Primary progressive aphasia and transient global amnesia.

W e read with great interest the article by GraffRadford and Josephs describing 3 patients with recurrent episodes of transient global amnesia (TGA) who developed primary progressive aphasia (PPA). In the First Brazilian Symposium on Frontotemporal Dementia in 2007, we described 2 patients with semantic dementia, one of the variants of PPA, who had recurrent episodes of TGA. The first patient, a 66-yearold woman, had 2 episodes of TGA 7 and 6 years before her presentation, with a 2-year history of naming impairment. The second patient, a 75-year-old man, had experienced 3 episodes of TGA 1 year before his presentation, with a 3-year history of naming and reading difficulties. Both patients had never had seizures, and their electroencephalograms did not show epileptic activity. Magnetic resonance imaging revealed severe left temporal lobe atrophy, which was more prominent in the anterior part but also involved the hippocampal formation, in both cases. In the first patient, TGA occurred before the onset of PPA, while in the second patient, language impairment started 2 years before the TGA episodes. In the cases described by Graff-Radford and Josephs, TGA preceded PPA in 2 patients, whereas the reverse occurred in 1. We think our data reinforce the hypothesis that this is not a chance association. Further research is needed to elucidate whether recurrent TGA may predispose to PPA or whether the presence of left temporal or frontal lobe pathology renders patients more susceptible to the disturbance that causes TGA.