The epidemiology of intracerebral hemorrhage

Introduction Advances in brain imaging have dramatically changed our understanding of intracerebral hemorrhage (ICH). In the pre-CT era, many small ICHs were misclassified as ischemic strokes and patients with massive ICH or subarachnoid hemorrhage (SAH) were often difficult to correctly classify. This chapter reviews the epidemiology of non-traumatic ICH in light of modern neuroimaging and includes discussions of the incidence, etiology, clinical presentation, and natural history of this condition. Incidence of intracerebral hemorrhage Intracerebral hemorrhage accounts for 10–15% of all strokes in Western populations and is defined as the non-traumatic, abrupt onset of severe headache, altered level of consciousness, or focal neurological deficit associated with a focal collection of blood within the brain parenchyma on neuroimaging or at autopsy which is not due to trauma or hemorrhagic conversion of a cerebral infarction. The incidence of ICH is defined as the percentage of a population experiencing a first ICH in a given time period (usually a year). When reviewing studies of ICH incidence it is important to consider the criteria utilized, as investigators may include or exclude hemorrhages associated with vascular malformations, anticoagulants, thrombolytic agents, or illicit drugs. Comparisons of incidence rates are further complicated by methodological differences in case ascertainment, imaging rates, variations in population structure, and the range of ages reported.