Bilateral Rasmussen's encephalitis associated with type II focal cortical dysplasia: Dormant 'second' epileptogenic zone in contralateral disease

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.

Bilateral Rasmussen Encephalitis: Good Outcome Following Hemispherotomy

BACKGROUND

Bilateral Rasmussen encephalitis is a rare variant of a debilitating, typically unihemispheric disease with limited treatment options. Few cases with bilateral histopathology have been reported, all with poor seizure control following surgery. Here we report a favorable outcome following hemispherotomy in a four-year-old male with biopsy-confirmed bilateral disease.

CASE

The patient presented with right hemispheric focal seizures with behavioral arrest and over a year progressed to left lower extremity clonic seizures, epilepsia partialis continua, and loss of ambulation, with transient response to steroids and tacrolimus. Histopathology confirmed bilateral disease. The patient developed super-refractory status epilepticus and underwent right functional hemispherotomy 4.5 years after initial presentation. In a 2.5-year follow-up period, an Engel 1D outcome classification was observed with substantially improved quality of life.

CONCLUSION

Previous reports of bilateral Rasmussen encephalitis describe universally poor outcomes, and hemispherotomy is often considered contraindicated. However, hemispherotomy in a patient with bilateral Rasmussen encephalitis may have a good outcome if seizures are unihemispheric.

A Special Case of Relapsing-Remitting Bilateral Encephalitis: Without Epilepsy, but Responding to Rituximab and with a Brain Biopsy Coinciding with Rasmussen Encephalitis

A nine-year-old boy manifested with headache, progressive mild cognitive decline and hemiparesis, but without clinical epileptic seizures (with abnormal EEG waves). Brain magnetic resonance imaging (MRI) showed bilateral cortical lesions mainly on the right hemisphere, and new lesions developed in frontal, parietal, occipital and temporal lobes around the old lesions presenting as a lace-like or ring-like enhancement in T1 with contrast over a disease course of five years. A suspected diagnosis of primary angiitis of the central nervous system was initially considered. Treated with high-dose corticosteroids, intravenous immunoglobulins and monthly pulse cyclophosphamide, his symptoms worsened with the intracranial lesion progression. Brain biopsy of the right frontal lobe was performed nearly five years after onset; prominent neuronal loss, a microglial nodule, as well as parenchymal and perivascular lymphocytic infiltrate within the cortex were found, which coincided with RE pathology changes. Encouragingly, after a regimen of rituximab, lesions on the follow-up brain MRI tended to be stable. Apparently, it was immune-mediated, but did not strictly fit any known disease entity, although it was similar to RE. We summarize this unique case, including clinical characteristics, imaging and pathology findings. We also discuss the diagnosis and treatment, focusing on comparison to RE as well as other possible neurological diseases.

A Case Series of Adult-Onset Rasmussen's Encephalitis: Diagnostic and Therapeutic Challenges

Rasmussen’s encephalitis (RE) is a rare neurologic disorder characterized by progressive cerebral hemiatrophy and medically refractory epilepsy. The majority of current literature on this topic is focused on the pediatric population. In this case series, we will review three cases of adult-onset 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, and pathologic sampling in all three patients. MR imaging and EEG data will be examined over time to characterize hallmark findings as well as progression. In addition, we will review the various forms of therapy attempted in these three patients, namely anti-epileptic drug therapy and immunomodulatory therapy. We will also utilize this case series to critically evaluate the broader context of atypical presentations of this disease and the value of current diagnostic criteria.

Neuropathology of epilepsy

Epilepsy is one of the most common neurologic disorders, affecting about 50 million people worldwide. The disease is characterized by recurrent seizures, which are due to aberrant neuronal networks resulting in synchronous discharges. The term epilepsy encompasses a large spectrum of syndromes and diseases with different etiopathogenesis. The recent development of imaging and epilepsy surgery techniques is now enabling the identification of structural abnormalities that are part of the epileptic network, and the removal of these lesions may result in control of seizures. Access of this clinically well-characterized neurosurgical material has provided neuropathologists with the opportunity to study a variety of structural brain abnormalities associated with epilepsy, by combining traditional routine histopathologic methods with molecular genetics and functional analysis of the resected tissue. This approach has contributed greatly to a better diagnosis and classification of these structural lesions, and has provided important new insights into their pathogenesis and epileptogenesis. The present chapter provides a detailed description of the large spectrum of histopathologic findings encountered in epilepsy surgery patients, addressing in particular the nonneoplastic pathologies, including hippocampal sclerosis, malformations of cortical development, Sturge-Weber syndrome, and Rasmussen encephalitis, and reviews current knowledge regarding the underlying molecular pathomechanisms and cellular mechanisms mediating hyperexcitability.

Rasmussen encephalitis with dual pathology in a patient without seizures: case report and literature review

PURPOSE

Rasmussen encephalitis without seizures is rare. We report a case of Rasmussen encephalitis and cortical dysplasia without epilepsy as well as describe the imaging, pathology, and clinical course and review the literature to investigate whether this may represent a rare subset of Rasmussen encephalitis.

CASE REPORT

We report the case of a 12-year-old girl with a history of cognitive decline and right arm weakness. Magnetic resonance imaging demonstrated diffuse left hemispheric cortical and subcortical atrophy suggestive of Rasmussen encephalitis. The patient had no clinical history of seizures, and electroencephalography did not demonstrate epileptiform abnormalities. Craniotomy for open brain biopsy was performed, and histopathologic evaluation identified Rasmussen encephalitis with cortical dysplasia (dual pathology).

CONCLUSIONS

To the best of our knowledge, this is the third case of Rasmussen encephalitis diagnosed by both imaging and histopathology that had no clinical or electroencephalographic evidence of seizures and is the only case of Rasmussen encephalitis with cortical dysplasia without epilepsy.