Investigations into the natural history of vestibular schwannomas

In the period from 1977 to 1996 143 vestibular schwannomas were diagnosed i n 138 patients in the County of Aarhus, Denmark. The natural history of ves tibular schwannomas was observed in 50 patients with 52 tumours who did not undergo immediate surgical removal of their tumour due to small tumour siz e, advanced age, poor general health and the patients' refusal of surgery. The management included serial CT- or MR-imaging and complete otoneurologic al evaluation. The imaging interval was between 6 months and 2 years and de pended on the recorded growth rate. Thirty-three (64%) of the tumours showe d continuous growth with a mean growth rate of 1.6 mm/year. In 11 (21%) of the tumours the size was unchanged and eight (15%) remitted. The last group consisted mainly of the largest tumours. Among the tumours with positive g rowth, 15 (45%) had a growth rate of I mm/year or less. Generally, our find ings showed that approximately two-thirds of all the tumours did not grow, were getting smaller or had a growth rate sufficiently small to be simply w atched. Additionally, our results suggest that some symptomatic tumours wil l grow to a certain point whereupon stagnation or remission occurs.