Rasmussen's encephalitis: early characteristics allow diagnosis.

Objective: To identify early manifestations of Rasmussen encephalitis (RE) that can prompt early and reasonably secure diagnosis, allowing medical or surgical therapies at an early stage when they may be more effective in slowing the disease.

Methods: The authors studied 12 patients with clinical and neuropathologic diagnosis of RE, followed from disease onset, assessing clinical history, imaging, and EEG and focusing on early characteristics. Anti-GluR3 antibody assays were also considered in 11 patients.

Results: By 4 months from first symptoms, all cases had 1) refractory focal seizures with a predominant motor component, 2) slow focal activity on EEG contralateral to the motor manifestations, and 3) focal contralateral white matter hyperintensity with insular cortical atrophy on neuroimaging. Less constant or later findings were epilepsia partialis continua, oligoclonal bands, and serum anti-GluR3 antibodies.

Conclusions: The association of partial seizures with focal EEG and neuroimaging changes allows a tentative diagnosis of RE 4 to 6 months after first symptoms.