Two Cases with Cerebral Infarction in the Left Middle Frontal Lobe Presented as Gerstmann's Syndrome

Gerstmann's syndrome is a neuropsychological disorder characterized by four symptoms, namely, acalculia, finger agnosia, left-right disorientation, and agraphia suggesting the presence of a lesion in the inferior parietal lobule of the dominant hemisphere, especially at the angular gyrus. Several descriptions of Gerstmann's syndrome have been reported in associated with a lesion to the left frontal lobe, but none of these reports fulfilled the full tetrad of diagnostic criteria. Herein, we report two cases with all four symptoms of Gerstmann's syndrome associated with an uncommon area in the left middle frontal lobe without an angular gyrus lesion. This apparent discrepancy could be explained by disconnection of functional fiber between the frontal and parietal cortex. Moreover, left frontal cortex or the subcortical area may be an important functional area which is closely connected with the parietal lobe in Gerstmann's syndrome.