Neurogenic stunned myocardium (NSM) is a potentially fatal cause of sudden cardiogenic dysfunction due to an acute neurological event, most commonly aneurysmal subarachnoid hemorrhage in adults. Only two pediatric cases of hydrocephalus-induced NSM have been reported. Here the authors report a third case in a 14-year-old boy who presented with severe headache, decreased level of consciousness, and shock in the context of acute hydrocephalus secondary to fourth ventricular outlet obstruction 3 years after standard-risk medulloblastoma treatment. He was initially stabilized with the insertion of an external ventricular drain and vasopressor treatment. He had a profoundly reduced cardiac contractility and became asystolic for 1 minute, requiring cardiopulmonary resuscitation when vasopressors were inadvertently discontinued. Over 1 week, his ventricles decreased in size and his cardiac function returned to normal. All other causes of heart failure were ruled out, and his impressive response to CSF diversion clarified the diagnosis of NSM secondary to hydrocephalus. He was unable to be weaned from his drain during his time in the hospital, so he underwent an endoscopic third ventriculostomy and has remained well with normal cardiac function at more than 6 months’ follow-up. This case highlights the importance of prompt CSF diversion and cardiac support for acute hydrocephalus presenting with heart failure in the pediatric population.