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ABSTRACT: To identify predictors of seizure recurrence following posterior quadrant epilepsy surgery.
Between 1983 and 2008, 43 medically refractory epilepsy patients underwent posterior quadrant epilepsy surgery. Epilepsy surgery involved the occipital lobe in all cases; some cases also included resection of the adjacent parietal or temporal cortex. Using a logistic regression model, we evaluated the relationship between outcome (Engel class I-IV) and 5 outcome predictors: absence of a visual aura, a temporal lobe type aura, versive head movement unaccompanied by a visual aura, non-focal interictal scalp EEG, and surgical pathology other than low grade tumor or cortical dysplasia. We also determined the relative risk for significant post-operative cognitive decline of Wechsler intelligence test score among those receiving complete lobectomies compared to those receiving partial lobectomies.
Overall, outcome was favorable at 1 year following surgery: 22 (51.2%) patients Engel class I, 10 (24%) patients Engel class II, 5 (12%) patients Engel class III, and 6 (14%) patients Engel class IV. The 3 best univariate predictors of seizure recurrence were versive head movement unaccompanied by visual aura, non-focal interictal scalp EEG, and pathology other than low grade tumor or cortical dysplasia. A multivariate predictor combining temporal lobe type aura, versive head movement unaccompanied by visual aura, non-focal interictal scalp EEG, and pathology other than low grade tumor or cortical dysplasia was optimum. Complete lobectomy significantly increased the risk of post-operative decline of Wechsler intelligence score.
These findings indicate that posterior quadrant epilepsy surgery may provide sustained seizure control. A multivariate model combining temporal lobe type aura, versive head movement unaccompanied by a visual aura, non-focal interictal scalp EEG, and pathology other than low grade tumor or cortical dysplasia may contribute to predicting seizure recurrence following posterior quadrant epilepsy surgery. The extent of cortical resection may predict significant cognitive decline in post-operative Wechsler intelligence score.
Seizure 08/2012; 21(9):722-8. · 1.80 Impact Factor
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ABSTRACT: Previous studies have shown that closed-loop or responsive neurostimulation can abort induced or spontaneous epileptiform discharges.
To assess the effectiveness of a programmable cranially implanted closed-loop neurostimulation system in the control of seizures originating from an area relatively inaccessible by open craniotomy.
A patient with drug-resistant partial epilepsy had previously undergone open resection of the left frontal opercular cortex and the underlying insular area. Although subdural-depth electrode ictal recordings had been nonlocalizing, depth electrode insular stimulation had produced the patient's habitual aura. Postoperatively, there was a sustained 50% reduction in seizure frequency. The residual seizures were identical to the preoperative seizures. Repeat depth electrode monitoring revealed that the ictal focus was immediately posterior to the previously resected insular area. A closed-loop cranial internal pulse generator system including left anterior insular and posterior orbitofrontal depth electrodes was implanted.
There was an additional 60% reduction of seizures.
Preliminary observation indicates that responsive neurostimulation may be an effective alternative to higher-risk resective epilepsy surgery.
Stereotactic and Functional Neurosurgery 01/2010; 88(5):281-7. · 1.85 Impact Factor
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ABSTRACT: Several cases of congenital or acquired temporal encephaloceles have been reported in the literature as the causative mechanism of simple and/or complex partial seizures. In this report the authors describe a rare case of spontaneous parietal encephalocele presenting with simple partial seizures and progressively increasing contralateral upper-extremity motor deficit. The unusual anatomical location of an encephalocele associated with seizures and the delayed seizure onset represent distinctive characteristics in this case. Preoperative imaging included surface electroencephalography, computerized tomography, and brain magnetic resonance imaging. Frameless neuronavigation and intraoperative cortical mapping were used to aid resection of the encephalocele, and the dural and bone defects were reconstructed. The surgical outcome in this case was excellent, and the patient has remained seizure free. The pertinent literature is reviewed in this report.
Neurosurgical FOCUS 10/2005; 19(3):E10. · 2.87 Impact Factor
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ABSTRACT: Open-loop stimulation studies have shown varying control of seizures with stimulation of different anatomical targets. A recent multi-institutional clinical study utilizing an external closed-loop stimulation system had promising results. A novel implantable closed-loop Responsive Neurostimulation System (RNS) (Neuropace, Inc., Mountainview, Calif., USA) consisting of a cranially implanted pulse generator, one or two quadripolar subdural strip or depth leads and a programmer is under testing in a prospective clinical trial. The RNS pulse generator continuously analyzes the patient's electrocortigrams (ECoGs) and automatically triggers electrical stimulation when specific ECoG characteristics programmed by the clinician, as indicative of electrographic seizures or precursor of epileptiform activities, are detected. The pulse generator then stores diagnostic information detailing detections and stimulations, including multichannel stored ECoGs. The RNS programmer communicates transcutaneously with the implanted pulse generator when initiated by a clinician. The RNS programmer can download diagnostics and store ECoGs for review. The RNS programmer can then be used to program detection and stimulation parameters. In our current communication, we describe the selection criteria for implanting this system, the preparation of the surgical candidates as well as the surgical technique. We also present our preliminary results with 8 patients who had an RNS implanted. Seven patients (87.5%) had more than 45% decrease in their seizure frequency. The mean follow-up time in our series was 9.2 months. The implantation of a closed-loop stimulation system, in our experience, represents a safe and relatively simple surgical procedure. However, the efficacy of this new treatment modality remains to be determined in further multi-institutional, prospective clinical studies.
Stereotactic and Functional Neurosurgery 02/2005; 83(4):153-8. · 1.85 Impact Factor
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ABSTRACT: Approved neural-stimulation therapies for epilepsy use prolonged intermittent stimulation paradigms with no ability to respond automatically to seizures.
A responsive neurostimulator that can automatically analyze electrocortical potentials, detect electrographic seizures, and rapidly deliver targeted electrical stimuli to suppress them was evaluated in an open multicenter trial in 50 patients, 40 of whom received responsive cortical stimulation via subdural electrodes implanted for epilepsy surgery evaluations.
Four patients, ages 15 to 28 years, monitored at three institutions, with clinical and electrographic response to neurostimulation, are described. Electrographic seizures were altered and suppressed in these patients during trials of neurostimulation lasting < or =68 h, with no major side effects. In one patient, stimulation appeared also to improve the baseline EEG.
Responsive cortical neurostimulation may be a safe and effective treatment for partial epilepsy. This information was derived from a small group of patients in an observation study. A double-blind, controlled Food and Drug Administration (FDA)-approved study of a permanently implanted responsive neurostimulation system to treat medically refractory partial seizures is under way.
Epilepsia 01/2005; 45(12):1560-7. · 3.96 Impact Factor
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ABSTRACT: Magnetic source imaging (MSI) of interictal epileptiform dipoles was studied in 100 epilepsy surgery candidates. Sixty underwent surgery. MSI epileptiform data were classified as focal, regional, multifocal, scattered or none. Resections of MSI epileptiform foci were classified as extensive (EXT) versus partial or none (P/N). MSI interictal epileptiform dipoles were found in 22 of 27 anterior temporal (ATL) cases, and in 31 of 33 extratemporal (XMT) cases. Of 10 EXT ATL cases, 5 (50%) were seizure free (SF). Of 12 P/N ATL cases, 7 (58%) were SF. Of 10 nonlesional EXT XMT resections, 8 (80%) were SF. Of 10 nonlesional P/N XMT resections, 1 (10%) was SF. Neither focality of MSI data or spatial agreement of electrographic and MSI data significantly affected outcomes.
Stereotactic and Functional Neurosurgery 02/2003; 80(1-4):14-7. · 1.85 Impact Factor
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ABSTRACT: In this study, we determined the influence of dipole orientation, dipole location, and number of recording sites on the precision of dipole localization in a spherical volume conductor. We compared localization from referential EEG (R-EEG), scalp current density EEG (SCD-EEG) and magnetoencephalography (MEG). Dipole orientation had a small influence on the precision of dipole localization for R-EEG and SCD-EEG. Dipole location relative to the recording sites, dipole depth, and number of recording channels strongly influenced the precision of dipole localization. Assuming equal signal to noise conditions for each recording method, MEG and SCD-EEG had a similar precision for dipole localization of a single tangential dipole source and both methods were more precise than R-EEG. However, SCD-EEG was inferior to MEG for distinguishing a single tangential current source from a pair of deeper radial current sources. In summary, these results suggest that the MEG will be most useful for localization of multiple simultaneous dipole sources.
Brain Topography 11/1995; 8(2):119-125. · 3.45 Impact Factor
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ABSTRACT: We report a mixed handed (L>R) patient with exclusive right cerebral language representation who de–veloped a permanent anterograde amnestic syndrome after right anterotemporal lobectomy. Preoperative neuropsychological performance consisted of impaired verbal memory and normal nonverbal memory. Wada memory performance was asymmetrical for objects presented soon after amobarbital injection in conjunction with no memory asymmetry for items presented later in the Wada evaluation. Preand postoperative magnetic resonance imaging (MRI) scans showed no structural lesions; however, postoperative MRI hippocampal volume measurements suggested decreased hippocampal volume for the nonresected temporal lobe. These results confirm the risk of anterograde amnesia after unilateral temporal lobectomy and demonstrate that baseline neuropsychological testing may falsely literalize material-specific memory functions in patients with atypical cerebral language dominance.
Epilepsia 06/1994; 35(4):757 - 763. · 3.96 Impact Factor
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ABSTRACT: Magnetoencephalography (MEG) was used to evaluate 50 seizure surgery candidates. Interictal spikes were recorded in 42 cases. Of 20 cases with other data suggesting a convexity (lateral neocortical) focus, MEG spikes were recorded from 19. In 17, MEG and electrographic data were localized to the same region. Invasive studies were or could have been avoided in 11 cases based on MEG and other noninvasive data. MEG spike data were present in 14 of 18 cases with anteromesial temporal foci, being localized to the same lobe as electrographic data in 11. MEG was not of value in surgical planning of cases with orbitofrontal foci, or depth nonlocalized seizures. Twenty-seven patients with MEG epileptiform data have had postoperative follow-up. Fourteen of 19 with electrographic and MEG data localized to the same region are seizure-free. Four of eight with spatial discordance of MEG and electrographic data are seizure-free. Preliminary conclusions are as follows: When MEG and electrographic data are localized to the same region, seizure-free surgical outcome is more likely. In convexity cases with MEG and noninvasive electrographic data localized to the same region, preoperative invasive studies may be unnecessary.
Journal of Epilepsy.
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ABSTRACT: We reviewed 187 depth recorded seizures in 33 patients with non-lesional temporal lobe complex partial seizures. All patients had a minimum of 1 year follow-up following temporal lobectomy. We classified seizure onset pattern as rhythmic activity, attenuation, or repetitive spikes or spike wave complexes. The most common pattern of seizure onset was rhythmic activity and the next most common pattern was repetitive spikes. Seventy-five seizures (49%) had only one seizure onset pattern, and 79 seizures (51%) had a combination of seizure onset patterns. The degree of hippocampal gliosis strongly predicted the type of seizure onset pattern (Chi square = 24.07, 2 d.f., P < 0.01). The rhythmic activity pattern was associated with mild gliosis, and the repetitive spike pattern was associated with severe gliosis. We classified seizure onset as focal or regional based on the number of electrode contacts that were involved by the ictal EEG. A focal seizure onset was associated with an excellent outcome following temporal lobectomy.
Electroencephalography and Clinical Neurophysiology.
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ABSTRACT: From December 1980 to December 1991, 171 depth electrode implantations, involving 711 trajectories, were performed on 164 ablative seizure surgery candidates. Twenty-seven complications (15.8%) occurred in 21 patients. There were 14 trajectory-related complications. Eight were related to vertex entry amygdaloid implants. This included two permanent complications (1.2%), one hemiparesis, and one hemiparesis with aphasia. In addition, one transient hemiparesis, one transient aphasia, one transient severe headache, two asymptomatic hematomas, and one symptomatic hematoma occurred. Five cases of transient global amnesia were related to occipital entry mesial temporal implants, all computed tomography (CT) guided. One case of transient lower extremity monoparesis was related to a parietal entry anterior cingulate implant. There were 13 nontrajectoryrelated, temporary complications. This included two brain abscesses, two skin infections, one symptomatic hematoma associated with one slowly resolving hemiparesis, ventriculitis (one septic and three chemical), one asymptomatic hematoma, and two broken anchor bolts. No permanent complications occurred in the last 99 patients. The risk of neurologic complications has been reduced by no longer using vertex-amygdalar trajectories and creating depth-electrode tracts prior to implantation. The risk of hemorrhage has been reduced by careful study of preimplant angiograms for avascular entry sites and not advancing any electrode through the meninges until hemostasis has been assured.
Journal of Epilepsy. 5(4):253-260.
