Ms L: a case of a reversible phenotypic and brain function equivalent of frontotemporal dementia.

Frontotemporal dementia (FTD) is second only to Alzheimer's disease in individuals younger than 65 years of age. Behavioral variant FTD (bvFTD) presents with nonspecific symptoms such as disinhibition, apathy, or emotional blunting. Although neuropsychological testing and structural neuroimaging are not very helpful in diagnosing bvFTD in its initial stages, newer quantitative structural methods and functional neuroimaging have better sensitivity and specificity. Ms L presented with blunted affect, disinhibition, impairments in insight, planning ability and social comportment, changed dietary habits, and episodes of mutism. Her brain magnetic resonance imaging was normal whereas her single-photon emission computed tomography (SPECT) pattern was consistent with FTD. Her clinical presentation was consistent with bvFTD yet both the symptoms and SPECT findings reversed after 2 years of follow-up. We suggest that Ms L had a reversible phenotypic and brain function equivalent of bvFTD. The case highlights the limitations of our diagnostic tools and the complex relationship between clinical symptoms, neuroimaging, and etiology.