Factors influencing the growth rate of vestibular schwannoma in patients with neurofibromatosis type 2.

Abstract

Neurofibromatosis type 2 (NF2) is a devastating disease with no well-accepted management guidelines. Better understanding of the disease process provides the basis for how or when to initiate treatment. Only few studies have addressed the factors influencing the growth rate of NF2-related vestibular schwannomas (VSs), and these studies have reported variable results. This study aimed to assess the clinical factors influencing the growth rate of NF2-related VSs. The medical records of 66 patients (totalling 74 VSs) were retrospectively analysed. The tumours were measured according to a two-component box model. The tumour growth rate was estimated by linear regression analysis of the changes in VS volumes over time. The clinical characteristics of all the patients were recorded. The relationship between the tumour growth rate and clinical factors were analysed. Linear regression, Pearson's correlation and Student's t-test were conducted using the SPSS 19.0 statistical package. The median follow-up duration was 4.9 years. The VSs growth rate was highly correlated with the initial VS volume (r = 0.97, p < 0.01). However, it was inversely correlated with the age at symptom onset (r = -0.41, p < 0.01). The average VS growth rate in patients with spinal tumours was 13.18 cm(3)/year compared with 0.19 cm(3)/year in patients without spinal tumours (p < 0.01). The VS growth rate in patients who had resection of a contralateral VS was slightly higher than that of patients with untreated VSs (p < 0.01). Other factors including sex, vestibular symptom, presence of other cranial schwannomas, family history and dermal abnormalities did not affect the VS growth rate. The potential clinical factors influencing the VS growth rate are the age at symptom onset, initial tumour volume and presence of spinal tumours. Surgical resection of VSs might accelerate the growth rate of contralateral tumours. The effects of these factors require further experimental confirmation.