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Nitin Tandon, Andreas V. Alexopoulos, Ann Warbel, Imad M. Najm, and William E. Bingaman

Object

Occipital resections for epilepsy are rare. Reasons for this are the relative infrequency of occipital epilepsy, difficulty in localizing epilepsy originating in the occipital lobe, imprecisely defined seizure outcome in patients treated with focal occipital resections in the MR imaging era, and concerns about producing visual deficits. The impact of lesion location on vision and seizure biology, the management decision-making process, and the outcomes following resection need elaboration.

Methods

The authors studied 21 consecutive patients who underwent focal occipital resections for epilepsy at Cleveland Clinic Epilepsy Center over a 13-year period during which MR imaging was used. Demographics, imaging, and data relating to the epilepsy and its surgical management were collected. The collateral sulcus, the border between the medial surface and the lateral convexity, and the inferior temporal sulcus were used to subdivide the occipital lobe into medial, lateral, and basal zones. Lesions that did not involve most or all of the occipital lobe (sublobar) were spatially categorized into these zones. Visual function, semiology, and scalp electroencephalography were evaluated in relation to these spatial categories. Preresection and postresection visual function and seizure frequency were evaluated and compared. Lastly, an exhaustive review and discussion of the published literature on occipital resections for epilepsy was carried out.

Results

Five lesions were lobar and 16 were sublobar. Patients with medial or lobar lesions had a much greater likelihood of preoperative visual field defects. Those with basal or lateral lesions had a greater likelihood of having a visual aura preceding some or all of their seizures and a trend (not significant) toward having a concordant lateralized onset by scalp electroencephalography. Invasive recordings were used in 8 cases. All patients had lesions (malformations of cortical development, tumors, or gliosis) that were completely resected, as evaluated on postoperative MR imaging. At last follow-up, 17 patients (81%) were seizure free or had only occasional auras (Wieser Class 1 or 2). The remaining 4 patients (19%) had a worthwhile improvement in seizure control (Class 3 or 4). Of the patients for whom both pre- and postoperative visual testing data were available, 50% suffered no new visual deficits, and 17% each developed a new quadrantanopia or a hemianopia.

Conclusions

Lesional occipital lobe epilepsy can be successfully managed with resection to obtain excellent seizure-free rates. Individually tailored resections (in lateral occipital lesions, for example) may help preserve intact vision in a subset of cases (38% in this series). Invasive recordings may further guide surgical decision-making as delineated by an algorithm generated by the authors. The authors' results suggest that the spatial location of the lesion correlates both with the semiology of the seizure and with the presence of visual deficit.

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Juan C. Bulacio, James Bena, Piradee Suwanpakdee, Dileep Nair, Ajay Gupta, Andreas Alexopoulos, William Bingaman, and Imad Najm

OBJECTIVE

The aim of this study was to investigate seizure outcomes after resective epilepsy surgery following stereoelectroencephalography (SEEG), including group characteristics, comparing surgical and nonsurgical groups and assess predictors of time to seizure recurrence.

METHODS

Clinical and EEG data of 536 consecutive patients who underwent SEEG at Cleveland Clinic Epilepsy Center between 2009 and 2017 were reviewed. The primary outcome was defined as complete seizure freedom since the resective surgery, discounting any auras or seizures that occurred within the 1st postoperative week. In addition, the rate of seizure freedom based on Engel classification was determined in patients with follow-up of ≥ 1 year. Presumably significant outcome variables were first identified using univariate analysis, and Cox proportional hazards modeling was used to identify outcome predictors.

RESULTS

Of 527 patients satisfying study criteria, 341 underwent resective surgery. Complete and continuous seizure freedom after surgery was achieved in 55.5% of patients at 1 year postoperatively, 44% of patients at 3 years, and 39% of patients at 5 years. As a secondary outcome point, 58% of patients achieved Engel class I seizure outcome for at least 1 year at last follow-up. Among surgical outcome predictors, in multivariate model analysis, the seizure recurrence rate by type of resection (p = 0.039) remained statistically significant, with the lowest risk of recurrence occurring after frontal and temporal lobe resections compared with multilobar and posterior quadrant surgeries. Patients with a history of previous resection (p = 0.006) and bilateral implantations (p = 0.023) were more likely to have seizure recurrence. The absence of an MRI abnormality prior to resective surgery did not significantly affect seizure outcome in this cohort.

CONCLUSIONS

This large, single-center series shows that resective surgery leads to continuous seizure freedom in a group of patients with complex and severe pharmacoresistant epilepsy after SEEG evaluation. In addition, up to 58% of patients achieved seizure freedom at last follow-up. The authors’ results suggest that SEEG is equally effective in patients with frontal and temporal lobe epilepsy with or without MRI identified lesions.

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Sumeet Vadera, Lara Jehi, Richard C. Burgess, Katherine Shea, Andreas V. Alexopoulos, John Mosher, Jorge Gonzalez-Martinez, and William Bingaman

Object

During the presurgical evaluation of patients with medically intractable focal epilepsy, a variety of noninvasive studies are performed to localize the hypothetical epileptogenic zone and guide the resection. Magnetoencephalography (MEG) is becoming increasingly used in the clinical realm for this purpose. No investigators have previously reported on coregisteration of MEG clusters with postoperative resection cavities to evaluate whether complete “clusterectomy” (resection of the area associated with MEG clusters) was performed or to compare these findings with postoperative seizure-free outcomes.

Methods

The authors retrospectively reviewed the charts and imaging studies of 65 patients undergoing MEG followed by resective epilepsy surgery from 2009 until 2012 at the Cleveland Clinic. Preoperative MEG studies were fused with postoperative MRI studies to evaluate whether clusters were within the resected area. These data were then correlated with postoperative seizure freedom.

Results

Sixty-five patients were included in this study. The average duration of follow-up was 13.9 months, the mean age at surgery was 23.1 years, and the mean duration of epilepsy was 13.7 years. In 30 patients, the main cluster was located completely within the resection cavity, in 28 it was completely outside the resection cavity, and in 7 it was partially within the resection cavity. Seventy-four percent of patients were seizure free at 12 months after surgery, and this rate decreased to 60% at 24 months. Improved likelihood of seizure freedom was seen with complete clusterectomy in patients with localization outside the temporal lobe (extra–temporal lobe epilepsy) (p = 0.04).

Conclusions

In patients with preoperative MEG studies that show clusters in surgically accessible areas outside the temporal lobe, we suggest aggressive resection to improve the chances for seizure freedom. When the cluster is found within the temporal lobe, further diagnostic testing may be required to better localize the epileptogenic zone.

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Shan Wang, Yingying Tang, Thandar Aung, Cong Chen, Masaya Katagiri, Stephen E. Jones, Richard A. Prayson, Balu Krishnan, Jorge A. Gonzalez-Martinez, Richard C. Burgess, Imad M. Najm, Andreas V. Alexopoulos, Shuang Wang, Meiping Ding, and Zhong Irene Wang

OBJECTIVE

Presurgical evaluation of patients with operculoinsular epilepsy and negative MRI presents major challenges. Here the authors examined the yield of noninvasive modalities such as voxel-based morphometric MRI postprocessing, FDG-PET, subtraction ictal SPECT coregistered to MRI (SISCOM), and magnetoencephalography (MEG) in a cohort of patients with operculoinsular epilepsy and negative MRI.

METHODS

Twenty-two MRI-negative patients were included who had focal ictal onset from the operculoinsular cortex on intracranial EEG, and underwent focal resection limited to the operculoinsular cortex. MRI postprocessing was applied to presurgical T1-weighted volumetric MRI using a morphometric analysis program (MAP). Individual and combined localization yields of MAP, FDG-PET, MEG, and SISCOM were compared with the ictal onset location on intracranial EEG. Seizure outcomes were reported at 1 year and 2 years (when available) using the Engel classification.

RESULTS

Ten patients (45.5%, 10/22) had operculoinsular abnormalities on MAP; 5 (23.8%, 5/21) had operculoinsular hypometabolism on FDG-PET; 4 (26.7%, 4/15) had operculoinsular hyperperfusion on SISCOM; and 6 (30.0%, 6/20) had an MEG cluster (3 tight, 3 loose) within the operculoinsular cortex. The highest yield of a 2-test combination was 59.1%, seen with MAP and SISCOM, followed by 54.5% with MAP and FDG-PET, and also 54.5% with MAP and MEG. The highest yield of a 3-test combination was 68.2%, seen with MAP, MEG, and SISCOM. The yield of the 4-test combination remained at 68.2%. When all other tests were negative or nonlocalizing, unique information was provided by MAP in 5, MEG in 1, SISCOM in 2, and FDG-PET in none of the patients. One-year follow-up was available in all patients, and showed 11 Engel class IA, 4 class IB, 4 class II, and 3 class III/IV. Two-year follow-up was available in 19 patients, and showed 9 class IA, 3 class IB, 1 class ID, 3 class II, and 3 class III/IV.

CONCLUSIONS

This study highlights the individual and combined values of multiple noninvasive modalities for the evaluation of nonlesional operculoinsular epilepsy. The 3-test combination of MAP, MEG, and SISCOM represented structural, interictal, and ictal localization information, and constituted the highest yield. MAP showed the highest yield of unique information when other tests were negative or nonlocalizing.