The two broad categories of stroke, hemorrhage and ischemia, are diametrically opposite conditions: hemorrhage is characterized by too much blood within the closed cranial cavity, while ischemia is characterized by too little blood to supply an adequate amount of oxygen and nutrients to a part of the brain . Each of these categories can be divided into subtypes that have somewhat different causes, clinical pictures, clinical courses, outcomes, and treatment strategies. As an example, intracranial hemorrhage can be caused by intracerebral hemorrhage (ICH), also called parenchymal hemorrhage, which involves bleeding directly into brain tissue, and subarachnoid hemorrhage (SAH), which involves bleeding into the cerebrospinal fluid that surrounds the brain and spinal cord .
This topic will review the categories of stroke and their clinical diagnosis. An overview of the evaluation of stroke and the clinical manifestations of transient cerebral ischemia are discussed separately. (See "Overview of the evaluation of stroke" and "Definition of transient ischemic attack".)
Stroke is classified into the following subtypes: intracerebral hemorrhage, subarachnoid hemorrhage, and brain ischemia due to thrombosis, embolism, or systemic hypoperfusion.
The classification of stroke is discussed in detail separately. (See "Etiology and classification of stroke".) The subtypes are reviewed here briefly.
Intracerebral hemorrhage — Bleeding in intracerebral hemorrhage (ICH) is usually derived from arterioles or small arteries. The bleeding is directly into the brain, forming a localized hematoma that spreads along white matter pathways. Accumulation of blood occurs over minutes or hours and the neurologic symptoms usually increase gradually over minutes or a few hours. In contrast to brain embolism and SAH, the neurologic symptoms do not begin abruptly and are not maximal at onset (figure 1).