Abstracts

Rationale: Since the first description of Rasmussens encephalitis (RE) several anecdotal reports and small case series have been published addressing the rare epilepsy syndrome characterized by unilateral, progressive hemispheric inflammation of unknown etiology. Larger series are lacking and insights into consistent patterns of disease activity and phenomenology are missing. Methods: A chart review of 34 RE patients (range 1.8 - 14.7 years at first seizure) from the Bethel Epilepsy Centre, Germany (1988-2006) was systematically performed focusing on initial presentation, clinical course, EEG changes, neuroimaging findings and long-term outcome. Diagnosis of RE was based on European guidelines (Bien et al., Brain 2005, 128, 460). Results: Despite few consistent observations (26 out of 34 patients developed epilepsia partialis continua [EPC], 31 out of 34 hemiparesis [HP], initial status epilepticus implied bad prognosis), heterogeneity and unpredictability were the main characteristic features of RE. 1)Onset was highly variable and could be acute and severe, slow and mild, or slow and severe. 2)Severity and frequency of EPC correlated poorly with degree of HP. 3)Prodromal, acute and residual phases could be diagnosed in 90%, but showed interindividually significant variations with regard to length, intensity and transition to the next stage. 4)Imaging findings (most frequently temporal T2 signal increase on MRI) and EEG results developed in highly variable time lines and had poor correlation to the clinical course. 5)Long-term outcome was unpredictable: the spectrum ranged from acute onset with major imaging findings and good outcome to mild onset, few changes on imaging and severe disability. Conclusions: This large series of RE patients suggests that heterogeneity is a key finding in Rasmussens encephalitis and predicting long-term outcome is impossible in an early stage. Our understanding of the way disease markers in RE intercorrelate and determine overall prognosis is poor. The underlying pathophysiological processes resulting in various phenotypes are speculative.