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ABSTRACT & COMMENTARY
By Padmaja Kandula, MD
Assistant Professor of Neurology, Comprehensive Epilepsy Center, Weill Cornell Medical College
Dr. Kandula reports no financial relationships relevant to this field of study.
SYNOPSIS: In this 20-year, retrospective study, the authors summarize surgical trends in three major German epilepsy centers and identified a declining prevalence of epilepsy surgery from 1998 to 2008.
SOURCE: Helmstaedter C, et al. Temporal lobe surgery in Germany from 1988 to 2008: Diverse trends in etiological subgroups. Europ J Neurol 2014;21:827-834.
Despite class I evidence and subsequent 2013 American Academy of Neurology (AAN) Practice Guidelines advocating early surgery in drug-resistant epilepsy (failure of two anti-epileptic agents), surgery for epilepsy has not increased in the United States over the last two decades. In this present retrospective study, the authors parallel the U.S. experience and summarize the experience of surgical trends in three major German epilepsy centers from 1988 to 2008. In contrast to previous papers, however, surgical trends with regards to other temporal lobe etiologies are taken into consideration.
In total, 2812 patients with temporal lobe epilepsy (TLE) underwent epilepsy surgery in all three centers combined. The authors addressed the number of surgeries over time, duration of epilepsy before surgical intervention, differences in trends between etiologic categories of TLE, and inter-institution variability.
Not surprisingly, with the advent of improved MRI technique, there was a steady increase in epilepsy surgeries for each 4-year epoch from 1988 to 2004, from 296 in the early epoch to more than 700 patients more recently. Correspondingly, there was an increase in patients with hippocampal sclerosis from 30-58% during the years of 1988-2004, with a subsequent plateau in the years thereafter. From 2005 to 2008, there was a subsequent decrease to 600 epilepsy surgeries with relative stability in the prevalence of hippocampal sclerosis (58%).
An interesting observation was the longer duration of epilepsy in patients with hippocampal sclerosis compared to other TLE etiologic subtypes, such as tumors, vascular lesions, and focal cortical dysplasia. In fact, the group with hippocampal sclerosis had continuously increasing age at time of surgery by an average of 7 years over the observed two decades.
The steady increase of patients with reported hippocampal sclerosis undergoing epilepsy surgery is not surprising. However, the overall decline in epilepsy surgeries with relative stability of the hippocampal sclerosis rate, from 2005-2008, is perplexing. In all three centers, there was a notable trend of increasing age at surgical intervention and increasing duration of epilepsy with an overall fixed rate of hippocampal sclerosis from 2005-2008. Various theories have been proposed to explain this inconsistency. One plausible explanation is the influence of disease-modifying factors such as aggressive treatment of brain infections, febrile seizures, and the advent of second- and third-generation anti-epileptic agents. Although the idea of influencing the natural course of hippocampal sclerosis via better medical care and aggressive pharmacologic treatment is satisfying, without larger population-based studies, no definitive conclusions can be drawn. Resective surgery is well established for the treatment of TLE, but the future of epilepsy treatment is evolving. Currently neuro-stimulatory treatment is in its infancy, but perhaps the nature of this discussion will become even more varied and intricate over the next two decades with a growing arsenal of treatment options.
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