Mutism: elective or selective, and acquired

When a child does not speak, this may be because there is no wish to do so (elective or selective mutism), or the result of lesions in the brain, particularly in the posterior fossa. The characteristics of the former children are described, especially their shyness; and it is emphasized that mild forms are quite common and a definitive diagnosis should only be made if the condition is significantly affecting the child and family. In the case of mutism due to organic causes, the commonest of these is trauma to the cerebellum. Operations on the cerebellum to remove tumours can be followed by mutism, often after an interval of a few days, and it may last for several months or longer, to be followed by dysarthria. Other rarer causes are discussed, and also the differential diagnosis. The so-called posterior fossa syndrome consists of mutism combined with ataxia, cranial nerve palsies, bulbar palsies, hemiparesis, cognitive impairment and emotional lability, but the post-operative symptoms are often dominated by the lack of speech. The most accepted cause for the condition is vascular spasm with involvement of the dentate nucleus and the dentatorubrothalamic tracts to the brain-stem, and subsequently to the cortex. Diaschisis may be involved in causing the loss of higher cerebral functions, and possibly, complicating hydrocephalus. The treatment of elective mutism is reviewed, either using a psychotherapeutic approach or a variety of drugs, or both. These may well be ineffective, and it must be remembered that the condition often resolves on its own. The former treatment must concentrate on the training of social skills and activities of daily life and must be targeted to both the child, the family, and the school. Also, all kinds of punishment and insistence on speech must be discouraged. The drug, which seems to be most effective, is fluoxetine. Discovering more about the causes of mutism due to organic causes may well depend on studies using such techniques as magnetic resonance imaging and single photon emission tomography.