The dichotomous view on IFG lesion and non-fluent aphasia.

A lesion in inferior frontal gyrus (IFG) is traditionally considered to be crucial for the occurrence of non-fluent aphasia. However, recent studies question the axiomatic causality between a lesion in this area and the expected non-fluent aphasic syndrome. The aim of the present study is to investigate the relationship between IFG lesions and non-fluent aphasia. To address this question, we present radiological and neuropsychological data of 49 chronic aphasic patients. Lesions were identified based on CT and/or MRI scans. Aphasia was assessed using the Boston Diagnostic Aphasia Examination-short form. Analysis indicated a statistically significant association between IFG lesion and non-fluent aphasic disturbances. Nevertheless, a large proportion of our patients did not confirm the traditional prediction, namely that non-fluent patients' lesions would include the inferior frontal gyrus and the opposite would be true for fluent patients. Our results stress the importance of taking into account the size of particular estimates when conducting group analyses. We also argue in favor of examining individual data in clinical practice, and further suggest that the traditional lesion to syndrome correspondence seems to be oversimplified and should be thoroughly revisited.