Ventricular access device placement in the fourth ventricle to treat malignant fourth ventricle brain tumors: technical note

Ventricular access devices (VADs) are commonly placed in the lateral ventricle but rarely placed in other ventricular compartments. This manuscript describes technical aspects of VAD placement into the fourth ventricle for the purpose of treating malignant posterior fossa brain tumors. As part of a pilot clinical trial to treat recurrent malignant brain tumors in children, seven patients underwent posterior fossa craniotomy and placement of a ventricular catheter under direct vision into the fourth ventricle. The catheter was placed without passing through any brain parenchyma. It was then connected to a VAD placed subcutaneously at the inferior aspect of the incision. Three of the seven patients underwent simultaneous subtotal resection of recurrent tumor located in the fourth ventricle or cerebellum, and one patient underwent simultaneous tumor biopsy. The VAD was used to administer chemotherapy (methotrexate) in five of the seven patients. Six patients had no new neurological deficits after surgery, and one patient had partial left-sided facial weakness that was attributed to resection of tumor close to the floor of the fourth ventricle. No new neurological deficits were caused by VAD placement or by methotrexate infusions into the fourth ventricle. A VAD for chemotherapy infusion can be placed safely into the fourth ventricle without damaging the brainstem or cerebellum. Attention to anatomical details specific to the fourth ventricle are important when placing a fourth ventricle VAD and when using it to administer chemotherapy.