The evolution of epilepsy surgery between 1991 and 2011 in nine major epilepsy centers across the United States, Germany, and Australia

Abstract

Summary Objective Epilepsy surgery is the most effective treatment for select patients with drug-resistant epilepsy. In this article, we aim to provide an accurate understanding of the current epidemiologic characteristics of this intervention, as this knowledge is critical for guiding educational, academic, and resource priorities. Methods We profile the practice of epilepsy surgery between 1991 and 2011 in nine major epilepsy surgery centers in the United States, Germany, and Australia. Clinical, imaging, surgical, and histopathologic data were derived from the surgical databases at various centers. Results Although five of the centers performed their highest number of surgeries for mesial temporal sclerosis (MTS) in 1991, and three had their highest number of MTS surgeries in 2001, only one center achieved its peak number of MTS surgeries in 2011. The most productive year for MTS surgeries varied then by center; overall, the nine centers surveyed performed 48% (95% confidence interval [CI] −27.3% to −67.4%) fewer such surgeries in 2011 compared to either 1991 or 2001, whichever was higher. There was a parallel increase in the performance of surgery for nonlesional epilepsy. Further analysis of 5/9 centers showed a yearly increase of 0.6 ± 0.07% in the performance of invasive electroencephalography (EEG) without subsequent resections. Overall, although MTS was the main surgical substrate in 1991 and 2001 (proportion of total surgeries in study centers ranging from 33.3% to 70.2%); it occupied only 33.6% of all resections in 2011 in the context of an overall stable total surgical volume. Significance These findings highlight the major aspects of the evolution of epilepsy surgery across the past two decades in a sample of well-established epilepsy surgery centers, and the critical current challenges of this treatment option in addressing complex epilepsy cases requiring detailed evaluations. Possible causes and implications of these findings are discussed.

Trends in epilepsy surgery: stable surgical numbers despite increasing presurgical volumes

“…We propose the following reasons for this trend:

An increasing proportion of difficult cases as the key reason for this phenomenon. Similar observations and suggestions have been provided by other publications7 9 10 33 and are substantiated in our own cohort: first, the proportion of patients with clear indications for surgical treatment decreased over time (figure 3: less patients with MTS, BT and temporal resections). Potential causes are a decreasing incidence of precipitating injuries leading to MTS6 (resulting in a decreasing prevalence after two decades of epilepsy surgery) and an increasing tendency to remove low-grade tumours without formal presurgical epilepsy diagnostics 34.

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“…This is in line with previous reports on increasing diagnostic facilities, increasing numbers of hospitalisations and video-EEG monitorings but stable surgical numbers 8 9 32. Another study even reported about a slight decrease in surgical numbers 33. This increasing gap was related to a declining proportion of patients proceeding to surgery in the smaller centres 8.…”

“…Second, since 2002, we found more non-lesional patients and an increasing need for invasive recordings (figure 3D). Other studies observed the same trend 9 33. Jehi et al 33 found more patients undergoing invasive recordings without subsequent surgery.…”

“…Potential causes are a decreasing incidence of precipitating injuries leading to MTS6 (resulting in a decreasing prevalence after two decades of epilepsy surgery) and an increasing tendency to remove low-grade tumours without formal presurgical epilepsy diagnostics 34. Other studies, too, observed a decline in MTS-related epilepsy surgery 6 12 33. One paper described a doubling of extratemporal resections from 2007 to 2012 9…”

Imaging Brain Inflammation: If We Can See It, Maybe We Can Treat It

“…If this is truly a localizing technique, it would be far more useful if it could identify a focus in patients with nonlesional/extratemporal epilepsy, where localization is much more difficult. Recent studies suggest that in the future, these patients will represent our surgical challenge, far more than TLE (8). One case study suggested that PK11195 (a less specific TPSO tracer) uptake was localizing in a patient with extratemporal epilepsy resulting from a cortical dysplasia (9).…”