ABSTRACT
The timing of an insult to the developing nervous system dramatically infl uences the pathogenesis, manifestations, and recovery from that insult. Perhaps no disease better exemplifi es this principle than stroke. Whereas a teenager with a left middle cerebral artery ischemic stroke might present with abrupt onset aphasia and a right hemiparesis, a 2-year-old with a stroke involving the exact same vascular distribution may present with drooling from the right side of the mouth, “clingy” behavior, and refusal to walk. A similar stroke in a neonate might manifest only with seizures, or may be clinically silent until he/she develops a pathologic early handedness (hand preference) in the fi rst year of life. These differences in clinical manifestation are only the tip of the iceberg; agedependent differences extend to the cellular level, where, for example, developmental differences in protein expression modify cellular responses to injury.
