RISK FACTORS

'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 [5].

predictors

'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 [6],  pre-operative language impairment [3], left-handedness [4] and intra-operative bilateral diffusion abnormalities of the proximal dentato-thalamo-cortical pathway [7]. 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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Definitions, Incidence, Symptoms, Anatomy, Pathophysiology, Imaging findings, Prognosis, Treatment, Prevention

1. Catsman-Berrevoets CE, van Dongen HR, Mulder PG, Geuze D, Paquier PF, Lequin MH (1999) Tumour type and size are high risk factors for the syndrome of "cerebellar" mutism and subsequent dysarthria. J Neurol Neurosurg Psychiatry 67: 755-757

2. Robertson PL, Muraszko KM, Holmes EJ, Sposto R, Packer RJ, Gajjar A, Dias MS, Allen JC (2006) Incidence and severity of postoperative cerebellar mutism syndrome in children with medulloblastoma: a prospective study by the Children's Oncology Group. J Neurosurg 105: 444-451

3. Di Rocco, Chieffo D, Frassanito P, Caldarelli M, Massimi L, Tamburrini G (2011) Heralding cerebellar mutism: evidence for pre-surgical language impairment as primary risk factor in posterior fossa surgery. Cerebellum 10: 551-562

4. Law N, Greenberg M, Bouffet E, Taylor MD, Laughlin S, Strother D, Fryer C, McConnell D, Hukin J, Kaise C, Wang F, Mabbott DJ (2012) Clinical and neuroanatomical predictors of cerebellar mutism syndrome. Neuro Oncol 14: 1294-1303

5. Gudrunardottir T, Sehested A, Juhler M, Schmiegelow K (2011) Cerebellar mutism : Review of the literature. Childs Nerv Syst

6. McMillan HJ, Keene DL, Matzinger MA, Vassilyadi M, Nzau M, Ventureyra EC (2009) Brainstem compression: a predictor of postoperative cerebellar mutism. Childs Nerv Syst 25: 677-681

7. Avula S, Kumar R, Pizer B, Pettorini B, Abernethy L, Garlick D, Mallucci C (2015) Diffusion abnormalities on intraoperative magnetic resonance imaging as an early predictor for the risk of posterior fossa syndrome. Neuro-Oncology 17(4): 614-22