Hanja (Ideogram) alexia and agraphia in patients with semantic dementia.
Posterior fusiform gyrus (BA 37) is responsible for Hanja (ideogram) alexia in stroke patients. Patients with semantic dementia (SD) have lesions in the basal temporal area. The close proximity in these two lesions and the fact that reading ideograms requires holistic processing as is necessary in recognition of objects, suggests a possibility that ideogram alexia/agraphia may occur in patients with SD. We established and carried out Hanja and Hangul (phonogram) reading/writing tasks on six SD patients and nine Alzheimer's disease (AD) patients as control to see if these two patient groups show dissociation in the two sets of tests. SPM analysis was performed on the SD patients' PET images to look for any dysfunctions in the posterior fusiform gyrus. The SD patients manifested Hanja alexia/agraphia whereas Hangul reading/writing ability was relatively preserved. There were group differences between SD and AD in the Hanja tasks but not in the Hangul tasks. The SPM analysis revealed no hypometabolism in the posterior fusiform gyrus, but only in the middle and the anterior part of the temporal gyrus. Dysfunction in the middle temporal gyrus (BA 21) may have disrupted the temporal lobe connections preventing the function of the posterior fusiform gyrus.
Suh
Mee Kyung
MK
Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Kim
Eun-Joo
EJ
Lee
Byung Hwa
BH
Seo
Sang Won
SW
Chin
Juhee
J
Kang
Sue J
SJ
Na
Duk L
DL
D000368:Aged; D000381:Agraphia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D001931:Brain Mapping; D004185:Disability Evaluation; D004292:Dominance, Cerebral / Q000502:physiology; D004410:Dyslexia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D057174:Frontotemporal Lobar Degeneration / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011932:Reading; D056910:Republic of Korea; D013561:Symbolism; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D014793:Visual Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D014795:Visual Pathways / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*