Object: The factors that determine the growth rates of vestibular schwannomas (VSs) in patients with neurofibromatosis Type 2 (NF2) are unknown. The authors undertook this study to determine if clinical factors or type of constitutional NF2 mutation were associated with VS growth rates in cases of NF2.
Methods: The authors reviewed serial gadolinium-enhanced magnetic resonance (MR) images of the head and full spine of 37 patients with sporadic NF2 who had been observed over periods ranging from 0.2 to 8 years (median 3.9 years) at a specialized referral clinic for NF2. A box model was used to calculate VS volumes so that tumor growth rates could be estimated. Temperature-gradient gel electrophoresis was used to screen for constitutional NF2 mutations. The VS growth rates tended to decrease with increasing patient age at onset of signs or symptoms (r2 = 0.23, p = 0.003) and at the time the baseline gadolinium-enhanced MR image was obtained (r2 = 0.38, p < 0.001). The authors did not find significant associations between VS growth rates and the number of non-VS cerebral or spinal tumors or different types of constitutional NF2 mutations.
Conclusions: There is considerable variability in growth rates of VSs in patients with NF2, but they tend to be higher in patients who are younger at onset of signs or symptoms.