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  • Updated 06.10.2019
  • Released 11.13.2003
  • Expires For CME 06.10.2022

Cerebellar mutism


This article includes discussion of cerebellar mutism, cerebellar cognitive affective syndrome, mutism and subsequent dysarthria syndrome, oral pharyngeal apraxia and mutism, postoperative cerebellar mutism syndrome, posterior fossa cerebellar mutism syndrome, posterior fossa syndrome, postoperative mutism, and pseudobulbar syndrome. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


This update on cerebellar mutism adds current literature regarding the possible risk factors associated with cerebellar mutism as well as the ongoing efforts to mitigate those risk factors. Longer-term neurocognitive prognosis following the diagnosis of cerebellar mutism is also included.

Key points

• Cerebellar mutism is not necessarily a transient disease that improves spontaneously in time. Although the mutism resolves, patients are still likely to have varying degrees of dysarthria. Cerebellar symptoms are cranial neuropathies making this more a chronic condition.

• A consensus statement has defined cerebellar mutism with the intent of clearly identifying and unifying the multiple signs and symptoms that are associated with cerebellar mutism. Specifically, it explicitly cites this disease as being a postoperative consequence in children in the effort to further research and improve the quality of life for these patients.

• Damage to the dentato-thalamo-cortical fiber tracts and proximal efferent cerebellar pathways are being identified via imaging and metabolic studies in patients with cerebellar mutism.

• There is still no clear cause for cerebellar mutism. However, bilateral cerebellar damage, brainstem invasion/compression by tumor, and large tumor size are noted as risk factors in multiple papers.

• Patients with cerebellar mutism exhibit greater short- and long-term neurocognitive impairment that require close follow-up and intervention.

Historical note and terminology

A child’s loss of speech after removal of a cerebellar tumor was initially described in 1958 (28). This complication of posterior fossa surgery was mentioned in the literature in the following decades (Fraioli and Guidetti 1975; 55; 106). This complication became more widely recognized after a landmark case series of 6 patients in 1985 (101). Since then, the descriptions of more than 200 cases have contributed to the understanding of this unique constellation of signs and symptoms that has come to be known as the posterior fossa or cerebellar mutism syndrome. This syndrome is characterized by partially reversible decreased production of speech and often mutism, frequently in association with diffuse cerebellar dysfunction (ataxia and axial hypotonia), and a variety of neurobehavioral affective disturbances consisting of prominent emotional lability with irritability and apathy (Fraioli and Guidetti 1975; 55; 106; 129; 101; 123; 12; 32; 40; 46; 83; 108; 23; 53; D’Avanzo et al 1993; 87; 09; 14; 65; 03; 27; 98; 121; 60; 74; 107; 19; 49; 59; 71; 120; 22; 35; 114; 48; 58; 124; 77; 117; 91; 93; 104).

Cerebellar mutism syndrome occurs most often after the surgical resection of posterior fossa tumors, the majority of which are medulloblastoma, but can be seen after trauma, hemorrhage, or ischemic injury involving the cerebellum or brainstem. The onset of symptoms is often delayed until 1 or 2 days after the surgery (129; 40; 83; 26; 98; 121; 107; 48). The first description of mutism after posterior fossa surgery was in regards to several patients who underwent stereotactic lesioning of the cerebellar dentate nucleus for treatment of dyskinesias (42). Wisoff and Epstein were the first to describe affected patients after midline posterior fossa tumor resection, but they emphasized the emotional features and considered the mutism as part of a syndrome they termed pseudobulbar palsy (129). Rekate and colleagues reported the syndrome in 6 children who underwent posterior fossa tumor surgery and were the first to refer to it as the cerebellar mutism syndrome (101). In the same year, Yonemasu noted the same complication in 4 patients who underwent surgery for cerebellar tumors (132). This postoperative constellation of signs has also been called the posterior fossa syndrome (113). In view of the finding that in many cases the mutism is followed by a period of dysarthric speech, it has also been described as mutism and subsequent dysarthria syndrome (20; 36; 35).

Given the multiple names and constellation of symptoms associated with mutism after cerebellar surgery a consensus statement was issued in 2016 by the Iceland Delphi Group introducing the term “post-operative pediatric cerebellar mutism syndrome (CMS)” in an effort to unify the literature. The consensus statement reads: “Post-operative pediatric CMS is characterized by delayed onset mutism/reduced speech and emotional lability after 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 may not return to normal, and other deficits of cognitive, affective and motor function often persist” (51).

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