A series of 34 patients with Rasmussen's encephalitis: Clinical course, EEG- and MRI findings

Purpose: Rasmussen encephalitis (RE) is a rare epilepsy syndrome manifesting primarily in childhood characterized by unilateral, progressive hemispheric inflammation of unknown etiology.

Refractory focal epilepsy and Epilepsia partialis continua, progressive hemiparesis, hemianopsia and cognitive decline are the cardinal features.

Our retrospective study analyses the longitudinal course of the electroclinical and imaging features of 34 patients with RE.

Method: 34 patients (range 1.8–14.7 years at first seizure) presenting between 1988 and 2006 in the Bethel Epilepsy Centre were studied and included clinical parameter: age onset, seizure (sz) types and frequency, status epilepticus (SE), Todd's paresis and hemiparesis, EEG patterns and MRI findings.

Results: Three distinctive phases could be identified in 85% patients who were categorized as:

• Prodromal Stage=PS

• Acute Stage=AS

• Residual Stage=RS

Focal and generalized SE presentation most often occurred in the AS of RE and was particularly correlated with bad prognosis when found as an initial symptom.

76% of RE patients had focal slowing on EEG already in the PS, mainly in the temporo-central region. Epileptiform activity was seen in 72% of the PS and in 100% of the AS. T2-Signal increase on MRI was progressive over time (22% in PS, 44% in AS, 93% in RS); local atrophy was present in already 11% of the PS and 100% when RS was reached.

Conclusion: Despite the heterogeneity of the clinical course, there was a striking intercorrelation between clinical, functional (EEG) and morphological (MRI) data reflecting continuous progression of the disease and allowing subcategorization in at least 3 subgroups.