Seventy-two patients with a unilateral vestibular schwannoma have been treated conservatively for a median of 121 months. They have been followed prospectively by serial clinical examination, MRI scans and audiometry. Twenty-five patients (35%, 95% CI: 24-47) failed conservative management and required active intervention during the study. No factors predictive of tumour growth or failure of conservative management could be identified. Seventy-five per cent of failures occurred in the first half of the 10-year study. The median growth rate for all tumours at 10 years was 1 mm/year (range -0.53-7.84). Cerebellopontine angle tumours grew faster (1.4 mm/year) than intracanalicular tumours (0 mm/year, P < 0.01); 92% had growth rates under 2 mm/year. Hearing deteriorated substantially even in tumours that did not grow, but did so faster in tumours that grew significantly (mean deterioration in pure tone average at 0.5, 1, 2 and 3 kHz was 36 dB; speech discrimination scores deteriorated by 40%). Patients who failed conservative management had clinical outcomes that were not different from those who underwent primary treatment without a period of conservative management.

Vestibular schwannomas have been traditionally managed with microsurgical removal and in recent years, stereotactic radiotherapy. However, there is a group of patients in whom a conservative management approach might represent a desirable alternative. The aim of this study was to determine the natural history and outcome following the conservative management of 72 patients with unilateral vestibular schwannomas. This is a prospective cohort review of a previously published group of patients [Clin. Otolaryngol. (2000) 25, 28-39] with unilateral vestibular schwannoma that were initially analysed at our institution in 1998 [Walsh R.M., Bath A.P., Bance M.L. et al., Clin. Otolaryngol. (2000) 25, 28]. The mean duration of follow-up was 80 months (range 52-242 months). All the patients in the study underwent serial magnetic resonance imaging (MRI) for assessment of tumour growth. Patients were deemed to have failed conservative management if there was evidence of rapid radiological tumour growth and/or increasing signs and symptoms, which necessitated active intervention. The mean tumour growth rate for the entire group at the second review was 1 mm/year (range -0.84-9.65 mm/year). The mean growth rate for cerebellopontine angle tumours (1.3 mm/year) was significantly greater than that of internal auditory canal (IAC) tumours (0 mm/year) (P = 0.005). The majority of tumours (87.14%) grew <2 mm/year. There was significant tumour growth seen in 38.9%, no or insignificant growth in 41.7%, and negative growth in 19.4%. Twenty-three patients (32%) failed conservative management at the second review. There was no difference in the outcome of these failed patients in comparison with patients who underwent primary treatment without a period of conservative management. The mean growth rate of tumours in patients that failed conservative management (3.1 mm/year) was significantly greater than that in patients who did not fail (0.2 mm/year) (P < 0.001). No factors predictive of tumour growth or failure of conservative management were identified. Hearing deterioration with pure tone averages (0.5, 1, 2, 3 kHz) and speech discrimination scores occurred irrespective of tumour growth. This prospective study further emphasizes the role of conservative management in selected cases of vestibular schwannomas. Tumours in this study confined to the IAC typically demonstrated minimal or no growth on serial MRI scanning. Regular follow-up with interval scanning is mandatory in all patients.

Although microsurgery is generally regarded as the conventional treatment of choice for most vestibular schwannomas, there remains a group of patients in whom a conservative management approach may be a desirable alternative. The aim of this study was to determine the natural history and outcome following the conservative management of 72 patients with unilateral vestibular schwannomas. The reasons for conservative management included poor general health, age, patient preference, small tumour size, minimal or no symptoms, and tumour in the only/better hearing ear. The mean duration of follow-up was 39.8 months (range 12-194 months). All patients underwent serial magnetic resonance imaging (MRI) for assessment of tumour growth. Patients were deemed to have failed conservative management if there was evidence of continuous or rapid radiological tumour growth and/or increasing symptoms or signs. The mean tumour growth rate, according to the 1995 guidelines of the American Academy of Otolaryngology/Head and Neck Surgery, was 1.16 mm/year (range: 0.75 9.65 mm/year). Approximately 83% of tumours grew at < 2 mm/year. Significant tumour growth was seen in 36.4%, no or insignificant growth in 50%, and negative growth in 13.6% of tumours. The growth rate of CPA tumours (1.4 mm/year) was significantly greater than that of IAC tumours (0.2 mm/year) (P = 0.001). Failure of conservative management, in which active treatment was required, occurred in 15.3%. The outcome of these patients appeared to be as favourable to a comparable group who underwent primary treatment, without a period of conservative management. The mean growth rate of tumours in patients who failed conservative management (4.2 mm/year) was significantly greater than that in patients who did not fail (0.5 mm/year) (P < 0.01). No factors predictive of tumour growth or failure of conservative management were identified. Deterioration of mean pure tone average (0.5, 1, 2, 3 kHz) and speech discrimination scores occurred regardless of whether radiological tumour growth was demonstrated or not. This study suggests that in a select number of cases of vestibular schwannoma, a conservative management approach may be appropriate. Regular follow-up with serial MRI is mandatory. Deterioration of auditory function occurs even in the absence of tumour growth.

Objective: To estimate the risk of loss of serviceable h earing during the conservative management of vestibular schwannomas. Study Design: Retrospective case review. Methods: Twe nty-five patients with a r a diological diagnosis of unilateral vestibular schwannoma were managed conservatively for a m ean duration of 43.8 months (range, 12-194 mo). The pure-tone average (PTA) (0.5, 1, 2, and 3 kHz) and sp eech d.iscrimination scores (SDS) were measured at regular inte rvals throughout the entire duration of follow-up. Serviceable hearing was d efined using two criteria: 70% SDS/30 dB PTA (the 70/30 rule) and 50o/ o SDS/50 dB PTA (the 50/50 rule). The size and growth rate of tumors were d e termined according to the American Academy of Otolaryngology-Head and Neck Surgery guidelines (1995). Intervention was r ecomme nded if there was evidence of continuous or rapid radiological tumor growth, and/or increasing symptoms or signs suggestive of tumor growth. R esults: The risk of loss of serviceable hearing for the total group was 43% u sing the 70/30 rule and 42% u s ing the 50/50 rule. Tumor growth was considered significant (> 1 mm) in 8 tumors (32%) and nonsignificant in 17 (68%). The risk of loss of serviceable hearing for the tumor-growth group was 67% u sing the 70/30 rule and 80% u sing the 50/50 rule. In contrast, the risk of Joss of serviceable h earing for the no tumol'-growth group was 25% u sing the 70/30 rule and 14% u sing the 50/50 rule. No audiological factors predictive of tumor growth were identified. Conclusions: There is a significant risk of loss of serviceable h earing during the conservative managem ent of vestibular schwannomas. This risk appears to be greater in tumors that d emonstrate significant growth. Key