[Relation between defect in comprehension and frontal lobe lesion]

We assessed anatomical findings and language defects in 14 right handed patients who had fluent aphasia following left frontal lobe lesion. From the onset of aphasia all of the patients showed fluent speech and excellent repetition but difficulty in word finding and impairment in language comprehension. We administered to all of the patients the Western Aphasia Battery, a 50-item pointing task using line drawings representing single words selected from among common Japanese words for language training for aphasics, and the Token Test. Anatomical analysis was performed using brain CT and/or MRI. The patients were divided into three groups on the basis of the extent of impairment in comprehension of single words: one group showed no impairment, another showed slight impairment and the other showed severe impairment. The lesion site differed among the groups. Each group had a different lesion site. We concluded the following: first, lesions in Brodmann's areas 6 and 9 produce impairment in comprehension of single words, with lesions extending to anterior to Broca's area producing more impairment than those without the extending lesions. Second, lesions in the frontal lobe produce impairment in comprehension of complex sentences.