Neuropsychological and Neuroimaging Findings of Semantic Dementia

ABSTRACT

BACKGROUND: Semantic dementia (SD) is a temporal variant of frontotemporal lobar degeneration (FTLD), which is characterized by naming difficulty, decreased comprehension of words, prosopagnosia and object visual agnosia. We report clinical features, neuropsychological and neuroimaging findings of 4 patients with SD. METHODS: Of 55 patients diagnosed as having FTLD between Jan 1995 and May 2001 at Samsung Medical Center, four patients fulfilled the diagnostic criteria of SD proposed by consensus on FTLD diagnostic criteria. We investigated their clinical features such as presenting symptoms and abnormal behaviors, neuropsychological and neuroimaging findings. Neuropsychological tests included the Seoul Neuropsychological Screening Battery, the Korean-version of Western Aphasia Battery and Hanja reading and writing. All patients underwent brain MRI and FDG-PET. RESULTS: All of the patients showed naming difficulty as a presenting symptom. Language assessments showed severe naming and compre-hension difficulties with preserved fluency and repetition, which were compatible with transcortical sensory aphasia. Whereas Hangul reading aloud and writing were intact, three patients were impaired at Hanja reading and writing. Other neuropsychological tests were remarkable for prosopagnosia, object visual agnosia and memory loss. Brain MRI showed asymmetric temporal atrophies, mainly left antero-inferior temporal cortices. FDG-PET also showed hypome-tabolism in bilateral anterior temporal lobes, more severe on the left. CONCLUSIONS: Our SD patients had characteristic neuropsychological and neuroimaging findings, which can be differentiated from other neurodegenerative diseases. We also found Hanja alexia and agraphia in SD patients, which has not been reported yet.