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. 2011;1(3):237-245.

Gamma knife radiosurgery for intralabyrinthine schwannomas

Nicolas Massager  1   2 , Landry Drogba  1   2 , Carine Delbrouck  1   3 , Nadir Benmebarek  1   2 , Françoise Desmedt  1 , Daniel Devriendt  1
Affiliations

Gamma knife radiosurgery for intralabyrinthine schwannomas

Nicolas Massager et al. J Radiosurg SBRT. 2011.

Abstract

Object: To analyze indications and technical specificities of treatment of intralabyrinthine schwannoma (ILS) by Gamma Knife radiosurgery.

Methods: Six patients were treated by Gamma Knife irradiation for a schwannoma arising from the cochleo-vestibular structures. Patients presented hearing worsening at different stages, tinnitus, imbalance and/or vertigo.

Results: ILS was intravestibular/intracochlear/intravestibulocochlear/ transmacular in respectively 2/1/2/1 patients. We cover the entire tumor volume with a margin prescription dose of 12-Gy. The tumor volume remained unchanged at last follow-up in all cases; for 4 patients with functional hearing still present before treatment, the audiological status remained stable in 2 patients, worsened moderately in 1 patientand worsened to cophosis in 1 patient. No patient experienced worsening of tinnitus, imbalance or vertigo after irradiation.

Conclusions: Gamma Knife treatment of ILS is technically feasible without risk thanks to the precision of current robotized Gamma Knife devices. Patients treated radiosurgically avoid some of the risks of microsurgery, could in some cases maintain useful hearing and prevent further symptoms worsening.

Keywords: Gamma Knife; Intralabyrinthine schwannomas; classification; cochlea; irradiation; outcome; radiosurgery; treatment; vestibule.

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Figures

Figure 1
Figure 1
Top: Stereotactic imaging acquisition during GKR procedure: high-resolution 3D T1-weighted gadolinium-enhanced MRI (left), high-resolution 3D T2-weighted MRI (middle), and high-resolution 3D bone CT-scan acquisition (right). Bottom: Image fusions used for dosimetric planning: fusion of MRI-T1gadolinium with bone CT (left), and fusion of MRI-T2 with bone CT (right). The white arrow shows the ILS.
Figure 2
Figure 2
Examples of 4 different locations of ILS: A: class Ia (intravestibular) ; B: class Ib (intracochlear); C: class Ic (intravestibulocochlear) ; D: C class IIa (transmacular).
Figure 3
Figure 3
GKR dosimetric plannings for ILS.
Figure 3
Figure 3
GKR dosimetric plannings for ILS.
See this image and copyright information in PMC

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