A longitudinal MRI study in children with Rasmussen syndrome

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.

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.

Diagnosis and treatment of Rasmussen's encephalitis pose a big challenge: Two case reports and literature review

Rasmussen encephalitis (RE) is a rare disease of unknown etiology that causes severe chronic unihemispheric inflammatory disease of the central nervous system mainly in children. It leads to intractable seizures, cognitive decline and progressive neurological deficits in the affected hemisphere.

We report two cases of RE, as defined by fulfillment of the 2005 Bien criteria. The diagnostic challenge of characterizing this rare disease will be highlighted by the extensive serum, CSF, MR imaging and EEG data in the two patients. In addition, we will review the various forms of therapy attempted in these two patients, namely anti-epileptic drug therapy and immunomodulatory therapy. Hemispherectomy was done for the second patient with favorable outcomes of controlling seizures, but unfortunately, he died because of meningitis.

Until the causes of Rasmussen's encephalitis are known, it is difficult to anticipate how treatments will improve. Such a situation creates a therapeutic dilemma; hemispherectomy is not favored because of the inevitable postoperative functional deficits, but a real risk exists that treatments used to delay progression of the disease will defer definitive surgical treatment beyond the time when an optimum post-hemispherectomy outcome could be expected.

•

Rasmussen encephalitis (RE) causes severe chronic unihemispheric inflammatory disease.

•

RE should be suspected in any patient with refractory seizures.

•

Its recognition is important because early intervention with surgery can improve outcomes.

Autoimmune Epilepsies

Autoimmune epilepsies describe clinical syndromes wherein the immune system is suspected to be involved in the pathogenesis of seizures or as a mechanism for neuronal injury following seizures. These diseases typically affect otherwise healthy children and are characterized by explosive onset of focal seizures, encephalopathy, cognitive deterioration, or other focal neurological deficits, or all of these. Traditional neurological diagnostics lack sensitivity and specificity in the diagnosis of autoimmune epilepsies, and results must be considered in the clinical context. Consideration of an autoimmune etiology early in the clinical course is important to ensure timely initiation of immunotherapy, as appropriate, as conventional antiepileptic drugs alone are typically unable to control seizures and other neurological symptoms. This article discusses the autoimmune epilepsies of autoimmune encephalitis (including anti-N-methyl-D-aspartate receptor encephalitis), Rasmussen's encephalitis, and febrile infection-related epilepsy syndrome. Further research is needed to better understand pathogenic mechanisms, optimal immunotherapy, and the effect of treatment on prognosis.

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.

Pharmacoresistent Partial Epilepsy Secondary to Progressive Inflammatory Poliodystrophy

BACKGROUND

Epilepsy with progressive cortical volume loss is described secondary to energy failure such as mitochondrial disorders, infectious, or inflammatory etiologies and associated with temporal lobe epilepsy. Postmortem studies do not support that spontaneous seizures even if present for prolonged periods universally result in cortical volume loss.

MAIN FINDINGS

We describe two children with extratemporal pharmacoresistent epilepsy, slowly progressive gray matter volume loss over several years, and evidence of central nervous system inflammation. Brain magnetic resonance imaging changes and antibody profiles were not typical of a well-defined, antibody-mediated central nervous system syndrome such as N-methyl-D-aspartate receptor encephalitis.

CONCLUSIONS

These patients illustrate a novel presentation of a subacute inflammatory central nervous system process with epilepsy and progressive cortical volume loss, supporting the role of sequential brain imaging in children with epilepsy.

Mechanisms of epileptogenesis in pediatric epileptic syndromes: Rasmussen encephalitis, infantile spasms, and febrile infection-related epilepsy syndrome (FIRES)

The mechanisms of epileptogenesis in pediatric epileptic syndromes are diverse, and may involve disturbances of neurodevelopmental trajectories, synaptic homeostasis, and cortical connectivity, which may occur during brain development, early infancy, or childhood. Although genetic or structural/metabolic factors are frequently associated with age-specific epileptic syndromes, such as infantile spasms and West syndrome, other syndromes may be determined by the effect of immunopathogenic mechanisms or energy-dependent processes in response to environmental challenges, such as infections or fever in normally-developed children during early or late childhood. Immune-mediated mechanisms have been suggested in selected pediatric epileptic syndromes in which acute and rapidly progressive encephalopathies preceded by fever and/or infections, such as febrile infection-related epilepsy syndrome, or in chronic progressive encephalopathies, such as Rasmussen encephalitis. A definite involvement of adaptive and innate immune mechanisms driven by cytotoxic CD8(+) T lymphocytes and neuroglial responses has been demonstrated in Rasmussen encephalitis, although the triggering factor of these responses remains unknown. Although the beneficial response to steroids and adrenocorticotropic hormone of infantile spasms, or preceding fever or infection in FIRES, may support a potential role of neuroinflammation as pathogenic factor, no definite demonstration of such involvement has been achieved, and genetic or metabolic factors are suspected. A major challenge for the future is discovering pathogenic mechanisms and etiological factors that facilitate the introduction of novel targets for drug intervention aimed at interfering with the disease mechanisms, therefore providing putative disease-modifying treatments in these pediatric epileptic syndromes.

Correlation between magnetic resonance imaging and histopathologic grades in Rasmussen syndrome

The aim of this study was to investigate the correlation between magnetic resonance imaging (MRI) and histopathologic findings in Rasmussen syndrome. Serial MRIs were obtained for five patients who had histologically proven Rasmussen syndrome. The histopathologic grades of the lesions were subdivided into phases: active 1-3, resolving 1-3, and chronic inflammatory. The images were then correlated with histopathologic findings. Neuropathologic findings in the central areas on MRI demonstrated only the chronic and resolving grades, but active inflammatory abnormalities were present not only at the margins of the lesions, but also in areas of subtle signal abnormality on MRI. Atrophic areas on MRI exhibited all grades of histopathologic abnormalities, but chronic and resolving grades were predominant. Seizure duration of less than 6 months was associated with very active grades, duration of 1-2 years with variable grades, and duration greater than 6 years with chronic and resolving grades only. The MRI images correlated highly with histopathologic analysis. These findings suggest that the lesions initially arise from one site in the brain, and so support the centrifugal spreading theory of this disease. Findings also suggest that the margin rather than the center of the MRI abnormality may be the most ideal site for biopsy.