Transcortical sensory aphasia: revisited and revised

Transcortical sensory aphasia (TSA) is characterized by impaired auditory c omprehension with intact repetition and fluent speech. We induced TSA trans iently by electrical interference during routine cortical function mapping in six adult seizure patients. For each patient, TSA was associated with mu ltiple posterior cortical sites, including the posterior superior and middl e temporal gyri, in classical Wernicke's area. A number of TSA sites were i mmediately adjacent to sites where Wernicke's aphasia was elicited in the s ame patients. Phonological decoding of speech sounds was assessed by audito ry syllable discrimination and found to be intact at all sites where TSA wa s induced. At a subset of electrode sites where the pattern of language def icits otherwise resembled TSA, naming and word reading remained intact. Lan guage lateralization testing by intracarotid amobarbital injection shelved no evidence of independent right hemisphere language. These results suggest that TSA may result from a one-way disruption between left hemisphere phon ology and lexical-semantic processing.