The roles of the wait-and-see strategy and proactive Gamma Knife surgery (GKS) in the treatment paradigm for small intracanalicular vestibular schwannomas (VSs) is still a matter of debate, especially when patients present with functional hearing. The authors compare these 2 methods.
Forty-seven patients (22 men and 25 women) harboring an intracanalicular VS were followed prospectively. The mean age of the patients at the time of inclusion was 54.4 years (range 20–71 years). The mean follow-up period was 43.8 ± 40 months (range 9–222 months). Failure was defined as significant tumor growth and/or hearing deterioration that required microsurgical or radiosurgical treatment. This population was compared with a control group of 34 patients harboring a unilateral intracanalicular VS who were consecutively treated by GKS and had functional hearing at the time of radiosurgery.
Of the 47 patients in the wait-and-see group, treatment failure (tumor growth requiring treatment) was observed in 35 patients (74%), although conservative treatment is still ongoing for 12 patients. Treatment failure in the control (GKS) group occurred in only 1 (3%) of 34 patients. In the wait-and-see group, there was no change in tumor size in 10 patients (21%), tumor growth in 36 patients (77%), and a mild decrease in tumor size in 1 patient (2%). Forty patients in the wait-and-see group were available for a hearing level study, which demonstrated no change in Gardner-Robertson hearing class for 24 patients (60%). Fifteen patients (38%) experienced more than 10 db of hearing loss and 2 of them became deaf. At 3, 4, and 5 years, the useful hearing preservation rates were 75%, 52%, and 41% in the wait-and-see group and 77%, 70%, and 64% in the control group, respectively. Thus, the chances of maintaining functional hearing and avoiding further intervention were much higher in cases treated by GKS (79% and 60% at 2 and 5 years, respectively) than in cases managed by the wait-and-see strategy (43% and 14% at 2 and 5 years, respectively).
These data indicate that the wait-and-see policy exposes the patient to elevated risks of tumor growth and degradation of hearing. Both events may occur independently in the mid-term period. This information must be presented to the patient. A careful sequential follow-up may be adopted when the wait-and-see strategy is chosen, but proactive GKS is recommended when hearing is still useful at the time of diagnosis. This recommendation may be a main paradigm shift in the practice of treating intracanalicular VSs.
Abbreviations used in this paper: ABR = auditory brainstem response; GKS = Gamma Knife surgery; IAC = internal auditory canal; PTA = pure tone average; SDS = speech discrimination score; TDT = tumor doubling time; TGR diam. = tumor growth rate based on diameter; TGR vol. = tumor growth rate based on volume; VS = vestibular schwannoma.
Address correspondence to: Jean Régis, M.D., Service de Neurochirurgie Fonctionnelle et Stereotaxique, Hôpital d'adulte de la Timone, 264 rue Saint Pierre, 13385 Marseille Cedex 05, France. email: email@example.com.
MyrsethEMøllerPPedersenPHVassbotnFSWentzel-LarsenTLund-JohansenM: Vestibular schwannomas: clinical results and quality of life after microsurgery or gamma knife radiosurgery. Neurosurgery56:927–9352005
PollockBEDriscollCLFooteRLLinkMJGormanDABauchCD: Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resection and stereotactic radiosurgery. Neurosurgery59:77–852006
SughrueMEKaneAJKaurRBarryJJRutkowskiMJPittsLH: A prospective study of hearing preservation in untreated vestibular schwannomas. Clinical article. J Neurosurg[epub ahead of print May 21 2010. DOI: 10.3171/2010.4.JNS091962]