Infantile Spasms Respond Poorly to Topiramate

Trends and Costs Associated With the Diagnosis and Treatment of Infantile Spasms: A 10-Year Multicenter Retrospective Review

OBJECTIVE

Early treatment of infantile spasms (IS) may be imperative for improvement of neurodevelopmental outcomes. Existing studies have led to inconclusive recommendations with variation in treatment. Our objective was to determine the national average cost, initial diagnostic workup, treatments, and hospital length of stay for patients with IS.

METHODS

This retrospective cohort study was designed to review data of patients < 2 years from 43 non-profit institutions. Data obtained included patient demographics, length of stay, admission cost, and treatments used from 2004 to 2014. Cost data were collected and adjusted to 2014 dollars, the year data were analyzed.

RESULTS

A total of 6183 patients met study criteria (n = 3382, 55% male). Three-quarters of patients (n = 4684, 76%) had an electroencephalogram, 56.4% had brain imaging (n = 3487), and 17% (n = 1050) underwent a lumbar puncture. Medication for IS was initiated during inpatient hospital stay in two-thirds of all patients (n = 4139, 67%). Most patients were initiated on corticotropin (n = 2066, 33%) or topiramate (n = 1804, 29%). Average length of stay was 5.8 days with an average adjusted cost of $18,348. Over time there was an 86.6% increase in cost from an average $12,534.54 (2004) to $23,391.20 (2014), a significant change (p < 0.01). This correlated with an increase in average length of stay.

CONCLUSIONS

Variability exists in diagnostic workup and pharmacotherapy initiated for IS, which may lead to differences in the cost of hospital stay. Further studies may help determine contributing factors to increased cost and improve health care utilization for IS patients.

Comparative Effectiveness of Initial Treatment for Infantile Spasms in a Contemporary US Cohort

OBJECTIVE

To compare the effectiveness of initial treatment for infantile spasms.

METHODS

The National Infantile Spasms Consortium prospectively followed up children with new-onset infantile spasms that began at age 2 to 24 months at 23 US centers (2012-2018). Freedom from treatment failure at 60 days required no second treatment for infantile spasms and no clinical spasms after 30 days of treatment initiation. We managed treatment selection bias with propensity score weighting and within-center correlation with generalized estimating equations.

RESULTS

Freedom from treatment failure rates were as follows: adrenocorticotropic hormone (ACTH) 88 of 190 (46%), oral steroids 42 of 95 (44%), vigabatrin 32 of 87 (37%), and nonstandard therapy 4 of 51 (8%). Changing from oral steroids to ACTH was not estimated to affect response (observed 44% estimated to change to 44% [95% confidence interval 34%-54%]). Changing from nonstandard therapy to ACTH would improve response from 8% to 39% (17%-67%), and changing to oral steroids would improve response from 8% to 38% (15%-68%). There were large but not statistically significant estimated effects of changing from vigabatrin to ACTH (29% to 42% [15%-75%]), from vigabatrin to oral steroids (29% to 42% [28%-57%]), and from nonstandard therapy to vigabatrin (8% to 20% [6%-50%]). Among children treated with vigabatrin, those with tuberous sclerosis complex (TSC) responded more often than others (62% vs 29%; p < 0.05).

DISCUSSION

Compared to nonstandard therapy, ACTH and oral steroids are superior for initial treatment of infantile spasms. The estimated effectiveness of vigabatrin is between that of ACTH/oral steroids and nonstandard therapy, although the sample was underpowered for statistical confidence. When used, vigabatrin worked best for TSC.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for children with new-onset infantile spasms, ACTH or oral steroids were superior to nonstandard therapies.

Medication selection, health services outcomes, and cost trajectories for Medicaid beneficiaries with infantile spasms

OBJECTIVE

There are three recommended first-line treatments for infantile spasms, adrenocorticotropic hormone (ACTH), oral corticosteroids, and vigabatrin, though non-standard treatments such as topiramate are sometimes selected. Is it uncertain how treatment selection influences health services outcomes.

METHODS

We conducted a retrospective cohort study of Medicaid beneficiaries newly diagnosed with infantile spasms from 2009-2010. We included infants with a new diagnosis of infantile spasms between age 2-9 months who filled ACTH (reference), prednisolone, vigabatrin, or topiramate prescriptions. Multivariable Cox proportional hazards regression compared time to first emergency department (ED) visit or hospitalization across treatment groups during 2 years of follow-up. Monthly costs for each treatment were examined in 6-month intervals and compared in a multivariable generalized linear model.

RESULTS

Among 256 children with infantile spasms, 116 received ACTH, 62 prednisolone, 15 vigabatrin, and 63 topiramate. The rate of ED visit or hospitalization per person-year did not differ significantly for prednisolone (0.9 [95 % CI 0.7-1.2]; adjusted hazard ratio [aHR] 0.84, 95 % CI 0.57-1.24), vigabatrin (0.8 [95 % CI 0.4-1.5]; aHR 0.91, 95% CI 0.45-1.84), or topiramate (1.7 [95 % CI 1.3-2.3]; aHR 1.15, 95 % CI 0.80-1.65), when compared to ACTH (1.1 [95 % CI 0.9-1.3]). The median payment for ACTH was $96,406 (interquartile range 70,742-138,476) during the first 6 months. The adjusted mean total payment in the first 6 months was 73% lower for prednisolone (95% CI -82, -61), 69% lower for vigabatrin (95% CI -84, -40), and 73% lower for topiramate (95% CI -82, -59). However, in subsequent 6-month intervals, costs associated with ACTH were not significantly different compared to other treatments.

SIGNIFICANCE

Compared to other treatments for infantile spasms, use of ACTH was associated with greater cost in the first 6 months of treatment, but not with reduced ED visits or hospitalizations. The cost effectiveness of ACTH depends on its relative clinical efficacy, and merits additional research.

Potential induction of epileptic spasms by nonselective voltage-gated sodium channel blockade: Interaction with etiology

PURPOSE

Epileptic spasms are often preceded by focal (or multifocal) seizures. Based on a series of case reports suggesting that carbamazepine and oxcarbazepine may induce epileptic spasms, we set out to rigorously evaluate the potential association between exposure to voltage-gated sodium channel blockade and latency to epileptic spasms.

METHODS

We identified 50 cases (children with focal seizures and evolution to epileptic spasms) and 50 controls (children with focal seizures without evolution to epileptic spasms). For each patient, we reviewed all sequential neurology encounters between onset of epilepsy and emergence of epileptic spasms. For each encounter we recorded seizure-frequency and all anti-seizure therapy exposures. Using multivariable Cox proportional hazards regression, we evaluated the association between voltage-gated sodium channel exposure (carbamazepine, oxcarbazepine, lacosamide, or phenytoin) and latency to epileptic spasms onset, with adjustment for etiology and seizure-frequency.

RESULTS

Latency to epileptic spasms onset was independently associated with exposure to sodium channel blockade (hazard ratio = 2.4; 95% CI 1.1-5.2; P = 0.03) and high-risk etiology (hazard ratio = 2.8; 95% CI 1.5-5.1; P = 0.001). With assessment for interaction between sodium channel blockade and etiology, we identified an estimated 7-fold increased risk of epileptic spasms with the combination of sodium channel blockade and high-risk etiology (hazard ratio = 7.0, 95% CI 2.5-19.8; P < 0.001).

CONCLUSION

This study suggests that voltage-gated sodium channel blockade may induce epileptic spasms among children at risk on the basis of etiology. Further study is warranted to replicate these findings, ascertain possible drug- and dose-specific risks, and identify potential mechanisms of harm.

Management of Infantile Spasms During the COVID-19 Pandemic

Circumstances of the COVID-19 pandemic have mandated a change to standard management of infantile spasms. On April 6, 2020, the Child Neurology Society issued an online statement of immediate recommendations to streamline diagnosis and treatment of infantile spasms with utilization of telemedicine, outpatient studies, and selection of first-line oral therapies as initial treatment. The rationale for the recommendations and specific guidance including follow-up assessment are provided in this manuscript. These recommendations are indicated as enduring if intended to outlast the pandemic, and limited if intended only for the pandemic health care crisis but may be applicable to future disruptions of health care delivery.

Limited efficacy of zonisamide in the treatment of refractory infantile spasms

A series of relatively small studies collectively suggest that zonisamide may be effective in the treatment of infantile spasms. Using a large single‐center cohort of children with infantile spasms, we set out to evaluate the efficacy and safety of zonisamide. We retrospectively identified all patients with infantile spasms who were treated with zonisamide at our center. For each patient, we recorded dates of birth, infantile spasms onset, response (if any), and most recent follow‐up. To quantify zonisamide exposure, we recorded daily dosage and patient weight at each sequential encounter so as to allow calculation of peak and weighted‐average weight‐based dosage. We identified 87 children who were treated with zonisamide, of whom 78 had previously been treated with hormonal therapy or vigabatrin. Peak and weighted‐average zonisamide dosage were 7.1 (interquartile range 3.6, 10.2) and 5.4 (interquartile range 3.0, 8.9) mg/kg/day, respectively. Whereas five (6%) patients exhibited resolution of epileptic spasms, only two (2%) patients exhibited video‐EEG confirmed resolution of both epileptic spasms and hypsarrhythmia (electroclinical response). Importantly, both electroclinical responders had not previously been treated with hormonal therapy or vigabatrin; in contrast, none of the 78 children with prior failure of hormonal therapy or vigabatrin subsequently responded to zonisamide. Zonisamide was well tolerated, and there were no deaths. This study suggests that zonisamide exhibits favorable tolerability but very limited efficacy among patients who do not respond to first‐line therapy.

Topiramate as an Adjunct in the Management of West Syndrome

OBJECTIVE

To evaluate the safety, tolerability, and effectiveness of oral topiramate therapy in children with West syndrome.

METHODS

The present study was designed as a prospective, observational study and was performed from July 2016 through June 2018 at a tertiary care pediatrics centre in North India. The study was approved by Institute Ethics Committee.

RESULTS

Data on 39 children with West syndrome were analyzed. Topiramate was used as an adjunct in 38 children who failed to hormonal therapy and/or vigabatrin and as initial monotherapy in one case. The study participants had a long treatment lag to hormonal therapy (median 2 mo, IQR 1-8), a preponderance of male sex (67%) and structural etiology (87%). Nine (23%) children had a cessation of epileptic spasms at a median dose of 3.8 mg/kg/d. However, seven children with initial response had relapses. There were no significant group differences between responders and non-responders. Overall, topiramate was well tolerated. Somnolence and lethargy with decreased oral intake were commonly observed adverse effects.

CONCLUSIONS

The study observed poor effectiveness of topiramate therapy, which is partially due to a long treatment lag and a high proportion of structural etiology.

Clobazam as an adjunctive treatment for infantile spasms

Infantile spasms constitute a catastrophic epileptic condition. Seizures in approximately half of children with infantile spasms fail to improve with initial treatment attempts; at present, data regarding alternative treatments are limited. We assessed the efficacy of clobazam as an adjunctive therapy in patients whose seizures failed to respond to initial regimens of standard treatment for infantile spasms. All patients from Severance Children's Hospital who received clobazam as adjunctive therapy for infantile spasms were selected for the study. The efficacy of clobazam was evaluated by assessing the daily spasm frequency. Patients were categorized as complete responders if the spasms disappeared within 2 weeks of introducing clobazam, and the patients became spasm-free during weeks 3 and 4. Tolerability was gauged by analyzing adverse events and discontinuation rates. In all, 171 patients qualified for the analysis. Clobazam was introduced after the administration of 2.6 (median; interquartile range [IQR], 1.0-4.0) failed antiepileptic drugs (AEDs), at the age of 8.2 months (IQR, 6.0-10.0 months). After clobazam therapy was initiated, 38 (22.2%) patients became spasm-free for ≥2 weeks. Thirteen out of the 38 complete responders remained spasm-free until the last follow-up and did not require the administration of other AEDs. In 10 patients, the electroencephalogram (EEG) tracings were also within normal limits. These patients were successfully weaned off of all AEDs. Patients with conditions of unknown etiology, who had fewer prior exposures to AEDs, and had not received prior adrenocorticotropic hormone (ACTH)/steroids were more likely to have complete spasm control than the others. Adverse effects were minor, and only 6 of 101 (6%) patients who experienced adverse events had their treatments discontinued during the 3-month follow-up period. The most common adverse events observed were hypersalivation, sedation, and sleep disturbance. Thus, clobazam might be an effective and safe alternative therapeutic option in patients whose seizures failed to respond to initial regimens of standard treatment for infantile spasms. Further prospective studies on clobazam for infantile spasms, focusing on specific good response groups, dosing protocols, and long-term outcome are needed.

Treatment of infantile spasms

The treatment of infantile spasms is challenging, especially in the context of the following: (1) a severe phenotype with high morbidity and mortality; (2) the urgency of diagnosis and successful early response to therapy; and (3) the paucity of effective, safe, and well-tolerated therapies. Even after initially successful treatment, relapse risk is substantial and the most effective therapies pose considerable risk with long-term administration. In evaluating any treatment for infantile spasms, the key short-term outcome measure is freedom from both epileptic spasms and hypsarrhythmia. In contrast, the most important long-term outcomes are enduring seizure-freedom and measures of intellectual performance in later childhood and adulthood. First-line treatment options-namely hormonal therapy and vigabatrin-display moderate to high efficacy but also exhibit substantial side-effect burdens. Data on efficacy and safety of each class of therapy, as well as the combination of these therapies, are reviewed in detail. Specific hormonal therapies (adrenocorticotropic hormone and various corticosteroids) are contrasted. Those etiologies that prompt specific therapies are reviewed briefly, as are an array of second-line therapies supported by less-compelling data. The ketogenic diet is discussed in greater detail, with a focus on the limitations of numerous available studies that generally suggest that it is efficacious. Special discussion is allocated to cannabidiol-the investigational therapy that has received the most attention, and which is already in use in the form of various artisanal cannabis extracts. Finally, a treatment algorithm reflecting the concepts and controversies discussed in this review is presented.

Improving Outcomes in Infantile Spasms: Role of Pharmacotherapy

Infantile spasms, and specifically within the context of West syndrome , is one of the most common epileptic encephalopathies to occur in early infancy. Early recognition and treatment can improve neurodevelopmental outcome in some cases, although the underlying aetiology is probably the most important prognostic factor in both spasm suppression and developmental outcome. Corticosteroids, either adrenocorticotrophic hormone (ACTH) or prednisolone, and vigabatrin are currently the preferred first-line treatment options. Vigabatrin is the treatment of choice when the underlying cause is tuberous sclerosis complex (TSC). Emerging evidence suggests that a combination of steroid and vigabatrin may be more effective in the suppression of spasms and resolution of hypsarrhythmia, the electro-encephalographic signal of spasms. Several other anti-epileptic drugs (AEDs) (levetiracetam, nitrazepam, sodium valproate, topiramate, zonisamide) are usually used as add-on or adjunctive treatment in refractory cases. Pyridoxine (or pyridoxal phosphate) and the ketogenic diet are established treatment options in refractory cases. There is some evidence that neuro-active steroids, including ganaxolone, may be effective; however, clinical trials undertaken intermittently for over a decade have yet to prove their efficacy, not only for the suppression of infantile spasms but also for the resolution of hypsarrhythmia, which may be as important as seizure control in developmental outcome in these children. Insights into developing novel treatment options have emerged from rodent models of infantile spasms, and research is continuing into the efficacy of rapamycin in improving outcomes in infantile spasms. This review provides a brief overview of the existing scientific literature around treatment options and outlines emerging newer treatment options in infantile spasms.