[Frontal lobe dementia--two cases diagnosed by SPECT].

Both patients 1 and 2 were males 73 and 77 years old, respectively, and over the past several years, both had gradually developed progressive loss of vigor, paucity speech, personality changes, and anosognosia, in addition to memory loss and disorientation. Patient 1 experienced emotional lability, mild pyramidal signs and parkinsonian features. The various diseases causing secondary dementia were ruled out. The Mini Mental Scale scores were 13 and 21, respectively. Brain CT scans and MRI showed cerebral atrophy, most prominent in the frontal and the temporal lobes. There were few lesions suggestive of cerebrovascular disease. The EEGs showed nonspecific diffuse slowing, and the cerebrospinal fluid was normal. 123I-amphetamine SPECT, which provided the most valuable diagnostic findings in these two cases, demonstrated selective hypoperfusion of the frontal and the temporal lobes in both patients. Frontal lobe dementia of the non-Alzheimer type (Gustafson, Neary), progressive subcortical gliosis (Neumann), Pick's disease, and Alzheimer's disease with frontal lobe predominance were considered the most likely of the various diseases causing frontal lobe dementia. The usefulness of SPECT in diagnosing and elucidating the pathophysiology of dementia are discussed.