, IQR 5.0-22.9) overall, and 13.3 months (IQR 5.2-23.2) for patients who discontinued vigabatrin. The most common reasons for discontinuation were controlled seizures in 31 (43.7%) of 71 and unsatisfactory therapeutic effect in 23 (32.4%) of 71. Median percent seizure reduction from baseline to first follow-up was 83.3% (IQR 27.4-99.8) and 96.7% (IQR 43.3-100) to last follow-up. Twenty-four (38.7%) of 62 patients with a follow-up posttreatment remained seizure-free. Four patients who had initially achieved seizure freedom relapsed. Patients with structural/metabolic etiology had greater median percent seizure reduction at first follow-up than patients with genetic etiology (98.7% vs. 61.4%, respectively, p = 0.001). Hypsarrhythmia resolved after therapy in 18 of 20 (90%, 95% confidence interval [CI] 70-97) patients with pretreatment hypsarrhythmia, and 2 patients presented with hypsarrhythmia posttreatment. Risk of having hypsarrhythmia was reduced by 32% (95% CI 14.9-49.1) posttreatment.

SIGNIFICANCE

Vigabatrin is efficacious in all seizure types and resolved hypsarrhythmia in most patients. In this series with a median treatment duration of 12.1 months, vigabatrin had a good safety profile with a low rate of discontinuation due to nonophthalmologic and ophthalmologic adverse effects.

Response to second treatment after initial failed treatment in a multicenter prospective infantile spasms cohort

OBJECTIVE

Infantile spasms (IS) represent a severe epileptic encephalopathy presenting in the first 2 years of life. Recommended first-line therapies (hormonal therapy or vigabatrin) often fail. We evaluated response to second treatment for IS in children in whom the initial therapy failed to produce both clinical remission and electrographic resolution of hypsarhythmia and whether time to treatment was related to outcome.

METHODS

The National Infantile Spasms Consortium established a multicenter, prospective database enrolling infants with new diagnosis of IS. Children were considered nonresponders to first treatment if there was no clinical remission or persistence of hypsarhythmia. Treatment was evaluated as hormonal therapy (adrenocorticotropic hormone [ACTH] or oral corticosteroids), vigabatrin, or "other." Standard treatments (hormonal and vigabatrin) were compared to all other nonstandard treatments. We compared response rates using chi-square tests and multivariable logistic regression models.

RESULTS

One hundred eighteen infants were included from 19 centers. Overall response rate to a second treatment was 37% (n = 44). Children who received standard medications with differing mechanisms for first and second treatment had higher response rates than other sequences (27/49 [55%] vs. 17/69 [25%], p < 0.001). Children receiving first treatment within 4 weeks of IS onset had a higher response rate to second treatment than those initially treated later (36/82 [44%] vs. 8/34 [24%], p = 0.040).

SIGNIFICANCE

Greater than one third of children with IS will respond to a second medication. Choosing a standard medication (ACTH, oral corticosteroids, or vigabatrin) that has a different mechanism of action appears to be more effective. Rapid initial treatment increases the likelihood of response to the second treatment.

Stiripentol and vigabatrin current roles in the treatment of epilepsy

INTRODUCTION

Stiripentol and vigabatrin are the two anticonvulsant drugs currently approved in severe infantile-onset epilepsies, respectively Dravet syndrome and infantile spasms.

AREAS COVERED

For both, the indication was discovered by chance thanks to an exploratory study. Both demonstrated indisputable efficacy through randomized-controlled trials. Stiripentol as adjunctive therapy to clobazam and valproate performed better than placebo, and vigabatrin as first-line monotherapy better than the reference steroid therapy in spasms due to tuberous sclerosis. At one-year treatment vigabatrin and steroids were equally efficient in the other etiologies of spasms. However, it took more than 20 years for both drugs to be approved world-wide.

EXPERT OPINION

Stiripentol suffered from pharmacokinetic potentiation of clobazam, thus raising the question whether it was efficient per se. Finally, animal models and pharmacogenetic data on CYP2C19 confirmed its specific anticonvulsant effect. Stiripentol (in comedication with clobazam and valproate) is therefore to be recommended for Dravet patients. Vigabatrin was found to have a frequent and irreversible retinal toxicity, which required an alternative visual testing to be detected in young children. Today the benefit/risk ratio of vigabatrin as first-line is considered to be positive in infantile spasms, given the severity of this epilepsy and the lack of a safer alternative therapy.

Recent advances in the pharmacotherapy of infantile spasms

Adrenocorticotrophic hormone (ACTH), oral corticosteroids and vigabatrin are now first-line treatments for infantile spasms in the US and Europe. There is now increased knowledge regarding the role of ACTH, corticosteroids and vigabatrin (e.g. efficacy, doses, side effects, treatment in specific aetiological subtypes of infantile spasms), and other antiepileptic drugs (i.e. topiramate, valproate, zonisamide, sulthiame, levetiracetam, lamotrigine, pyridoxine, ganaxolone), as well as adjunctive flunarizine and novel drugs not yet in clinical use for infantile spasms (i.e. pulse rapamycin and melanocortin receptor agonists). The existence of a latent period, weeks to months following a precipitating brain insult, raises the possibility of preventive interventions. Recent experimental data emerging from animal models of infantile spasms have provided optimism that new and innovative treatments can be developed, and knowledge that drug treatment can affect long-term cognitive outcome is increasing. The aim of this article is to review recent developments in the pharmacotherapy of infantile spasms and to highlight the practical implications of the latest research.

Optimal management of seizures associated with tuberous sclerosis complex: current and emerging options

Seizures are clinically significant manifestations associated with 79%-90% of patients with tuberous sclerosis complex. Often occurring within the first year of life in the form of infantile spasms, seizures interfere with neuropsychiatric, social, and cognitive development and carry significant individual and societal consequences. Prompt identification and treatment of seizures is an important focus in the overall management of tuberous sclerosis complex patients. Medical management, either after seizure onset or prophylactically in infants with electroencephalographic abnormalities, is considered first-line therapy. Vigabatrin and adrenocorticotropic hormone have emerged over the past few decades as mainstay pharmacologic modalities. Furthermore, emerging research on mammalian target of rapamycin inhibitors demonstrated promise for the management of seizures and subependymal giant cell astrocytoma. For appropriate surgical candidates with an epileptogenic zone associated with one or more glioneuronal hamartomas, ideally in noneloquent cortex, resective surgery can be considered, which provides a cure in 56% of patients. For medically refractory patients who do not meet criteria for curative surgery, palliative surgical approaches focused on reducing seizure burden, in the form of corpus callosotomy and vagus nerve stimulation, are alternative management options. Lastly, the ketogenic diet, a reemerging therapy based on the anticonvulsant effects of ketone bodies, can be utilized independently or in conjunction with other treatment modalities for the management of difficult-to-treat seizures.

Treatment strategies

There has been important progress in the identification of antiepileptic compounds and their indications in children over the past 15 years: their number has doubled and specific pediatric trials are being performed to document their effect according to seizures and syndromes as well as their tolerability in pediatrics. The improved understanding of pharmacokinetics and drug-drug interactions has helped to optimize treatment. Specific issues specific of infants have also been studied although new antiepileptic drugs are still dramatically lacking for this age group. Before reaching a syndromic diagnosis, the choice of a first- line agent goes to compounds with the largest range of efficacy and least identified risks. Subsequent choices are mainly based on the epilepsy syndrome and seizure type in addition to good clinical practice to determine dose, adverse effect profile, risk of aggravating seizures and drug interactions, clinician's experience, cultural habits, and availability of drugs. If there are several options, preference is given to the compound that exhibits the best risk/benefit ratio, or the most rapid titration when seizure frequency is the major issue. For new antiepileptic compounds, price is often a limiting factor in countries with poor insurance coverage. Third generation anti-epileptic drugs are emerging which also seem to be promising.

Quality-of-care indicators for infantile spasms

We developed a comprehensive set of quality-of-care indicators for the management of children with infantile spasms in the United States, encompassing evaluation, diagnosis, treatment, and prevention and management of side effects and comorbidities. The indicators were developed using the RAND/UCLA Modified Delphi Method. After a focused review of the literature and guidelines by the study team, an expert panel (nominated by leaders of Child Neurology Society, American Epilepsy Society, and National Institute for Neurologic Disorders) rated the draft indicators anonymously, met face-to-face to discuss each indicator, and rerated the revised indicators on validity, feasibility, and importance. The panel recommended 21 indicators, of which 8 were identified as most likely to have a large positive impact on improving quality of life and/or health outcomes for children with infantile spasms. The proposed indicators can be used to assess and document variations and gaps in quality-of-care and inform future research and quality improvement interventions.

Infantile spasms (West syndrome) in children with inborn errors of metabolism: a review of the literature

West syndrome (infantile spasms) is an epileptic encephalopathy that includes psychomotor deterioration. In rare cases, it is due to an inherited, progressive metabolic disease. More than 25 inborn errors of metabolism have been considered etiologic or predisposing factors for infantile spasms. This is a review of the literature on reported cases of children diagnosed with a metabolic disease who developed infantile spasms. This article presents in brief the most frequent inborn errors of metabolism that have been associated with West syndrome and also illustrates the importance of screening for inborn errors of metabolism in infantile spasms.

Balancing clinical benefits of vigabatrin with its associated risk of vision loss

Vigabatrin is an effective and well-tolerated antiepileptic drug (AED) for the treatment of refractory complex partial seizures (rCPS) and infantile spasms (IS), but its benefits must be evaluated in conjunction with its risk of retinopathy with the development of peripheral visual field defects (pVFDs). Vigabatrin should be considered for rCPS if a patient has failed appropriate trials of other AEDs or is not a suitable candidate for other AEDs, is not an optimal surgical candidate, and continues to experience debilitating effects from seizures. Vigabatrin is indicated as monotherapy for pediatric patients with IS. Its efficacy in achieving improved seizure control should be apparent within 12 weeks in patients with rCPS and within 2-4 weeks after attaining appropriate dosage for patients with IS. Because 12 weeks is well less than the known time of onset of visual defects, the risk of developing pVFDs may be minimized by discontinuing vigabatrin early during the course of therapy for patients with inadequate response. Appropriate vision screening is recommended at baseline, every 3 months during continued vigabatrin treatment, and at 3-6 months after discontinuation (if therapy has spanned more than a few months). If a pVFD is detected at any point and the decision is made to discontinue therapy, the pVFD is not likely to progress after discontinuation of vigabatrin. Although some patients will be at risk of retinopathy, vigabatrin is an appropriate treatment option for patients who achieve substantial clinical benefit, especially given the severe consequences of rCPS and uncontrolled IS. While retinopathy with the development of pVFDs is a serious adverse event, it is not life-threatening and its risk can be effectively managed.

Understanding and interpreting vision safety issues with vigabatrin therapy

Vigabatrin is an irreversible inhibitor of γ-aminobutyric acid (GABA) transaminase. It is effective as adjunctive therapy for adult patients with refractory complex partial seizures (rCPS) who have inadequately responded to several alternative treatments and as monotherapy for children aged 1 month to 2 years with infantile spasms. The well-documented safety profile of vigabatrin includes risk of retinopathy characterized by irreversible, bilateral, concentric peripheral visual field constriction. Thus, monitoring of visual function to understand the occurrence and manage the potential consequences of peripheral visual field defects (pVFDs) is now required for all patients who receive vigabatrin. However, screening for pVFDs for patients with epilepsy was conducted only after the association between vigabatrin and pVFDs was established. We examined the potential association between pVFDs and epilepsy in vigabatrin-naïve patients and attempted to identify confounding factors (e.g., concomitant medications, method of vision assessment) to more accurately delineate the prevalence of pVFDs directly associated with vigabatrin. Results of a prospective cohort study as well as several case series and case reports suggest that bilateral visual field constriction is not restricted to patients exposed to vigabatrin but has also been detected, although much less frequently, in vigabatrin-naïve patients with epilepsy, including those who received treatment with other GABAergic antiepileptic therapy. We also reviewed published data suggesting an association between vigabatrin-associated retinal toxicity and taurine deficiency, as well as the potential role of taurine in the prevention of this retinopathy.

Vigabatrin therapy for infantile spasms: review of major trials in Europe, Canada, and the United States; and recommendations for dosing

Infantile spasms (IS) are a unique and severe form of epilepsy associated with poor neurologic and developmental outcomes. The refractory spasms and abnormal electroencephalogram (EEG) patterns associated with the condition are believed to have a progressively detrimental impact. Therefore, rapid and complete control of spasms is the primary goal of treatment. Well-controlled clinical trials in Europe, Canada, and the United States have demonstrated that vigabatrin is efficacious and generally well-tolerated as monotherapy for IS. Several key studies, including pivotal trials that led to United States approval of vigabatrin in 2009, as well as comparative trials of vigabatrin and hormonal treatment, are the focus of this review. All studies assessed spasm cessation - usually as the primary endpoint - and adverse events. Vigabatrin dosages generally ranging from 100 to 150 mg/kg/day demonstrated efficacy to decrease or eradicate spasms and eliminate hypsarrhythmic EEG in patients with newly diagnosed IS. Several studies demonstrated long-term sustainability of spasm freedom with no negative impact on developmental outcomes. Vigabatrin was generally well-tolerated with few severe adverse events. Visual field defects cannot be adequately assessed in infants and young children, so this potential adverse effect was not evaluated in children with spasms. Notably, the time to response with vigabatrin was very rapid, generally occurring within 2 weeks of initial treatment. This allows for early treatment modification as needed. For infants who respond well to vigabatrin, treatment duration up to 6 months appears to be appropriate for realizing spasm freedom while limiting potential risks of adverse events and recurrences.

Surgical treatment for localization-related infantile spasms: excellent long-term outcomes

OBJECTIVE

Focal epileptogenic lesions can manifest as infantile spasms, a catastrophic type of epilepsy. Although early surgery for catastrophic epilepsies has shown positive effects, little is known regarding long-term outcomes. The present study examined long-term outcomes in patients with localization-related infantile spasms treated surgically.

METHODS

Data from localization-related infantile spasm cases treated surgically between 1998 and 2002 at the Asan Medical Center were retrospectively reviewed. Presurgical evaluation, surgery, postoperative seizure frequency and developmental outcome data were analyzed.

RESULTS

Five patients met the inclusion criteria, and had etiologies of tuberous sclerosis, fetal infection, encephalomalacia, malformation of cortical development and low-grade astrocytoma, respectively. The mean seizure onset age was 5.4 months (range, 3 days to 11 months), and the mean age at surgery was 19 months (range, 9-29 months). Two patients underwent a functional hemispherectomy, and the remaining three underwent lesionectomy or temporal lobectomy. The follow-up duration was 6-9 years. We found that following surgery, 4 of the 5 patients were seizure-free at the final follow-up. The 2 patients with low grade astrocytoma and cortical dysplasia, respectively showed relatively good developmental outcomes.

CONCLUSION

Surgery may be an excellent option for treating selected patients with infantile spasms due to unilateral or focal congenital or early-acquired cortical lesions. However, developmental outcomes appear to be strongly linked to etiology and the pre-operative developmental level.

Factors associated with treatment lag in infantile spasms

AIM

the aim of this study was to evaluate the conditions in which infantile spasms are diagnosed and their possible impact on the course of the disease.

METHOD

we carried out a retrospective study of the reasons for delayed treatment of infantile spasms (treatment lag) in western France over the period 1990-2003. A total of 156 infants, 87 male (55%) and 69 female (45%), with infantile spasms were identified, in 45 (29%) of whom the spasms were symptomatic. They were aged 1 week to 24 months (median 20wks, mean 22.4, SD 13.3) at first symptoms. To be included in the study, participants had to exhibit a combination of clusters of spasms, altered psychomotor development, and paroxysmal electroencephalographic (EEG) activity, as defined by the International League Against Epilepsy. We did not restrict onset to the first year of life as infantile spasms may begin after the age of 1 year.

RESULTS

the mean time from appearance of first symptom to first visit to a medical practitioner was 4 weeks. In 14% of cases, the reason for the visit was non-neurological, the parents having noticed no neurological symptoms before the visit. The diagnosis was missed at first visit in 38% of the cases examined, with the incorrect diagnosis mostly commonly being gastro-oesophageal reflux or no abnormality. This increased to 74% after a second visit, in all cases based on an abnormal EEG. However, in 5% the time between first presentation and diagnosis was over 2 months and up to 10 visits were required. The time lag between first presentation and diagnosis was significantly longer for individuals presenting to general practitioners than to paediatricians (p=0.03). Response to treatment was poorer in those in whom diagnosis was delayed.

INTERPRETATION

various steps could be taken to reduce treatment lag such as training general practitioners, informing the parents of individuals at risk about the possibility of infantile spasms, and recommending that EEG is performed before brain imaging in children with unexplained psychomotor delay.

Favourable prognostic factors with infantile spasms

The following aspects are reviewed: Does the aetiology influence the outcome of infantile spasms? Does the treatment influence the outcome? Can the outcome be predicted? Can we improve the prognosis? Favourable factors are the following: cryptogenic aetiology, age at onset > or =4 months, absence of atypical spasms and partial seizures, and absence of asymmetrical EEG abnormalities, short treatment lag, and an early and sustained response to treatment. Not only patients with a cryptogenic aetiology have a favourable outcome. We can already at the first clinical evaluation tell the parents if the prognosis looks favourable. The final goal of the treatment is improved mental outcome. Steroids and vigabatrin are the first-line drugs for infantile spasms in Europe. In a prospective study from the United Kingdom short-term outcome was better with hormonal than with vigabatrin therapy (tuberous sclerosis excluded). However, the numbers of patients who were seizure-free at 3-4 months in different studies have been very similar. Moreover, an early response to treatment seems to be of predictive value for the cognitive outcome in children with cryptogenic spasms. The long-term outcome is known only after hormonal therapy. The side effects of steroids are usually treatable and reversible. In Finland ACTH therapy is given at the minimum effective dose and for the minimum effective time with minimal side effects. The risks of VGB are irreversible visual field defects. As of yet there is no method to examine the visual fields in patients with infantile spasms. Early treatment of infantile spasms seems to be important. Prevention of infantile spasms with some aetiological groups might be possible.

Transient brain magnetic resonance imaging hyperintensity in basal ganglia and brain stem of epileptic infants treated with vigabatrin

Vigabatrin is an antiepileptic drug that produces intramyelinic edema in several animal models. This study investigates the effect of vigabatrin on the developing human brain. The authors retrospectively blindly review 34 brain magnetic resonance imaging of 22 epileptic infants (age: 9 +/- 1 months) that received vigabatrin, focusing on the presence of hyperintensity on T2- and diffusion-weighted images. Patients treated with vigabatrin displayed significant magnetic resonance imaging hyperintensity of basal ganglia and brain stem (P < .001, Wilcoxon test). This hyperintensity was transient and maximal 3 to 6 months after the beginning of vigabatrin. Hyperintensity was independent from duration and type of epilepsy, and from the presence or absence of seizures. The authors conclude that vigabatrin treatment is associated with transient hypersignal of the basal ganglia and brain stem in epileptic infants. Such transient hyperintensity is likely to be age-dependent and time-dependent because it has never been observed in adult patients.

Current trends in the treatment of infantile spasms

Infantile spasms are an epilepsy syndrome with distinctive features, including age onset during infancy, characteristic epileptic spasms, and specific electroencephalographic patterns (interictal hypsarrhythmia and ictal voltage suppression). Adrenocorticotropic hormone (ACTH) was first employed to treat infantile spasms in 1958, and since then it has been tried in prospective and retrospective studies for infantile spasms. Oral corticosteroids were also used in a few studies for infantile spasms. Variable success in cessation of infantile spasms and normalization of electroencephalograms was demonstrated. However, frequent significant adverse effects are associated with ACTH and oral corticosteroids. Vigabatrin has been used since the 1990s, and shown to be successful in resolution of infantile spasms, especially for infantile spasms associated with tuberous sclerosis. It is associated with visual field constriction, which is often asymptomatic and requires perimetric visual field study to identify. When ACTH, oral corticosteroids, and vigabatrin fail to induce cessation of infantile spasms, other alternative treatments include valproic acid, nitrazepam, pyridoxine, topiramate, zonisamide, lamotrigine, levetiracetam, felbamate, ganaxolone, liposteroid, thyrotropin-releasing hormone, intravenous immunoglobulin and a ketogenic diet. Rarely, infantile spasms in association with biotinidase deficiency, phenylketonuria, and pyridoxine-dependent seizures are successfully treated with biotin, a low phenylalanine diet, and pyridoxine, respectively. For medically intractable infantile spasms, some properly selected patients may have complete cessation of infantile spasms with appropriate surgical treatments.

Cerebral MRI abnormalities associated with vigabatrin therapy

PURPOSE

Investigate whether patients on vigabatrin demonstrated new-onset and reversible T(2)-weighted magnetic resonance imaging (MRI) abnormalities.

METHODS

MRI of patients treated during vigabatrin therapy was reviewed, following detection of new basal ganglia, thalamus, and corpus callosum hyperintensities in an infant treated for infantile spasms. Patients were assessed for age at time of MRI, diagnosis, duration, and dose, MRI findings pre-, on, and postvigabatrin, concomitant medications, and clinical correlation. These findings were compared to MRI in patients with infantile spasms who did not receive vigabatrin.

RESULTS

Twenty-three patients were identified as having MRI during the course of vigabatrin therapy. After excluding the index case, we detected new and reversible basal ganglia, thalamic, brainstem, or dentate nucleus abnormalities in 7 of 22 (32%) patients treated with vigabatrin. All findings were reversible following discontinuation of therapy. Diffusion-weighted imaging (DWI) was positive with apparent diffusion coefficient (ADC) maps demonstrating restricted diffusion. Affected versus unaffected patients, respectively, had a median age of 11 months versus 5 years, therapy duration 3 months versus 12 months, and dosage 170 mg/kg/day versus 87 mg/kg/day. All affected patients were treated for infantile spasms; none of 56 patients with infantile spasms who were not treated with vigabatrin showed the same abnormalities.

DISCUSSION

MRI abnormalities attributable to vigabatrin, characterized by new-onset and reversible T(2)-weighted hyperintensities and restricted diffusion in thalami, globus pallidus, dentate nuclei, brainstem, or corpus callosum were identified in 8 of 23 patients. Young age and relatively high dose appear to be risk factors.

Topiramate monotherapy in infantile spasm

Infantile spasm is an age-related refractory epilepsy. Topiramate is a new anticonvulsant with multiple mechanisms of action, and it may be effective for treating pediatric epilepsies. To evaluate the efficacy and tolerability of first-line topiramate treatment for infantile spasm, 20 patients received topiramate monotherapy during this study. They were treated with an initial dose of 1mg/kg/day, with a progressive titration of 1 mg/kg a week until their spasms were controlled and a maximum dose of 12 mg/kg/day was achieved. The evaluation of the treatment efficacy was based on the spasm frequency data that was obtained by the scalp and video-EEG, and by the parental count of spasm. Thirty percent of the subjects became spasm-free during the study. Six of 20 subjects (30%) had cessation of spasm and disappearance of hypsarrhythmia as seen via the video EEG; four (50%) of eight idiopathic patients had a response, whereas two (17%) of 12 patients with symptomatic infantile spasm responded. Seventy of the patients, including the spasm-free patients, had a reduction in their seizure frequency of more than 50%, and 10% of the patients had a reduction in their seizure frequency of less than 50%. The clusters of spasm frequency decreased from 10.6 +/- 8.5 to 3.5 +/- 1.4 clusters/day. Topiramate is effective and tolerated in those patients suffering from infantile spasm. Our results suggest that this drug should be considered as a new first-line drug for treating infantile spasm.

Practitioner review: use of antiepileptic drugs in children

BACKGROUND

The aim in treating epilepsy is to minimise or control seizures with full respect of quality-of-life issues, especially of cognitive functions. Optimal treatment first demands a correct recognition of the major type of seizures, followed by a correct diagnosis of the type of epilepsy or of the specific syndrome.

METHODS

Review of data from literature and personal clinical experience in treating children with epilepsy.

RESULTS

After summarising the general aspects on the diagnosis and treatment of the main forms of childhood epilepsy, we review key issues about management of seizure disorders, including when to start treatment, how to proceed when the first treatment fails, and how to set the targets of treatment. A special section is devoted to the new concept of epileptic encephalopathy and to the influence of "interictal" EEG abnormalities on cognition, behaviour, and motor abilities in children, providing some suggestions on why and how to treat these conditions. A second section approaches the choice of treatment according to the specific syndromes including infantile spasms, focal epilepsies, syndromes with typical absence seizures, the myoclonic epilepsies and the Lennox-Gastaut syndrome.

CONCLUSIONS

Antiepileptic drugs (AEDs) can efficiently control seizures in most children. However, the specificity of AEDs is relatively limited, although continuing research is leading to a better understanding of the relationship between pathogenesis and the mechanism(s) and site(s) of drug action.

[Efficacy and tolerability of vigabatrin in West syndrome]

West syndrome (WS) is a severe epileptic encephalopathy of childhood, characterized by spasms, developmental deterioration and hipsarhythymia.

OBJECTIVE

To evaluate the safety and efficacy of vigabatrin (VGB) in the treatment of WS.

METHOD

We evaluated every patient diagnosed with WS seen at the pediatric epilepsy clinic and exposed to VGB. Patients were interviewed according to a semistructured questionnaire and we analyzed gender, age, etiology (cryptogenic or symptomatic), associated diseases, age of seizure onset, neuroimaging findings, EEG prior and after VGB, use of other antiepileptic drugs, time for seizure control, electroretinogram, visual complaints, adverse events and family history of epilepsy.

RESULTS

Twenty-three patients were evaluated, 16 boys, ages ranging from 1.25 years to 11.5 years (mean=5y3m). Sixteen (69.5%) patients were seizure free, five (22%) had partial seizure control and in two (8.5%) there was no improvement. Only one patient presented gabaergic retinopathy. Six (26%) patients presented adverse events: somnolence, aggressivity or retinopathy. Patients with seizure onset after 6 months of age presented better results after VGB introduction (p<0.05). There was no difference in seizure control according to duration of epilepsy before VGB treatment or etiology of the seizures (p>0.05). After VGB, no patient presented hipsarrhythymia and 50% had a normal EEG.

CONCLUSION

Although VGB may be associated with serious adverse events such as gabaergic retinopathy, our results show that it should be considered in the treatment of WS.

Beneficial interaction between vigabatrin and valproate against seizures induced by pentylenetetrazole in mice

The anticonvulsant effects of adding a non-protective dose of vigabatrin (VGB) to increasing single doses of sodium valproate (VPA) against seizures induced by 110 mgkg(-1) of pentylenetetrazole (PTZ) or by 4.5 mgkg(-1) of picrotoxin (PIC) were compared in CD1 mice with those of VPA alone and vice versa. Neurotoxicity was evaluated by the rotarod test. The study also assessed changes in concentrations of anticonvulsants, gamma-aminobutyric acid (GABA) and glutamate in the whole brain. VGB increased the potency ratio of VPA against PTZ (1.62, P < 0.05) but not against PIC (1.08, n.s.). VGB slightly decreased the neurotoxicity of VPA (0.93, n.s.) and the protective index of VPA was, therefore, increased from 1.93 to 3.34 for the PTZ model and from 1.40 to 1.61 for the PIC model. VGB did not modify brain concentrations of VPA, and increased brain GABA in relation to VPA alone. On the other hand, VGB did not achieve a complete protection neither against seizures induced by PTZ nor against seizures induced by PIC and a non-protective dose of VPA did not significantly modify the effects of increasing doses of VGB. In conclusion, the addition of a non-protective dose of VGB increased the anticonvulsants effects and the protective index of VPA in the PTZ model. A more than expected brain GABA increase together with the lack of a pharmacokinetic interaction support a pharmacodynamic basis for this interaction.

Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology Society

OBJECTIVE

To determine the current best practice for treatment of infantile spasms in children.

METHODS

Database searches of MEDLINE from 1966 and EMBASE from 1980 and searches of reference lists of retrieved articles were performed. Inclusion criteria were the documented presence of infantile spasms and hypsarrhythmia. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, and presence or absence of epilepsy or an epileptiform EEG. One hundred fifty-nine articles were selected for detailed review. Recommendations were based on a four-tiered classification scheme.

RESULTS

Adrenocorticotropic hormone (ACTH) is probably effective for the short-term treatment of infantile spasms, but there is insufficient evidence to recommend the optimum dosage and duration of treatment. There is insufficient evidence to determine whether oral corticosteroids are effective. Vigabatrin is possibly effective for the short-term treatment of infantile spasm and is possibly also effective for children with tuberous sclerosis. Concerns about retinal toxicity suggest that serial ophthalmologic screening is required in patients on vigabatrin; however, the data are insufficient to make recommendations regarding the frequency or type of screening. There is insufficient evidence to recommend any other treatment of infantile spasms. There is insufficient evidence to conclude that successful treatment of infantile spasms improves the long-term prognosis.

CONCLUSIONS

ACTH is probably an effective agent in the short-term treatment of infantile spasms. Vigabatrin is possibly effective.

Infantile spasms: therapy and outcome

Up-to date information about corticotropin (ACTH) in the treatment of infantile spasms and evaluation of the long-term outcome was provided to answer questions about (1) the efficacy of doses of ACTH in comparison with other drugs, especially with vigabatrin, and the efficacy in patients with tuberous sclerosis; (2) tolerability; and (3) long-term outcome. In two studies, high doses were not more effective than low doses but were more effective in another study. In the follow-up of the studies, there was no difference. In an open, randomized, prospective study, the efficacy and relapse rates of ACTH and vigabatrin treatment did not differ significantly. The high response rates in tuberous sclerosis complex were similar. Both drugs had severe side effects. In the long-term follow-up of 20 to 35 years, one third of the patients died, the intellectual outcome of the remaining patients was normal or slightly subnormal, and one quarter and one third of the patients were seizure free. ACTH should be the first choice for treatment of infantile spasms. The side effects of ACTH, unlike those of vigabatrin, are well known, treatable, and reversible. However, an open, prospective study to compare the efficacy, relapse rate, and long-term outcome of treatment with ACTH and vigabatrin is urgently needed. The frequency of visual field defects after vigabatrin therapy should be evaluated.

Infantile spasms in Down syndrome--effects of delayed anticonvulsive treatment

To investigate the impact of treatment lag in infantile spasms (IS) on treatment response, occurrence of later epilepsy, and long-term cognition and behavior in patients with one single etiological entity, we examined 18 patients with Down syndrome (DS) and earlier IS retrospectively (follow-up period of 32-180 months with a mean of 85.1 months), and determined their history and present condition, in terms of previously mentioned items. There was a statistically significant correlation between treatment lag and lag to cessation of spasms (R=0.55, P=0.02), developmental quotient (DQ) (R=-0.75, P=0.003), and score of autistic features (AF) (R=0.57, P=0.04). Moreover we found that the later the response to treatment of IS, the lower was the DQ (R=-0.86, P=0.001) and the higher was the score of autistic features (R=0.5, P=0.06). A long duration of spasms also determined a low DQ (R=-0.93, P<0.0001) and a high score of autistic features (R=0.66, P<0.01). All patients with persistent epilepsy (n=5) had had a treatment lag of over 2 months. Conversely, for all children treated within 2 months (n=8) spasms ceased within 3 months of treatment and none of them had later epilepsy. This group of patients with a treatment lag of less than 2 months had earlier treatment response (P=0.002), higher DQ (P=0.004) and lower score of autistic features (P=0.006). The data stress the importance of a short treatment lag in view of mental development and prevention of later epilepsy and autistic features, and raise the question of antiepileptogenic effect in this specific condition.

Pharmacotherapy of paediatric epilepsy

Childhood epilepsy is a common condition, with an annual incidence of approximately 40 of 100,000 in the first decade of life. Although childhood epilepsy is more likely to remit than epilepsy in adults, the developmental and social impact of epilepsy during childhood may extend beyond the childhood years, affecting the individual's potential in cognitive, emotional and socio-economic arenas. The goal of medical management of childhood epilepsy is seizure freedom, with minimal or no adverse effects. Achievement of this goal is crucial in the effort to minimise the long-term disabilities associated with childhood epilepsy. Pharmacotherapy is a cornerstone of management of childhood epilepsy. This review addresses some of the challenges in treatment of epilepsy, which are unique to childhood, and reviews the newer anticonvulsants available and what is known about their role in childhood epilepsy.

Treatment of infantile spasms: an evidence-based approach

The object of this work was to subject established empirical medical treatment regimens for infantile spasms to evidence-based medicine analysis in order to determine the current best practice for the treatment of infantile spasms in children. Clinical studies of infantile spasms reported during the presteroid era were reviewed critically to define the natural history of the disorder. Treatment trials of infantile spasms conducted since 1958 were rigorously assessed using MEDLINE and hand searches of the English language literature. Inclusion criteria were the documented presence of infantile spasms and hypsarrhythmia. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, the presence or absence of epilepsy, and/or an epileptiform electroencephalogram. Evidence was defined as class I, II, or III, and practice parameter recommendations were made using the framework devised by the American Academy of Neurology. Class I and III evidence support a standard of practice recommendation for the use of vigabatrin in the treatment of infantile spasms in children with tuberous sclerosis. Class I and III evidence support a guidelines recommendation for the use of either ACTH or vigabatrin in infantile spasms in nontuberous sclerosis patients. There is no strong evidence that successful treatment of infantile spasms improves the long-term prognosis for cognitive outcome or decreases the incidence of later epilepsy. A practice option recommendation for the use of oral corticosteroids in the treatment of infantile spasms is supported by limited and inconclusive class I and III data. Based on the evidence, no recommendation can be made for the use of pyridoxine, benzodiazepines, or the newer antiepileptic drugs in the treatment of infantile spasms. ACTH and vigabatrin are the most effective agents in the treatment of infantile spasms, but concerns remain about the risk/benefit profiles of these drugs.

New antiepileptic drug therapies

The introduction of these new antiepileptic drugs, from felbamate to levetiracetam, raised hope of control of epilepsy with fewer adverse effects and improved quality of life. Unfortunately, many patients continue to experience refractory epilepsy despite the use of these new agents, and dose-related adverse effects and idiosyncratic reactions continue to be problematic. A recent report describes six new compounds in preclinical development, and five in clinical trials [131]. As the number of available, effective, but imperfect antiepileptic drugs increases, many challenges remain. These include: choosing the drug appropriate for the epileptic syndrome, assessing accurately the range of a drug's adverse effects in an individual patient, and considering carefully the drug's interactions in combination drug therapy. In considering drug combinations, differing mechanisms of drug action and favorable pharmacodynamic interactions (an area requiring additional studies) are of importance. Clinicians caring for children who have epilepsy anticipate further advances in the pharmacogenetics and molecular pathophysiology of epilepsy, leading to individually tailored, effective, and safe therapy.