Predicting Long-term Outcome in Childhood- onset Epilepsy
Predicting Long-term Outcome in Childhood- onset Epilepsy
Abstract & Commentary
By Dr. Temitayo Oyegbile, MD, PhD, and Dr. Steven Weinstein, MD. Dr. Oyegbile is a Fellow, Pediatric Neurology Department, New York Presbyterian Hospital. Dr. Weinstein is Director of the Pediatric Comprehensive Epilepsy Program, Weill Cornell Medical School, New York Presbyterian Hospital. Neither Dr. Temitayo nor Dr. Weinstein report any financial relationships relevant to this field of study.
Synopsis: In this rare 40-year follow-up study of children with epilepsy, those with idiopathic seizures were more easily controlled and more likely to enter remission compared to those with symptomatic seizures who are at greater risk for seizure refractoriness and mortality.
Source: Sillanpaa M, Schmidt D. Early seizure frequency and aetiology predict long term medical outcome in childhood-onset epilepsy. Brain 2009;132: 989-998.
Pediatric neurologists need to provide an accurate prognosis of outcome for children with new-onset epilepsy. Since the late 1970s, the literature has suggested that, in general, 66% of patients with epilepsy will enter a remission period at some point. However, individual predictors of remission have not been well defined. The available literature is sparse on the topic, and few studies have followed patients for more than 10 years. It is accepted that early identification of refractory epilepsy can guide the need for more aggressive therapeutic approaches to preserve overall neurologic function.
This Finnish population-based cohort study identified 150 patients age 0-15 years diagnosed with epilepsy (two or more unprovoked seizures) from 1961 to 1964. During a 40-year follow-up period, patients were excluded from the cohort if there was less than a 10-year follow-up period (six patients), if they were lost to follow-up (three patients), or if episodes of status epilepticus occurred (41 patients). At the end of the 40-year period, 102 patients remained in the study and multiple potential predictors of outcome were assessed, including age of onset, gender, generalized vs. focal epilepsy, initial seizure frequency, and symptomatic vs. idiopathic/cryptogenic epilepsy. Outcome was assessed by episodes of remission and mortality. Remission was operationally defined as at least one year of being seizure-free.
The study showed that 93% of these children with epilepsy will have at least one year of seizure freedom; 20% were seizure-free from the first year of treatment until the end of the 40-year follow-up period. Factors predicting a poor outcome include symptomatic epilepsy and a poor early response to antiepileptic medications, although even in this subgroup the chance of having a one-year remission in the first decade was still 76%-81%. This study also supported the notion that immediate treatment after a first seizure may not be necessary. In this group of patients, the pretreatment seizure count was not an independent predictor of refractoriness to medication at a later time. Unfortunately, the study also showed that 20% of well-controlled patients with epilepsy will become drug resistant over time.
Commentary
It is important to consider that this is a population-based study. Patients presenting to an emergency room or admitted to a hospital frequently have status epilepticus, and the data from this study are not applicable to them. The inclusion of patients with status epilepticus could potentially alter the data by increasing the number and severity of the symptomatic cases that would increase the percentage with refractory seizures and perhaps increased mortality. Age was not found to be a predictor; however, the children were divided into groups-older than 6 years and younger than 6 years of age. The more devastating epilepsies tend to appear before age 1 year, and given the small number of children in this study with West syndrome and other metabolic/genetic entities (diagnosable when the subjects were recruited), their impact on this data is probably underestimated. Furthermore, these data show few children having frequent pretreatment seizures in the categories of absence, juvenile myoclonic, West syndrome, and Lennox-Gastaut syndrome. Finally, inherent in a study of this duration, the diagnostic tools and anticonvulsants available have changed over the decades. It is not certain how more recent therapies could impact on the natural history of these patients with epilepsy.
Group statistics remain the cornerstone of clinical practice decision analysis, but how it is applied to the individual patient sitting in the office remains within the art of medicine. These data do support the conclusion that most children with epilepsy do well over the ensuing decades.
In this rare 40-year follow-up study of children with epilepsy, those with idiopathic seizures were more easily controlled and more likely to enter remission compared to those with symptomatic seizures who are at greater risk for seizure refractoriness and mortality.Subscribe Now for Access
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