Abstracts

Rationale: Rasmussen encephalitis (RE) is a T-cell mediated inflammatory disease that causes explosive onset refractory focal epilepsy that typically affects children. It was initially described in 1958 as a chronic hemispheric encephalitis that leads to unilateral atrophy. It is extremely rare with an incidence of 1.7-2.4 per 10,000,000 and can often be overlooked and misdiagnosed in early stages. Left untreated, it can lead to irreversible progressive hemiparesis and cognitive decline. Patients with left hemispheric involvement have been reported to have lower verbal intelligence quotient (IQ), and those with right hemispheric involvement with lower nonverbal IQ with 50% of overall IQs below 80. For patients in which the dominant hemisphere is affected, language skills may reorganize to the non-encephalopathic hemisphere. Functional hemispherectomy has remained the only effective treatment, now considered standard of care, with modern medical therapies having limited efficacy. The aim of this study is to evaluate neuropsychological profiles of pediatric patients with RE.

Methods: Patients with a clinical diagnosis of RE were retrospectively reviewed from 1/1/2019 to 6/1/2022 at a large tertiary care pediatric center. Neuropsychological evaluations included assessment of intellectual, language, visual motor integration, fine motor dexterity, and verbal and visual memory abilities.

Results: Five patients (3 males) with a diagnosis of RE were identified (Table 1). Median age was 4 years (4-14 years). Seizure types included focal motor clonic (n=3), focal non-motor (n=1), and mixed (n=1).  MRI showed discrete T2/FLAIR hyperintense lesions (n=3) and slight unilateral cerebral atrophy (n=3). Four patients with PET scans showed unilateral hemispheric hypometabolism, 2 with more hypometabolism around lesions, 1 with multifocal white matter encephalomalacia, and 1 with small periventricular nodular heterotopia. Three patients with focal lesions had ECOG-guided resection, one followed by SEEG-guided resection and functional hemispherotomy. Pathology showed 2 patients with CD8+ lymphocytic encephalitis, 1 with CD8+ predominant lymphocytosis, and 1 with CD3/CD8+ predominant lymphocytosis. Neuropsychology evaluations were done on average 9.4 months after seizure onset (range, 1-26 months). Cognitive decline was noted qualitatively in four of the five patients following seizure onset. Comparison of neuropsychological evaluation findings between younger (4 years old) (n=3) and older children/adolescents (11 and 14 years old) (n=2) revealed that the younger group did not demonstrate a strongly lateralizing neuropsychological profile, whereas the older group’s profiles showed characteristic lateralization with greater dysfunction in the encephalitic hemisphere (Table 2).

Conclusions: Results from our limited study found that neuropsychological profiles of patients with RE varied by age, with younger children having non-lateralizing profiles and older children/adolescents having lateralizing profiles. These findings highlight the importance of early evaluation and intervention for this population in order to preserve functional outcome.

Funding: No funding was provided for this study.