Gerstmann Syndrome as a Disconnection Syndrome: A Single Case Diffusion Tensor Imaging Study.

Gerstmann syndrome (GS) is a rare syndrome that occurs when there is a lesion of the dominant inferior parietal lobule (IPL), causing agraphia, acalculia, finger agnosia, and right-left disorientation. A 49-year-old right-handed male was diagnosed as GS after left parieto-occipital lobe hemorrhage. The patient showed mild anomic aphasia with agraphia in the language test and the neuropsychological test revealed acalculia, impaired right-left discrimination, and finger agnosia. In diffusion tensor tractography, the tracts of left superior longitudinal fasciculus (SLF), middle longitudinal fasciculus, U-fibers and posterior corpus callosum (CC) were disrupted around the left IPL. In addition, fractional anisotropy (FA) values were markedly decreased in left SLF, and posterior CC when compared to twelve healthy control subjects. Our clinical and neuroimaging findings support that GS is a disconnection syndrome caused by lesion in the white matter pathway surrounding IPL. In future, more studies of the correlation between the white matter disconnection and the development of GS including high quality imaging technique are needed.