Post-operative Pediatric Cerebellar Mutism Syndrome
In 2015 the Board of the Posterior Fossa Society initiated and international consensus process in order to create formal definition of the clinical entities commonly known as cerebellar mutism (CM) and posterior fossa syndrome (PFS) [1, 2], as seen in children after posterior fossa tumor surgery. This resulted in a new definition of Post-operative Pediatric Cerebellar Mutism Syndrome:
"Post-operative pediatric CMS is characterized by delayed onset mutism/reduced speech and emotional lability after cerebellar or 4th ventricle tumor surgery in children. Additional common features include hypotonia and oropharyngeal dysfunction/dysphagia. It may frequently be accompanied by the cerebellar motor syndrome, cerebellar cognitive affective syndrome and brain stem dysfunction including long tract signs and cranial neuropathies. The mutism is always transient, but recovery from CMS may be prolonged. Speech and language may not return to normal, and other deficits of cognitive, affective and motor function often persist." 
See definitions for further specification of individual phrases in the new CMS definition, and description of older terms that have often been used in relation to this condition.
Cerebellar cognitive affective syndrome
The Cerebellar Cognitive Affective Syndrome (CCAS) refers to a persistent pattern of executive, visual-spatial, affective and language-related symptoms most commonly described in adults with a wide range of lesions and diseases of the cerebellum . It can also be observed in children .
Post-operative Pediaric CMS versus CCAS
Per definition, those affected by post-operative pediatric CMS always become mute or have severely reduced speech output, and are frequently affected by motor deficits that can be either cerebellar in origin (e.g. hypotonia, ataxia) or brainstem-related (e.g. hemiparesis, cranial nerve palsies). In contrast, those affected by the CCAS do not become mute or have motor problems, and the anatomical substrate of their symptoms is confined to the cerebellum. In reality, however, many have cerebellar motor symptoms too, since the CCAS is often observed in people with a variety of neurological leasions that affect motor function. Both syndromes can be said to represent the same pattern of cerbellar dysfunction, occurring either acutely after surgery and designated post-operative pediatric CMS, or persistently over time and termed the CCAS . The main differences have to do with surgery, mutism and brainstem involvement.
Posterior Fossa Society
The Posterior Fossa Society is an international group of researchers and health care professionals (doctors, nurses, psychologists, speech pathologists, linguists, neuroscientists etc.) who are dedicated to research into the causes, features, treatment and prevention of the post-operative pediatric CMS and CCAS in children and adults. It reaches its goals by systematically gathering and exchanging information both online and during international meetings and conferences
The Posterior Fossa Society will be getting it’s own website soon. Keep an eye out for
Disclaimer: This website was created by Thora Gudrunardottir, MD, and the information published here represents the gathered results of her own research and review of the litterature only. It does not reflect the views of any particular hospital, institute, professional society or organization. It cannot be guaranteed that all the information is 100% up to date all the time, although every effort is made to keep it that way.
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, 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
3. Gudrunardottir T, Morgan AT, Lux AL, Walker DA, Walsh KS, Wells EM, Wisoff JH, Juhler M, Schmahmann JD, Keating RF, Catsman-Berrevoets C, for the Iceland Delphi Group (2016) Consensus Paper on Post-operative Pediatric Cerebellar Mutism Syndrome: The Iceland Delphi Results. Childs Nerv Syst May 3. [Epub]
4. Schmahmann, J. D. & Sherman, J. C. (1998). The cerebellar cognitive affective syndrome. Brain, 121 ( Pt 4), 561-579
5. 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
6. Turkel, S. B., Shu, C. L., Nelson, M. D., Hyder, D., Gilles, F. H., Woodall, L. et al. (2004). Case series: acute mood symptoms associated with posterior fossa lesions in children. J.Neuropsychiatry Clin.Neurosci., 16, 443-445