According to a comprehensive review  the overall incidence of cerebellar mutism (CM) in children with posterior fossa tumors is 11-29% [1], but numbers vary considerably depending on definitions used and tumor types studied [2]. In a large multicenter study the incidence ofCMS (old definition of CM, ataxia, hypotonia and irritability) for children with medulloblastoma only was 24% [3]. According to a recent, prospective study of 148 pediatric posterior fossa tumor patients the overall incidence of the PFS was 28% (note the broad definition). Sub-divided by tumor pathology it was 40% for medulloblastoma, 16% for pilocytic astrocytoma and 4% for ependymoma [4].

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Generally speaking, narrow definitions (e.g. CM or TCM) and retrospective studies render lower incidence figures than broader definitions (e.g. CMS or PFS) and prospective studies [5]. Until recently, there existed no international consensus on these matters; thus the results of previous studies cannot easily be compared. The new definition of post-operative pediatric CMS has not been implemented yet.

Links to:

Definitions, Symptoms, Anatomy, Pathophysiology, Imaging findings, Risk factors, Prognosis, Treatment, Prevention

1. Gudrunardottir T, Sehested A, Juhler M, Schmiegelow K (2011) Cerebellar mutism : Review of the literature. Childs Nerv Syst 27(3):355-63

2. Gudrunardottir T, Sehested A, Juhler M, Schmiegelow K (2011) Cerebellar mutism: incidence, risk factors and prognosis. Childs Nerv Syst 27: 513-514

3. 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

4. Catsman-Berrevoets, C. E. & Aarsen, F. K. (2010). The spectrum of neurobehavioural deficits in the Posterior Fossa Syndrome in children after cerebellar tumour surgery. Cortex, 46, 933-946

5. Gudrunardottir T, De Smet H, Bartha-Döring L, Van Dun K, Verhoeven J, Paquier P, Mariën P. Posterior Fossa Syndrome and Cerebellar Mutism. Chapter in: Mariën P, Monti M (eds). The Linguistic Cerebellum, 1st edn. Academic Press (Elsevier), Oxford, UK,  pp 257-281