Integration of functional neuronavigation and intraoperative MRI in surgery for drug-resistant extratemporal epilepsy close to eloquent brain areas

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The authors performed a retrospective study to assess the impact of functional neuronavigation and intraoperative MRI (iMRI) on surgery of extratemporal epileptogenic lesions on postsurgical morbidity and seizure control.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Twenty-five patients (14 females and 11 males) underwent extratemporal resections for drug-resistant epilepsy close to speech/motor brain areas or adjacent to white matter tracts. The mean age at surgery was 34 years (range 12–67 years). The preoperative mean disease duration was 13.2 years. To avoid awake craniotomy, cortical motor-sensory representation was mapped during preoperative evaluation in 14 patients and speech representation was mapped in 15 patients using functional MRI. In addition, visualization of the pyramidal tract was performed in 11 patients, of the arcuate fascicle in 7 patients, and of the visual tract in 6 patients using diffusion tensor imaging. The mean minimum distance of tailored resection between the eloquent brain areas was 5.6 mm. During surgery, blood oxygen level–dependent imaging and diffusion tensor imaging data were integrated into neuronavigation and displayed through the operating microscope. The postoperative mean follow-up was 44.2 months.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In 20% of these patients, further intraoperative resection was performed because of intraoperatively documented residual lesions according to iMRI findings. At the end of resection, the final iMRI scans confirmed achievement of total resection of the putative epileptogenic lesion in all patients. Postoperatively, transient complications and permanent complications were observed in 20% and 12% of patients, respectively. Favorable postoperative seizure control (Engel Classes I and II) was achieved in 84% and seizure freedom in 72% of these consecutive surgical patients.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>By using functional neuronavigation and iMRI for treatment of epileptogenic brain lesions, the authors achieved a maximum extent of resection despite the lesions' proximity to eloquent brain cortex and fiber tracts in all cases. The authors' results underline possible benefits of this technique leading to a favorable seizure outcome with acceptable neurological deficit rates in difficult-to-treat extratemporal epilepsy.</jats:p></jats:sec>

The role of intraoperative MRI in resective epilepsy surgery for peri-eloquent cortex cortical dysplasias and heterotopias in pediatric patients

“…Again, our reported rates of 36% transient and no permanent new neurological deficits in the iMRI cohort are consistent with those of Sommer et al, who reported 20% transient and 12% permanent neurological deficits in their cohort of iMRI-resected extratemporal epilepsy adjacent to eloquent cortex. 32 Importantly, this represents a reduction in deficits over conventional resections in our study, and in previous studies that have reported postoperative neurological deficits ranging from 50% to 83%. [1][2][3]25 Hence, our results demonstrate that iMRI-assisted resections are less prone to incurring neurological deficits.…”

“…Using iMRI in conjunction with functional MRI and diffusion tensor imaging (DTI), Sommer et al previously reported achieving GTR in all patients and 72% complete seizure freedom in resection of lesional epilepsy in close proximity to eloquent cortex. 32 Of note, their cohort consisted of 7 (28%) of 25 patients with intractable epilepsy secondary to FCD (1 Type IIA and 6 Type IIB), with the remainder of the cases secondary to mixed etiology including posttraumatic glial scars and cavernous hemangiomas. Importantly, surgical outcomes in our study are consistent with those reported by Sommer et al and considerably improved over conventional resection both in our current study and in the literature.…”

“…To counter this, iMRI has been successfully integrated with these imaging techniques in lesional epilepsy surgery. 7,32 In addition to traditional intraoperative CT and MRI, further technologies such as advanced intraoperative ultrasonography and intraoperative elasticity imaging may better aid in real-time identification of dysplastic lesions and in more accurate depiction of margins. 5,18 Furthermore, intraoperative ultrasonography has been shown to successfully integrate with functional MRI and DTI to provide an intraoperative update to neuronavigation accounting for brain shift.…”

“…13,19,30,31 Furthermore, iMRI has been successfully integrated into pediatric cases and has been shown to aid in intraoperative evaluation of the extent of resection in epilepsy surgery. 3,4,21,32 Hence, we sought to adapt this technology in resective epilepsy surgery for epileptogenic lesions located adjacent to eloquent cortex. The current study is a comparative analysis of postoperative seizure and neurological outcomes in patients undergoing resection of FCD and heterotopias adjacent to eloquent cortex using iMRI-assisted versus conventional resective techniques.…”

Intraoperative MRI–guided resection of focal cortical dysplasia in pediatric patients: technique and outcomes

“…3,8,9,21,24,25 Our objective in this study was to assess the impact of iMRI on intraoperative evaluation, surgical course of reabbreviations ECoG = electrocorticography; FCD = focal cortical dysplasia; iMRI = intraoperative MRI; OE = operative event; OR = operating room; SPGR = spoiled gradient echo recalled; 3DGM = 3D gyral map. obJective Previous meta-analysis has demonstrated that the most important factor in seizure freedom following surgery for focal cortical dysplasia (FCD) is completeness of resection.…”