Intraoperative magnetic resonance for the surgical treatment of lesions producing seizures (original) (raw)
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Use of Intraoperative Magnetic Resonance Imaging in Tailored Temporal Lobe Surgeries for Epilepsy
Epilepsia, 2002
Purpose: We investigated whether intraoperative magnetic resonance imaging (MRI) was able to assess immediately the extent of a tailored temporal lobe resection for epilepsy in comparison to delayed postoperative MRI. The recently proposed concept of an individually tailored procedure, preserving tissue not involved in seizures, leads to a variety of differently shaped resections.
Stereoelectroencephalography in presurgical assessment of MRI-negative epilepsy
Brain, 2007
According to most existing literature, the absence of an MRI lesion is generally associated with poorer prognosis in resective epilepsy surgery. Delineation of the epileptogenic zone (EZ) by intracranial recording is usually required but is perceived to be more difficult in 'MRI negative' cases. Most previous studies have used subdural recording and there is relatively less published data on stereoelectroencephalography (SEEG). The objective of this study was to report the experience of our group in using SEEG in presurgical evaluation, comparing its effectiveness in normal and lesional MRI cases. One hundred consecutive patients undergoing SEEG for presurgical assessment were studied. Forty-three patients out of one hundred (43%) had normal MRI and 57 (57%) had lesional MRI. Successful localization was achieved with no difference between these two groups, in 41/43 (95%) normal MRI and in 55/57 (96%) lesional MRI cases (P = 1.00). Surgery was proposed in 84/100 patients and contraindicated in 16/100 with no significant difference between lesional and MRI-negative groups (P`0.05). At 1 year follow-up, 11/20 (55%) of those having undergone cortectomy in the MRI-negative group and 21/40 (53%) in the lesional MRI group were entirely seizure free (P`0.05) and these proportions were maintained at 2 years follow-up. Significant improvement in seizure control (ILAE outcome groups 1^4) was achieved in`90% cases with no difference between groups (P`0.05). Of MRI-negative cases that underwent surgery, 10/23 (43%) had focal cortical dysplasia. This series showed that SEEG was equally effective in the presurgical evaluation of MRInegative and lesional epilepsies.
Neurosurgery, 2005
To report on indications, surgical technique, results, and morbidity of stereoelectroencephalography (SEEG) in the presurgical evaluation of patients with drug-resistant focal epilepsy. METHODS: Two-hundred fifteen stereotactic implantations of multilead intracerebral electrodes were performed in 211 patients (4 patients were explored twice), who showed variable patterns of localizing incoherence among electrical (interictal/ictal scalp electroencephalography), clinical (ictal semeiology), and anatomic (magnetic resonance imaging [MRI]) investigations. MRI scanning showed a lesion in 134 patients (63%; associated with mesial temporal sclerosis in 7) and no lesion in 77 patients (37%; with mesial temporal sclerosis in 14 patients). A total of 2666 electrodes (mean, 12.4 per patient) were implanted (unilaterally in 175 procedures and bilaterally in 40). For electrode targeting, stereotactic stereoscopic cerebral angiograms were used in all patients, coupled with a coregistered three-dimensional MRI scan in 108 patients. RESULTS: One hundred eighty-three patients (87%) were scheduled for resective surgery after SEEG recording, and 174 have undergone surgery thus far. Resections sites were temporal in 47 patients (27%), frontal in 55 patients (31.6%), parietal in 14 patients (8%), occipital in one patient (0.6%), rolandic in one patient (0.6%), and multilobar in 56 patients (32.2%). Outcome on seizures (Engel's classification) in 165 patients with a follow-up period of more than 12 months was: Class I, 56.4%; Class II, 15.1%; Class III, 10.9%; and Class IV, 17.6%. Outcome was significantly associated with the results of MRI scanning (P ϭ 0.0001) and with completeness of lesion removal (P ϭ 0.038). Morbidity related to electrode implantation occurred in 12 procedures (5.6%), with severe permanent deficits from intracerebral hemorrhage in 2 (1%) patients. CONCLUSION: SEEG is a useful and relatively safe tool in the evaluation of surgical candidates when noninvasive investigations fail to localize the epileptogenic zone. SEEG-based resective surgery may provide excellent results in particularly complex drug-resistant epilepsies.
Epilepsy surgery with intraoperative MRI at 1.5 T
Neurosurgery clinics of North America, 2005
Despite the infancy of iMRI in epilepsy surgery and the paucity of literature on this topic, some conclusions may be reached. Although iMRI is a useful adjunct during epilepsy procedures, a randomized control trial is necessary to determine its true impact.
Clinical Ictal Symptomatology and Anatomical Lesions: Their Relationships in Severe Partial Epilepsy
Epilepsia, 2007
High-resolution imaging techniques can demonstrate anatomic alterations in most patients identified as candidates for surgical treatment of their partial epilepsy. The demonstration of an anatomic lesion is only one step in the presurgical diagnostic procedure, which includes video-EEG and, when necessary, video-stereo-EEG recordings of seizures. A review of the literature shows that the simple removal of the magnetic resonance imaging (MR1)-evident lesion ("lesionectomy") reduces but does not completely suppress seizures in a large percentage of patients, especially those with neuronal migration disorders. This phenomenon could, at least in part, be explained by preliminary data (in 33 patients) showing that less than 20% of seizures correspond to a well-localized, intralesional discharge in about 40% of stereo-EEG-investigated patients with at least one intralesional electrode. The authors illustrate some anatomo-electroclinical examples of intraindividual variability of the ictal symptomatology, raising the problem of the decision about the extent of the surgical removal. Recent histologic and immunohistochemical studies have demonstrated several kinds of structural alterations in the stereo-EEG-defined epileptogenic zone, not always overlapping with the MRI-visible lesion. This aspect can further explain some failures of MRI-guided lesionectomies. That relationships between "lesions" and epileptogenic zones may be variable is also suggested by reports of patients who present with multiple lesions (i.e., cavernous angiomas, Bourneville syndrome) and are cured by removal of only one of them. Key Words: Severe partial epilepsy-Epileptogenic lesions-Stereo-EEG-Intralesional electrical activity-Epilepsy surgery.
Seizure, 2011
Epilepsy surgery is an option for patients with medically refractory epilepsy. To achieve a better outcome post surgery, it is very important to take various presurgical evaluations into account for determining an appropriate surgical plan. Over the past two decades, more comprehensive presurgical assessments and advanced techniques have become available. High-resolution magnetic resonance imaging (MRI) has been known as the best preoperative diagnosis for patients with lesional refractory neocortical epilepsy (NE). 1-3 Digital video electroencephalography (VEEG) provides us with a definitive diagnosis of seizure-like events, while intracranial VEEG (iVEEG) is commonly used to define the ictal onset zone (IOZ). However, surgical resection of the IOZ alone does not always yield a favorable operative outcome because iVEEG electrodes only record signals in their direct vicinity and are blind for other areas, making it difficult to judge whether the IOZ really represents the ictal generator or is the result of propagation from elsewhere. 4 However, in a number of reports, 5 it was pointed out that it is also difficult to judge whether spike foci represent the epileptogenic zone. Furthermore, Holmes et al. 6 reported that only unifocal interictal epileptiform discharges (IEDs) restricted to the seizure onset zone could be used as a marker for epileptogenicity, while others showed that (rapid) spike Seizure 20 (2011) 692-700
Epileptic disorders : international epilepsy journal with videotape, 2006
The rationale for this case report is to assess the degree of congruency between the results of several advanced functional, metabolic, and structural neuroimaging techniques used in patients with MRI-negative focal epilepsy. We investigated the presurgical evaluation and post-operative outcome of a patient with intractable, extratemporal epilepsy. Because the habitual seizures in this patient could be easily induced, six, advanced, neurodiagnostic techniques were successively applied (SISCOM, ictal FDG-PET, ictal fMRI, postictal diffusion-weighted imaging, voxel-based morphometry, and MRS imaging). The findings for the neuroimaging methods investigated, within the left central region, were fairly congruent. Subsequent, invasive EEG recordings revealed a seizure-onset zone at the site where most of the neuroimaging had shown abnormal findings. The surgical removal of the epileptogenic zone, as defined by concordant neuroimaging and SEEG data, resulted in seizure-free postoperative o...
Epilepsia, 2008
Purpose: Excisional surgery achieves seizure freedom in a large proportion of children with intractable lesional epilepsy, but the outcome for children without a focal lesion on MRI is less clear. We report the outcome of a cohort predominantly of children with nonlesional intractable partial epilepsy undergoing resective surgery. Methods: We studied 102 patients with nonlesional intractable partial epilepsy who underwent excisional surgery. The epileptogenic region was identified by integrating clinical exam and video-EEG data complemented by ictal SPECT (n = 40), PET (n = 10), extraoperative subdural monitoring (n = 80), and electrocorticography (n = 22). All patients had follow-up greater than 2 years, 76 patients had 5-year follow-up, and 43 patients had 10year follow-up. Results: A total of 66 resections were unilobar; 36 were multilobar. One patient died of causes unrelated to seizures or surgery. At 2-year follow-up, 44 of 101 patients were seizure-free, 15 experi-enced >90% reduction, 17 had >50% reduction, and 25 were unchanged. At 5-year follow-up, 35 of 76 patients were seizure-free, 12 experienced >90% reduction, 12 had >50% reduction, and 17 were unchanged. At 10-year follow-up, 16 of 43 patients were seizure-free, 13 experienced >90% reduction, 7 had >50% reduction, and 7 were unchanged. Outcomes correlated with the presence of convergent focal interictal spikes (p < 0.005) on the scalp EEG and completeness of resection (p < 0.0005). Conclusions: Our findings demonstrate that excisional surgery is successful in the majority of children with nonlesional partial epilepsy. A multimodal integrative approach can minimize the size of resection and alleviate the need for invasive EEG monitoring. Focal interictal spikes and completeness of resection predict good outcome. The benefits of surgery are long-lasting.