Anomalous cerebral dominance neurobehavioral studies and three-dimensional magnetic resonance imaging

Numerous cases of atypical cerebral lateralization have appeared in the literature, yet these are heterogeneous and often fail to illuminate causal mechanisms. We evaluated neurobehavioral and neuroanatomical asymmetries in a 32-year-old woman with insulin-dependent diabetes mellitus, nonspecific immune dysfunction, and premature birth who developed Broca's aphasia, Gerst-mann's syndrome, hemispatial neglect, and receptive paralinguistic impairments following a right frontoparietal infarction. She performed five out of seven tasks with her right hand, including writing. Using three-dimensional reconstructions of magnetic resonance images, we quantified the sizes of the left and right planum temporale (PT) and found her right PT to be larger than her left, a pattern associated with left-handedness. The presence of this structural asymmetry, which is known to develop prenatally, suggests that the factors responsible for this individual's anomalous neurobehavioral profile were present in the prenatal environment.