Cerebellar mutism

Kevin C De Braganca MD (Dr. De Braganca of Memorial Sloan Kettering Cancer Center has no relevant financial relationships to disclose.)
Roger J Packer MD, editor. (Dr. Packer of George Washington University; Senior Vice President, Center for Neuroscience and Behavioral Medicine; and Gilbert Endowed Distinguished Professor in Neurofibromatosis and Director, Gilbert Neurofibromatosis Institute and Brain Tumor Institute, Children’s National Health System, has no relevant financial relationships to disclose.)
Originally released November 13, 2003; last updated June 12, 2017; expires June 12, 2020

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.

Overview

This update on cerebellar mutism includes the 2016 consensus statement from the Delphi Iceland results. It also adds current literature substantiating the role of the proximal efferent cerebellar pathway and the dentato-thalamo-cortical fiber tracts in the pathogenesis of cerebellar mutism.

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.

Historical note and terminology

A child's loss of speech after removal of a cerebellar tumor was initially described in 1958 (Daly and Love 1958). This complication of posterior fossa surgery was mentioned in the literature in the following decades (Fraioli and Guidetti 1975; Hirsch et al 1979; Sakai et al 1980). This complication became more widely recognized after a landmark case series of 6 patients in 1985 (Rekate et al 1985). 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; Hirsch et al 1979; Sakai et al 1980; Wisoff and Epstein 1984; Rekate et al 1985; Volcan et al 1986; Ammirati et al 1989; Dietze and Mickle 1990; Ferrante et al 1990; Gaskill and Martin 1991; Nagatani et al 1991; Salvati et al 1991; Catsman-Berrevoets et al 1992; Herb and Thyen 1992; D'Avanzo et al 1993; Oiwa et al 1993; Al-Jarallah et al 1994; Asamoto et al 1994; Kingma et al 1994; Aguiar et al 1995; Dailey et al 1995; Pollack et al 1995; Van Calenbergh et al 1995; Jones et al 1996; Mastronardi 1996; Salvati et al 1996; Bhatoe 1997; Germano et al 1998; Janssen et al 1998; Liu et al 1998; Turgut et al 1998; Catsman-Berrevoets et al 1999; Doxey et al 1999; Siffert et al 2000; Gelabert-Gonzalez and Fernandez-Villa 2001; Ildan et al 2002; Wang et al 2002; Mewasingh et al 2003; Steinbok et al 2003; Ozimek et al 2004; Papavasiliou et al 2004; Robertson et al 2006).

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 (Wisoff and Epstein 1984; Ferrante et al 1990; Nagatani et al 1991; Crutchfield et al 1994; Pollack et al 1995; van Calenbergh et al 1995; Salvati et al 1996; Gelabert-Gonzalez and Fernandez-Villa 2001). 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 (Fraoli and Guidetti 1975). 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 (Wisoff and Epstein 1984). 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 (Rekate et al 1985). In the same year, Yonemasu noted the same complication in 4 patients who underwent surgery for cerebellar tumors (Yonemasu 1985). This postoperative constellation of signs has also been called the posterior fossa syndrome (Siffert et al 1995). 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 (Cakir et al 1994; Dunwoody et al 1997; Doxey et al 1999).

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” (Gudrunardottir et al 2016).

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