Review
doi: 10.1111/j.1528-1167.2011.03339.x. Epub 2011 Dec 22.Radiosurgery for epilepsy: clinical experience and potential antiepileptic mechanisms
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- PMID:22191545
- PMCID: PMC3519388
- DOI: 10.1111/j.1528-1167.2011.03339.x
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Review
Radiosurgery for epilepsy: clinical experience and potential antiepileptic mechanisms
Mark Quigg et al. Epilepsia.2012 Jan.
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Abstract
Stereotactic radiosurgery, well established in the noninvasive treatment of focal lesions that are otherwise difficult to access through open surgery, is an emerging technology in the treatment of focal epileptic lesions. Recent studies suggest that seizures from hypothalamic hamartomas and mesial temporal lobe epilepsy remit at clinically significant rates with radiosurgery, but large variations among different studies have raised questions about appropriate treatment protocols and mechanisms. Proposed anticonvulsant mechanisms include neuromodulatory effects or ischemic necrosis of epileptic tissue. An ongoing trial that directly compares efficacy, morbidities, and cost of radiosurgery versus open surgery for mesial temporal lobe epilepsy is underway.
Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.
Figures
Effect of 50% isodose volume of a 24Gy dose in early trials of radiosurgery for mesial temporal lobe epilepsy (Régis, personal correspondence). Responses are reported in an edema-severity scale (Hayashi, et al. 2002) with the highest number designating mass effect with midline shift. A relatively narrow window of efficacy and toxicity appears between 5.5–7.5ml and was the basis for treatment volume restrictions in the US Multicenter Pilot Study (Barbaro, et al. 2009).
Dose-response curve of treatment of human mesial temporal lobe epilepsy with radiosurgery with response = percent “seizure-free” (typically Engels outcome 1B or better) as defined by each trial. Each point designates the total number of patients in each trial paired with a letter designating first author of each report. Studies with more than one dose are shown divided among doses. 2 studies (Régis, et al. 2004, Vojtĕch, et al. 2009) list 6 overlapping patients, but are shown independently here. A = Régis 1999 (Régis, et al. 1999); B = Kawai 2001 (Kawai, et al. 2001); C = Cmelek 2001 (Cmelak, et al. 2001); D = Srijvilaikul (Srikijvilaikul, et al. 2004); E = Régis 2004 (Régis, et al. 2004); F = Prayson 2007 (Prayson and Yoder 2007); G = Hoggard 2008 (Hoggard, et al. 2008); H = Barbaro (Barbaro, et al. 2009); J = Vojteck (Vojtĕch, et al. 2009). Orange = prospective multicenter, yellow = single center case series.
From the US Multicenter Pilot Trial (Barbaro, et al. 2009), MRI changes at 12 months after radiosurgery–specifically the volume of T2-weighted edema–predicted subsequent seizure remission between months 24–36. No patient with edema volumes< 200cc had seizure remission. These findings may help triage patients for subsequent standard open surgery if noninvasive RS is insufficient (Chang, et al. 2010).
10× (A) and 20× (B) views of hippocampal sections after anterior temporal lobectomy performed on a patient with MTLE. Surgery was performed 15 months after radiosurgery with 24Gy because of persisting headaches and visual changes. The patient was seizure-free for 3 months before surgery. Evidence of diffuse vascular hyalinization and inflammation, leading to small infarcts and astrocyctic reaction, predominate. Some changes attributable to acute ischemia during surgery are present as well. * = regions of chronic infarct. V = hyalinized vessels. Arrows = reactive astrocytes. / = acute ischemic changes associated with surgery. mo = molecular layer. Gr = granulocytes. Bars = 100μm.
Proportion of patients with auras with symptoms attributable to mesial localization (orange) vs nonmesial localization (blue) during baseline, 12m, and 36m after radiosurgery in the US Multicenter Pilot Trial (Barbaro, et al. 2009). P-values from McNemar’s test. The proportion of auras of mesial onset declined significantly during the course of the trial. Epig = epigastric; o-g = olfactory-gustatory; exp = experiential; sens = sensory; vis = visual.
References
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