Diagnostic imaging in 13 cases of Rasmussen's encephalitis: can early MRI suggest the diagnosis?

Association of Cortical Atrophy Patterns With Clinical Phenotypes and Histopathological Findings in Patients With Rasmussen Syndrome

BACKGROUND AND OBJECTIVES

Automated MRI analyses have identified variable patterns of cortical atrophy in Rasmussen syndrome. In this study, we aim to identify imaging phenotypes of Rasmussen syndrome, to clinically characterize these phenotypes, and to validate this imaging-based approach through histopathologic analysis.

METHODS

For this retrospective case-control study, individuals with Rasmussen syndrome diagnosed according to the European Consensus Statement and at least one 3D T1-weighted MRI scan (<20 years after onset) were identified from the University Hospital Bonn (1995-2023). Healthy controls were selected from databases at the University Hospital Bonn, Charité University Hospital Berlin, and the Human Connectome Project. Disease epicenters, describing brain regions highly connected to atrophy regions, were mapped individually using network-based atrophy modeling. Subtypes were identified through k-means clustering. Neuropsychological test results and results from neuropathologic analyses of biopsies were ascertained, and correlations between subtype-specific atrophy maps and normative maps (enhancing neuro imaging genetics through meta analysis [ENIGMA] and neuromaps toolbox) were used to characterize atrophy profiles and epicenter susceptibility.

RESULTS

The study incorporated 54 individuals with Rasmussen syndrome (median age at MRI: 18 years, range 2-61, 65% female) and 270 healthy individuals (median age at MRI: 26.5 years, range 3-61, 49% female). Four distinct atrophy subtypes were identified (temporoparietal, centrotemporal, frontal, and bilateral). Individuals with the centrotemporal subtype were younger at onset (median 5.5 years) than individuals with temporoparietal (median 11.5 years, p = 0.02) and frontal (median 6 years, p = 0.02) subtypes. Most severe neuropsychological impairment was observed for the temporoparietal and frontal subtypes. In the temporoparietal and frontal subtypes, atrophy occurred preferentially in hubs (r = -0.28, p = 0.006; r = -0.30, p = 0.02). Disease epicenter susceptibility was associated with higher cortical thickness (r = -0.57, p = 0.005), lower myelin content (r = 0.47, p = 0.02), lower cerebral blood flow (r = 0.42, p = 0.03), lower blood volume (r = 0.57, p = 0.006), and lower oxygen metabolism (r = 0.47, p = 0.01). Brain biopsies showing strong inflammation were taken from likely epicenters, whereas biopsies with weaker inflammation came from less likely epicenters (p = 0.04).

DISCUSSION

Using Rasmussen syndrome as a model, we validate imaging-based mapping of individual disease epicenters with histopathologic evidence. With further validation, network-based mapping of individual disease epicenters could potentially be used in Rasmussen syndrome to guide biopsy site selection, inform treatment decisions, and improve outcome prognoses.

Three cases of atypical Rasmussen's encephalitis with delayed-onset seizures

We retrospectively analyzed the clinical characteristics of three ARE cases with delayed-onset seizures treated at Peking University First Hospital and Sanbo Brain Hospital from May 2021 to January 2023. We also reviewed previously reported atypical cases of Rasmussen's encephalitis (RE) in the literature, summarizing onset symptoms, seizure symptomatology, imaging findings, electroencephalogram (EEG) results, treatment course, and prognosis. The onset age of the three cases ranged from 1 year and 9 months to 7 years and 5 months. All three initially presented with limb motor disorders, which progressively worsened. Two cases developed focal seizures within 1 month of onset, whereas the third case had no seizures over 3 years. Brain MRIs revealed progressive unilateral hemispheric atrophy with multifocal abnormal signals, and PET-CT showed decreased metabolism in the affected hemisphere. EEGs exhibited asymmetric background rhythms with slow waves in the affected hemisphere. In the two children with seizures, epileptiform discharges from the affected hemisphere were recorded, including one case of sustained partial epilepsy. One child was initially diagnosed with autoimmune encephalitis, whereas two were suspected of having RE at onset. The two children with seizures were treated with immunotherapy and various antiseizure medications. Both underwent hemispherectomy because neither seizures nor limb motor disorders were effectively controlled. Post-surgery, neither experienced seizures during 2 years of follow-up, and both showed cognitive and motor improvements. The child without seizures received intermittent steroids and immunoglobulin therapy over 3 years. During 18 months of follow-up, the patient's motor function improved, and no seizures occurred. Seizures are common initial symptoms of RE. Such cases are often misdiagnosed or missed, leading to delays in optimal treatment. If symptoms are predominantly unilateral and EEG and imaging findings show laterality, the possibility of RE should be considered. Early diagnosis and treatment can reduce unnecessary investigations and improve prognosis. PLAIN LANGUAGE SUMMARY: Rasmussen's encephalitis (RE) is a rare disease that typically begins with seizures and generally has a poor prognosis. However, over the past 20 years, there have been reports of RE cases where the initial symptoms are not seizures. Our center has diagnosed and treated three such cases in the past 5 years. We aim to provide an overview of these atypical RE patients, focusing on clinical features, electroencephalographic (EEG) findings, and imaging characteristics to inspire early detection and diagnosis of RE, thus improving treatment timing and outcomes for RE patients.

Rasmussen Encephalitis: Clinical Features, Pathophysiology, and Management Strategies-A Comprehensive Literature Review

Rasmussen encephalitis (RE) is a rare and progressive form of chronic encephalitis that typically affects one hemisphere of the brain and primarily occurs in pediatric individuals. The current study aims to narratively review the literature about RE, including historical information, pathophysiology, and management of this condition. RE often occurs in individuals with normal development, and it is estimated that only a few new cases are identified each year in epilepsy centers. Approximately 10% of cases also occur in adolescents and adults. The hallmark feature of RE is drug-resistant focal seizures that can manifest as epilepsia partialis continua. Also, patients with RE usually develop motor and cognitive impairment throughout the years. Neuroimaging studies show progressive damage to the affected hemisphere, while histopathological examination reveals T-cell-dominated encephalitis with activated microglial cells and reactive astrogliosis. The current therapy guidelines suggest cerebral hemispherotomy is the most recommended treatment for seizures in RE, although significant neurological dysfunction can occur. Another option is pharmacological management with antiseizure medications and immunomodulatory agents. No significant progress has been made in understanding the pathophysiology of this condition in the last decades, especially regarding genetics. Notably, RE diagnosis still depends on the criteria established by Bien et al., and the accuracy can be limited and include genetically different individuals, leading to unexpected responses to management.

Rasmussen's encephalitis in a pediatric patient with subtle early MRI changes: A case report

Rasmussen's encephalitis (RE) is a progressive inflammatory neurological process most commonly occurring in children characterized by drug-resistant focal epilepsy, hemiplegia, and cognitive decline, with brain atrophy and white matter changes typically localized to 1 hemisphere of the brain. Because the clinical course of RE is often indistinguishable from a variety of medical conditions, MRI has historically been the primary diagnostic tool. Here, we report both the clinical course and progression of neuroimaging findings of a 5-year-old female who had very subtle early cortical and white matter changes on MRI and was diagnosed with RE by correlating the clinical presentation, imaging, and electrographic findings.

Current practices in the diagnosis and treatment of Rasmussen syndrome: Results of an international survey

PURPOSE

Rasmussen syndrome (RS) is marked by progressive unihemispheric atrophy, resulting in hemiparesis, refractory epilepsy, and cognitive/language decline. Detailed diagnostic and treatment algorithms are currently lacking. We aimed to survey medical providers on their current practices in the diagnosis and treatment of RS.

METHODS

A steering committee was formed to create the survey, which was disseminated to the international medical community. One hundred twelve surveys were completed. Descriptive statistics, as well as comparisons by level of experience, patient age group cared for, and geographic region using Fisher's exact test, were conducted.

RESULTS

Analysis of cerebrospinal fluid (82 %) and serum (78 %) for autoimmune encephalitis (AE) are completed by most, while approximately one-third obtain genetic and metabolic studies in all patients (36 % and 38 %, respectively). Providers in US and Europe more readily pursue serum AE antibody panels (85 % and 85 %, respectively, versus 67 %, p = 0.019) and genetic testing (56 % and 47 %, respectively, versus 14 %, p < 0.001) than the rest of the world. Thirty-six percent proceed to biopsy in patients otherwise meeting diagnostic criteria, and US providers are more likely to suggest this than others (73 % versus 14-41 %, p < 0.001). Opinions differed on the prioritization of hemispherectomy/hemispherotomy versus immunotherapy in 14 clinical scenarios with various neurologic deficit severity provided. Preferred immunotherapy regimens also varied, with US providers more often choosing IVIG as first-line (67 %) compared to others (28 %-32 %, p = 0.030). Surgical standard of care was identified as functional hemispherectomy or hemispherotomy by 90 %.

CONCLUSION

The survey highlights trends but also significant variations in clinical practice that can serve as targets for future research and expert consensus guidelines.

Rasmussen's encephalitis: structural, functional, and clinical correlates of contralesional epileptiform activity

Progressive inflammation of one hemisphere characterises Rasmussen's encephalitis (RE), but contralesional epileptiform activity has been repeatedly reported. We aimed to quantify contralesional epileptiform activity in RE and uncover its functional and structural underpinnings. We retrospectively ascertained people with RE treated between 2000 and 2018 at a tertiary centre (Centre 1) and reviewed all available EEG datasets. The temporal occurrence of preoperative contralesional epileptiform activity (interictal/ictal) was evaluated using mixed-effects logistic regression. Cases with/without contralesional epileptiform activity were compared for cognition, inflammation (ipsilesional brain biopsies), and MRI (cortical and fixel-based morphometry). EEG findings were validated in a second cohort treated at another tertiary centre (Centre 2) between 1995 and 2020. We included 127 people with RE and 687 EEG samples. Preoperatively, contralesional epileptiform activity was seen in 30/68 (44%, Centre 1) and 8/59 (14%, Centre 2). In both cohorts, this activity was associated with younger onset age (OR = 0.9; 95% CI 0.83-0.97; P = 0.006). At centre 1, contralesional epileptiform activity was associated with contralesional MRI alterations, lower intelligence (OR = 5.19; 95% CI 1.28-21.08; P = 0.021), and impaired verbal memory (OR = 10.29; 95% CI 1.97-53.85; P = 0.006). After hemispherotomy, 11/17 (65%, Centre 1) and 28/37 (76%, Centre 2) were seizure-free. Contralesional epileptiform activity was persistent postoperatively in 6/12 (50%, Centre 1) and 2/34 (6%, Centre 2). Preoperative contralesional epileptiform activity reduced the chance of postoperative seizure freedom in both cohorts (OR = 0.69; 95% CI 0.50-0.95; P = 0.029). Our findings question the concept of strict unilaterality of RE and provide the evidence of contralesional epileptiform activity as a possible EEG predictor for persisting postoperative seizures.

MRI and pathology comparisons in Rasmussen's encephalitis: a multi-institutional examination of hemispherotomy outcomes relative to imaging and histological severity

PURPOSE

Rasmussen encephalitis (RE) is a very rare chronic neurological disorder of unilateral inflammation of the cerebral cortex. Hemispherotomy provides the best chance at achieving seizure freedom in RE patients, but with significant risks and variable long-term outcomes. The goal of this study is to utilize our multicenter pediatric cohort to characterize if differences in pathology and/or imaging characterization of RE may provide a window into post-operative seizure outcomes, which in turn could guide decision-making for parents and healthcare providers.

METHODS

This multi-institutional retrospective review of medical record, imaging, and pathology samples was approved by each individual institution's review board. Data was collected from all known pediatric cases of peri-insular functional hemispherotomy from the earliest available electronic medical records. Mean follow-up time was 4.9 years. Clinical outcomes were measured by last follow-up visit using both Engel and ILAE scoring systems. Relationships between categorical and continuous variables were analyzed with Pearson correlation values.

RESULTS

Twenty-seven patients met study criteria. No statistically significant correlations existed between patient imaging and pathology data. Pathology stage, MRI brain imaging stages, and a combined assessment of pathology and imaging stages showed no statistically significant correlation to post-operative seizure freedom rates. Hemispherectomy Outcome Prediction Scale scoring demonstrated seizure freedom in only 71% of patients receiving a score of 1 and 36% of patients receiving a score of 2 which were substantially lower than predicted.

CONCLUSIONS

Our analysis did not find evidence for either independent or combined analysis of imaging and pathology staging being predictive for post peri-insular hemispherotomy seizure outcomes, prompting the need for other biomarkers to be explored. Our data stands in contrast to the recently proposed Hemispherectomy Outcome Prediction Scale and does not externally validate this metric for an RE cohort.

Focal cortical dysplasia is a frequent coexistent pathology in patients with Rasmussen's encephalitis

INTRODUCTION

Rasmussen's encephalitis (RE) is a rare, predominantly pediatric epilepsy disorder of unknown etiology. It classically affects one of the cerebral hemispheres and histologically shows cortical chronic inflammation, gliosis, and neuronal loss. The etiopathogenesis of RE remains unknown, with genetic, infectious, and autoimmune factors all speculated to play a role. Although the histologic findings in RE are well described, few studies have investigated a large cohort of cases looking for the coexistence of RE with focal cortical dysplasia (FCD).

DESIGN

The study is a retrospective review of RE patients who underwent surgical resection of brain tissue between 1979 and 2021. Relevant patient history was retrieved, and available histologic slides were reviewed. The histologic severity of RE was described according to the Pardo criteria. In cases where FCD was present, the observed patterns of FCD (namely Ia, Ib, IIa, IIb, etc.) were described using the International League Against Epilepsy (ILAE) classification.

RESULTS

Thirty-eight resection specimens from 31 patients formed the study cohort. Seventeen patients (54.8 %) were male; average age at surgery was 8 years (range: 2-28 years). Twenty-seven resection specimens (71.1 %) from 23 patients (74 %) showed evidence of coexistent FCD. Most cases with FCD resembled the ILAE type Ib (n = 23) pattern. Cases of RE that did not show FCD were either Pardo stage 1 (n = 5) or 4 (n = 6), with all Pardo stage 2 and 3 cases demonstrating FCD.

CONCLUSIONS

FCD was found in most patients with RE (74 %). The most observed pattern of FCD was ILAE Ib.

Globally altered microstructural properties and network topology in Rasmussen's encephalitis

Rasmussen's encephalitis is an immune-mediated brain disorder characterised by progressive unilateral cerebral atrophy, neuroinflammation, drug-resistant seizures and cognitive decline. However, volumetric changes and epileptiform EEG activity were also observed in the contralateral hemisphere, raising questions about the aetiology of contralateral involvement. In this study, we aim to investigate alterations of white matter integrity, structural network topology and network efficiency in Rasmussen's encephalitis using diffusion-tensor imaging. Fourteen individuals with Rasmussen's encephalitis (11 female, median onset 6 years, range 4-22, median disease duration at MRI 5 years, range 0-42) and 20 healthy control subjects were included. All subjects underwent T1-weighted structural and diffusion-tensor imaging. Diffusion-tensor images were analysed using the fixel-based analysis framework included in the MRtrix3 toolbox. Fibre density and cross-section served as a quantitative measure for microstructural white matter integrity. T1-weighted structural images were processed using FreeSurfer, subcortical segmentations and cortical parcellations using the Desikan-Killiany atlas served as nodes in a structural network model, edge weights were determined based on streamline count between pairs of nodes and compared using network-based statistics. Global efficiency was used to quantify network integration on an intrahemispheric level. All metrics were compared cross-sectionally between individuals with Rasmussen's encephalitis and healthy control subjects using sex and age as regressors and within the Rasmussen's encephalitis group using linear regression including age at onset and disease duration as independent variables. Relative to healthy control subjects, individuals with Rasmussen's encephalitis showed significantly (family-wise-error-corrected P < 0.05) lower fibre density and cross-section as well as edge weights in intrahemispheric connections within the ipsilesional hemisphere and in interhemispheric connections. Lower edge weights were noted in the contralesional hemisphere and in interhemispheric connections, with the latter being mainly affected within the first 2 years after disease onset. With longer disease duration, fibre density and cross-section significantly (uncorrected P < 0.01) decreased in both hemispheres. In the contralesional corticospinal tract, fibre density and cross-section significantly (uncorrected P < 0.01) increased with disease duration. Intrahemispheric edge weights (uncorrected P < 0.01) and global efficiency significantly increased with disease duration in both hemispheres (ipsilesional r = 0.74, P = 0.001; contralesional r = 0.67, P = 0.012). Early disease onset was significantly (uncorrected P < 0.01) negatively correlated with lower fibre density and cross-section bilaterally. Our results show that the disease process of Rasmussen's encephalitis is not limited to the cortex of the lesioned hemisphere but should be regarded as a network disease affecting white matter across the entire brain and causing degenerative as well as compensatory changes on a network level.

Early Positive Brain 18F-FDG PET and Negative MRI in Rasmussen Encephalitis

ABSTRACT

A 15-year-old adolescent boy with left body epilepsia partialis continua, hemiparesis, and electroencephalogram abnormalities lateralized to the right hemisphere. MRI finding was small hyperintense signal in the left putamen. 18F-FDG PET showed focal glucose hypermetabolism in the right paracentral lobule and hypometabolism in the inferior right frontal and precentral gyri. One month later, a new MRI showed a hyperintense signal over the paracentral lobule. Biopsy on this region confirmed the diagnosis of Rasmussen encephalitis. This patient finally underwent right hemispherotomy and became seizure free. This case emphasize the PET as an important early tool for the diagnosis of Rasmussen encephalitis.

Rasmussen's encephalitis: Early diagnostic criteria in children

Rasmussen's encephalitis (RE) is a rare chronic inflammatory brain disorder resulting in progressive neurodegeneration in one cerebral hemisphere. The inflammatory process is accompanied by progressive loss of function of the affected hemisphere, associated with drug-resistant partial epilepsy. The diagnosis is based on a range of clinical, electroencephalographic, radiological and biochemical arguments, without any specific formal marker, which makes the diagnosis of the disease complex, especially in its initial phase. Seizures are refractory to anti-seizures medication (ASM) and to classical immunomodulatory treatments. These treatments are also ineffective to stop the degenerative process. Only surgical treatment with hemispherotomy (surgical disconnection of a cerebral hemisphere) allows definitive cessation of seizures but this leads to definitive motor and cognitive deficits. The etiology of RE is not known, but there is strong evidence for an immunopathogenic mechanism involving T-cell mediated immunity. The emergence of biotherapies targeting against various cytokines offers potential therapeutic perspectives. This disease is currently a real challenge in terms of: (i) early diagnosis, before the constitution of marked hemispheric atrophy and the appearance of neurological and cognitive consequences; (ii) recognition of incomplete form; (iii) therapeutic management due to advances in the field of targeted treatment of inflammation; (iv) surgery and recovery possibilities.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset at a variable age: position statement by the ILAE Task Force on Nosology and Definitions

The goal of this paper is to provide updated diagnostic criteria for the epilepsy syndromes that have a variable age of onset, based on expert consensus of the International League Against Epilepsy Nosology and Definitions Taskforce (2017-2021). We use language consistent with current accepted epilepsy and seizure classifications and incorporate knowledge from advances in genetics, electroencephalography, and imaging. Our aim in delineating the epilepsy syndromes that present at a variable age is to aid diagnosis and to guide investigations for etiology and treatments for these patients.

Autoimmune diseases of the brain, imaging and clinical review

There is an extensive spectrum of autoimmune entities that can involve the central nervous system, which has expanded with the emergence of new imaging modalities and several clinicopathologic entities. Clinical presentation is usually non-specific, and imaging has a critical role in the workup of these diseases. Immune-mediated diseases of the brain are not common in daily practice for radiologists and, except for a few of them such as multiple sclerosis, there is a vague understanding about differentiating them from each other based on the radiological findings. In this review, we aim to provide a practical diagnostic approach based on the unique radiological findings for each disease. We hope our diagnostic approach will help radiologists expand their basic understanding of the discussed disease entities and narrow the differential diagnosis in specific clinical scenarios. An understanding of unique imaging features of these disorders, along with laboratory evaluation, may enable clinicians to decrease the need for tissue biopsy.

The correspondence between morphometric MRI and metabolic profile in Rasmussen's encephalitis

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The GM atrophy located in the insular and temporal cortices of the affected side.

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Positive correlation was found in the brain region featuring MRI atrophy and FDG-PET.

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GM atrophy was spatially correlated with dopaminergic and serotonergic mapping in RE.

Volumetric magnetic resonance imaging (MRI) atrophy is a hallmark of Rasmussen’s encephalitis (RE). Here, we aim to investigate voxel-wise gray matter (GM) atrophy in RE, and its associations with glucose hypometabolism and neurotransmitter distribution utilizing MRI and PET data. In this study, fifteen RE patients and fourteen MRI normal subjects were included in this study. Voxel-wise GM volume and glucose metabolic uptake were evaluated using structural MRI and FDG-PET images, respectively. Spatial Spearman’s correlation was performed between GM atrophy of RE with FDG uptake alterations, and neurotransmitter distributions provided in the JuSpace toolbox. Compared with the control group, RE patients displayed extensive GM volume loss not only in the ipsilateral hemisphere, but also in the frontal lobe, basal ganglia, and cerebellum in the contralateral hemisphere. Within the RE group, the insular and temporal cortices exhibited significantly more GM atrophy on the ipsilesional than the contralesional side. FDG-PET data revealed significant hypometabolism in areas surrounding the insular cortices in the ipsilesional hemisphere. RE-related GM volumetric atrophy was spatially correlated with hypomebolism in FDG uptake, and with spatial distribution of the dopaminergic and serotonergic neurotransmitter systems. The spatial concordance of morphological changes with metabolic abnormalities suggest FDG-PET offers potential value for RE diagnosis. The GM alterations associated with neurotransmitter distribution map could provide novel insight in understanding the neuropathological mechanisms and clinical feature of RE.

MRI in Late-Onset Rasmussen Encephalitis: A Long-Term Follow-Up Study

Late-onset Rasmussen encephalitis (LoRE) is a rare unihemispheric progressive inflammatory disorder causing neurological deficits and epilepsy. The long-term radiological evolution has never been fully described. We retrospectively analyzed the MR images of 13 LoRE patients from a total of 136 studies, and searched for focal areas of volume loss or signal intensity abnormality in grey matter or white matter. Each subject had a median of nine MRI studies (IQR 7–13). Frontal and temporal lobes were the most affected regions (13/13 and 8/13, respectively) and showed the greatest worsening over time in terms of atrophic changes (9/13 and 5/8, respectively). A milder cortical atrophy was found in the insular and parietal lobes. The caudate nucleus was affected in seven patients. Hyperintensities of grey matter and white matter on T2-WI and FLAIR images were observed in all patients, and transiently in eight patients. In two cases out of the latter patients, these transient alterations evolved into atrophy of the same region. Disease duration was significantly associated with signal abnormalities in the grey matter at last follow-up. LoRE MRI alterations are milder, and their progression is markedly slower compared to radiological findings described in the childhood form.

Rituximab in Rasmussen’s encephalitis: A single center experience and review of the literature

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Rituximab in the early course of the disease results in good control of seizures and EPC.

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Rituximab can reverse or stabilize motor deficits as well as MRI changes and halt progression of disease.

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Rituximab is a safe, efficacious, well tolerated and rapidly acting drug in RE, and can be used as a steroid sparing agent.

Rasmussen's encephalitis (RE) is a rare chronic inflammatory disease of the brain resulting in unilateral hemispheric atrophy with drug-resistant focal epilepsy associated with a variable degree of progressive hemiparesis and cognitive decline. The precise etiology of RE is unknown but presumed to have a neuroinflammatory pathobiological basis. Only surgery halts progression of the disease, but may occur at the expense of a fixed but otherwise inevitable neurological deficit. Therefore, the question of medical management is an important consideration. Reports of rituximab use in patients with RE were presented at the American Epilepsy Society annual meeting in 2008. Good published evidence for its usage has been very slow to emerge since then. However, rituximab continues to be listed in discussions of treatment options for patients with RE, though other monoclonal antibodies have since been used with comparable outcomes.

We describe a series of nine patients including two with adult-onset RE. Rituximab was used early in the disease course (range 1–108 months; mean 32 months).

Of nine patients with RE, there was significant benefit in their seizure burden with rituxamab. Seizure freedom occurred in 3 patients. Epilepsia partialis continua (EPC) was present in 4/9 and no focal motor deficit noted in 4/9. No progression of a neurological deficit was present in 2/9 and evidence of progression with neuroimaging was terminated with rituxamab in 5/9 supporting early use of rituxamab in patients with RE.

Rasmussen syndrome in a tropical environment: a study of six (6) observations

Background

In sub-Saharan Africa, encephalitis of various etiologies is a major public health problem and Rasmussen syndrome is rarely diagnosed due to under-medicalization. The objective of this study is to describe the clinical and neuroradiological forms, especially since this affection is little known in sub-Saharan Africa as evidenced by the scarcity of publications.

Results

A retrospective, descriptive and analytical study of six (6) cases of Rasmussen syndrome, shows that it is an unrecognized disease in Africa. Men were more represented with a frequency of 67% with a young age. The clinical picture dominated by 100% seizures, mental deterioration and hemiparesis. The etiology is still questionable, probably autoimmune in our study.

Conclusion

Rasmussen syndrome accounts for 3% in 219 patients hospitalized for epileptic conditions. This study shows a clinical profile dominated by recurrent epileptic seizures refractory to the drugs Phenobarbital, Valproic Acid and Carbamazepine, the only antiepileptics available in the country. These results are valid for therapeutic and prognostic discussion.

Infratentorial MRI Findings in Rasmussen Encephalitis Suggest Primary Cerebellar Involvement

Background and Objective

Rasmussen encephalitis (RE) is characterized by its unilateral cerebral involvement. However, both ipsi- and contralesional cerebellar atrophy have been anecdotally reported raising questions about the nature and extent of infratentorial findings. Using MRI, we morphometrically investigated the cerebellum and hypothesized abnormalities beyond the effects of secondary atrophy, implicating a primary involvement of the cerebellum by RE.

Methods

Voxel-based morphometry of the cerebellum and brainstem was conducted in 57 patients with RE and in 57 matched controls. Furthermore, patient-specific asymmetry indices (AIs) of cerebellar morphometry and fluid-attenuated inversion recovery (FLAIR) intensity were calculated. Using diffusion tensor imaging, the integrity of the cortico-ponto-cerebellar (CPC) tract was assessed. Finally, a spatial independent component analysis (ICA) was used to compare atrophy patterns between groups.

Results

Patients with RE showed bilateral cerebellar and predominantly ipsilesional mesencephalic atrophy (p < 0.01). Morphometric AIs revealed ipsilesional < contralesional asymmetry in 27 and ipsilesional > contralesional asymmetry in 30 patients. In patients with predominant ipsilesional atrophy, morphometric AIs strongly correlated with FLAIR intensity AIs (r = 0.86, p < 0.0001). Fractional anisotropy was lower for ipsilesional-to-contralesional CPC tracts than opposite tracts (T = 2.30, p < 0.05). ICA revealed bilateral and strictly ipsi- and contralesional atrophy components in patients with RE (p < 0.05).

Discussion

We demonstrated atrophy of the ipsilesional-to-contralesional CPC pathway and, consequently, interpret the loss of contralesional gray matter as secondary crossed cerebellar atrophy. The ipsilesional cerebellar atrophy, however, defies this explanation. Based on FLAIR hyperintensities, we interpret ipsilesional atrophy to be due to inflammation in the scope of a primary involvement of the cerebellum by RE.

Posterior-onset Rasmussen's encephalitis with ipsilateral cerebellar atrophy and uveitis resistant to rituximab

Rasmussen encephalitis (RE) is a disorder characterized by drug-resistant seizures and progressive unihemispheric atrophy, hemiparesis, and varying degrees of cognitive decline. The pathophysiology of RE remains elusive, with hypotheses suggesting underlying autoimmune- and T cell-mediated processes. In this case report, we describe a single patient's clinical course from the first day of presentation until definitive treatment for atypical Rasmussen encephalitis at a tertiary care pediatric center. The patient exhibited several atypical features of Rasmussen encephalitis, including a posterior predominance of initial seizure onset with the development of severe choreoathetosis and ipsilateral cerebellar atrophy. He subsequently developed coexistent autoimmune disorders in the form of psoriasis and uveitis, and underwent multiple forms of immunotherapy with limited benefit.

This patient shows an association of RE with other autoimmune conditions supporting an autoimmune mechanism of disease while exhibiting several atypical features of RE. Rarely, occipital lobe seizures have been documented as the presenting semiology of this syndrome. This case highlights the need to be mindful of atypical features that may delay hemispherectomy, which remains the definitive treatment. It also suggests that children may be predisposed to the development of autoimmune disorders in later stages of the disease.

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Occipital seizure localization and semiology should not dissuade the diagnosis of Rasmussen's encephalitis

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Movement disorders, can accompany Rasmussen's encephalitis

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Ipsilateral cerebellar atrophy has been described in Rasmussen's encephalitis

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Children with Rasmussen's encephalitis may be predisposed to autoimmune disorders in the later stages of the disease

Understanding Childhood Neuroimmune Diseases of the Central Nervous System

Immune-mediated diseases of the central nervous system (CNS) in childhood are a heterogeneous group of rare conditions sharing the inflammatory involvement of the CNS. This review highlights the growing knowledge of childhood neuroimmune diseases that primarily affect the CNS, outlining the clinical and diagnostic features, the pathobiological mechanisms and genetics, current treatment options, and emerging challenges. The clinical spectrum of these conditions is increasingly expanded, and the underlying mechanisms of dysregulation of the immune system could vary widely. Cell-mediated and antibody-mediated disorders, infection-triggered and paraneoplastic conditions, and genetically defined mechanisms can occur in previously healthy children and can contribute to different stages of the disease. The careful evaluation of the clinical presentation and temporal course of symptoms, the specific neuroimaging and immunological findings, and the exclusion of alternative causes are mandatory in clinical practice for the syndromic diagnosis. A common feature of these conditions is that immunotherapeutic agents could modulate the clinical course and outcomes of the disease. Furthermore, specific symptomatic treatments and comprehensive multidisciplinary care are needed in the overall management. We focus on recent advances on immune-mediated demyelinating CNS disorders, autoimmune encephalitis, interferonopathies, and possible neuroimmune disorders as Rasmussen encephalitis. Better knowledge of these conditions could allow prompt diagnosis and targeted immunotherapy, to decrease morbidity and mortality as well as to improve clinical outcomes, reducing the burden of the disease due to possible long-term neuropsychiatric sequelae. Persisting controversies remain in the rigorous characterization of each specific clinical entity because of the relative rarity in children; moreover, in a large proportion of suspected neuroimmune diseases, the immune "signature" remains unidentified; treatment guidelines are mostly based on retrospective cohort studies and expert opinions; then advances in specific molecular therapies are required. In the future, a better characterization of specific immunological biomarkers may provide a useful understanding of the underlying pathobiological mechanisms of these conditions in order to individualize more tailored therapeutic options and paradigms. Multicenter collaborative research on homogeneous groups of patients who may undergo immunological studies and therapeutic trials could improve the characterization of the underlying mechanisms, the specific phenotypes, and tailored management.

Morphometric MRI findings challenge the concept of the "unaffected" hemisphere in Rasmussen encephalitis

Rasmussen encephalitis (RE) is an immune-mediated brain disease with progressive unihemispheric atrophy. Although it is regarded as a strictly one-sided pathology, volumetric magnetic resonance imaging (MRI) studies have revealed atrophy in the so-called unaffected hemisphere. In contrast to previous studies, we hypothesized that the contralesional hemisphere would show increased gray matter volume in response to the ipsilesional atrophy. We assessed the gray matter volume differences among 21 patients with chronic, late-stage RE and 89 age- and gender-matched healthy controls using voxel-based morphometry. In addition, 11 patients with more than one scan were tested longitudinally. Compared to controls, the contralesional hemisphere of the patients revealed a higher cortical volume but a lower subcortical gray matter volume (all P < 0.001, unpaired t test). Progressive gray matter volume losses in bilateral subcortical gray matter structures were observed (P < 0.05, paired t test). The comparatively higher cortical volume in the contralesional hemisphere can be interpreted as a result of compensatory structural remodeling in response to atrophy of the ipsilesional hemisphere. Contralesional subcortical gray matter volume loss may be due to the pathology or its treatment. Because MRI provides the best marker for determining the progression of RE, an accurate description of its MRI features is clinically relevant.

Rasmussen's Epileptogenic Encephalitis in a Tropical Country

Background

Encephalitis of Rasmussen is an inflammatory hemiencephalopathy of unknown etiology. It is a cause of drug-resistant epilepsy.

Aim

To report two cases of Rasmussen's encephalitis (RE) in a low-income setting.

Clinical Observation

The cases concerned were that of an 8-year-old boy and a 4-year-old girl. The illness began with daily several seizures at the age of 28 months in the boy and 23 months for the girl. Epileptic seizures were generalized in the elder one and focal in the younger. The elder presented right hemiplegia with severe cognitive impairment. In the younger child, the expression of the language was disturbed, associated with right hemiparesis at 4/5. The electroencephalography recording showed background theta asymmetric rhythm associated with discharges of periodic lateralized epileptiform discharges (PLEDs) into the left hemisphere in the two cases. Brain imaging showed left hemisphere atrophy. The seizures had decreased in intensity after association of several anticonvulsant molecules over a period of 3-6 months. The diagnosis of RE was based on clinical, paraclinical, therapeutic, and evolution arguments.

Conclusion

There was a delay to establish the diagnosis. Further studies are needed to evaluate rehabilitation capacities in children with RE before brain maturation.

Arterial spin-labeling perfusion imaging of childhood encephalitis: correlation with seizure and clinical outcome

PURPOSE

In childhood encephalitis, perfusion abnormalities have been infrequently reported to associate with clinical status. We investigated whether perfusion abnormalities correlated with seizure and clinical outcome in encephalitis.

METHODS

We retrospectively analyzed the MR studies of 77 pediatric patients with encephalitis. Pseudo-continuous arterial spin-labeling (ASL) imaging was performed on a 3-T scanner. The patients were divided into five groups according to ASL perfusion imaging pattern: normal perfusion (NP), focal hypoperfusion (Lf), extreme global hypoperfusion (LE), focal hyperperfusion (Hf), and extreme global hyperperfusion (HE). Clinical outcome at 3 weeks was dichotomized to unfavorable or favorable outcome according to the Glasgow outcome scale. Multivariate logistic regression was conducted to predict unfavorable outcome and presence of seizure separately, based on explanatory variables including age, sex, and ASL pattern.

RESULTS

Twenty-seven (35%) patients were designated as in group Hf, five (7%) in group Lf, 11 (14%) in group LE, none in group HE, and 34 (44%) in group NP. Multivariate logistic regression analysis showed that ASL pattern was significantly associated with unfavorable outcome (P = 0.005) and with presence of seizure (P = 0.005). For ASL pattern, group LE was 17.31 times as likely to have an unfavorable outcome as group NP (odds ratio confidence interval [CI] 3.084, 97.105; P = 0.001). Group Hf was 6.383 times as likely to have seizure as group NP (CI 1.765, 23.083; P = 0.005).

CONCLUSIONS

In childhood encephalitis, patients with extreme global hypoperfusion had poor neurological outcome and those with focal hypoperfusion were more likely to have seizure.

Functional neuroimaging in Rasmussen syndrome

PURPOSE

For a diagnosis of Rasmussen syndrome (RS), clinical course together with electroencephalography (EEG) and magnetic resonance imaging (MRI) findings are considered important, but there are few reports on functional neuroimaging. This study investigated cerebral blood flow (CBF)-single photon emission computed tomography (SPECT), central benzodiazepine receptor (BZR)-SPECT, and fluorine-18 fluorodeoxy glucose-positron emission tomography (FDG-PET) in RS patients, and correlated neuroimaging results with MRI and pathological findings.

METHODS

Twenty-three patients diagnosed with RS according to Bien's (2005) diagnostic criteria (including 12 patients with a histological diagnosis) were studied. CBF-SPECT, BZR-SPECT and FDG-PET images were visually evaluated, and the findings correlated with MRI and histological findings.

RESULTS

Hypoperfusion areas were observed in 16 of 22 patients by interictal CBF-SPECT. Hyperperfusion areas were observed in 10 of 12 patients by ictal CBF-SPECT, which correlated with ictal onset area by ictal EEG (IOAE). In the limited data of BZR-SPECT in nine patients, lowered uptake was detected in all nine patients, including two with no MRI abnormalities. Lowered glucose metabolism was observed in affected areas in all five patients by FDG-PET. Histological examination revealed findings of chronic encephalitis in all 12 patients examined, concomitant with focal cortical dysplasia in five patients.

CONCLUSION

In RS patients, functional neuroimaging reveals clear abnormal findings, even before the appearance of MRI abnormalities. BZR-SPECT and FDG-PET could detect the IOAE efficiently even in the absence of MRI abnormalities, while interictal CBF-SPECT occasionally failed to detect IOAE if MRI was normal. Based on BZR-SPECT, refractory epileptic seizures in RS may suggest possible impairment of inhibitory neurons.

Arterial spin labeling hyperperfusion in Rasmussen's encephalitis: Is it due to focal brain inflammation or a postictal phenomenon?

BACKGROUND AND PURPOSE

The study evaluated the utility of arterial spin labeling (ASL) perfusion imaging in Rasmussen's encephalitis (RE).

MATERIAL AND METHODS

The hospital electronic database was searched using the search words "encephalitis," "autoimmune encephalitis" and "Rasmussen's encephalitis" for the period of 1 Jan 2015 to 31 Jan 2017. Clinically diagnosed cases of RE for which epilepsy protocol magnetic resonance imaging (MRI) with perfusion imaging (ASL) performed on a 3T scanner were retrieved. The diagnosis of RE was based on Bien's criteria (Bien et al., 2005). We obtained patient's demographic details, clinical features, electrophysiological studies, and follow-up data from electronic hospital records.

RESULTS

We included nine patients with RE of whom seven patients showed increased perfusion, and two patients decreased perfusion. Among these patients, MRI changes of gyral hyperintensity without volume loss corresponded to regional ASL hyperperfusion in six patients and ASL hypoperfusion in one patient. Two patients who showed ASL hypoperfusion had corresponding atrophy on MRI. Eight patients of RE had epilepsia partialis continua (EPC) or daily seizures, and one patient was seizure-free post-surgery. Five patients showed a concordance of ASL hyperperfusion with clinical ictal onset zone. Among the seven patients with ASL hyperperfusion, the finding was concordant (complete or partial) with the electroencephalogram (EEG) ictal onset zone in six patients and with interictal epileptiform discharges (IED) in seven patients.

CONCLUSION

Increased perfusion in ASL of the involved brain parenchyma in RE is a common MRI finding and may be due to either active inflammation of the brain involved or a seizure-related finding.

Can head trauma trigger adult-onset Rasmussen's encephalitis?

Rasmussen's encephalitis (RE) is a rare unilateral inflammatory brain disorder that causes progressive neurocognitive deterioration and refractory epilepsy including epilepsia partialis continua (EPC). We describe a patient with a unique presentation, where right upper limb EPC due to RE began within 2weeks of a concussive left frontal head injury, in a 36-year-old female without other identifiable etiology, no prior neurological deficit nor suggestion of intracranial pathology or infection, and no preceding seizures. The diagnosis of RE followed extensive investigation, excluding confounding diagnoses, with supportive histopathology, and her EPC has proven refractory to treatment. In the absence of a satisfactory alternative etiology and exclusion of differential diagnoses, the most likely cause or precipitant of this patient's RE was head trauma.

Functional hemispherotomy in Rasmussen syndrome in the absence of classic MRI findings

A 7-year-old previously healthy girl presented with a left-sided focal seizure without impaired consciousness and subsequently developed epilepsia partialis continua. Initial MRI was normal, and the subsequent images only showed a focal T2/FLAIR hyperintense area without cortical atrophy. She was diagnosed with Rasmussen syndrome by pathology and promptly treated with functional hemispherotomy. Rasmussen syndrome is a rare progressive neurological disorder, the only definitive cure for which is hemispheric disconnection. The disease presents a management dilemma, especially early in disease course without characteristic neuroimaging features. A high index of suspicion, multidisciplinary approach, and clear timely communication with the family are critical.

Neurological Disorders Associated with Striatal Lesions: Classification and Diagnostic Approach

Neostriatal abnormalities can be observed in a very large number of neurological conditions clinically dominated by the presence of movement disorders. The neuroradiological picture in some cases has been described as "bilateral striatal necrosis" (BSN). BSN represents a condition histo-pathologically defined by the involvement of the neostriata and characterized by initial swelling of putamina and caudates followed by degeneration and cellular necrosis. After the first description in 1975, numerous acquired and hereditary conditions have been associated with the presence of BSN. At the same time, a large number of disorders involving neostriata have been described as BSN, in some cases irrespective of the presence of signs of cavitation on MRI. As a consequence, the etiological spectrum and the nosographic boundaries of the syndrome have progressively become less clear. In this study, we review the clinical and radiological features of the conditions associated with MRI evidence of bilateral striatal lesions. Based on MRI findings, we have distinguished two groups of disorders: BSN and other neostriatal lesions (SL). This distinction is extremely helpful in narrowing the differential diagnosis to a small group of known conditions. The clinical picture and complementary exams will finally lead to the diagnosis. We provide an update on the etiological spectrum of BSN and propose a diagnostic flowchart for clinicians.

Automated MRI Volumetric Analysis in Patients with Rasmussen Syndrome

BACKGROUND AND PURPOSE

Rasmussen syndrome, also known as Rasmussen encephalitis, is typically associated with volume loss of the affected hemisphere of the brain. Our aim was to apply automated quantitative volumetric MR imaging analyses to patients diagnosed with Rasmussen encephalitis, to determine the predictive value of lobar volumetric measures and to assess regional atrophy differences as well as monitor disease progression by using these measures.

MATERIALS AND METHODS

Nineteen patients (42 scans) with diagnosed Rasmussen encephalitis were studied. We used 2 control groups: one with 42 age- and sex-matched healthy subjects and the other with 42 epileptic patients without Rasmussen encephalitis with the same disease duration as patients with Rasmussen encephalitis. Volumetric analysis was performed on T1-weighted images by using BrainSuite. Ratios of volumes from the affected hemisphere divided by those from the unaffected hemisphere were used as input to a logistic regression classifier, which was trained to discriminate patients from controls. Using the classifier, we compared the predictive accuracy of all the volumetric measures. These ratios were used to further assess regional atrophy differences and correlate with epilepsy duration.

RESULTS

Interhemispheric and frontal lobe ratios had the best prediction accuracy for separating patients with Rasmussen encephalitis from healthy controls and patient controls without Rasmussen encephalitis. The insula showed significantly more atrophy compared with all the other cortical regions. Patients with longitudinal scans showed progressive volume loss in the affected hemisphere. Atrophy of the frontal lobe and insula correlated significantly with epilepsy duration.

CONCLUSIONS

Automated quantitative volumetric analysis provides accurate separation of patients with Rasmussen encephalitis from healthy controls and epileptic patients without Rasmussen encephalitis, and thus may assist the diagnosis of Rasmussen encephalitis. Volumetric analysis could also be included as part of follow-up for patients with Rasmussen encephalitis to assess disease progression.

Rethinking the Magnetic Resonance Imaging Findings in Early Rasmussen Encephalitis: A Case Report and Review of the Literature

OBJECTIVE

We present a child with Rasmussen encephalitis and highlight the pitfalls of diagnosis when magnetic resonance imaging (MRI) is negative for atrophy. We review the literature regarding this issue, introduce the FreeSurfer software as a potential means of noninvasive diagnosis, and discuss methods for prompt and definitive treatment.

METHODS

In addition to the patient description, we review the English language literature regarding pathologic diagnosis of Rasmussen encephalitis using the key words Rasmussen encephalitis, focal lesions, MRI, atrophy, epilepsia partialis continua and hemiparesis in PubMed. We conducted a retrospective, volumetric analysis of our patient's MRIs using FreeSurfer.

RESULTS

Unlike the majority of patients in the literature with Rasmussen encephalitis, our patient's initial MRI was normal and later showed only a small area of T2 and fluid-attenuated inversion recovery high signal despite the presence of epilepsia partialis continua and a rapidly deteriorating clinical course. She did not meet the Rasmussen encephalitis diagnostic criteria until biopsy was obtained but is now seizure-free after functional hemispherotomy performed six months after her initial seizure. FreeSurfer analysis did not show cortical atrophy.

CONCLUSION

The Bien criteria have poor sensitivity for the diagnosis of Rasmussen encephalitis when the MRI is negative for atrophy. Tissue diagnosis is essential in such instances. We suggest a high clinical index of suspicion and multidisciplinary collaboration between radiology, pathology, and neurosurgery to facilitate a greater emphasis on biopsy followed by hemispherotomy as definitive therapy for individuals with early Rasmussen encephalitis.

Rasmussen's encephalitis: advances in management and patient outcomes

PURPOSE

Rasmussen's encephalitis (RE) is a hemispheric inflammatory disorder resulting in progressive epilepsy, hemiparesis, and cognitive decline. Controversy surrounds the most effective timing of surgery with respect to language dominance, functional status, and seizure outcome. We describe our experience with RE to inform treatment decisions.

METHODS

A retrospective chart review was performed in children diagnosed with RE from 1983 to 2012.

RESULTS

Thirteen consecutive cases were identified: six males and seven females with a mean age of 10.6 years (range 5-18). Nine patients received immunotherapy, with transient benefit in three, treatment-associated complications in two, and no difference in their mean time to treatment (5.38 vs 6.37 years p = 0.74) or long-term outcome. Mean follow-up was 5.6 years (range 0.58-12.25). There was no difference in outcome based on pre-operative duration of seizures. At last follow-up, 63 % of surgically treated patients achieved seizure freedom, 100 % had improved seizure control, 90 % had improved cognitive function, 36 % stopped medication, and 63 % tapered medication. Language improved in 83 % of patients with dominant disease. These findings were not associated with age at treatment. All surgical patients were ambulatory at last follow-up.

CONCLUSIONS

Hemispherotomy achieves good seizure control with cognitive improvement and ambulatory status post-operatively. Time to surgery and dominant disease were not associated with outcome, suggesting that hemispherotomy can be offered early or late, with expectations of good seizure control and functional outcome, even with dominant disease.

Utility of Ictal SPECT in the Presurgical Evaluation of Rasmussen's Encephalitis

BACKGROUND

Rasmussen's encephalitis is a progressive disease characterized by severe progressive neurological and cognitive deficits. It is a difficult condition to treat with conventional medical treatment and requires, in most of the cases, surgical intervention.

METHODS

We present the case of a patient with Rasmussen's encephalitis who presented with epilepsia partialis continua, who did not respond to antiepileptic treatment and was evaluated for possible surgical intervention.

RESULTS

The electroencephalographic studies revealed bihemispheric involvement during seizures, although magnetic resonance imaging (MRI) showed a marked right hemispheric atrophy. Hyperperfusion over the right hemisphere was seen with the performance of ictal single photon emission computed tomography (SPECT), which finally guided a right functional hemispherectomy and subsequent seizure control.

CONCLUSION

Ictal SPECT could be a useful tool in the armamentarium of tools used for the localization of the epileptogenic focus in patients with Rasmussen's encephalitis and other localization-related epilepsies.

Evolution of MRI changes in Rasmussen's encephalitis

PURPOSE

We studied the MRI findings in 16 patients with Rasmussen's encephalitis (RE), further analysed serial MRI changes in 11 of them and correlated it with clinical features.

METHODOLOGY

The diagnosis of RE was based on the European consensus statement (Brain, 128, 2005, 454). Details related to demographical, clinical, MRI observations were analysed.

RESULTS

Forty MRIs of brain of 16 patients were reviewed. Eleven patients had undergone serial brain MRIs ranging from two to five occasions. All the patients had unihemispheric focal cortical atrophy, predominantly in the perisylvian region (n = 13). Other features were white matter signal changes (n = 14), and ipsilateral caudate (n = 6) and putamen (n = 4) atrophy. Signal alterations in putamen and caudate were noted in four each. In all the 11 patients with serial MRI, there was progression of cerebral atrophy and a trend towards increase in MRI staging. The MRI signal changes remained same in five patients, resolved in three patients, differential change in two patients and increased in one patient. Diffusion-weighted imaging showed facilitated diffusion (n = 5), and MR spectroscopy showed reduced N-acetyl-aspartate and elevated lactate (n = 2).

CONCLUSIONS

Pattern recognition of MRI findings and the changes in serial MRI might serve as a surrogate marker of disease viz. unihemispheric progressive focal cortical atrophy and signal changes predominantly in the perisylvian distribution and caudate followed by putamen involvement. This might assist in understanding and monitoring of the disease progression.

Hemispherotomy in Rasmussen encephalitis: long-term outcome in an Italian series of 16 patients

Surgical disconnection of the affected hemisphere is considered the treatment of choice for Rasmussen encephalitis (RE), however few data on long-term outcomes after disconnective surgery are available. We report on long-term seizure, cognitive and motor outcomes after disconnective surgery in 16 (8 M, 8 F) RE patients. Pre- and post-operative evaluations included long-term video-EEG monitoring, MRI, assessment of motor function, and cognitive evaluation. Hemispherotomy, by various techniques was used to obtain functional disconnection of the affected hemisphere. The patients, of median current age 23.5 years, range 12-33, were operated on between 1993 and 2009. Median age at disease onset was 5.8 years (range 3-11.4). Median time from seizure onset to surgery was 3.8 years, range 8 months to 21 years. Post-surgical follow-up was a median of 9.5 years, range 3-20. At surgery all patients were receiving two or more antiepileptic drugs (AEDs). All but three patients were seizure-free at latest follow-up. AEDs had been stopped in ten patients; in the remaining six AEDs were markedly reduced. Postural control improved in all patients. Gain in cognitive functioning was significantly (p=0.002) related to disease duration. The long-term outcomes, in terms of seizure control, motor improvement, and cognitive improvement provide important support for disconnective surgery as first choice treatment for RE.

Rasmussen's encephalitis: clinical features, pathobiology, and treatment advances

Rasmussen's encephalitis is a rare chronic neurological disorder, characterised by unilateral inflammation of the cerebral cortex, drug-resistant epilepsy, and progressive neurological and cognitive deterioration. Neuropathological and immunological studies support the notion that Rasmussen's encephalitis is probably driven by a T-cell response to one or more antigenic epitopes, with potential additional contribution by autoantibodies. Careful analysis of the association between histopathology and clinical presentation suggests that initial damage to the brain is mediated by T cells and microglia, suggesting a window for treatment if Rasmussen's encephalitis can be diagnosed early. Advances in neuroimaging suggest that progression of the inflammatory process seen with MRI might be a good biomarker in Rasmussen's encephalitis. For many patients, families, and doctors, choosing the right time to move from medical management to surgery is a real therapeutic dilemma. Cerebral hemispherectomy remains the only cure for seizures, but there are inevitable functional compromises. Decisions of whether or when surgery should be undertaken are challenging in the absence of a dense neurological deficit, and vary by institutional experience. Further, the optimum time for surgery, to give the best language and cognitive outcome, is not yet well understood. Immunomodulatory treatments seem to slow rather than halt disease progression in Rasmussen's encephalitis, without changing the eventual outcome.

Rasmussen's encephalitis presenting as focal cortical dysplasia

Rasmussen's encephalitis is a rare syndrome characterized by intractable seizures, often associated with epilepsia partialis continua and symptoms of progressive hemispheric dysfunction. Seizures are usually the hallmark of presentation, but antiepileptic drug treatment fails in most patients and is ineffective against epilepsia partialis continua, which often requires surgical intervention. Co-occurrence of focal cortical dysplasia has only rarely been described and may have implications regarding pathophysiology and management. We describe a rare case of dual pathology of Rasmussen's encephalitis presenting as a focal cortical dysplasia (FCD) and discuss the literature on this topic.

Unilateral brain oedema related to focal status epilepticus

We present a female patient in her late 30s, with baseline vegetative state following prior traumatic brain injury, who presented with prolonged right hemispheric status epilepticus. The neuroimaging revealed a striking right-sided pancortical oedema with left (crossed) cerebellar diaschisis and dilation of right hemispheric arteries. EEG was concordant and showed nearly continuous right hemispheric seizure discharges with suppressed background. Infective and vascular aetiologies were ruled out. The patient showed clinical and electrographic improvement following treatment with antiepileptic drugs. Unilateral cerebral oedema is a rare presentation of focal status epilepticus, and should be considered as a differential diagnosis in the appropriate clinical scenario.

Childhood inflammatory brain diseases: pathogenesis, diagnosis and therapy

Inflammatory brain diseases (IBrainDs) are a leading cause of devastating neurological deficits or neuropsychiatric syndromes in previously healthy children. The spectrum is expanding rapidly and new disease entities have been discovered in the last decade. IBrainD can occur as a primary disease or may occur secondary to an underlying cause. This review focuses on the clinical presentation, diagnostic features, pathology and histology characteristics and treatment of the primary childhood IBrainDs.

Structural abnormalities in patients with insular/peri-insular epilepsy: spectrum, frequency, and pharmacoresistance

SUMMARY

Between 2002 and 2010, a total of 48 patients were seen at our epilepsy clinic with insular/peri-insular cortex epilepsy. Review of their MR imaging scans revealed a neoplastic lesion in 27% of patients, a malformation of cortical development in 21%, a vascular malformation in 19%, and atrophy/gliosis from an acquired insult in 17%. MR imaging results were normal in 4 patients. Other miscellaneous findings included a case of Rasmussen encephalitis, a nonspecific insular millimetric T2 signal abnormality, a neuroepithelial cyst, and hippocampal sclerosis without MR imaging evidence of dual insular pathologic features (despite depth electrode-proven insular seizures). Refractoriness to antiepileptic drug treatment was present in 56% of patients: 100% for patients with malformations of cortical development (1.0; 95% CI, 0.72-1.0), 50.0% (0.5; 95% CI, 0.21-0.78) in the presence of atrophy/gliosis from acquired insults, 39% (0.39; 95% CI, 0.14-0.68) for neoplastic lesions, and 22.2% (0.22; 95% CI, 0.06-0.55) for vascular malformations.

Extrarolandic electroclinical findings in the evolution of adult-onset Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a rare immunomediated disorder characterized by unilateral hemispheric atrophy, drug-resistant focal epilepsy, and progressive neurological deficits. Its onset typically occurs in childhood, though it has also been reported in adult age (A-RE) with atypical clinical features. The aim of this study was to describe the electroclinical features in a group of seven patients with A-RE. We retrospectively studied seven women aged 23-43years (mean: 32.1years) with a diagnosis of RE according to commonly accepted diagnostic criteria. All the patients were clinically evaluated and underwent prolonged video-EEG monitoring, laboratory investigations, and high-resolution MRI follow-up. All the patients displayed an ictal electroclinical pattern whose evolution varied. We identified an early phase characterized by polymorphic ictal electroclinical manifestations (temporal semiology in five cases, frontal in one, and parietal in the remaining case) and a late phase clinically characterized by viscerosensitive phenomena followed by somatosensitive signs, experiential symptoms, and motor signs in all the cases. In the late phase, the ictal EEG pattern was characterized by monomorphic, pseudorhythmic, repetitive slow-wave theta activity over the frontal and central regions, with ipsilateral propagation and/or secondary spreading to contralateral perisylvian structures. Patients were treated with a combination of AEDs and immunotherapy (steroids and IVIg); epilepsy surgery was performed in 3 cases. Our results show that A-RE is characterized by early and late clinical- and EEG-different features which may reflect a progressive involvement of a specific "extrarolandic" network in the advanced phase of the disease and may suggest that the electroclinical expression of RE varies according to the different stages of the pathological process.

Clinical application and evaluation of the Bien diagnostic criteria for Rasmussen encephalitis

PURPOSE

The 2005 diagnostic criteria for Rasmussen encephalitis (RE) are based on seizures, clinical deficits, electroencephalography (EEG), neuroimaging, and pathology (Brain, 128, 2005, 451). We applied these criteria to patients evaluated for RE and epilepsy surgery controls to determine the sensitivity, specificity, and positive and negative predictive values (PPVs, NPVs) using pathology as the gold standard.

METHODS

We identified patients evaluated for RE based on medical records from 1993 to 2011. Fifty-two control patients with refractory epilepsy, unilateral magnetic resonance imaging (MRI) changes, and biopsies were selected from an epilepsy surgery database from matching years. Patients meeting all three of group A and/or two of three group B criteria were classified as meeting full criteria (positive). Patients not meeting full criteria were classified as negative. When available, pathology findings were re-reviewed with neuropathologists, and MRI imaging was re-reviewed with a neuroradiologist.

KEY FINDINGS

RE was considered in the differential diagnosis for 82 patients, of whom 35 had biopsies. Twenty patients met full criteria (positive) without another explanation, including seven for whom biopsy was required to meet criteria and one in whom another etiology was identified. Two patients met full criteria but had another explanation. Thirty-five met partial criteria (negative), of whom 14 had another etiology identified. Twenty-five met no criteria (negative). The diagnostic criteria had a sensitivity of 81% with four false negatives (criteria-negative, biopsy-positive) when compared to pathology as a gold standard. Five false positives (criteria positive, biopsy negative) had identifiable alternate diagnoses.

SIGNIFICANCE

The 2005 Bien clinical diagnostic criteria for RE have reasonably high sensitivity and specificity and good clinical-pathologic correlation in most cases. We suggest modification of the criteria to allow inclusion of cases with well-described but less common features. Specifically we suggest making the diagnosis in the absence of epilepsia partialis continua (EPC) or clear progression of focal cortical deficits or MRI findings if biopsy is positive and two of the A criteria are met (B3 plus two of three A criteria). This would improve the sensitivity of the criteria.