RESUMEN
INTRODUCTION: Spontaneous third ventriculostomy (STV) is characterized by the spontaneous rupture of one of the ventricle walls due to increased pressure in the third ventricle caused by obstructive hydrocephalus. Clinically, STV results in resolution of signs and symptoms of intracranial hypertension and head circumference stabilization. No spontaneous STV cases in patients with myelomeningocele have been reported in the literature. The objective of this study was to report three cases of STV in patients with type 2 Chiari malformation who underwent intrauterine treatment. CASE PRESENTATION: All patients presented clinically with increased head circumference during outpatient follow-up. Only one patient required a ventriculoperitoneal shunt implantation. The other patients did not require further intervention. CONCLUSION: STV is a rare entity that is difficult to diagnose and should always be suspected in spontaneous hydrocephalus resolution, especially in early childhood. STV is not synonymous with hydrocephalus resolution.