Favorable Outcomes in a Rare Case of Chiari Malformation Type III: A Clinical Report

This report details the case of a 1-year and 11-month-old Filipino female patient who presented with a persistent occipital mass that was soft, non-tender, mobile, and lit through upon transillumination. A neurological test revealed a global developmental delay. Neuroimaging revealed a bony defect at the posterior cranial fossa with herniation of the occipital lobe, cerebrospinal fluid, and the meninges, consistent with Chiari malformation type III, a rare and severe form accounting for less than 1% of Chiari malformations. While this condition typically carries a poor prognosis, the patient showed a favorable outcome following neurosurgical intervention. We present this case to share our clinical experience with this exceedingly rare condition and highlight its potential for positive post-surgical outcomes.