Pediatric hydrocephalus is a well-studied and still incompletely understood entity. One of the physiological means by which hydrocephalus and intracranial hypertension evolve is through perturbations to normal vascular dynamics. Here the authors report a unique case of an extracranial vascular anomaly resulting in persistently elevated intracranial pressures (ICPs) independent of CSF diversion in a patient with a Joubert syndrome-related disorder. The patient developed worsening intracranial hypertension after successful CSF diversion of Dandy-Walker malformation-associated hydrocephalus via endoscopic third ventriculostomy-choroid plexus cauterization (ETV/CPC). Vascular workup and imaging revealed an extracranial arteriovenous fistula of the superficial temporal artery at the site of a prior scalp intravenous catheter. Following microsurgical obliteration of the lesion, ICP normalized from > 30 cm H2O preoperatively to 11 cm H2O postoperatively. A repeat lumbar puncture at 4 months postoperatively again demonstrated normal pressure, and the patient remained asymptomatic for 9 months. Recurrent symptoms at 9 months were attributed to inadequate CSF diversion, and the patient underwent ventriculoperitoneal shunt placement. This is the first report of an extracranial-to-extracranial vascular anastomosis resulting in intracranial hypertension. This case report demonstrates the need to consider extracranial vascular anomalies as potential sources of persistently elevated ICP in the syndromic pediatric population.