Predictors of Trigeminal Neuropathy after Radiosurgery for Vestibular Schwannomas

Publication date: Available online 15 January 2016
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Suhan Senova, Mourad Aggad, Jean-Louis Golmard, Dominique Hasboun, Ioannis Lamproglou, Catherine Jenny, Philippe Cornu, Jean-Jacques Mazeron, Charles A. Valery
ObjectivesThe incidence of trigeminal neuropathy (TN) after vestibular schwannomas (VS) radiosurgery (RS) varies between 0 and 29 % across recent series. The lack of detailed guidelines regarding dosimetry in order to avoid TN after VS RS may account for it. The primary objective of this study is to analyze relationship between dosimetrical characteristics and symptoms related to TN observed after RS. Secondary objectives are to propose guidelines to optimize planification in VS RS regarding trigeminal nerve preservation and to precise the mechanism of trigeminal nerve impairment after VS RS.Methods and MaterialsOne hundred and seventy nine patients treated between 2011 and 2013 for VS RS and without trigeminal impairment before RS were included in a retrospective study. Univariate and multivariate analysis were peformed in order to determine predictors of TN among characteristics of the patients, the dosimetry and the VS.ResultsThere were 20 grade I, 99 grade II, 57 grade III and 3 grade IV KOOS.Fourteen patients (7.8%) presented a transitory or permanent TN. Between the patients with and without TN after VS RS, there was no significant difference regarding dosimetry or VS volume itself. Significant differences (univariate analysis p<0.05, Mann-Whitney test) were found for parameters related to cisternal portion of the trigeminal nerve: total integrated dose, maximum dose, mean dose, volume of the Vth nerve (Volv), volume of the Vth nerve receiving at least 11Gy (VolVcist>11Gy) but also for maximal dose to the Vth nerve nucleus and intra-axial portion (Dose maxVax). After multivariate analysis, the best model predicting TN included: VolVcist>11Gy (p=0.0045), Dose maxVax (p=0,0006) and Volv. (p=0.0058).The negative predictive value of this model was 97%.ConclusionsVolVcist>11Gy ,Dose maxVax and Volv should be checked when designing dosimetry for VS RS.

Teaser

The incidence of trigeminal neuropathy after vestibular schwannomas (VS) radiosurgery (RS) varies between 0 and 29 % across series probably due to the lack of Vth nerve dedicated guidelines. Retrospective multivariate analyses on 179 patients showed that the volume of the cisternal portion of the Vth nerve receiving at least 11Gy, volume of the cisternal Vth nerve and maximal dose to the Vth nerve nucleus and intra-axial portion should be precisely restricted when designing dosimetry for VS RS.


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