Background: Trapped fourth ventricle (TFV) is a rare entity that occurs when the fourth ventricle is obstructed and isolated from the normal cerebrospinal fluid (CSF) circulation. While not always symptomatic, TFV can lead to compression of the cerebellum and brainstem, with potential for serious consequences. Treatment of TFV can be challenging, with options including CSF diversion via shunts versus open or endoscopic fenestrations. In this report, we describe a case of TFV that was managed endoscopically. Methods: A seven-year-old girl with a history of myelomeningocele and hydrocephalus, presented with a change in neurological status. Imaging of the brain and spine showed syringomyelia, markedly dilated ventricles, and a TFV. An endoscopic approach was used to fenestrate the wall of the fourth ventricle. Results: While there was an early favorable outcome, the first fenestration closed over within one month, requiring a repeat endoscopic fenestration. Both procedures were complicated by transient seizures, requiring a pediatric intensive care unit (PICU) admission after the second intervention. Pre- and post-operative clinical and diagnostic imaging findings are reported. Conclusions: Endoscopic fenestration can be an effective treatment option for management of TFV. The patient, family, and treating team should be prepared to deal with acute peri-operative complications that may require PICU management.