A protocol for the conservative management of vestibular schwannomas.

OBJECTIVES: To devise a protocol for the safe surveillance of vestibular schwannomas. STUDY
DESIGN: Retrospective review of case records.
SETTING: Tertiary referral neurotology clinic. PATIENTS: Three hundred twenty patients have been managed conservatively with a mean follow-up of 43 months since 1997. Two hundred seventy-six patients with at least 1 follow-up scan have been included in the study. INTERVENTION: Review of case records and radiologic data to devise management protocol. MAIN OUTCOMES MEASURED: Tumor growth rates, timing of detection of growth in growing tumors, and timing of detection of growth in tumors growing at different rates.
RESULTS: Of 276 patients, 62 (22%) demonstrated growth. The mean growth rate for growing tumors was 4 mm annually (range, 0.5-17 mm/yr). Of the growing tumors, 65% grew slowly (0.5-5 mm/yr) and 35% grew more rapidly (>5-17 mm/yr). Four tumors displayed genuine nonlinear growth. Of the rapidly growing tumors, 16 of 19 were detected at the first follow-up magnetic resonance imaging (6 mo). Of all growing tumors, 90% were detected within 3 years. The remaining 10% were detected within a further 3 years.
CONCLUSION: Growth is usually manifest in the first 3 years after presentation. We recommend an initial magnetic resonance imaging scan at 6 months, with scans to take place at annual intervals for 2 years. A further scan 2 years later will identify any patient with indolent tumors. Thereafter, follow-up should be lifelong every 5 years. Cystic tumors represent a particular threat to patients and should only be treated conservatively with caution.