Impact of clinical variables on intellectual outcomes after hemispherotomy for Rasmussen's encephalitis: a...

Rasmussen's encephalitis (RE) affects the structure and function of one cerebral hemisphere, typically during childhood. Hemispherotomy is a surgical treatment that functionally disconnects the affected hemisphere. The cognitive consequences of surgery and the potential for postoperative recovery remain poorly understood, however, due to their complex and multifactorial nature. This study aimed to examine the long-term cognitive outcomes of patients with RE following hemispherotomy and identify the clinical factors influencing recovery.

Forty-four patients who underwent childhood hemispherotomy for RE (28 girls, 23 with left RE) were included in this retrospective study. Neuropsychological assessments were conducted during postoperative follow-up, and verbal (VIQ) and nonverbal (performance IQ [PIQ]) IQ scores from the most recent evaluation were analyzed. The impact of age at seizure onset (ASO), age at hemispherotomy, preoperative epilepsy duration, side of hemispherotomy, age at neuropsychological evaluation, and postoperative follow-up duration on intellectual efficiency scores was assessed using partial least squares analysis.

The mean ASO was 5.9 years, the mean age at hemispherotomy was 9.6 years, the mean epilepsy duration was 3.7 years, and the mean postoperative follow-up duration was 9.5 years. After hemispherotomy, 91% of patients were seizure free (Engel class I), and 86% were no longer receiving antiepileptic medication. Patients who underwent hemispherotomy of the language-dominant hemisphere (Hdom) had lower VIQ scores but higher PIQ scores compared to those with hemispherotomy of the nondominant hemisphere (Hnondom). Results showed that higher VIQ was significantly associated with several clinical factors, including a shorter epilepsy duration before surgery, a younger age at surgery, and hemispherotomy of the nondominant hemisphere for language. In contrast, no clear link was found between clinical variables and PIQ.

In RE, early hemispherotomy performed soon after disease onset appears to be associated with better long-term intellectual outcomes. Verbal functions can be recovered following hemispherotomy of the dominant hemisphere, highlighting the preferential reorganization of language in postoperative cognitive recovery. These findings underscore the critical importance of early surgical decision-making in optimizing patient care and maximizing postoperative recovery.