Meningitis due to inflammatory reaction to <i>Echinococcus</i> antigen after the resection of cerebral alveolar hydatid cyst

Meningitis after resection of a cerebral alveolar hydatid cyst (CAHC) is rare. Although several etiologies are proposed for meningitis, including recurrence or inflammatory reaction to dead echinococcal antigens, the effectiveness of treatment strategies specifically targeting the inflammatory reaction has not been reported. A 72-year-old patient presented with a brain cyst suggestive of CAHC. The cyst ruptured during resection, which was immediately replaced with 95% ethanol to obliterate the viable larvae, followed by cyst removal. One-month post-surgery, the patient showed signs of meningitis suggestive of a recurrence of cerebral hydatidosis. However, the negative sign of the recurrence on the brain and whole spine MRI suggested an inflammatory reaction to the obliterated <i>Echinococcus</i> antigen. An increased dose of prednisone resulted in the patient's complete recovery without recurrence for 1.8 years. Adding steroids to the anthelmintic maintenance treatment could be reasonable if the inflammatory reaction is more likely to be the cause.