Transient global amnesia associated with a single metastasis in the non-dominant hemisphere. Case report.

A patient in whom transient global amnesia (TGA) led to the diagnosis of a metastasis of a transition-cell carcinoma of the bladder to the non-dominant hemisphere is described. In previously reported cases of TGA associated with brain tumors, the tumors involved either the dominant or both hemispheres. The etiology of TGA associated with a brain tumor is most likely vascular, as suggested by the sudden development and the transitory character of the event. In contrast to the "common" form of TGA (where both temporal lobes suffer temporary ischemia), in these patients only one side of the limbic system is affected, because a brain tumor has already compromised the other limbic area. Therefore, the dominance of the hemisphere with the tumor is of no consequence, as both hemispheres have been involved. It is concluded that the TGA in these patients is not due to, but is rather associated with, a unilateral brain tumor.