Article
Non-lesional-epilepsy surgery in comparison with lesional-epilepsy surgery
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Authors
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P.A. Winkler
- Neurochirurgische Klinik und Poliklinik, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
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M. Sailer
- Neurochirurgische Klinik und Poliklinik, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
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A. Peraud
- Neurochirurgische Klinik und Poliklinik, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
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S. Noachtar
- Neurochirurgische Klinik und Poliklinik, Klinikum Großhadern, Ludwig-Maximilians-Universität, München
| Published: | May 20, 2009 |
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Outline
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Objective: Recently more patients with pharmacoresistant seizures but without a detectable lesion on high-resolution magnetic resonance imaging (MRI) are being considered for possible epilepsy surgery, here defined as “non-lesional-epilepsy surgery”. In such cases the resection of the epileptogenic foci is mainly based on the results of the initially non-invasive and later invasive video-EEG-monitoring. The present study examined the selection, presurgical evaluation, and outcome of this ever growing subgroup of patients selected for epilepsy surgery.
Methods: A total of 192 patients were included in the study. A focal lesion was detected with high-resolution-MRI in 172 patients. In this lesional group there were 129 temporal and 43 extratemporal localizations of the epileptogenic focus. No focal lesion detectable on MRI was found in 20. In this non-lesional group there were 7 temporal and 13 extratemporal cases. All patients underwent non-invasive and the majority of them also invasive video-EEG-monitoring. The follow-up (at least one year) was classified 1. according to the Engel-classification (I–IV) and 2. according to the ILAE (International Liga against Epilepsy, Lüders and Wieser) in order to compare both classification modalities.
Results: The lesional-group showed good results (Engel I–II) in 89.5% and seizure freedom (Engel I) in 79.7%. The non-lesional-group had good results in 65% and seizure freedom in 55%. The non-lesional-group thus showed a significantly lower rate of seizure freedom Engel I (p=0.013) and good seizure control Engel I-II (p=0.002) compared to the lesional-group. In the multivariate analysis the presence of an MRI-detectable focal lesion was ascertained to be an independent prognostic factor for seizure freedom (p=0.034).
Conclusions: Compared to current relevant literature, we obtained better results in the non-lesional-group of patients selected for presurgical evaluation and surgical treatment. Nevertheless, the results in our series are also not as good as in the lesional group. This demonstrates the complexity of the epileptogenic propagation in the non-lesional subgroup. Future efforts should focus on improving visualization-techniques to “reduce” the number of non-lesional-cases. Epilepsy surgery still reduces seizures in the majority of patients and allows therefore a significant improvement of the quality of life of these patients.
