Epilepsy surgery for dominant-side mesial temporal lobe epilepsy without hippocampal sclerosis.

Although anterior temporal lobectomy (ATL) is an established surgery for medically intractable mesial temporal lobe epilepsy (MTLE), it can harm memory function, especially in dominant-side MTLE patients without hippocampal sclerosis (HS). To avoid this complication, multiple hippocampal transection (MHT) was developed, but its efficacy has not been fully elucidated. We report the detailed treatment results of MHT compared with that of ATL. We retrospectively analysed the records of 30 patients who underwent surgery for dominant-side MTLE. ATL was completed for 23 patients with HS, and MHT was completed for 7 patients without HS. The seizure control status, number of anti-seizure medicines, neurocognitive function, and psychiatric disorders of each patient were reviewed. The mean follow-up period was 70 months. Seizure control of Engel class I was achieved in 16 patients (70%) in the ALT group versus 5 patients (71%) in the MHT group. The mean number of anti-seizure medicines administered in the ATL group changed significantly from 2.4 to 1.9 (p = 0.01), while that in the MHT group was unchanged (from 2.1 to 2.0, p = 0.77). Eleven patients (48%) in the ATL group developed psychiatric disorders during the postoperative follow-up period, whereas no psychological complications were observed in the MHT group. Neither group showed neurocognitive decline after the surgery in any of the WAIS-III or WMS-R subtests. In conclusion, MHT may achieve reasonable postoperative seizure reduction, preserve neurocognitive function, and reduce postoperative psychiatric complications. Therefore, it can be considered as a therapeutic option for dominant-side MTLE without HS.

Ictal direct current shifts contribute to defining the core ictal focus in epilepsy surgery.

Identifying the minimal and optimal epileptogenic area to resect and cure is the goal of epilepsy surgery. To achieve this, EEG analysis is recognized as the most direct way to detect epileptogenic lesions from spatiotemporal perspectives. Although ictal direct-current shifts (below 1 Hz) and ictal high-frequency oscillations (above 80 Hz) have received increasing attention as good indicators that can add more specific information to the conventionally defined seizure-onset zone, large cohort studies on postoperative outcomes are still lacking. This work aimed to clarify whether this additional information, particularly ictal direct-current shifts which is assumed to reflect extracellular potassium concentration, really improve postoperative outcomes. To assess the usefulness in epilepsy surgery, we collected unique EEG data sets recorded with a longer time constant of 10 s using an alternate current amplifier. Sixty-one patients (15 with mesial temporal lobe epilepsy and 46 with neocortical epilepsy) who had undergone invasive presurgical evaluation for medically refractory seizures at five institutes in Japan were retrospectively enrolled in this study. Among intracranially implanted electrodes, the two core electrodes of both ictal direct-current shifts and ictal high-frequency oscillations were independently identified by board-certified clinicians based on unified methods. The occurrence patterns, such as their onset time, duration, and amplitude (power) were evaluated to extract the features of both ictal direct-current shifts and ictal high-frequency oscillations. Additionally, we examined whether the resection ratio of the core electrodes of ictal direct-current shifts and ictal high-frequency oscillations independently correlated with favourable outcomes. A total of 53 patients with 327 seizures were analyzed for wide-band EEG analysis, and 49 patients were analyzed for outcome analysis. Ictal direct-current shifts were detected in the seizure-onset zone more frequently than ictal high-frequency oscillations among both patients (92% versus 71%) and seizures (86% versus 62%). Additionally, ictal direct-current shifts significantly preceded ictal high-frequency oscillations in patients exhibiting both biomarkers, and ictal direct-current shifts occurred more frequently in neocortical epilepsy patients than in mesial temporal lobe epilepsy patients. Finally, although a low corresponding rate was observed for ictal direct-current shifts and ictal high-frequency oscillations (39%) at the electrode level, complete resection of the core area of ictal direct-current shifts significantly correlated with favourable outcomes, similar to ictal high-frequency oscillation outcomes. Our results provide a proof of concept that the independent significance of ictal direct-current shifts from ictal high-frequency oscillations should be considered as reliable biomarkers to achieve favourable outcomes in epilepsy surgery. Moreover, the different distribution of the core areas of ictal direct-current shifts and ictal high-frequency oscillations may provide new insights into the underlying mechanisms of epilepsy, in which not only neurons but also glial cells may be actively involved via extracellular potassium levels.

[A Case of Cerebral Tuberculoma].

Cerebral tuberculoma is a rare and serious form of tuberculosis. Despite advancements in imaging and laboratory diagnostics, it is challenging to diagnose cerebral tuberculoma due to its insidious nature and nonspecific findings. A 56-year-old woman was referred to our hospital for headaches. The patient had previously undergone treatment for pulmonary tuberculosis, which had been completely cured 2 months prior to presentation. Brain MRI revealed an enhanced mass lesion with surrounding edema in the right frontal lobe. Although a mild increase in the serum carcinoembryonic antigen(CEA)level and a moderate accumulation of FDG on FDG-PET indicated inflammatory changes or a malignant brain tumor, other imaging and laboratory findings were nonspecific. The mass lesion was indistinguishable from a brain tumor. Hence, the patient underwent surgical removal, and the pathological diagnosis was tuberculoma. In patients with a history of tuberculosis, cerebral tuberculoma should be considered in the differential diagnosis of intracranial mass lesions, even if the original lesion is completely cured. A mild increase in the serum CEA level and a moderate accumulation of FDG on FDG-PET were considered indicative of intracranial inflammation and consistent with cerebral tuberculoma.

Effects of sevoflurane anesthesia on intraoperative high-frequency oscillations in patients with temporal lobe epilepsy.

PURPOSE: This is a cross-sectional study without an unexposed group. We elucidated the effects of sevoflurane anesthesia on high-frequency oscillations (HFOs) to examine the usefulness of assessing intraoperative HFOs. METHODS: We recorded electrocorticography in seven patients with medication-resistant temporal lobe epilepsy (TLE) caused by unilateral hippocampal sclerosis who were seizure-free after temporal lobectomy. We analyzed the number of intraoperative spikes and HFOs on spikes in the epileptogenic parahippocampal gyrus and nonepileptogenic superior temporal gyrus with sevoflurane concentrations of 1.5%, 2.0%, 2.5%, and 3.0%. RESULTS: The number of spikes and HFOs in the epileptogenic area significantly increased with an increase in the sevoflurane concentration. In the nonepileptogenic area, spikes and HFOs did not significantly increase with increases in the sevoflurane concentration. However, 2.5% sevoflurane markedly induced spikes and ripples but no fast ripples (FRs) in one patient, and 3.0% sevoflurane induced marked increases in both ripples and FRs in two patients. CONCLUSIONS: The proconvulsant effect of sevoflurane on intraoperative HFOs in patients with TLE depends on the concentration. While HFOs induced by higher sevoflurane concentrations may be a useful biomarker for epileptogenic areas, careful interpretation is also needed because a higher sevoflurane concentration can also induce false-positive HFOs in nonepileptogenic areas.

Effectiveness of perampanel as a first add-on antiepileptic drug for the treatment of partial epilepsy.

BACKGROUND: Perampanel (PER) is a newly introduced antiepileptic drug (AED) and is used in over 50 countries. In the current study, we analyzed the efficacy of PER for patients with partial epilepsy who were recruited from two hospitals that had both an epilepsy center and a general neurosurgical unit over a 1-year period. METHODS: The present study was a retrospective observational study that evaluated the effects of PER for the treatment of partial epilepsy in 51 patients. We analyzed the effects of PER at two checkpoints, i.e., 6 and 12 months after starting adjunctive PER treatment. Following this, we analyzed the effects of PER as a first add-on (only one prior AED) and late add-on (≥2 prior AEDs) therapy, and focused on the characteristics of the patients who achieved seizure freedom. RESULTS: Of the initial 51 patients, 45 and 39 patients were evaluated at the 6- and 12-month checkpoints, respectively. Overall, after starting treatment with PER, 29% (13/45) and 28% (11/39) of patients were seizure-free at 6 and 12 months, respectively. The tolerance rate of PER was 67% (30/45) at 6 months and 53.8% (21/39) at 12 months following treatment. The seizure-free rate of the 30 patients who were continuously treated with PER for 6 months was significantly higher in the patients who used PER as a first add-on treatment (75.0%, 6/8) than it was in the patients who used PER as a late add-on treatment (31.8%, 7/22) (p = 0.049). The seizure-free rate of the 21 patients who were continuously treated with PER for 12 months was significantly higher in the patients who used PER as a first add-on treatment (100%, 5/5) than it was in the patients who used PER as a late add-on treatment (37.5%, 6/16) (p = 0.035). Among the patients who achieved seizure freedom, the most frequently administered dose of PER was 2 mg at 6 (62%, 8/13) and 12 months (64%, 7/11). Levetiracetam was the most frequently administered concomitant AED at both 6 (92%, 12/13) and 12 months (91%, 10/11). CONCLUSION: This retrospective observational study provides evidence supporting the effectiveness of PER as a first add-on therapy in patients with partial epilepsy. Importantly, the seizure-free rate was better when PER was used as a first, rather than a second or later, add-on treatment.

Usefulness of [11C] Methionine PET in the Differentiation of Tumefactive Multiple Sclerosis from High Grade Astrocytoma.

Tumefactive multiple sclerosis (tumefactive MS) is an atypical variant of MS characterized by a large isolated demyelinating lesion. Because tumefactive MS mimics high grade astrocytoma clinically and radiologically, it is difficult to distinguish between the two using only traditional diagnostic modalities, such as routine magnetic resonance imaging. [11C] methionine positron emission tomography (MET PET) has been known as a useful diagnostic tool for glioma. However, it has not been established as a diagnostic tool for tumefactive MS yet. Therefore, the objective of this study was to evaluate the performance of MET PET in differentiating tumefactive MS from high grade astrocytoma. We studied patients with tumefactive MS [six patients (three men, three women), 7 lesions] and 77 patients with astrocytoma (World Health Organization grade II: 13 patients, grade III: 28 patients, and grade IV: 36 patients), and we compared MET uptake of tumefactive demyelinating lesions and astrocytoma. For MET PET analysis, Lesion/Normal region ratios (L/N ratios) were calculated and compared between tumefactive demyelinating lesions and astrocytoma. On MET PET, the L mean/N ratio of tumefactive MS was 1.18 ± 0.50, which was significantly lower than that of high-grade glioma (astrocytoma grade III: 1.95 ± 0.62, P = 0.006; grade IV: 2.35 ± 0.54, P <0.0001). The L maximum (L max)/N ratio of tumefactive demyelinating lesion was also significantly lower than that of high grade astrocytoma (tumefactive MS: 1.89 ± 0.55; astrocytoma grade III: 3.37 ± 1.36, P = 0.0232; astrocytoma grade IV: 4.35 ± 1.30, P <0.0001). In conclusion, MET PET can help differentiate tumefactive MS from high grade astrocytoma.