Right temporal variant frontotemporal dementia initially presenting with gradually progressing heading disorientation: A case report.

Abstract

Objective: Previous studies of topographical disorientation have focused on cerebrovascular diseases. However, a detailed assessment of patients with neurodegenerative diseases may aid our understanding of spatial navigation. We report the case of a patient with right temporal variant frontotemporal dementia (rtvFTD) initially presenting with heading disorientation, a distinct category of topographical disorientation. Method: The patient was a 71-year-old woman with gradually increasing episodes of getting lost in a familiar environment. Detailed neuropsychological assessment, magnetic resonance imaging (MRI), and positron emission tomography (PET) studies were performed. Results: Topographical disorientation was conspicuous in the patients' cognitive dysfunction despite preserved general cognition. She could not dictate a route or draw a map from her nearest train station to her home, although she recognized environmental landmarks relatively well. Neuropsychological assessments, including the card-placing test, suggested heading disorientation. The MRI and PET abnormalities were large but confined to the right hemisphere and involved the retrosplenial region, an area associated with heading disorientation in cerebrovascular diseases, and the cortical areas that comprise a network together with the retrosplenial region. Amyloid PET was negative, ruling out Alzheimer's disease. Her topographical symptoms gradually worsened. Behavioral symptoms and loss of empathy gradually became apparent fulfilling the criteria for rtvFTD. Conclusions: Neuropsychological assessment revealed heading disorientation in the initial stage of rtvFTD. Based on previous studies, heading disorientation was likely attributed to neurodegeneration in the right hemispheric network centered in the retrosplenial region. The gradual progression of topographical symptoms contrasted with previous reports of heading disorientation due to cerebrovascular diseases.