Cerebellar Mutism Syndrome (CMS) is a neurological complication of posterior fossa
(PF) tumour surgery in children, and postoperative speech impairment (POSI) is the
cardinal symptom of CMS. The role of tumour volume on the risk of POSI remains unexplored.
This study investigates the association between tumour volume and the risk of POSI.We
included 360 patients from the European CMS study with available preoperative T1-weighted
contrast-enhanced brain MRI. Speech status was assessed within two weeks postoperatively
and categorised into three levels: habitual speech, severely reduced speech, and mutism.
Tumour volumes were calculated using the BrainLab Elements SmartBrush™, a semi-automated
segmentation tool. We used proportional odds models to estimate the odds ratio (OR)
with adjustments for tumour location, pathology, and age. Based on the primary analysis,
a risk stratification model for medulloblastoma patients was constructed, and the
optimal volume cut-off was determined with Youden's Index.We found no effect of the
overall tumour volume on the risk of POSI. This result did not change when adjusted
for tumour location, pathology, and age. We found an association between tumour volume
of medulloblastoma and the risk of POSI (unadjusted OR of 1.04 per increase in cm3
(95% CI 1.01;1.07, p = 0.01)), which did not change when adjusting for tumour location
and age. The risk stratification cut-off for the tumour volume of medulloblastoma
was calculated to be 16,5 cm3. Patients with medulloblastoma and preoperative tumour
volumes below 16,5 cm3 had an absolute risk of 13% for POSI (low-risk group), whereas
patients with preoperative tumour volumes above 16,5 cm3 had an absolute risk of 50%
for POSI (high-risk group).Our data showed an association between preoperative tumour
volume and the risk of POSI in children with medulloblastoma, while no association
was found for the volume of other tumour types. We suggest a straightforward cut-off
risk model for assessing the risk of POSI in children with medulloblastoma based on
preoperative tumour volume. This approach can aid clinicians in informing patients
and parents about the complications related to CMS following PF tumour surgery in
children.ID NCT02300766 (October 2014).
