[Motor impersistence].

Motor impersistence is the term introduced by Fisher to describe the inability to sustain certain simple voluntary acts such as keeping eyes closed, protruding the tongue etc. He considered it a specific, nondominant hemisphere symptom, but some investigators denied its relationship to the right hemisphere damage. We considered that this difference might depend on the following two features of MI; the one is inability to maintain one of these simple acts so long as normal persons do, the other is inability to perform more than two of these acts simultaneously. When we attached importance to the latter feature and defined MI as inability to protrude the tongue with eyes closed, this phenomenon was clearly related to the right hemisphere damage. The responsible lesion was suggested to be located in area 6 or 8 in the territory of the right middle cerebral artery. The mechanism of MI was also reported.