Successful epilepsy surgery in catastrophic postencephalitic epilepsy

Neurosurgery in canine epilepsy

Epilepsy surgery is functional neurosurgery applied to drug-resistant epilepsy. Although epilepsy surgery has been established and achieves fair to good outcomes in human medicine, it is still an underdeveloped area in veterinary medicine. With the spread of advanced imaging and neurosurgical modalities, intracranial surgery has become commonplace in the veterinary field, and, therefore, it is natural that expectations for epilepsy surgery increase. This review summarizes current standards of intracranial epilepsy surgery in human medicine and describes its current status and expectation in veterinary medicine. Intracranial epilepsy surgery is classified generally into resection surgery, represented by cortical resection, lobectomy, and lesionectomy, and disconnection surgery, such as corpus callosotomy and multiple subpial transection. In dogs with drug-resistant epilepsy, corpus callosotomy is available as a disconnection surgery for generalized epilepsy. However, other types of disconnection and resection surgeries for focal epilepsy are limited to experimental studies in laboratory dogs and/or anecdotal case reports of lesionectomy, such as tumor or encephalocele removal, without epileptogenic evidence. Veterinary epilepsy surgery is a new and challenging neurosurgery field; with the development of presurgical evaluations such as advanced electroencephalography and neuroimaging, it may become more readily practiced.

Efficacy and potential predictors of vagus nerve stimulation therapy in refractory postencephalitic epilepsy

BACKGROUND

Vagus nerve stimulation (VNS) is a therapeutic approach for patients with refractory postencephalitic epilepsy (PEE), which is characterized by drug resistance and disappointing surgical outcomes. However, the efficacy of VNS has not yet been studied in patients with refractory PEE. The present study aimed to demonstrate the efficacy of VNS and evaluate potential clinical predictors in patients with refractory PEE.

METHODS

We retrospectively collected the outcomes of VNS with at least a 1-year follow-up in all patients with refractory PEE. Subgroups were classified as responders and non-responders according to the efficacy of VNS (⩾50% or < 50% reduction in seizure frequency). Preoperative data were analyzed to screen for potential predictors of VNS responsiveness.

RESULTS

A total of 42 refractory PEE patients who underwent VNS therapy were enrolled, with an average age of 21.13 ± 9.70 years. Seizure frequency was reduced by more than 50% in 64.25% of patients, and 7.14% of patients achieved seizure-free events after VNS therapy. In addition, the response rates increased over time, with 40.5%, 50.0% and 57.1%, respectively at 6 months, 12 months, and 24 months after VNS therapy. Preoperative duration of epilepsy, monthly seizure frequency, and spatial distribution of interictal epileptic discharges (IEDs) were correlated with responders (p < 0.05) in the univariate analysis. Further multivariate regression analysis demonstrated that refractory PEE patients with high monthly seizure frequency or Focal IEDs (focal or multifocal epileptiform discharges) achieved better efficacy on VNS (p = 0.010, p = 0.003, respectively).

CONCLUSION

VNS is an effective palliative therapy for patients with refractory PEE. Focal IEDs (focal or multifocal epileptiform discharges) and high seizure frequency were potential preoperative predictors of effectiveness after VNS therapy.

Predictors of Seizure Freedom in Patients Undergoing Surgery for Central Nervous System Infection-Related Epilepsy: A Systematic Review and Meta-Analysis

Objective: Central nervous system infections (CNSIs), especially viral encephalitis and meningitis, are well-recognized causes of medically refractory epilepsy. Although surgery is an effective and durable intervention against these infections, the seizure control outcomes described in previous surgical series have been variable. Accordingly, it is not clear which variables are most valuable in predicting seizure control following surgery for CNSI. The aim of this meta-analysis was to identify the predictors of favorable surgical outcomes in CNSI-related epilepsy.

Methods: The PubMed, EMBASE, Cochrane Library, WANGFANG, VIP, CBM, and CNKI databases were searched for studies according to the inclusion criteria. Prognostic factors, surgical outcomes, and patient characteristics were extracted. Heterogeneity was detected by the I² and Q statistics.

Results: Seventeen studies were included in our meta-analysis. Eight predictors of favorable outcomes (Engel Class I/II) were determined, including abnormal MRI findings, meningitis, temporal location only, regional ictal pattern, unilateral ictal pattern, older age at epilepsy, longer silent period, and longer time from infection, as follows: OR = 3.34 (95% CI 1.44–7.74), OR = 0.31 (95% CI 0.13–0.70), OR = 0.34 (95% CI 0.16–0.74), OR = 5.65 (95% CI 1.75–18.30), and OR = 9.53 (95% CI 2.36–38.48), respectively, and MD = 2.15 (95% CI 0.20–4.11), MD = 2.40 (95% CI 0.09–4.70), and MD = 8.49 (95% CI 1.50–15.48), respectively. A subgroup analysis found the following associations: regional and unilateral ictal patterns in viral encephalitis, a younger age at infection in parasitic encephalopathy, an older age at surgery, a longer time from onset, and a longer time from infection in unexplained meningitis. A sensitivity analysis restricted to studies that included each variable yielded robust results. Little evidence of publication bias was observed.

Conclusions: This meta-analysis suggests that abnormal MRI findings, meningitis, temporal location only, regional and unilateral ictal patterns, older age at epilepsy, longer silent period, and longer time from infection are predictive factors in patients with favorable surgical outcomes in CNSI-related epilepsy. In addition, different infective agents influenced the results in regional and unilateral ictal patterns in ictal electroencephalography, as well as the relationship between age at infection and surgery and the time from epilepsy onset and infection.

Perisylvian vulnerability to postencephalitic epilepsy

OBJECTIVE

Postencephalitic epilepsy is often resistant to antiseizure medications, leading to evaluation for epilepsy surgery. Characterizing its localization carries implications for optimal surgical approach. We aimed to determine whether a prior history of encephalitis is associated with specific epileptogenic networks among patients with drug resistant epilepsy undergoing stereotactic EEG (SEEG).

METHODS

We conducted a retrospective cohort study of drug resistant epilepsy, with and without a prior history of encephalitis. We analyzed SEEG recordings to identify patterns of seizure onset and organization. Seventeen patients with a history of encephalitis (of infectious etiology in two subjects) were identified from a database of patients undergoing SEEG and were compared to seventeen drug-resistant epilepsy controls without a history of encephalitis matched for confounding variables including pre-implantation hypotheses, epilepsy duration, age, and sex.

RESULTS

Independent bilateral seizures were noted in 65% of the postencephalitic epilepsy cohort. We identified four SEEG-ictal patterns in patients with a prior history of encephalitis: (1) anteromesial temporal onset (24%), (2) anteromesial temporal onset with early spread to the perisylvian region (29%), (3) perisylvian (59%) and (4) synchronized anteromesial temporal and perisylvian (29%) onsets. Patterns 3 and 4, with perisylvian involvement at onset, were unique to the encephalitis group (p = 0.0003 and 0.04 respectively) and exhibited a "patchwork" organization. None of the encephalitis patients vs 5/7 matched controls had Engel I outcome (p = 0.0048).

CONCLUSIONS

Postencephalitic epilepsies involve anteromesial temporal and perisylvian networks, often in a bilateral independent manner. Unique ictal patterns involving the perisylvian regions was identified in the encephalitis group, but not in the matched control group.

SIGNIFICANCE

These findings may reflect a selective vulnerability of the perisylvian regions to epilepsy resulting from encephalitis, significantly mitigating the chances of success with SEEG-guided temporal resections.

Surgical treatment in children with intractable epilepsy after viral encephalitis

PURPOSE

To investigate the surgical outcome in children with epilepsy after viral encephalitis (VE), we studied the prognostic factors for surgery and summarized the surgical strategies of children with epilepsy secondary to VE.

METHODS

We retrospectively analyzed 23 surgically treated children with VE. The subjects were divided into two groups according to their surgical outcome. All presurgical evaluation data were collected and analyzed.

RESULTS

Among the 23 operated children, the mean age at surgery was 6.1 years. Surgeries were hemispherotomy (n = 12), temporal-parietal-occipital disconnection (n = 4), whole corpus callosotomy (n = 3), lobectomy (n = 3), and vagus nerve stimulation (n = 1). The mean patient follow-up time was 37.2 months, and 13 children had a good outcome (ILAE classification 1-3). Univariate analyses revealed that the latency from infection to the first unprovoked seizure, MRI laterality, concordance of PET and MRI abnormalities, and acute postoperative seizure (APOS) were prognostic factors of seizure outcomes (P < 0.05). No correlation was found between generalized seizures and poor outcome (P = 0.229).

CONCLUSIONS

We concluded that the children who achieve favorable surgical outcomes are those with longer latency, unilateral abnormalities on MRI, consistency of PET and MRI abnormalities, and no APOS. Without invasive studies, epilepsy surgery may be successful for selected children with epilepsy after VE, despite diffuse interictal epileptiform discharges on scalp EEG. In addition, children with generalized seizures were not an absolute contraindication for surgery.

Clinical features and surgical treatment of epilepsy after viral encephalitis

Encephalitis is an acute inflammatory process of the brain parenchyma, which is often caused by viral infection. It is an vital cause of acute symptomatic seizures and subsequent epilepsy. The incidence of unprovoked and recurrent seizures after previous infections of the central nervous system is high and accounts for 1%~5% of the cases of epilepsy. Viral encephalitis (VE) is directly caused by viral infection. The occurrence of seizures after VE is associated with poor prognosis. In survivors of VE, among other neurological sequelae, the risk of developing epilepsy is increased 10-fold. The risk of severe neurological sequelae after VE is particularly high in very young children. Studies on seizure occurrence, possible underlying mechanisms, clinical characteristics, and clinical treatment (especially surgical treatment) of VE have yielded only limited detailed data. We reviewed the most recent literature on the clinical features and surgical treatment of post-VE epilepsy.

Chronic post-encephalitic epilepsy following Japanese encephalitis: Clinical features, neuroimaging data, and outcomes

PURPOSE

Japanese encephalitis (JE), the main cause of viral encephalitis in Asia, usually presents with acute symptomatic seizures; however, there have been very few systematic reports regarding late unprovoked seizures and epilepsy. We aimed to describe the clinical features and outcomes of post-encephalitic epilepsy following JE.

METHODS

Patients with epilepsy with a previous confirmed diagnosis of JE visiting West China Hospital from 2013 to 2019 were enrolled in the observational case-controlled study. Patients with epilepsy with a history of other non-specific viral encephalitis were enrolled as controls. For all enrolled subjects, disease related information was recorded.

RESULTS

Forty-eight patients with JE (20 males; median age, 21.0 years; average epilepsy duration, 8.55 years) were identified. The median duration from JE to the first unprovoked seizure was 7.73 years, which significantly differed from that of the controls (7.73 vs. 2.69 years, respectively; p = 4.59 × 10^-6). Most patients had focal epilepsy, and 29 (78.38%) were drug resistant. Among 45 patients with available neuroimaging data, three in fourth had no obvious abnormality, and the temporal lobe and hippocampus (22.22%) were the most affected brain regions. Six patients had surgery, and three achieved class-one seizure-free status.

CONCLUSION

The latency to the first unprovoked seizure was longer in patients with JE than controls. Regarding chronic epilepsy, three in four had structural abnormalities, and the long-term outcomes of post-encephalitic epilepsy following JE were poor. Surgery remains an option for drug-resistant epilepsy.

Surgical outcomes in patients with epilepsy after viral encephalitis: contribution of SEEG study

Background

Nowadays, few surgery analysis has been reported in cases of epilepsy after viral encephalitis(VE). Herein, this study was to evaluate the efficacy of surgery and capability of stereoelectroencephalography (SEEG) in the definition of the epileptogenic zone (EZ) after VE, and also to explore the relationship between the SEEG features and the surgical outcomes.

Methods

We retrospectively analyzed 10 surgically treated patients that identified to suffer from epilepsy secondary to VE using SEEG, and investigated the SEEG features associated with surgical outcomes in these patients. Besides visual analysis, we used the epileptogenicity index (EI), a semi-quantitative and supplementary tool to evaluate the validity of SEEG in the context of VE.

Results

Among the 10 operated patients, 3 of them became completely seizure-free. The patients who got totally seizure free or significant improvement, the seizure onset was located either in the antero-mesial temporal structures or focal gyrus; patients who got worthwhile improvement or no improvement, the seizure started from multiple brain lobes. The number of electrodes classified as epileptogenic visually involved were closely correlated with EI positive onses.Anatomic areas defined and shown as EZ on MRI by visual assessment were also defined as epileptogenic by the EI in these cases.

Conclusion

Apart from exploring the surgical outcome related to epilepsy after VE, we also bring insight into the relationship between the SEEG features and surgical outcome with the application of the supplementary methods.

Recurrent nonconvulsive status epilepticus in a patient with progressive left hemispheric leukoencephalopathy after a remote viral meningoencephalitis

Nonconvulsive status epilepticus (NCSE), defined as changes in behavior and/or mental processes from baseline with continuous epileptiform discharges, remains a diagnostic and treatment challenge. Here, we present a 68-year-old female who developed 3 episodes of NCSE 10 years after a viral meningoencephalitis which gradually progressed to left hemispheric leukoencephalopathy. In this case, we hypothesize that immune-mediated mechanisms and perhaps genetic predisposition played a role in epileptogenesis, and these will be discussed. This article is part of a Special Issue entitled "Status Epilepticus".

Risk factors for postencephalitic epilepsy in children: a hospital-based study in Taiwan

To identify clinical, neurophysiological and neuroradiological features in acute encephalitis with predictive value for postencephalitic epilepsy (PEE) in children, a retrospective cohort study by following up 0-17-year-old children with the diagnosis of acute encephalitis was done. Total 330 children were enrolled. Of these, 54 (16.4%) developed epilepsy with a mean follow-up period of 6+/-4.6 years, and 79.6% had the diagnosis of epilepsy within six months after encephalitis. Significant risk factors for PEE include the presence of recurrent seizures, status epilepticus, severe disturbance of consciousness, the existence of focal neurological sign, and the presence of neurological deterioration during hospitalization. Patients with abnormal electroencephalogram, including focal (P<0.05), or profound cerebral dysfunction (P<0.001), and focal cortical abnormalities in neuroimaging (P<0.01), also have higher incidence of epilepsy. Furthermore, children with refractory status epilepticus at presentation also significantly increased the possibility of intractable PEE (P<0.01). We concluded that PEE is not a rare complication of acute encephalitis. Children with refractory status epilepticus or poor control of seizures are more likely to have intractable PEE.

Devastating epileptic encephalopathy in school-aged children (DESC): A pseudo encephalitis

PURPOSE

To describe the characteristics of a previously overlooked devastating epileptic encephalopathy that presents as intractable bilateral perisylvian epilepsy starting with prolonged status epilepticus (SE) in normally developing school-aged children.

METHODS

Retrospective study over 7 years of all normally developing children admitted in our institution for a prolonged SE following non-specific febrile illness with at least one seizure recorded on EEG.

RESULTS

Fourteen children were included at a median age of 7.5 years (4-11) (median follow-up of 4 years (1-7)). Intractable SE lasted 4-60 days (median 30). CSF cell count was normal in five cases and moderately increased in the others. During SE, seizures were recorded in 11 patients and involved temporal lobes in 7; the other 4 patients exhibited perisylvian clinical features with secondary generalization. Intractable epilepsy followed SE in all cases without any latent period. Persisting seizures were recorded in 10 patients and involved temporo-perisylvian regions in 8, frontal regions in 2; 3 others had perisylvian ictal semiology. Spiking was bilateral in 10 cases. MRI showed bilateral hippocampal hypersignal and/or atrophy in 10 cases (extended to the neocortex in 3). All children had major cognitive sequelae. When feasible (six patients), detailed neuropsychology suggested fronto-temporal impairment.

CONCLUSIONS

Among so called grey matter encephalitis patients, we identified a recognizable pattern we propose to call Devastating Epileptic encephalopathy in School-age Children (DESC) that begins with prolonged SE triggered by fever of unknown cause, and persists as intractable perisylvian epilepsy with severe cognitive deterioration.

Childhood febrile convulsions--which factors determine the subsequent epilepsy syndrome? A retrospective study

To analyze the spectrum of epilepsy syndromes which follow childhood febrile convulsions (FC) and to examine whether retrospective analysis of clinical features of the FC enables discrimination of patients who develop temporal lobe epilepsy (TLE) from those who develop generalized epilepsy (GE). One hundred and thirteen patients with epilepsy and antecedent FC were retrospectively analyzed. We inquired in detail about the clinical characteristics of FC (age, duration, number, focal symptoms) as well as family history, birth history, neurological status, and psychomotor development before onset of FC. Forty five (39.8%) patients had TLE, 41 (36.6%) GE, and 27 (23.9%) had extratemporal epilepsy (ETE). Patients with TLE had a significantly longer duration of FC (P< or =0.001), more often focal features (P< or =0.001), and febrile status epilepticus (P< or =0.001) than patients with GE. Age at FC, Number of FC, family history, birth history and neurological status at FC did not differ between groups. A stepwise discriminant model allowed correct assignment after cross validation in 84.2% to TLE and in 100% to GE. A broad spectrum of epilepsy syndromes follow FC. We found a strong association of prolonged and focal FC with later development of TLE. Short generalized FC were associated with GE.

Severe Amnesia in Epilepsy: Causes, Anatomopsychological Considerations, and Treatment

Severe amnesia in epileptic patients is a catastrophic condition that may be due to different etiologies. Because of the striking findings and thorough neuropsychological studies of Patient H.M., the literature has focused on postsurgical occurrence of such memory impairment, with much less emphasis on other causes. Here we summarize, for comparison, the history of H.M. We report five patients with pronounced memory loss who had extensive neuropsychological and electroencephalographic testing. MRI was also performed in four of the patients, MRI volumetric measurements of amygdala and hippocampal formation in three, and measurements of entorhinal cortex in two. The amnesia occurred after head trauma in one patient, following encephalitis in one, after partial status epilepticus in two, and after unilateral surgical resection in a woman with bilateral lesions. On the basis of these studies it was impossible to distinguish the role of recurrent temporal lobe epileptic seizures as distinct from underlying lesions in the genesis and course of the memory loss. We review here the anatomical substrate, neuropsychological, and other investigations and the etiological factors leading to the amnesia in these patients, together with current concepts regarding possible causes of such severe memory dysfunction. In patients with this degree of severity of memory deficit, temporal resection in an attempt to control seizures did not lead to a measurable increase in memory problems. It also, however, did not bring about worthwhile improvement in seizure control.