Endoscopic Third Ventriculostomy in a Patient with Giant Bilateral Vestibular Schwannomas

Background: Surgical management of patients with bilateral vestibular schwannomas in the setting neurofibromatosis 2 is controversial and challenging for the physician and burdensome for the patient. There is evidence in contemporary literature that the size of these tumors can dictate hearing and facial nerve outcomes. The author presents a case of a patient with a known history of enlarging bilateral vestibular schwannomas that began to cause the patient hydrocephalus, tonsillar herniation and neurologic deterioration. Strategic interventions were necessary to avoid future complications.

Case Report: The patient is a 34-year-old female who has a 10-year history of bilateral vestibular schwannomas. She refused surgical treatment for many years and was managed with bevacizumab as a result. Ultimately, her bilateral tumors grew from 2.3 cm × 2 cm × 2.4 cm to 5 cm × 3.8 cm × 4.8 cm on the left and 1.8 cm × 1 cm × 1.3 cm to 4.2 cm × 2.2 cm × 3 cm on the left. Because of her progressive gait instability with associated severe brainstem compression, hydrocephalus, tonsillar herniation, and nonserviceable hearing on the right side, she ultimately agreed to a right translabyrinthine approach and external ventricular drain. Her surgery was complicated by a cerebellar hematoma and she had a subtotal resection. The patient remained at her neurologic baseline postoperatively and her drain remained open. She was placed on hypertonic saline to reduce the cytotoxic edema from the intraparenchymal hemorrhage. She ultimately failed a clamping trial of her drain. Because she had a significant residual tumor burden I felt that the patient would ultimately need further surgery via a retrosigmoid approach. Also because she had a large left sided tumor as well, the goal was to avoid placing ventriculoperitoneal shunt tubing in either retroauricular space. On evaluation of a head CT done related to her clamp trial, her prepontine space had opened and, consequently, an endoscopic third ventriculostomy (ETV) was suggested to the patient as a solution to the dilemma regarding CSF diversion. The patient ultimately had an ETV done and needed no further shunting procedures.

Conclusion: The patient continued to suffer from obstructive hydrocephalus after her translabyrinthine approach. Even though she had significant tumor burden that remained in her posterior fossa, an ETV was a successful and optimal strategy. This outcome proved to be beneficial as the patient would likely need both her retrosigmoid spaces available for further surgical options that may be employed during her life. An ETV should also be considered as an option for these sorts of patients.

No conflict of interest has been declared by the author(s).