gms | German Medical Science

Objective: Midline tumors of the posterior fossa involving the fourth ventricle are a challenge in pediatric neurosurgery. The aim of surgery is to remove as much tumor as possible while preserving neurological function. There is controversy about the impact of vermian splitting on neurological function, but there is increasing evidence that postoperative posterior fossa syndroms are related to lesion of the vermis. To avoid vermian splitting alternative surgical approaches are increasingly used including the telovelar or the infratentorial-supracerebellar approach or a combination of both. We present our experience using vermian-saving techniques.

Method: Forty-three pediatric patients with posterior fossa tumors involving the fourth ventricle were operated microsurgically aiming to avoid splitting of the cerebellar vermis. Data were collected retrospectively analysing the degree of resection, complications and the incidence of posterior fossa syndrome.

Results: A telovelar approach was feasible in 26/43 patients (60%). In 4/43 patients (9%) a supracerebellar approach was chosen, in 3/43 patients (7%) a combined approach while in 10/43 patients (24%) a transcerebellar approach was possible. Complete resection was achieved on postoperative MRI in 72% of the patients. The average diameter of residual tumor was 9 mm. In 28/43 patients (65%) the cerebellar vermis was completely intact according to postoperative MRI, while in 15/43 patients (35%) there was limited lesion to the vermis. Posterior fossa syndrome was noted in 3/43 patients (7%), all of them had lesions of the cerebellar vermis. Posterior fossa syndrome had resolved at the last follow-up examination.

Conclusions: Vermian-saving approaches are feasible in the majority of patients to safely remove pediatric midline tumors. Splitting of the cerebellar vermis is, in general, not necessary for removal of such tumors. Lesion of the cerebellar vermis, however, cannot be avoided, in some instances.