NIMG-70DEVELOPMENT OF A POTENTIAL PRE-OPERATIVE RISK STRATIFICATION TOOL OF CEREBELLAR MUTISM SYNDROME IN CHILDREN WITH POSTERIOR FOSSA TUMOUR - A PRELIMINARY RISK SCORING SCHEME

Abstract

BACKGROUND: Despite identification of numerous pre-operative cerebellar mutism syndrome (CMS) clinical and radiological predictors, a unifying pre-operative risk stratification model for use during surgical consent is currently lacking. We have previously assembled a cohort of posterior fossa tumour patients and developed a pre-operative risk stratification model using classification algorithms. Our aim is to further develop a preliminary risk-scoring scheme to flag patients at higher risk of post-operative CMS. METHODS: The combined cohort consists of 89 patients from two major treatment centres (age: 2-23yrs, gender 28M,61F, MRI pathology estimate 36 medulloblastoma, 40 pilocytic astrocytoma, 12 ependymoma, 1 non-committal). Post-operative CMS status was ascertained from clinical notes and pre-operative MRI scans, blinded to CMS status, underwent structured evaluation. Multiple logistic regression coefficients for the six predictors selected by decision tree (cerebellar hemisphere invasion, bilateral invasion at middle cerebellar peduncle, dentate nucleus invasion, pathology estimate ependymoma, middle cerebellar peduncle compression and age > 12.4 years) were converted into risk scores. Predicted CMS probability, diagnostic and predictive values were calculated to explore the potential cut-off points. RESULTS: Of the 89 patients, 26 (29%) developed post-operative CMS. Patient's total risk score ranged from -57 to 263, with a greater number being associated with increased risk of CMS. The cut-off with the highest sum of sensitivity and specificity was total score ≥1, with sensitivity 92%, specificity 86%, positive predictive value 73% and negative predictive value 96%. Using cut-off of 0 and 15 allowed separation of the cohort into low (46/89, predicted probability 50%). CONCLUSIONS: A risk stratification model for post-operative CMS could flag patients at increased risk pre-operatively and may influence strategies for surgical treatment of cerebellar tumours. Following future testing and prospective validation, this risk scoring scheme may be utilised during the surgical consenting process.