Vestibular schwannomas with neuroimaging signs of spontaneous regression: frequency of continued growth after surgery

Purpose. To determine the frequency of continued growth after surgical treatment in patients with neuroimaging signs of spontaneous regression of vestibular schwannoma. Material and methods. The study included 55 patients with histologically verified vestibular schwannoma. For a comparative assessment of the results of the study, 2 groups were formed: group I included 58.2 % of patients who had no signs of spontaneous regression (gender ratio — 1:4, more often — women), group II included 41.8 % of patients with the presence of one of the MR signs of regression (gender ratio was 1:1.3). The following parameters were analyzed as the studied MR characteristics: the presence of scalloped borders, the filling of the internal auditory canal with cerebrospinal fluid, and the heterogeneity of the accumulation of contrast agent by the tumor. The retrosigmoid access was used for the patients of the studied groups. Results. The patients with these neuroimaging parameters were characterized by a prolonged asymptomatic period which led to the diagnosis of vestibular schwannoma in the late stages — KOOS 4 (𝜒2=4.8; p<0.03). In the patients with MR characteristics of spontaneous regression with any size of vestibular schwannoma, a high frequency of continued growth after surgical treatment was revealed (p<0.05), which demonstrates the «aggressiveness» of the course of the disease. The results obtained indicate the need for increased oncological alertness in these patients. Conclusions. A detailed study of the MR characteristics of spontaneous regression of vestibular schwannomas can improve the patients’ quality of life and treatment outcomes.