Immunomodulation With Azathioprine Therapy in Rasmussen Syndrome: A Multimodal Evaluation

OBJECTIVE:To verify safety and efficacy of the corticosteroid-sparing drug Azathioprine (AZA) in Rasmussen syndrome (RS), we retrospectively analyzed a cohort of RS patients recruited in a single pediatric neuroscience center. METHODS:We compared outcomes in 30 RS patients who received AZA with 23 patients who were not treated with this drug. We used a multimodal approach to correlate therapy with clinical features (seizures, epilepsia partialis continua [EPC], hemiparesis) and neuroimaging markers of progressive brain atrophy. RESULTS:AZA was well tolerated; only one patient discontinued treatment due to pancytopenia. In 27/30 AZA patients, all of whom were corticosteroid responders, corticosteroid therapy could be weaned or reduced without worsening of seizures in 89%. AZA patients had a lower prevalence of EPC (42% vs. 67% in controls) and hemiparesis (64% vs. 92%, respectively). Cox regression showed for the AZA group compared to controls a delayed time to1) EPC (of about 2 years, Exp(B)=0.295, 95%CI[0.108, 0.807];p=0.017), 2) hemiparesis (about one year, Exp(B)=0.315, 95%CI[0.137, 0.724];p=0.007), and 3) surgery (about 2 years, Exp(B)=2.068, 95%CI[1.012, 4.227];p=0.046). However, there were no group differences in cognitive decline over time (IQ change per year) or in hemispheric grey matter atrophy on serial MRI scans. CONCLUSION:AZA treatment appears to slow clinical progression of Rasmussen syndrome in steroid responders; this will give most advantage in patients in the early stages of the disease in whom surgical decision-making may require further time. CLASSIFICATION OF EVIDENCE:This study provides Class III evidence that for pediatric RS patients AZA is well tolerated and slows hemiparesis and appearance of EPC.