Occipital interhemispheric transtentorial approach for microsurgical resection of a posterior fossa medulloblastoma: 2-dimensional operative video

Background: Medulloblastoma is a highly aggressive tumor, usually arising in the posterior fossa in children. Adult cases have different features compared to younger patients. Case Description: We present the case of a 26-year-old male patient, presenting with several posterior fossa symptoms progressing over months. During this time, he underwent a ventriculoperitoneal shunt performed by an external department. Pre-operative magnetic resonance imaging (MRI) depicted a lesion with heterogeneous contrast enhancement in the tentorial surface of the cerebellum insinuating over the brainstem. Extensive cerebellar edema was also observed, including tonsillar bulging causing middle cerebellar peduncle compression and eighth cranial nerve disturbance. Considering a vertical straight sinus and the lesion to be adjacent to the vein of Galen and brainstem, we preferred to employ an occipital interhemispheric transtentorial approach to get a more direct and shorter pathway to the lesion. It was possible to successfully resect the mass, preserving the surrounding neurovascular structures. Post-operative MRI demonstrated complete tumor resection and expressive improvement of cerebellar edema, including the compressive effect over the middle cerebellar peduncle. The patient presented a favorable outcome with no new neurological deficits, improvement of previous complaints, and no significant alteration in campimetry. Pathology confirmed the lesion to be a medulloblastoma, and he was referred next for adjuvant therapy. No tumor dissemination was observed in the pre-operative and post-operative spine MRI, with negative oncotic cytology on 1.5-month post-operative lumbar puncture. The patient consented to the procedure and publication of this operative video. Conclusion: Careful pre-operative planning can guide successfully throughout the surgical procedure to achieve a favorable outcome.