|Year : 2019 | Volume
| Issue : 5 | Page : 1279
Surgery for Vestibular Schwannoma following Stereotactic Radiosurgery
Department of Neurosurgery, I/C Gamma Knife Centre, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||19-Nov-2019|
Prof. Manmohan Singh
Department of Neurosurgery, I/C Gamma Knife Centre, All India Institute of Medical Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh M. Surgery for Vestibular Schwannoma following Stereotactic Radiosurgery. Neurol India 2019;67:1279
Stereotactic radiosurgery (SRS) for smaller vestibular schwannoma has become the standard of care now. SRS is well tolerated by patients with excellent long-term tumor outcome with practically no facial nerve morbidity and good hearing control in patients with preserved hearing before SRS. The authors of the article have well described the operative findings and difficulties encountered during surgical excision of post SRS vestibular schwannomas., Following radiosurgery, vestibular schwannomas undergo central radio necrosis followed by reduction of tumor size over 1 to 2 years. Transient vestibular schwannoma enlargement following SRS is well documented in 20% of patients due to radiation effects rather than true tumor progression and only observation is recommended rather than surgical excision.
The arachnoid thickening around the tumor is an usual finding. Authors have used higher median radiation dose of 13Gy to the tumors that may be one reason for more arachnoid thickening around tumor. The average size of the tumor is also bigger in the present study, which might be responsible for surgical difficulties faced by authors. In our experience of vestibular schwannomas treated with gamma knife radiosurgery at our center, we did find subtle arachnoid thickening around the tumor but it did not influence tumor removal or pose surgical difficulties. The interface with brainstem was preserved in all cases. We attribute this to lower radiation marginal dose of 12 Gy used to treat tumors. We also operated upon the tumors when they were relatively smaller in size, as we offered them surgery early due to closer follow up and patients were also not much symptomatic before surgery. The tumors were not vascular in most of the cases and removal was not difficult. The central core of the tumors was invariably less vascular and soft. To prevent facial nerve damage, tumor in the internal acoustic meatus was left behind and was not retreated with SRS. In the follow up period, the residual tumor in the internal acoustic meatus remained static in size.
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