Role of intracanalicular volumetric and dosimetric parameters on hearing preservation after vestibular schwannoma radiosurgery.
OBJECTIVE
To analyze the relationship between hearing preservation after gamma knife radiosurgery (GKR) for vestibular schwannoma (VS) and some volumetric and dosimetric parameters of the intracanalicular components of VS.


METHODS
This study included 82 patients with a VS treated by GKR; all patients had no NF2 disease, a Gardner-Robertson hearing class 1-4 before treatment, a marginal dose of 12 Gy, and a radiologic and audiologic follow-up > or =1 year post-GKR. The volume of both the entire tumor and the intracanalicular part of the tumor and the mean and integrated dose of these two volumes were correlated to the auditory outcomes of patients.


RESULTS
At last hearing follow-up, 52 patients had no hearing worsening, and 30 patients had an increase of > or =1 class on Gardner-Robertson classification. We found that hearing preservation after GKR is significantly correlated with the intracanalicular tumor volume, as well as with the integrated dose delivered to the intracanalicular tumor volume.


CONCLUSIONS
Some volumetric and dosimetric parameters of the intracanalicular part of the tumor influence hearing preservation after GKR of VS. Consequently, we advise the direct treatment of patients with preserved functional hearing and a VS including a small intracanalicular volume.
Massager
Nicolas
N
Gamma Knife Center, Erasme Hospital, Université Libre de Brixelles, Brussels, Belgium. nmassage@ulb.ac.be
Nissim
Ouzi
O
Delbrouck
Carine
C
Devriendt
Daniel
D
David
Philippe
P
Desmedt
Françoise
F
Wikler
David
D
Hassid
Sergio
S
Brotchi
Jacques
J
Levivier
Marc
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006309:Hearing / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000473:pathology / Q000601:surgery*; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D018709:Statistics, Nonparametric