[Primary progressive aphasia (Mesulam syndrome)].

Primary progressive aphasia is defined as a gradually appeared and gradually worsening disorder of speech without any major alteration of the other cognitive functions. It is regarded by some authors as a syndrome which may be due to various degenerative diseases of the cerebral cortex (notably Alzheimer's disease, owing to its frequency), while others see in it an autonomous disease related to a neuropathological process that is distinct from the main degenerative dementias. The principal clinical particularity of primary progressive aphasia is that it spares the patient's autonomy for a long time, but ultimately turns into global dementia. Despite the diversity of aphasic aspects accompanied or not, in neuroimaging, by morphological and metabolic asymmetry to the expense of the left hemisphere, a review of the autopsy cases published shows that the vast majority corresponded to a neuropathological pattern devoid of the characteristic features of Alzheimer's disease and nearer to Pick's disease. In practice, the diagnosis of Alzheimer's disease can be excluded in all patients whose clinical presentation and cerebral neuroimaging results are compatible with primary progressive aphasia. Moreover, the fact that this new clinicoanatomical entity has been individualized constitutes a definite step towards a better comprehension of degenerative dementias.