Radiosurgical third ventriculostomy: Technical note

Upfront Radiosurgery for Treatment of Symptomatic Obstructive Hydrocephalus due to Brain Tumors

Introduction

Hydrocephalus is a build-up of cerebrospinal fluid (CSF) in the brain and is characterized by abnormal dilatation of the cerebral ventricles. Patients can be either asymptomatic, have symptoms related to primary tumors, or have hydrocephalus-related symptoms. Generally, symptomatic patients are candidates for ventriculoperitoneal (VP) shunt placement to reduce acute symptoms. Little evidence exists regarding the resolution of symptomatic hydrocephalus secondary to brain tumors using stereotactic radiosurgery (SRS) alone as a primary treatment option.

Methods

The present study is a retrospective series of eight patients (six men and two women) diagnosed with obstructive hydrocephalus due to brain tumors treated with radiosurgery between April 2013 and February 2021. The primary endpoint of the present study is to report our institutional experience regarding the control of symptomatic obstructive hydrocephalus due to brain tumors treated with upfront radiosurgery.

Results

The mean age was 52 years (range, 5-79). The most common presenting symptoms included headache (100%), vision-related symptoms (75%), and ataxia (37.5%). All patients showed symptom improvement after radiosurgery, five (62.5%) patients showed resolution in less than three days and the rest of the patients resolved hydrocephalus in a longer timeframe (more than three days). All patients lowered their Evans index compared to the index documented before radiosurgery, in a range from 0.02 to 0.17.

Conclusion

Radiosurgery is a non-invasive alternative treatment for primary and secondary brain tumors that debut with obstructive hydrocephalus, tumors expected to have a high alpha/beta ratio might be suitable to attempt radiosurgery to avoid permanently implanted devices such as VP shunts or other invasive procedures such as a third ventriculostomy. The present study demonstrated that in selected cases SRS can lead to hydrocephalus symptom resolution along with a decrease in ventricular size in a relatively short time frame. Little evidence exists regarding the effect of SRS on symptomatic hydrocephalus resolution and further histology-specific studies are required. We acknowledge that this approach requires immediate access to radiosurgery and close clinical follow-up to ensure success.

Frameless radiosurgical third ventriculostomy: Technical report

Background:

We describe the technical report and results of the first image-guided, linear accelerator, frameless radiosurgical third ventriculostomy.

Methods:

We report a 20 years old man, with diplopia, balance disturbances, and limitation for gaze supraversion. Magnetic resonance imaging resonance imaging of the brain and cranial computed tomography showed showed a left thalamic-midbrain lesion that caused partial compression of the Silvio aqueduct and mild ventricular dilatation. The biopsy revealed the diagnosis of pleomorphic xanthoastrocytoma. Before radical treatment of the tumor with fractionated stereotactic radiotherapy, the patient underwent to frameless radiosurgical third ventriculostomy, on the TrueBeam STX® platform with the ExacTrac localization system. The target used was the one defined on the floor of the third ventricle, at the midpoint between the mammillary bodies and the infundibular recess. The prescription dose was 120 Gy, given using a monoisocentric technique of multiple noncoplanar circular arches. The geometric arrangement of the plan consisted of 15 arches, with a 4 mm cone, distributed over a 110° table.

Results:

There was symptomatic and image improvement two days after radiosurgery. On CT, a reduction in ventricular dilation was observed with a reduction in the Evans index from 0.39 (initial CT) to 0.29 (CT at 15 days). In 3.0T magnetic resonance image at 3 months, we showed the third ventriculostomy. There have been no treatment failures or complications.

Conclusion:

It is possible to effectively perform the frameless radiosurgical third ventriculostomy without associated morbidity in the short term.