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Does Surgery Influence Mortality in Refractory Partial Epilepsy?
Abstract and Commentary:
By Padmaja Kandula, MD, Assistant Professor of Neurology and Neuroscience, Comprehensive Epilepsy Center, Weill Medical College of Cornell University. Dr. Kandula reports no financial interest in this field of study
Synopsis: Successful surgical resection of an epileptic focus appears to reduce the long-term mortality by reducing the probability of severe epilepsy.
Source: Bell GS, et al. Premature mortality in refractory partial epilepsy: does surgical treatment make a difference? J Neurol Neurosurg Psychiatry 2010;81:716-718.
The decision to undergo surgery for refractory epilepsy often involves discussion of immediate operative risks such as infection, bleeding, and injury to eloquent areas of cortex. However, risk of premature mortality may not be emphasized. The authors in this study tried to answer the question: "Does surgery in medically refractory patients influence mortality?"
In this single institution, prospective study, both medical and surgical cohorts were followed from the time of initial presurgical evaluation or surgery, until the time of death or date last known to be alive. Surgical patients were assigned to six groups. Groups 1 and 2 had no seizures, or only simple partial seizures (auras). Groups 3-6 had increasingly more frequent seizures.
In the 641 nonsurgical patients, 40 deaths occurred. A little over half the deaths were attributable to SUDEP (sudden unexplained death in epilepsy). One death was due to drowning, and another was due to status epilepticus. SUDEP, drowning, and status epilepticus were classified as epilepsy-related deaths.
The maximum duration of follow up was 15.4 years. In the 561 surgical patients, 19 deaths occurred. Two patient deaths were due to SUDEP in the surgical group. The maximum follow-up for the surgical group was 17.4 years.
Of the patients in the surgical cohort at post operative year one, four deaths occurred in groups 1 and 2 (no seizures or simple partial seizures only). Nine deaths occurred in groups 3-6.
Non-operated patients were nearly 2.5 times as likely to die during follow up as those who had surgery and were 4.5 times more likely to die from an epilepsy-related cause. Surgical patients in group 3-6 were four times as likely to die as those in group 1 or 2.
The decision to undertake resective surgery for refractory epilepsy is a difficult decision for both patients and their doctors. Several factors, such as seizure-freedom rate, quality of life, mortality, and morbidity are important considerations in long term care planning.
Previous studies, such as the landmark Wiebe paper1 also showed seizure-freedom rate was statistically significant (58%) for the surgically treated temporal lobe epilepsy group versus 8% for the medically treated group. Again, in the Wiebe1 study, the sole death in the 40 patients randomized to medical treatment was due to presumed SUDEP. No deaths were noted in the 40 patients randomized to surgery.
The authors of this study found that successful epilepsy surgery, as defined by no seizures or only simple partial seizures at follow up, was associated with decreased mortality as compared to the non-surgical cohort. However, a strong limitation of the study is the failure to address the intrinsic differences in epilepsy syndromes that may influence mortality. Further stratification of patients in both the medical and surgical cohorts according to cortical region of onset and mesial versus neocortical onset in the case of temporal lobe epilepsy, may have yielded slightly different results. In addition, there was no mention of the relative contribution of underlying pathology. A follow-up study addressing differences in epilepsy syndromes, and whether early versus late surgical intervention influences mortality is an area of further study that is needed.
1. Wiebe S, et al. A randomized, controlled trial of surgery for temporal lobe epilepsy. N Engl J Med 2001;345: 311-318.