Pre- and postsurgical cognitive trajectories and quantitative MRI changes in Rasmussen syndrome

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.

Structural signatures of language reorganization after left hemispherotomy in patients with Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a rare neurological disorder affecting a single cerebral hemisphere, often requiring hemispherotomy as a curative treatment. While significant brain plasticity occurs due to the pathology and surgical intervention, the mechanisms underlying cognitive functioning in the remaining hemisphere remain poorly understood. This multiple-case study longitudinally investigates neurocognitive reorganization in childhood after left hemispherotomy for RE and identifies structural patterns in the right hemisphere associated with language recovery. Indeed, the mechanisms that allow the right hemisphere to support language, after left hemispherotomy remain unclear. Cognitive trajectories were analyzed in three RE patients, and their cortical thickness (CT) changes were compared with data from a publicly available cohort of 393 healthy subjects. Language neuropsychological scores and T1-weighted MRI data were assessed in the healthy right hemisphere before hemispherotomy, one year, and five years post-surgery. Specifically, principal component analysis, structural covariance, and graph theory approaches were employed to investigate language network organization in patients and controls. Results reveal diverse language recovery trajectories among the three patients. Regarding CT, three potential signatures associated with favorable language outcomes were identified: (1) normal or below-normal CT values in cortical regions; (2) a more associative and integrative organization of the language network; and (3) increased global efficiency. These preliminary longitudinal findings provide novel insights into the mechanisms of neurocognitive reorganization following left hemispherotomy in childhood. By emphasizing structural patterns linked to favorable postoperative language recovery, this study highlights their value for guiding future research and clinical interventions.

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.

Insights on cognitive reorganization after hemispherectomy in Rasmussen's encephalitis. A narrative review

Rasmussen's encephalitis is a rare neurological pathology affecting one cerebral hemisphere, therefore, posing unique challenges. Patients may undergo hemispherectomy, a surgical procedure after which cognitive development occurs in the isolated contralateral hemisphere. This rare situation provides an excellent opportunity to evaluate brain plasticity and cognitive recovery at a hemispheric level. This literature review synthesizes the existing body of research on cognitive recovery following hemispherectomy in Rasmussen patients, considering cognitive domains and modulatory factors that influence cognitive outcomes. While language function has traditionally been the focus of postoperative assessments, there is a growing acknowledgment of the need to broaden the scope of language investigation in interaction with other cognitive domains and to consider cognitive scaffolding in development and recovery. By synthesizing findings reported in the literature, we delineate how language functions may find support from the right hemisphere after left hemispherectomy, but also how, beyond language, global cognitive functioning is affected. We highlight the critical influence of several factors on postoperative cognitive outcomes, including the timing of hemispherectomy and the baseline preoperative cognitive status, pointing to early surgical intervention as predictive of better cognitive outcomes. However, further specific studies are needed to confirm this correlation. This review aims to emphasize a better understanding of mechanisms underlying hemispheric specialization and plasticity in humans, which are particularly important for both clinical and research advancements. This narrative review underscores the need for an integrative approach based on cognitive scaffolding to provide a comprehensive understanding of mechanisms underlying the reorganization in Rasmussen patients after hemispherectomy.

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.

Volume-based structural connectome of epilepsy partialis continua in Rasmussen's encephalitis

Rasmussen's encephalitis is a rare, progressive neurological inflammatory with hemispheric brain atrophy. Epilepsy partialis continua (EPC) is a diagnostic clinical condition in patients with Rasmussen's encephalitis. However, the incidence of EPC in the natural course of Rasmussen's encephalitis is only about 50%. The majority of experts hold the belief that EPC is associated with dysfunction in the motor cortex, yet the whole pathogenesis remains unclear. We hypothesize that there is a characteristic topological discrepancy between groups with EPC and without EPC from the perspective of structural connectome. To this end, we described the structural MRI findings of 20 Rasmussen's encephalitis cases, 11 of which had EPC, and 9 of which did not have EPC (NEPC), and 20 healthy controls. We performed voxel-based morphometry to evaluate the alterations of grey matter volume. Using a volume-based structural covariant network, the hub distribution and modularity were studied at the group level. Based on the radiomic features, an individual radiomics structural similarity network was constructed for global topological properties, such as small-world index, higher path length, and clustering coefficient. And then, the Pearson correlation was used to delineate the association between duration and topology properties. In the both EPC and NEPC groups, the volume of the motor cortex on the affected side was significantly decreased, but putamen atrophy was most pronounced in the EPC group. Hubs in the EPC group consisted of the executive network, and the contralateral putamen was the hub in the NEPC group with the highest betweenness centrality. Compared to the NEPC, the EPC showed a higher path length and clustering coefficient in the structural similarity network. Moreover, the function of morphological network integration in EPC patients was diminished as the duration of Rasmussen's encephalitis increased. Our study indicates that motor cortex atrophy may not be directly related to EPC patients. Whereas atrophy of the putamen, and a more regularized configuration may contribute to the generation of EPC. The findings further suggest that the putamen could potentially serve as a viable target for controlling EPC in patients with Rasmussen's encephalitis.

Long-term neuropsychological trajectories in children with epilepsy: does surgery halt decline?

Neuropsychological impairments are common in children with drug-resistant epilepsy. It has been proposed that epilepsy surgery might alleviate these impairments by providing seizure freedom; however, findings from prior studies have been inconsistent. We mapped long-term neuropsychological trajectories in children before and after undergoing epilepsy surgery, to measure the impact of disease course and surgery on functioning. We performed a retrospective cohort study of 882 children who had undergone epilepsy surgery at Great Ormond Street Hospital (1990-2018). We extracted patient information and neuropsychological functioning [obtained from IQ tests (domains: full-scale IQ, verbal IQ, performance IQ, working memory and processing speed) and tests of academic attainment (reading, spelling and numeracy)] and investigated changes in functioning using regression analyses. We identified 500 children (248 females) who had undergone epilepsy surgery [median age at surgery = 11.9 years, interquartile range = (7.8, 15.0)] and neuropsychological assessment. These children showed declines in all domains of neuropsychological functioning in the time leading up to surgery (all P-values ≤0.001; e.g. βFSIQ = -1.9, SEFSIQ = 0.3, PFSIQ < 0.001). Children lost on average one to four points per year, depending on the domain considered; 27%-43% declined by ≥10 points from their first to their last preoperative assessment. At the time of presurgical evaluation, most children (46%-60%) scored one or more standard deviations below the mean (<85) on the different neuropsychological domains; 37% of these met the threshold for intellectual disability (full-scale IQ < 70). On a group level, there was no change in performance from pre- to postoperative assessment on any of the domains (all P-values ≥0.128). However, children who became seizure free through surgery showed higher postoperative neuropsychological performance (e.g. rrb-FSIQ = 0.37, P < 0.001). These children continued to demonstrate improvements in neuropsychological functioning over the course of their long-term follow-up (e.g. βFSIQ = 0.9, SEFSIQ = 0.3, PFSIQ = 0.004). Children who had discontinued antiseizure medication treatment at 1-year follow-up showed an 8- to 13-point advantage in postoperative working memory, processing speed and numeracy, and greater improvements in verbal IQ, working memory, reading and spelling (all P-values ≤0.034) over the postoperative period compared with children who were seizure free and still receiving antiseizure medication. In conclusion, by providing seizure freedom and the opportunity for antiseizure medication cessation, epilepsy surgery might not only halt but reverse the downward trajectory that children with drug-resistant epilepsy display in neuropsychological functioning. To halt this decline as soon as possible or, potentially, to prevent it from occurring in the first place, children with focal epilepsy should be considered for epilepsy surgery as early as possible after diagnosis.

Pediatric epilepsy syndromes with associated developmental impairment

In 2022, the International League Against Epilepsy revised their classification of epilepsy syndromes for clinicians to better understand the relationships between different epilepsy syndromes, their underlying causes, and their associated developmental and behavioral features. This review highlights portions of the current classification with an emphasis on epilepsy syndromes that readily present with developmental challenges and provides a unique framework, based on electroencephalography, to easily identify and understand these syndromes. Included in this review are a helpful categorization scheme with visual aid, descriptions of updated epilepsy syndromes, figures of relevant identifiers of syndrome and information regarding future directions toward treatment and research. Covered syndromes include developmental and epileptic encephalopathy, Dravet syndrome, Rasmussen syndrome, and infantile epileptic spasm syndrome, among others. WHAT THIS PAPER ADDS: The revised epilepsy syndrome classification by the International League Against Epilepsy aims to improve the outcomes for children with epilepsy. The electroencephalography features of epilepsy syndromes are grouped based on a categorization model. This model allows clinicians to understand overlapping phenotypes and aid with both identification and diagnosis.

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.

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.

The influencing factors and changes of cognitive function within 40 Rasmussen encephalitis patients that received a hemispherectomy

OBJECTIVE

To evaluate the influencing factors and cognitive functional changes in Rasmussen encephalitis (RE) patients who received a hemispherectomy.

METHODS

Forty RE patients underwent a hemispherectomy with at least a 2 years follow- up were included in this study . Postoperative seizure outcomes were evaluated according to the Engle classification scale. Univariate analysis and a multivariate logistic regression model in a backward fashion were used to identify the potential predictors of cognitive function.

RESULTS

All 40 patients had an Engle classification outcome at a 2 years follow-up. Univariate and multivariate analyses revealed that seizure duration (OR 10.06, 95% CI 1.54-3.85, p = 0.038), age at surgery (OR 3.06, 95% CI 1.21-3.56, p = 0.043), and MRI score (OR 0.09, 95% CI 0.01-0.67 p = 0.024) are associated with postoperative cognitive outcomes respectively. Moreover,  VIQ and PIQ were negatively correlated linearly with duration of seizures and MRI score. Patients with a good VIQ and PIQ before the operation were more likely to have a better VIQ and PIQ postoperatively (p < 0.001 and p < 0.001, respectively). And, operation side is an important factor affecting cognitive function; therefore, a left hemispherectomy has a greater impact on the patient's IQ and language.

CONCLUSIONS

RE patients' cognitive dysfunctions are improved after a hemispherectomy. Right-side operation can achieve better postoperative cognitive outcomes especially in VIQ and language. A shorter duration of seizures, early age at surgery, and less severe brain atrophy suggest better cognitive outcomes after a hemispherectomy.

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.

Rasmussen's encephalitis: mechanisms update and potential therapy target

Rasmussen’s encephalitis (RE) is rare neurological diseases characterized as epilepsia partialis continua, invariably hemiparesis, and cognitive impairment. This disease is encountered frequently in childhood and presents with progressive atrophy of the unilateral hemisphere, and there are also sustained neurological complications. Owing to uncertain pathogenesis, the most effective way to limit the influence of seizures currently is cerebral hemispherectomy. In this review, we focus on four main lines of pathogenesis: virus infection, antibody-mediated, cell-mediated immunity, and microglia activation. Although one or more antigenic epitopes may give rise to infiltrating T cell responses in RE brain tissue, no exact antigen was confirmed as the definite cause of the disease. On the other hand, the appearance of antibodies related with RE seem to be a secondary pathological process. Synthetic studies have suggested an adaptive immune mechanism mediated by CD8⁺ T cells and an innate immune mechanism mediated by activated microglia and neuroglia. Accordingly, opinions have been raised that immunomodulatory treatments aimed at initial damage to the brain that are induced by cytotoxic CD8⁺ T cell lymphocytes and microglia in the early stage of RE slow down disease progression. However, systematic exploration of the theory behind these therapeutic effects based on multicenter and large sample studies are needed. In addition, dysfunction of the adenosine system, including the main adenosine removing enzyme adenosine kinase and adenosine receptors, has been demonstrated in RE, which might provide a novel therapeutic target for treatment of RE in future.

Immunomodulation With Azathioprine Therapy in Rasmussen Syndrome: A Multimodal Evaluation

OBJECTIVE

To verify safety and efficacy of the corticosteroid-sparing drug azathioprine (AZA) in Rasmussen syndrome (RS), we retrospectively analyzed a cohort of patients with RS recruited in a single pediatric neuroscience center.

METHODS

We compared outcomes in 30 patients with RS who received AZA with 23 patients who were not treated with this drug. We used a multimodal approach to correlate therapy with clinical features (seizures, epilepsia partialis continua [EPC], hemiparesis) and neuroimaging markers of progressive brain atrophy.

RESULTS

AZA was well tolerated; only 1 patient discontinued treatment due to pancytopenia. In 27 of 30 patients receiving AZA, all of whom were corticosteroid responders, corticosteroid therapy could be weaned or reduced without worsening of seizures in 89%. Patients receiving AZA had a lower prevalence of EPC (42% vs 67% in controls) and hemiparesis (64% vs 92%, respectively). Cox regression showed for the AZA group compared to controls a delayed time to (1) EPC (≈2 years, exp[B] = 0.295, 95% confidence interval [CI] 0.108-0.807; p = 0.017), (2) hemiparesis (≈1 year, exp[B] = 0.315, 95% CI 0.137-0.724; p = 0.007), and (3) surgery (≈2 years, exp[B] = 2.068, 95% CI 1.012-4.227; p = 0.046). However, there were no group differences in cognitive decline over time (IQ change per year) or in hemispheric gray matter atrophy on serial MRI scans.

CONCLUSION

AZA treatment appears to slow clinical progression of RS in steroid responders; this will give the greatest advantage in patients in the early stages of the disease in whom surgical decision-making may require further time.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for pediatric patients with RS AZA is well tolerated and slows hemiparesis and appearance of EPC.

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.