Objective: To study the immediate and chronic effects of high-dose, long-te
rm human IV immunoglobulin (hIVIg) therapy in two patients with advanced ad
ult-onset Rasmussen's encephalitis (RE). Background: Despite advances in ou
r understanding of the autoimmune pathogenesis of RE, medical options for c
hronic treatment are limited. Methods: In an open-label treatment trial, tr
eatment started with monthly cycles of high-dose hIVIg (0.4 g/kg/d for 5 da
ys) followed by maintenance therapy (0.4 g/kg 1 day each month) after the p
atients' conditions began to improve. Outcome measures included clinical, p
sychological, functional, and laboratory assessments before and at relevant
intervals throughout I year of treatment. Results: In both patients, unrel
enting pretreatment deterioration halted, and after this they displayed str
iking improvements in seizure control, hemiparesis, and cognition that prod
uced useful recovery of function. Improvements were delayed until after 2 t
o 4 monthly cycles of high-dose hIVIg and continued when patients switched
to maintenance treatment. Their recoveries were accompanied by increased ce
rebral perfusion on interictal SPECT and suppression of inflammatory marker
s in CSF. Conclusions: hIVIg can be a useful, possibly disease-modifying, l
ong-term therapy for adult-onset RE that should be considered before radica
l surgery is performed. Because improvements can be delayed, we propose gui
delines for intensive and prolonged trials of immunomodulatory therapy in a
dults with this syndrome.