Suboccipital trans-horizontal fissure approach for cerebellar hemorrhage with rupture into the upper fourth and third ventricles: the first clinical experience. Illustrative cases

BACKGROUND The authors’ previous cadaveric study reported a new surgical approach that can expose the deep cerebellar hemisphere, cerebellopontine angle, and upper fourth ventricle through dissection of the horizontal fissure of the suboccipital cerebellar hemisphere. Here, the authors present their experience with the first clinical use of the suboccipital trans-horizontal fissure (SOTHF) approach requiring access to the third and upper fourth ventricle lesions, a challenging compartment to access by traditional approaches. OBSERVATIONS In cases 1 and 2, computed tomography demonstrated large hematomas in the left cerebellar hemisphere with extension into the third ventricle and/or the upper fourth ventricle, resulting in obstructive hydrocephalus. Large hematomas in both the cerebellar hemisphere and the upper fourth ventricle were successfully removed via an SOTHF approach alone without external ventricular drainage. Furthermore, the hematoma in the third ventricle was removed through the aqueduct in case 2. Access to the upper fourth ventricle and the third ventricle were intraoperatively verified using a neuronavigation system. The patients immediately regained consciousness, and the result of cerebellar function testing was almost normal after the operation. LESSONS An SOTHF approach can achieve the removal of cerebellar and intraventricular hematomas simultaneously, is a faster and potentially safer method than others, and subsequently allows rapid clinical improvement.