'Risk factors' refers to factors that have been statistically proven in two or more studies to put patients at increased risk of developing post-operative pediatric CMS. A patient may possess any of them, and still not get the syndrome. Currently known risk factors are tumor type (medulloblastoma), midline location and brainstem involvement [1, 2].
Studies have been inconclusive as far as vermal incision, tumor size, radical resection and younger age at diagnosis are concerned, while hydrocephalus, post-operative CNS infections, gender, lenght of vermal incision, type of neurosurgeon (adult/pediatric) and edema/swelling in the cerebellum show no statistically relevant correlation with the development of post-operative pediatric CMS .
'Predictors' refers to factors that have been observed pre- or intra-operatively amongst those patients that have subsequently gone on to develop post-operative pediatric CMS. When considering all subjects at risk, predictors may thus help with forecasting who will and will not get the syndrome. Various predictors have been described in different studies so far; these include pre-operative brainstem compression , pre-operative language impairment , left-handedness  and intra-operative bilateral diffusion abnormalities of the proximal dentato-thalamo-cortical pathway . They may reflect the presence of known risk factors (e.g. brainstem involvement), or represent independent risk factors in and of themselves. All remain to be verified in future studies.
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