Transient and permanent magnetic resonance imaging abnormalities after complex partial status epilepticus

Magnetic resonance imaging fingerprints of status epilepticus: A case-control study

OBJECTIVE

Status epilepticus (SE) is frequently associated with peri-ictal magnetic resonance imaging (MRI) abnormalities (PMA). However, the anatomical distribution of these alterations has not been systematically studied. The aim of this study was to assess the localization patterns of PMA in patients with SE.

METHODS

In this prospective case-control study, we compared the distribution and combinations of diffusion-restricted PMA to diffusion-restricted lesions caused by other neurological conditions. All patients of the SE group and the control group underwent MRI including a diffusion-weighted imaging sequence. Patients with SE were imaged within 48 h after its onset.

RESULTS

We enrolled 201 patients (51 with SE and 150 controls). The most frequent locations of PMA in SE were cortex (25/51, 49%), followed by hippocampus (20/51, 39%) and pulvinar of thalamus (10/51, 20%). In the control group, the cortex was involved in 80 of 150 (53%), white matter in 53 of 150 (35%), and basal ganglia in 33 of 150 (22%). In the control group, the pulvinar of thalamus was never affected and hippocampal structures were rarely involved (7/150, 5%). Involvement of the pulvinar of thalamus and the hippocampus had high specificity for SE at 100% (95% confidence interval [CI] = 98-100) and 95% (95% CI = 91-98), respectively. The sensitivity, however, was low for both locations (pulvinar of thalamus: 20%, 95% CI = 10-33; hippocampus: 39%, 95% CI = 26-54).

SIGNIFICANCE

Diffusion-restricted MRI lesions observed in the pulvinar of thalamus and hippocampus are strongly associated with SE. These changes may help physicians in diagnosing SE-related changes on MRI in an acute setting, especially in cases of equivocal clinical and electroencephalographic manifestations of SE.

Brain MRI in status epilepticus: Relevance of findings

Status epilepticus (SE) represents one of the most common neurological emergencies, associated with high mortality and an important risk of functional sequelae in survivors. Magnetic resonance imaging (MRI) offers the possibility of early and noninvasive observation of seizure-induced parenchymal disturbances secondary to the epileptic process. In the present review, we propose a descriptive and comprehensive understanding of current knowledge concerning seizure-induced MRI abnormalities in SE, also called peri-ictal MRI abnormalities (PMAs). We then discuss how PMAs, as a noninvasive biomarker, could be helpful to optimize patient prognostication in SE management. Finally, we discuss alternative promising MRI approaches, including arterial spin labeling (ASL), susceptibility-weighted imaging (SWI), dynamic contrast-enhanced (DCE) MRI and dynamic susceptibility contrast (DSC) MRI that could refine our understanding of SE, particularly in non-convulsive form.

Imaging of status epilepticus: Making the invisible visible. A prospective study on 206 patients

BACKGROUND

Peri-ictal MRI abnormalities (PMA) frequently affect the cerebral cortex, hippocampus, pulvinar of the thalamus, corpus callosum, and cerebellum. In this prospective study, we aimed to characterize the spectrum of PMA in a large cohort of patients with status epilepticus.

METHODS

We prospectively recruited 206 patients with SE and an acute MRI. The MRI protocol included diffusion weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR), arterial spin labeling (ASL), and T1-weighted imaging pre-and post-contrast application. Peri-ictal MRI abnormalities were stratified as either neocortical or non-neocortical. Amygdala, hippocampus, cerebellum, and corpus callosum were regarded as non-neocortical structures.

RESULTS

Peri-ictal MRI abnormalities were observed in 93/206 (45%) of patients in at least one MRI sequence. Diffusion restriction was observed in 56/206 (27%) of patients, which was mainly unilateral in 42/56 (75%) affecting neocortical structures in 25/56 (45%), non-neocortical structures in 20/56 (36%) and both areas in 11/56 (19%) of patients. Cortical DWI lesions were located mostly in frontal lobes 15/25 (60%); non-neocortical diffusion restriction affected either the pulvinar of the thalamus or hippocampus 29/31 (95%). Alterations in FLAIR were observed in 37/203 (18%) of patients. They were mainly unilateral 24/37 (65%); neocortical 18/37 (49%), non-neocortical 16/37 (43%), or affecting both neocortical and non-neocortical structures 3/37 (8%). In ASL, 51/140 (37%) of patients had ictal hyperperfusion. Hyperperfused areas were located mainly in the neocortex 45/51 (88%) and were unilateral 43/51 (84%). In 39/66 (59%) of patients, PMA were reversible in one week. In 27/66 (41%), the PMA persisted and a second follow-up MRI was performed three weeks later in 24/27 (89%) patients. In 19/24 (79%) PMA were resolved.

CONCLUSIONS

Almost half of the patients with SE had peri-ictal MRI abnormalities. The most prevalent PMA was ictal hyperperfusion followed by diffusion restriction and FLAIR abnormalities. Neocortex was most frequently affected especially the frontal lobes. The majority of PMAs were unilateral. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

Quantitative Analysis of Diffusion-Restricted Lesions in a Differential Diagnosis of Status Epilepticus and Acute Ischemic Stroke

Background and Purpose

Distinction between acute ischemic stroke (AIS) and status epilepticus (SE) on MRI can be challenging as restricted diffusion may occur in both conditions. In this study, we aimed to test a tool, which could help in differentiating AIS from SE when restricted diffusion was present on MRI.

Materials and Methods

In diffusion weighted imaging (DWI) with a b-value of 1,000 and apparent diffusion coefficient (ADC) maps, we compared the ratios of intensities of gray values of diffusion-restricted lesions to the healthy mirror side in patients with AIS and SE. Patients were recruited prospectively between February 2019 and October 2021. All patients underwent MRI and EEG within the first 48 h of symptom onset.

Results

We identified 26 patients with SE and 164 patients with AIS. All patients had diffusion-restricted lesions with a hyperintensity in DWI and ADC signal decrease. Diffusion restriction was significantly more intense in patients with AIS as compared to patients with SE. The median ratios of intensities of gray values of diffusion-restricted lesions to the healthy mirror side for DWI were 1.42 (interquartile range [IQR] 1.32–1.47) in SE and 1.67 (IQR 1.49–1.90) in AIS (p < 0.001). ADC decrease was more significant in AIS as compared to SE with median ratios of 0.80 (IQR 0.72–0.89) vs. 0.61 (IQR 0.50–0.71), respectively (p < 0.001). A cutoff value for ratios of DWI signal was 1.495 with a sensitivity of 75% and a specificity of 85%. Values lower than 1.495 were more likely to be associated with SE and higher values were with AIS. A cutoff value for ADC ratios was 0.735 with a sensitivity of 73% and a specificity of 84%. Values lower than 0.735 were more likely to be associated with AIS and higher values were with SE.

Conclusion

Diffusion restriction and ADC decrease were significantly more intense in patients with AIS as compared to SE. Therefore, quantitative analysis of diffusion restriction may be a helpful tool for differentiating between AIS and SE when restricted diffusion is present on MRI.

Evolution of magnetic resonance imaging features in cerebral parenchyma from prolonged focal status epilepticus: a case study

It has rarely been documented that permanent alteration of cerebral structures occurs by focal status epilepticus (FSE). We report the case of a 16-year-old boy with FSE in whom serial T1-weighted magnetic resonance volumetry and conventional magnetic resonance imaging were useful for investigating an evolving pattern of morphological changes during and after the FSE, including cortical laminar necrosis (CLN), increased T2 signal intensities, and marked regional atrophy on the corresponding areas. Despite cessation of FSE after adequate medication (combination therapy including clobazam of 1 mg/kg/day), further significant cerebral atrophy was detected at the limited regions where discrete CLN had occurred during the FSE.

Seizure-induced reversible MRI abnormalities in status epilepticus: A systematic review

In the context of status epilepticus (SE), seizure-induced reversible MRI abnormalities (SRMA) can be difficult to differentiate from epileptogenic pathologies. To identify patterns and characteristics of SRMA, we conducted a systematic review in accordance with the Preferred Items Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included publications describing patients (a) presenting with status epilepticus, (b) exhibiting seizure-induced MRI abnormalities, (c) who demonstrated complete resolution of MRI abnormality at follow-up, and (d) who had availability of descriptive MRI results. A total of 49 cases from 19 publications fulfilled our eligibility criteria. Signal abnormalities were most frequently reported on T2-weighted sequences followed by diffusion-weighted and fluid-attenuated inversion recovery imaging. Both unilateral and bilateral SRMA were reported. Unilateral EEG abnormalities were often associated with ipsilateral SRMA. The signal changes appeared during the ictus itself in some subjects whilst the median time to SRMA appearance and resolution were 24 h and 96.5 days, respectively. Based on the distribution of reversible signal alterations, we identified five 'composite patterns': (1) predominant cortical (with or without subcortical, leptomeningeal or thalamic involvement), (2) hippocampal (with or without cortical, subcortical, leptomeningeal, or thalamic involvement), (3) claustrum, (4) predominant subcortical, and (5) splenium involvement. Amongst treatment-responsive SE patients, the cortical pattern was the most prevalent whereas hippocampal involvement was most frequently reported in refractory SE. Cortical atrophy, hippocampal sclerosis, and cortical laminar necrosis were common long-term sequelae after the resolution of SRMA. In this review, we highlight many limitations of the literature and discuss future directions for research.

Peri-ictal magnetic resonance imaging in status epilepticus: Temporal relationship and prognostic value in 60 patients

PURPOSE

Magnetic resonance imaging (MRI) changes associated with status epilepticus (SE) have been described in recent studies. Our aim was to evaluate the diagnosis and prognosis of the peri-ictal MRI changes detected in SE patients.

METHOD

All adults diagnosed with SE and examined by MRI within 240 h after SE onset were enrolled (2011-2017). Demographic, clinical and electroencephalography data, and functional status at admission and discharge were collected. MRI findings were recorded and relationships between clinical and MRI data, and between these data and functional outcome were analyzed.

RESULTS

Sixty patients included, 50% women, mean age 57.5 years. Median duration of SE was 51.46 h and median time from SE onset to MRI was 86.5 h. Of the total, 41.7% had a restricted diffusion pattern on diffusion-weighted imaging (DWI) and 63.3% had hyperintensities suggestive of edema on T2-weighted (T2WI)/FLAIR sequences. The factors independently associated with T2WI hyperintensities were the presence of acute cerebral lesions (p = 0.023), baseline STESS (p = 0.007), and MRI performed within 84 h (p = 0.007). Variables independently associated with diffusion restriction were a potentially fatal cause (p = 0.020), SE duration >24 h (p = 0.022), and MRI performed within the first 84 h (p = 0.045). In patients undergoing MRI within 84 h, the DWI and T2WI abnormalities were both highly associated with an unfavorable outcome.

CONCLUSIONS

Characteristic signal changes on DWI and T2WI sequences were seen in approximately half our SE patients undergoing early (<84 h) brain MRI studies, and were independently related to the patients' functional status at discharge.

Pharmacotherapy for Refractory and Super-Refractory Status Epilepticus in Adults

Patients with prolonged seizures that do not respond to intravenous benzodiazepines and a second-line anticonvulsant suffer from refractory status epilepticus and those with seizures that do not respond to continuous intravenous anesthetic anticonvulsants suffer from super-refractory status epilepticus. Both conditions are associated with significant morbidity and mortality. A strict pharmacological treatment regimen is urgently required, but the level of evidence for the available drugs is very low. Refractory complex focal status epilepticus generally does not require anesthetics, but all intravenous non-anesthetizing anticonvulsants may be used. Most descriptive data are available for levetiracetam, phenytoin and valproate. Refractory generalized convulsive status epilepticus is a life-threatening emergency, and long-term clinical consequences are eminent. Administration of intravenous anesthetics is mandatory, and drugs acting at the inhibitory gamma-aminobutyric acid (GABA)_A receptor such as midazolam, propofol and thiopental/pentobarbital are recommended without preference for one of those. One in five patients with anesthetic treatment does not respond and has super-refractory status epilepticus. With sustained seizure activity, excitatory N-methyl-d-aspartate (NMDA) receptors are increasingly expressed post-synaptically. Ketamine is an antagonist at this receptor and may prove efficient in some patients at later stages. Neurosteroids such as allopregnanolone increase sensitivity at GABA_A receptors; a Phase 1/2 trial demonstrated safety and tolerability, but randomized controlled data failed to demonstrate efficacy. Adjunct ketogenic diet may contribute to termination of difficult-to-treat status epilepticus. Randomized controlled trials are needed to increase evidence for treatment of refractory and super-refractory status epilepticus, but there are multiple obstacles for realization. Hitherto, prospective multicenter registries for pharmacological treatment may help to improve our knowledge.

An exploration of the spectrum of peri-ictal MRI change; a comprehensive literature review

PURPOSE

The aim of this review was to identify published studies in the literature relating to ictal induced MRI change and to identify certain common themes, practical points for clinicians and areas for future research.

METHODS

We identified 96 articles that satisfied our inclusion criteria yielding 575 cases. All articles were analysed; number of subjects, spectrum of MRI and EEG change, aetiology, and follow-up (both clinical and imaging) were noted.

RESULTS

The most frequent imaging changes were restricted diffusion, T2-hyperintensity and reduced ADC values. The mesial temporal structures and neocortex were most commonly affected locations though subcortical structures like the thalamus and pulvinar were also described. Practical clinical points included; the development of PLEDS concordant with ictal imaging change was associated with worse clinical prognosis, patients with seizures due to symptomatic aetiology may be more likely to develop ictal related imaging change and follow up is vitally important to ensure that ictal related oedema is not misidentified as a mass lesion or conversely that a mass lesion is not misidentified as ictal related change.

CONCLUSION

Qualitative MRI studies have provided clinicians with useful in-vivo insights into the dynamic ictal neuronal environment. Changes are not only localised to the ictal focus but can be remote and irreversible. Small patient numbers varying study design and high numbers of symptomatic seizures makes comparison between studies problematic. Also there is possible microstructural quantitative MRI changes that are missed on qualitative MRI. There is a need for prospective quantitative MRI studies in patients with epilepsy peri-icatlly with a uniform period of follow up and comparison to control data.

Management of status epilepticus

Status epilepticus is a neurologic and medical emergency manifested by prolonged seizure activity or multiple seizures without return to baseline. It is associated with substantial medical cost, morbidity, and mortality. There is a spectrum of severity dependent on the type of seizure, underlying pathology, comorbidities, and appropriate and timely medical management. This chapter discusses the evolving definitions of status epilepticus and multiple patient and clinical factors which influence outcome. The pathophysiology of status epilepticus is reviewed to provide a better understanding of the mechanisms which contribute to status epilepticus, as well as the potential long-term effects. The clinical presentations of different types of status epilepticus in adults are discussed, with emphasis on the hospital course and management of the most dangerous type, generalized convulsive status epilepticus. Strategies for the evaluation and management of status epilepticus are provided based on available evidence from clinical trials and recommendations from the Neurocritical Care Society and the European Federation of Neurological Societies.

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".

Status epilepticus in adults

Status epilepticus is a common neurological emergency with considerable associated health-care costs, morbidity, and mortality. The definition of status epilepticus as a prolonged seizure or a series of seizures with incomplete return to baseline is under reconsideration in an effort to establish a more practical definition to guide management. Clinical research has focused on early seizure termination in the prehospital setting. The approach of early escalation to anaesthetic agents for refractory generalised convulsive status epilepticus, rather than additional trials of second-line anti-epileptic drugs, to avoid neuronal injury and pharmaco-resistance associated with prolonged seizures is gaining momentum. Status epilepticus is also increasingly identified in the inpatient setting as the use of extended electroencephalography monitoring becomes more commonplace. Substantial further research to enable early identification of status epilepticus and efficacy of anti-epileptic drugs will be important to improve outcomes.

Diffusion imaging in epilepsy

Epilepsy is the most common serious neurological disease. Seizures are refractory to medication in approximately 30% of patients with focal epilepsy, and surgical treatment is potentially curative should the epileptic focus be accurately localized. MRI has revolutionized the investigation of such patients; however, up to 20% of patients with refractory focal epilepsy have an undetermined etiological basis for their epilepsy despite extensive investigation. Diffusion imaging is an advanced MRI technique that is sensitive to the molecular displacement of water molecules and provides additional information on the microstructural arrangement of tissue. Both qualitative and quantitative analyses of the interictal and peri-ictal states are possible and provide valuable insights into the epileptic brain in vivo. Furthermore, advanced postacquisition processing can reveal additional information on, for example, anatomical connectivity. The description, application and limitations of diffusion imaging in epilepsy are the focus of this review. Future directions of research required in this area are also discussed in the context of existing literature.

Nonconvulsive status epilepticus: the encephalopathic pediatric patient

OBJECTIVE

A high prevalence of nonconvulsive status epilepticus (NCSE) has been reported in critically ill adults and neonates. Recent prospective pediatric studies focus on critically ill children and show wide variability in the frequency of NCSE. This study examines prevalence of pediatric NCSE regardless of inpatient setting and retrospectively identifies risk factors indicating a need for urgent continuous EEG.

METHODS

Medical records from patients aged 3 months to 21 years were identified either by (1) searching a clinical EEG database (n = 18) or (2) consecutive inpatient EEG referrals for NCSE over an 8-month period (n = 57).

RESULTS

Seventy-five children, mean age of 7.8 years, were studied. NCSE was identified in 26 patients (35%) and in 8 of 57 (14%) patients referred for possible NCSE. More than half of the patients referred were outside of the ICU. A witnessed clinical seizure was observed in 24 of 26 (92%) patients with NCSE. Acute cortical neuroimaging abnormalities were significantly more frequent in patients with NCSE. The presence of clinical seizures and acute neuroimaging abnormality was associated with an 82% probability of NCSE. All but 1 patient with NCSE had electrographic or electroclinical seizures within the first hour of monitoring.

CONCLUSIONS

A high prevalence of NCSE was observed, comparable to adult studies, but within a wider range of inpatient settings. Children with acute encephalopathy should undergo continuous EEG. This evaluation is more urgent if certain clinical risk factors are present. Optimal duration of monitoring and the effect of NCSE on prognosis should be studied.

Update on neuroimaging in epilepsy

Neuroimaging in epilepsy is a very large and growing field. Researchers in this area have quickly adopted new methods, resulting in a lively literature. Basic features of common epilepsies are well known, but, outside of the specific area of epilepsy surgery evaluation, new methods evolving in the last few years have had limited new beneficial clinical impact. Here, an overview of the epilepsy neuroimaging literature of the last 5 years, with an emphasis on mesial temporal lobe epilepsy, idiopathic generalized epilepsies, presurgical evaluation and new developments in functional MRI is presented. The need for attention to clinical translation, as well as immediate opportunities and future trends in this field, are discussed.

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities (TPMA) remains largely unclear. This prompted us to perform a prospective observational cohort study, including electroencephalography (EEG) and multi-sequence MRI, in 19 consecutive patients (8 female, mean age 51.7 years) with TPMA induced by convulsive and non-convulsive status epilepticus (n=14) or isolated seizures. TPMA were associated with focal, lateralized or diffuse EEG abnormalities, and were mostly focal unilateral and cortico-subcortical (n=11), less frequently cortically restricted, bilateral, hemispheric and with remote lesions (pulvinar, cerebellum); 66.7% had cortico-pial contrast enhancement and 93.7% restriction on diffusion-weighted imaging, with cortical cytotoxic edema on apparent-diffusion coefficient, only tumor-like TPMA (n=5) presenting noticeable subcortical vasogenic edema. The heterogeneity of clinical, EEG and MRI findings contributed to a 38.6% strict focal topographic concordance between them, with the more widespread findings also attributable to the time lag between studies, seizure dynamics/etiologies and cerebral reserve. At follow-up (mean duration 29.6 months, 3-120), the brain damage induced by TPMA was responsible for a high incidence of clinical and MRI sequelae (63.2%), only tumor-like/small TPMA induced by acute symptomatic seizures presenting good clinical outcomes. Our findings may contribute to a better definition and comprehension of the TPMA electroclinical-imagiological spectrum, pathophysiology and long-term outcome.

Arterial spin labeling demonstrates that focal amygdalar glutamatergic agonist infusion leads to rapid diffuse cerebral activation

OBJECTIVES

To investigate acute effects of intra-amygdalar excitatory amino acid administration on blood flow, relaxation time and apparent diffusion coefficient in rat brain.

MATERIALS AND METHODS

Several days after MR-compatible cannula placement in right basolateral amygdala, anesthetized rats were imaged at 7 T. Relative cerebral blood flow (CBF) was measured before and 60 min after infusion of 10 nmol KA, cAMPA, ATPA, or normal saline using arterial spin labeling. Quantitative T(2) and diffusion-weighted images were acquired. rCBF, T(2) and ADC values were evaluated in bilateral basolateral amygdala, hippocampus, basal ganglia, frontal and parietal regions.

RESULTS

KA led to the highest, and ATPA lowest bilateral rCBF increases. Time courses varied among drugs. T(2) for KA and AMPA was higher while ADC was lower for KA.

CONCLUSIONS

Intra-amygdalar injection of GluR agonists evoked bilateral seizure activity and increased rCBF, greater for KA and AMPA than selective ATPA GluR5 activation.

Current themes in neuroimaging of epilepsy: brain networks, dynamic phenomena, and clinical relevance

Brain scanning methods were first applied in patients with epilepsy more than 30years ago. A very substantial literature now exists in this field, which is exponentially increasing. Contemporary neuroimaging studies in epilepsy reflect new concepts in the epilepsies, as well as current methodological developments. In particular, this area is emphasising the role of networks in epileptogenicity, the existence of dynamic phenomena which can be captured by imaging, and is beginning to validate the implementation of neuroimaging in the clinic. Here, recent studies of the last 5years are reviewed, covering the full range of neuroimaging methods with SPECT, PET and MRI in epilepsy.

De novo epileptic confusion in the elderly: a 1-year prospective study

PURPOSE

Nonconvulsive status epilepticus (NCSE) is clinically difficult to diagnose, especially in old patients without epilepsy, and requires electroencephalography (EEG) for diagnosis. Its incidence among elderly patients with confusion of unknown origin (CUO) remains undetermined.

METHODS

A 1-year prospective study was conducted in patients aged 60 years or older, for whom EEG was requested because of confusion considered to be of unknown origin after initial clinical, biologic, and imaging investigations. Diagnosis criteria included a validated clinical assessment scale to confirm confusion.

RESULTS

Of 44 patients with confirmed CUO, 7 presented with de novo NCSE. NCSE population had a mean age of 76 years (range, 60-97 years). No statistically significant differences were found between NCSE patients and others for age, drugs, presence of myoclonia, eyelid myoclonia, tachycardia, or agitation. In contrast, an acute onset (<24 h), gender (100% female among NCSE patients), and lack of clinical response to simple commands were significantly associated with NCSE. No differences between the two groups were evidenced for mortality and morbidity (length of hospitalization, social outcome, and so on).

DISCUSSION

Almost 16% of patients aged 60 or older with confusion of unknown origin had NCSE, according to this first prospective study. Female patients with rapid onset (<24 h) of symptoms and lack of response to simple commands were at a higher risk of presenting with NCSE.

Periictal magnetic resonance imaging in status epilepticus

PURPOSE

To determine the changes of magnetic resonance imaging (MRI) during the periictal phase in status epilepticus (SE).

PATIENTS AND METHODS

We identified 15 patients diagnosed of status epilepticus with corresponding MRI changes, including 11 patients with generalized convulsive status epilepticus (GCSE), 2 with complex partial status epilepticus (CPSE), and 2 with simple partial status epilepticus (SPSE). All MRI changes, corresponding electroencephalogram, and prognosis were evaluated.

RESULTS

Regional cortical lesions were observed on MRI, including restricted diffusion in diffusion-weighted images (DWIs) (11 out of 15) and hyperintense signal change in fluid-attenuated inversion recovery (FLAIR) images (12 out of 15) with hypervascularity and parenchymal swelling. The remote lesions included crossed cerebellar diaschisis (3 patients), ipsilateral thalamic lesion (4 patients), and basal ganglia lesions (3 patients). Although the periictal MRI changes were usually reversible, irreversible changes were also found, especially in GCSE, such as focal brain atrophy, cortical laminar necrosis, and mesial temporal sclerosis. GCSE patients with periodic epileptic form discharges had higher possibilities of widespread MRI abnormalities and poor prognosis in the future.

CONCLUSIONS

In this study, DWIs and FLAIR images were proved useful in determining the extent and severity of early neuronal damage caused by epileptic discharges in SE patients. Seizure-induced long-term injuries were also observed in the follow-up MRI.

Seizure-induced inflammation in focal cortical dysplasia resulting in imaging progression that simulates neoplasia

A 5-year-old girl with previously well-controlled partial epilepsy secondary to focal cortical dysplasia (FCD) developed an increase in seizure frequency. Two months later, magnetic resonance showed a substantial alteration in lesion imaging characteristics. The lesion was resected. FCD was confirmed but inflammatory changes were also present. We propose that chronic inflammation was induced by unremitting seizure activity and suggest that inflammation may be implicated as a basis for alteration in the imaging characteristics of FCD.

Hippocampal sclerosis and status epilepticus: cause or consequence? A MRI study

BACKGROUND

Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in status epilepticus. These abnormalities can be followed by hippocampal sclerosis.

CASE REPORT

We report a 15-year-old lady with focal non convulsive status epilepticus (NCSE) and focal slowing on EEG. DWI exhibited abnormal hyperintense signals in bilateral temporal and insular cortices. After 3 weeks, MRI performed a localizated hippocampal atrophy.

CONCLUSION

The MRI findings indicated vasogenic and cytotoxic edema during seizure activity and subsequent loss of brain parenchyma.

MR imaging-compatible electroencephalography electrode system for an epilepsy monitoring unit

We studied the usefulness of an MR imaging-compatible electroencephalography (EEG) electrode system for continuous EEG recordings in our epilepsy monitoring unit (EMU) by comparing 100 consecutive patients with MR imaging-compatible and MR imaging-incompatible EEG recording electrodes who underwent MR imaging between 3:00 pm and 7:00 am. The MR imaging-compatible system captured seizures in 21/50 (42%) patients and clinically valuable new electrographic data in 13/50 (26%) patients during the study interval, whereas possible seizures were lost to recording in 19/50 (38%) patients in the MR imaging-incompatible system. EEG recording was comparable by both systems, but the nurses could disconnect and reconnect the patients to their electrode cables only in the MR imaging-compatible system during the study interval while the EEG technologists were off duty. This study shows that the MR imaging-compatible system could be used routinely for long-term monitoring of the patients in EMUs.

Epileptiform synchronization in the rat insular and perirhinal cortices in vitro

The hippocampus plays a primary role in temporal lobe epilepsy, a common form of partial epilepsy in adults. Recent studies, however, indicate that extrahippocampal areas such as the perirhinal and insular cortices represent important participants in this epileptic disorder. By employing field potential recordings in the in vitro 4-aminopyridine model of temporal lobe epilepsy, we have investigated here the contribution of glutamatergic and GABAergic signaling to epileptiform activity in these structures. First, we provide evidence of epileptiform synchronicity between the perirhinal and insular cortices, and resolve some pharmacological and network mechanisms involved in sustaining the interictal- and ictal-like discharges recorded there. Second, we report that in the absence of ionotropic glutamatergic transmission, GABAergic networks produce synchronous potentials that spread between the perirhinal and insular cortices. Finally, we have established that such activity is modulated by activating micro-opioid receptors. Our findings support clinical and experimental evidence concerning the involvement of the perirhinal and insular cortex networks in temporal lobe epilepsy, and provide observations that may impact research focussing on the role of the insular cortex in nociception.

Irreversible brain injury following status epilepticus

Described here is a patient with medically intractable generalized epilepsy who developed status epilepticus (SE) affecting his right cerebral hemisphere for about 48 hours, which led to irreversible injury to that hemisphere. His partial SE did not respond to the first-line therapies, repeated doses of midazolam, or continuous intravenous infusion of propofol. Extensive investigations failed to find a cause of his SE except for a low serum valproic acid. A minor trauma that he suffered 1 week prior to his SE was of questionable significance. Neurological examination, neuropsychological testing, electroencephalography, and magnetic resonance imaging all demonstrated striking abnormalities limited to the affected cerebral hemisphere that did not resolve with repeated testing. This case illustrates permanent focal brain injury following prolonged partial SE in a patient with previously known generalized seizure disorder.

Nonconvulsive status epilepticus manifesting as pure alexia (alexia without agraphia)

Pure alexia is a rare disorder usually caused by an ischemic or hemorrhagic stroke. We describe a case of pure alexia due to nonconvulsive status epilepticus (NCSE). This 57-year-old man presented in a hyperosmolar, nonketotic state with fluctuations in mental status and an inability to read. His EEG was diagnostic of NCSE originating from the left temporo-occipital region. MRI of the brain revealed increased FLAIR signal over the left occipitotemporal region. Following initiation of antiepileptic treatment, his neurological examination normalized concomitantly with resolution of the NCSE. A follow-up MRI scan of the brain obtained 1 month later was normal. NCSE can have unusual clinical manifestations, and a high index of suspicion is necessary to correctly diagnose these patients.

Non-convulsive status epilepticus in adults: clinical forms and treatment

Non-convulsive status epilepticus (NCSE) is one of the great diagnostic and therapeutic challenges of modern neurology. Because the clinical features of this disorder may be very discrete and sometimes hard to differentiate from normal behaviour, NCSE is usually overlooked and consequently not treated properly. It is important to be familiar with the clinical subtypes such as absence, simple and complex partial, and subtle status epilepticus because each requires tailored management. In order to improve overall care of patients with NCSE, strict diagnostic criteria are needed that should be based on clinical alterations and ictal electroencephalographic changes. NCSE should be terminated rapidly to prevent patients from serious injuries, particularly if consciousness is impaired.