Frontotemporal decreases in rCBF correlate with degree of dysnomia irm primary progressive aphasia

Primary progressive aphasia (PPA) is an uncommon degenerative dementia char acterized by gradual impairment of language function with initial sparing o f the memory domain. Using semi-quantitative Tc-99m-hexamethyl propyleneami ne oxime (HMPAO) brain SPECT as a measure of regional cerebral blood flow ( rCBF), we investigated the relationship between reduced Tc-99m-HMPAO uptake and the severity of dysnomia in PPA. Methods: Seven right-handed patients with PPA had their dysnomia assessed by the Boston Naming Test (BNT), a sub test of the Boston Diagnostic Aphasia Examination. Neuroimaging studies, in cluding Tc-99m-HMPAO brain SPECT, CT, and MRI, were performed. Correlationa l analysis between reduced rCBF and BNT was performed. Results: Brain SPECT showed a reduction in Tc-99m-HMPAO uptake involving the frontal and tempor al lobes in all 7 patients. CT and MRI showed mild to moderate cerebral atr ophy in 4 patients. Low scores on the BNT correlated with low frontotempora l Tc-99m-HMPAO (Spearman r = 0.97, P = 0.004) in the 5 patients with left-h emisphere involvement. Conclusion: Decreased rCBF to the frontotemporal reg ion characterized the cerebral abnormalities associated with PPA. The findi ng of focal rCBF abnormalities in the right hemisphere of 2 right-handed wo men corroborates that PPA symptoms may arise from a "non-left-dominant"-hem isphere degenerative process. Our results support the usefulness of rCBF SP ECT imaging as a diagnostic aid in PPA.