Rasmussen's encephalitis: structural, functional, and clinical correlates of contralesional epileptiform activity.

Area of Science:

• Neurology
• Neuroscience
• Epileptology

Background:

• Rasmussen's encephalitis (RE) is characterized by progressive inflammation in one brain hemisphere.
• However, epileptiform activity in the opposite hemisphere (contralesional) has been frequently observed.

Purpose of the Study:

• To quantify contralesional epileptiform activity in RE patients.
• To investigate the functional and structural correlates of this activity.
• To assess its impact on surgical outcomes.

Main Methods:

• Retrospective analysis of EEG data from 127 RE patients across two tertiary centers.
• Evaluation of preoperative contralesional epileptiform activity using logistic regression.
• Comparison of cognitive function, MRI findings, and surgical outcomes between patients with and without contralesional activity.

Main Results:

• Preoperative contralesional epileptiform activity was present in 44% (Centre 1) and 14% (Centre 2) of patients.
• This activity was associated with younger onset age, contralesional MRI alterations, lower intelligence, and impaired verbal memory.
• Contralesional epileptiform activity reduced the likelihood of postoperative seizure freedom in both cohorts.

Conclusions:

• The findings challenge the strict unilaterality concept of RE.
• Contralesional epileptiform activity is a significant predictor of persistent postoperative seizures.
• EEG evaluation for contralesional activity is crucial for predicting surgical success in RE.