Gamma Knife Surgery for Refractory Insular Cortex Epilepsy

Abstract

Background: Resection of the epileptogenic insular cortex is surgically challenging. We sought to evaluate the potential of Gamma Knife® surgery (GKS) for the treatment of pharmacoresistant insular cortex epilepsy (ICE) in patients who underwent GKS between 2005 and 2010. Adverse events and effects on seizure frequency were assessed. Methods: Three cases of refractory ICE were treated by GKS between 2005 and 2010. Results: Case 1 had refractory nonlesional ICE, proven by depth electrodes only partially helped by a left posterior insulectomy. Case 2 had refractory ICE due to a left insular cavernoma. Case 3 had refractory ICE, confirmed by an invasive study but complicated by transient dysphasia from contusion of Wernicke's area. The marginal and maximum radiation doses delivered were 20 and 40 Gy, respectively. Treatment volume ranged from 1.2 to 3.2 cm³. Two out of 3 patients experienced significant seizure reduction and the third had a worthwhile improvement (follow-up 30-76 months). Complete antiepileptic drug withdrawal was un-fortunately not possible. Complications included transient lightheadedness and new-onset seizures responsive to medical treatment, both in the same patient. Conclusion: GKS is a promising technique for selected drug-resistant ICE patients. Additional observations are necessary.

Evidence on the efficacy of primary radiosurgery or stereotactic radiotherapy for drug-resistant non-neoplastic focal epilepsy in adults: A systematic review

“…Barbaro et al [12] randomized patients by dose; they demonstrated that the higher dose arm had better outcomes (within statistical power limits). This same effect was found in other small series underlining the tendency of higher doses to have a better antiepileptic effect than lower doses [40][41][42][43]. Maesawa et al [44] showed in a rat model, that SRS controlled epilepsy accompanied by stabilization of memory compared with untreated epileptic rats without causing subsequent behavioral impairment, for high (60 Gy) as well as low dose (30 Gy), supporting the hypothesis that even this relatively lower dose RT could be effective.…”

Stereotactic thermocoagulation for insular epilepsy: Lessons from successes and failures

“…Thermoablations combined with cortectomies reportedly resulted in up to 80% of patients achieving seizure freedom, with 20% experiencing postoperative complications (including 5% of permanent morbidity); however, the additional value of combining both procedures was undetermined . Finally, radiosurgery is described as promising; however, this series is currently limited to three patients, with favorable outcome in two . Notably, one patient postoperatively developed new spells, with a feeling of evisceration, genital pain, and head/right hemibody athetoid movements occurring in clusters.…”

“…44 Finally, radiosurgery is described as promising; however, this series is currently limited to three patients, with favorable outcome in two. 45 Notably, one patient postoperatively developed new spells, with a feeling of evisceration, genital pain, and head/right hemibody athetoid movements occurring in clusters. All these innovative techniques emphasize the difficulties and the functional risks inherent to surgery for insular epilepsies.…”

Gamma Knife Radiosurgery of Paracentral Epilepsy

“…In addition, different neuronal systems may have different radiosensitivities [22]. However, the GK parameters used in the present series (volume: 1.6-3.18 cm 3 , marginal dose: 24 Gy) are similar to a series of 3 published cases of insular epilepsy [17], which treated volumes of 1.2-3.2 cm 3 with a marginal dose of 20 Gy.…”

“…A recent case series described significant seizure reduction in 2 out of 3 patients treated with GK for pharmacoresistant epilepsy involving insular cortex [17]. However, use of GK in the primary motor cortex has not previously been described.…”