gms | German Medical Science

Objective: Cerebellar Mutism Syndrome (CMS) was first described in 1979 and summarizes not only cerebellar motor deficits but also neurocognitive and behavioral deficits at longterm follow-up after treatment of posterior fossa tumors in childhood. The incidence of CMS varies between 8% and 32% in different series of children with cerebellar tumors. It has been postulated that splitting of the vermis is a major factor contributing to the appearance of CMS, but this has been disputed.

Methods: Between 2004 and 2018 a consecutive series of 68 children (age: 3-201 months, mean: 90.7 months, median: 79 months) with posterior fossa tumors was studied. All were operated using a vermian saving approach as far as possible. In this retrospective study, we evaluated pre- and postoperatively findings and postoperative imaging data. We also sought to identify possible risk factors including tumor histology.

Results: Three children (4%) developed CMS postoperatively. The histology was a pilocytic astrocytoma in all 3 cases. One of them had already a speech disturbance since 6 months preoperatively. Two patients were operated via a bilateral telovelar approach, and the third using a combined approach (bilateral telovelar and infratentorial/supracerebellar approach). In one patient, the postoperative MRI showed a large lesion of the vermis in all three portions (upper, middle and lower vermis). In the other two, the postoperative MRI showed a lesion in the upper cerebellar peduncle, and a small lesion in the lower vermis respectively. On longterm follow-up (24 months or longer) two patients had mild persistent speech disturbances.

Conclusion: The pathophysiology of CMS is still not fully understood. Its occurrence was relatively low in our series. Vermian saving approaches may result in avoidance of CMS.