A case report of pathological rule-governed syllable intrusion.

A detailed analysis of a unique speech disturbance, marked by the frequent appearance in the speech stream of a meaningless intrusive syllable, is presented. Following a lengthy thoracic surgery, an American English speaking patient began to speak with non-English prosodic patterns, which evolved to a conspicuous intrusion in his speech of the syllable /sis/. This syllable and its variants were attached to words in a manner which conformed to the regular phonological rules in English (for formation of plural, possessive, and third person singular morphemes). The distribution and frequency of the intrusive syllable are described, and possible explanations for the abnormal occurrence of this particular syllable are discussed.