063. Vestibular schwannomas and growth rate: Monitoring by MRI

Vestibular schwannomas (VS) are generally slow-growing tumours. In the last few years, increased access to magnetic resonance imaging (MRI) and a better awareness among patients and specialists of the diagnosis of VS led to a gradual increase in the incidence of the tumour. Moreover, the number of small and medium-sized tumours is progressively becoming prevalent in comparison with the larger ones. Consequently, in some circumstances, a conservative management of VS is preferred to microsurgical removal and radiosurgical treatment. Between January 1990 and February 2001, 321 patients were treated or followed up at our interdisciplinary centre. Among them, 70 patients (21.8%) were initially observed. Four patients were excluded from this study because they underwent only one neuroradiologic examination. Therefore, the study group comprised 66 patients (36 men, 30 women), affected by unilateral VS in 65 cases and by bilateral VS in 1 case; the mean age of the subjects was 60.6 years (range, 26-84). All the patients were examined by MRI; the mean follow-up period was 42.0 months (range, 5-122 months), and 34/66 (51.5%) of the subjects were monitored for at least 3 years. In each case, the maximum diameter of the tumour in the 3 axes of projection was recorded, considering the intracanalicular portion. The maximum initial diameter ranged between 2 and 33 mm (mean, 10.8 mm); it was