Analysis of an Unusual Case of Nonfluent Aphasia With Predominantly Posterior Perisylvian Lesion: An Apparent Paradox

Lesion site-aphasia type discordance has garnered increasing interest in cognitive neuroscience over the last century. Diaschisis, the network concept of cognitive functions, and interindividual variability are among the plausible explanations cited in the literature for such unusual clinical cases. We describe here the case of a nonfluent type of aphasia following an ischemic stroke predominantly affecting the left posterior perisylvian cortex in a right-handed Bengali-speaking woman. The patient's comprehension was well preserved; however, she presented with a severe motor speech defect. MRI revealed an ischemic lesion in the left parietotemporal area, with slight involvement of the postero-inferior frontal cortex. We suggest two plausible explanations for this lesion-aphasia discordance: Our patient had bilateral representation of language receptive functions in her brain, and additional areas neighboring the classical Broca area may support some critical mechanisms of speech production. Taken together, these explanations may clarify why our patient was able to maintain the ability to decode language even though her language production was significantly affected.