[Angiographically occult vascular malformations of the brain stem. Apropos of 25 cases].

Due to the current use of magnetic resonance imaging (MRI), angiographic occult vascular malformations (AOVM) located in the brain stem are frequently reported in the last ten years. The term AOVM is ambiguous and controvers. For, most of these lesions presented with MRI pattern of a cavernous angioma, but only few cases received pathological confirmation. In this location, the operative treatment while worthwhile could be hazardous indeed, so a conservative management is more commonly discussed first. However, the potential risk of rebleeding or poor clinical condition sometimes encourage a more aggressive decision. We report our experience in 25 patients (4 children and 21 adults) admitted between 1982 and 1994 with an AOVM located in the brain stem. In 17 patients, the cryptic vascular lesion was removed surgically. A cavernous angioma was strictly confirmed in only 8 cases. Conversely, 8 patients were managed conservatively. In the surgically treated group of patients, 10 improved their neurological deficit postoperatively, 2 patients remained unchanged, 3 patients worsened, and 2 patients died. The final outcome in 14 patients was evaluated after 51 months of mean follow-up (17 to 70 months). In 5 cases (35.7%) the result was excellent (no symptoms), 5 cases had a good result (normal activity with minimal residual disability), and 4 cases (28.5%) remained with severe permanent disability. In the non-surgically treated group of patients, the final outcome was evaluated after a mean follow-up period of 67 months (from 1 to 120 months). One patient experienced a rebleeding and remained severely disabled. Another patient had two bleeding episodes leaving only a minor facial numbness. Four patients were symptom-free, and the last case was lost for follow-up.