[Mutism in central motor disorders--a review of the literature]

Mutism can be defined as "a condition in which there is no, or very little, oral-verbal expression, whereas comprehension of speech ... is normal or at least at a considerably higher level" (Lebrun, 1990). Benson (1979) enumerates five neuroanatomical correlates of mutism: (a) damage to the Broca region, (b) lesion of the supplementary motor area of the dominant hemisphere, (c) dysfunction of the mesencephalic reticular system, (d) thalamotomy, and (e) bilateral pathology of cortical and subcortical motor structures. The last item refers to syndromes of mutism resulting from central motor disorders. Depending on location and size of the lesion this pathophysiological interpretation should hold true for the fourth point as well. In mutism due to central motor disturbances lacking verbal expression represents the most severe degree of dysarthria, i.e. anarthria. The present review provides a detailed description of mutism following corticobulbar, striatal, and cerebellar dysfunctions.