• MRI-guided stereotactic laser ablation of presumed cavernous malformations in drug-resistant epilepsy: clinical and imaging outcomes

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    Jon Timothy Willie MD PhD; D. Jay McCracken MD; Robert E. Gross MD PhD

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    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting

    Introduction: Open surgical resection is indicated for cavernous malformations (CM) associated with medically refractory epilepsy. Minimally invasive alternatives may maintain therapeutic efficacy while minimizing complications and disfigurement. MRI-guided stereotactic laser ablation (SLA) is a novel approach to treating focal epilepsy and tumors by delivering laser thermal energy via a commercial, FDA-cleared device. We present a series of five cases of SLA of presumed CM associated with refractory epilepsy. We include data regarding safety, ablation volumes, seizure outcomes, and follow up imaging.

    Methods: Five patients with medically refractory epilepsy undergoing standard presurgical evaluation (3-Tesla MRI, fluoro-deoxyglucose PET, neuropsychological evaluation, and inpatient video-EEG studies) were found to have corresponding lesions consistent with CM. Each underwent stereotactic placement of a laser fiber assembly (optical fiber in a saline-cooled 1.6-mm diameter catheter, Visualase, Inc.) via twist drill hole under general anesthesia. Real-time MR anatomic and thermal imaging verified placement and extent of ablation of CM and surrounding cortical rim during ablation with a 15W diode laser.

    Results: Procedural MR imaging revealed no evidence of hemorrhage following fiber placement within presumed CM. Immediate post-procedure contrasted imaging confirmed ablation in all cases. We detected no adverse events or neurological deficits. No ICU admissions were indicated and patients were discharged within 24-36 hours. Three of four patients with at least 6 months of follow up (range 6-20 months) are seizure free (75%). Follow up is < 6 months in the fifth patient. Failure to achieve seizure freedom in one subject could not be explained by pre-procedure lesion size, or post-procedure ablation characteristics, but might indicate a wider seizure network in a subject with prolonged epilepsy duration (>45 years). Available follow up MR imaging at 6 months indicates non-enhancing cystic necrosis limited to the ablation zone.

    Conclusions: Minimally invasive MRI-guided SLA of presumed epileptogenic CM is a potentially safe and effective alternative to open resection. We have performed this procedure without complication in five patients with excellent seizure outcomes. With additional experience this technique may be a first line alternative for patients with epileptogenic CM and perhaps symptomatic hemorrhagic CM as well.

    Patient Care: By providing a minimally invasive alternative to treating drug- resistant epilepsy secondary to cavernous malformations, patients will experience shorter hospital stays and complications. The initial results show a favorable reduction in seizure frequency and intensity, if not complete cessation, compared to open resection. With more experience, this could become an excellent first option to treating patients with this disease and reserving open resection for patients who fail to achieve their desired outcome with the initial procedure.

    Learning Objectives: By the end of the presentation, participants should be able to: 1) Describe the natural history and classical treatment of cavernoma related drug-resistant epilepsy 2) Describe the technique for minimally invasive stereotactic laser ablation of cavernous malformations 3) Understand the potential benefits, risks, and complications associated with the new procedure.


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