Primary intraventricular brain abscess resulting in isolated dilation of the inferior horn and unilateral hydrocephalus

Primary intraventricular brain abscesses are rare, and there are no established treatment guidelines for this condition. We report a case in which isolated ventricular dilatation and unilateral hydrocephalus developed after seemingly successful conservative management and which required surgical diversion of the cerebrospinal fluid. A 59-year-old woman presented to our emergency department with high-grade fever and headache. Brain magnetic resonance imaging (MRI) revealed abscesses in the bilateral posterior horn. Although surgical evacuation of the abscesses was considered, conservative management with antibiotics was selected because of the paucity of severe neurological deficits and the concern that an attempt to evacuate the intraventricular abscess might lead to inadvertent rupture of the abscess capsule and acute ventriculitis. Despite reduction in the abscess volume, the patient developed an altered mental status 4 weeks after admission. Follow-up MRI revealed isolated dilation of the left inferior horn, compressing the brainstem. Emergency fenestration of the dilated inferior horn was performed, and endoscopic observation revealed an encapsulated abscess with adhesion to the ventricular wall which was thought responsible for the ventricular dilation and unilateral hydrocephalus. Two weeks after the initial surgery, the unilateral hydrocephalus was treated by placement of a ventriculoperitoneal shunt. Eradication of the intraventricular brain abscesses without surgical evacuation may justify the conservative management of this patient. However, the possibility that earlier surgical evacuation might have prevented development of the isolated ventricular dilation cannot be denied. Additional clinical experience is required to determine which treatment (surgical vs. conservative) is more appropriate in patients with primary intraventricular brain abscesses.