Endoscopic Fourth Ventriculostomy: Suboccipital Transaqueductal Approach for Fenestration of Isolated Fourth Ventricle: Case Report and Technical Note

Abstract

Trapped or isolated fourth ventricle is a known, late sequela after lateral ventricular shunt placement for hydrocephalus, particularly after infection or hemorrhage. It may cause brainstem compression and insidiously present with ataxia, dysarthria, and intracranial hypertension, further delaying diagnosis. There is no universally agreed on treatment algorithm, and options include open fenestration through a suboccipital craniotomy, fourth ventricle shunting, and minimally invasive options including endoscopic stenting and fenestration through a precoronal approach. We describe a young child with epilepsy and symptomatic brainstem compression from a dilated fourth ventricle, with a history of streptococcal parietal abscess and posthemorrhagic hydrocephalus requiring shunt placement. Given his history of infection and nearly neurologically intact examination, we pursued minimally invasive endoscopy through a suboccipital, transaqueductal approach to fenestrate his fourth ventricle. Magnetic resonance imaging (MRI) demonstrated complex, loculated hydrocephalus and a dilated fourth ventricle. Under electromagnetic navigation, we endoscopically fenestrated his fourth ventricle using a rarely described suboccipital, transaqueductal approach. He tolerated the procedure without complication and improved neurologically, although his follow-up MRI demonstrated no change in fourth ventricular dilation at 1 year. Although there was no decrease in size of the fourth ventricle on follow-up MRI, we describe an alternative, well-tolerated, suboccipital approach for the management of a trapped fourth ventricle. Fenestration of a web of tissue in the aqueduct of Sylvius provided long-term clinical improvement and may provide a rescue approach for patients who are not candidates for standard approaches.