A protocol for the conservative management of vestibular schwannomas

To devise a protocol for the safe surveillance of vestibular schwannomas. Retrospective review of case records. Tertiary referral neurotology clinic. 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. Review of case records and radiologic data to devise management protocol. Tumor growth rates, timing of detection of growth in growing tumors, and timing of detection of growth in tumors growing at different rates. 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. 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.