Multilocular hydrocephalus is a complication of neonatal hydrocephalus. Its main feature is the presence of multiple cysts inside the ventricles, which requires a specific therapeutic approach. The case of a preterm infant with intracranial hemorrhage grade II-III and central nervous system infection is reported. The cysts developed at the subependymal layer in the posterior area of the patient's thalamus. Their growth and development were charted by ultrasound imaging for several weeks. These types of cysts may grow to occupy the totality of the lateral ventricles, isolating the temporal horns. Of all the reviewed pathogenic mechanisms, we support the hypothesis of an inflammatory vasculitis at the subependymal level, with the subsequent infarct giving rise to the cysts. The osmotic pressure within the cavities, rather than intraventricular fluid, would account for the enlargement of the cysts.