Intracerebral Hemorrhage

Intracerebral hemorrhage is bleeding directly into the brain parenchyma, the most lethal common form of stroke. It arises when a small vessel ruptures, often on a background of chronic hypertension or cerebral amyloid angiopathy, and its course is dominated by the size and location of the hematoma and the risk of early expansion.

Definition

Intracerebral hemorrhage is bleeding into the brain parenchyma from rupture of a cerebral vessel, producing a hematoma whose size, location, and tendency to expand drive neurological injury; spontaneous forms are most often related to chronic hypertension or cerebral amyloid angiopathy.

Scope

This entry defines spontaneous (non-traumatic) intracerebral hemorrhage, outlines its principal causes and the mechanism of hematoma expansion, and orients the reader to the determinants of severity. It is a reference and educational overview and does not provide diagnostic or treatment recommendations for any individual.

Core questions

• What causes a small cerebral vessel to rupture into the brain parenchyma?
• Why is early hematoma expansion an important determinant of outcome?
• How do hypertensive (deep) and amyloid-related (lobar) hemorrhages differ?
• Why does intracerebral hemorrhage carry higher early mortality than ischemic stroke?

Key concepts

• Parenchymal hematoma
• Chronic hypertensive small-vessel disease
• Cerebral amyloid angiopathy
• Deep versus lobar location
• Hematoma expansion
• Perihematomal edema
• Intraventricular extension and hydrocephalus
• Raised intracranial pressure

Mechanisms

Spontaneous intracerebral hemorrhage results from rupture of small intracerebral vessels weakened by chronic disease. Long-standing hypertension damages deep perforating arteries, favoring hemorrhage in the basal ganglia, thalamus, pons, and cerebellum, whereas cerebral amyloid angiopathy weakens cortical and leptomeningeal vessels and favors lobar hemorrhage. The extravasated blood forms a hematoma that injures tissue by direct disruption and mass effect; early hematoma expansion in the first hours worsens prognosis, and surrounding perihematomal edema, intraventricular extension, and raised intracranial pressure contribute to secondary injury (Cordonnier et al., 2018). The tissue-based stroke definition classifies symptomatic parenchymal hemorrhage as a stroke subtype (Sacco et al., 2013).

Clinical relevance

Understanding the causes, location patterns, and mechanism of hematoma expansion supports critical reading of the hemorrhagic-stroke literature. This entry describes how intracerebral hemorrhage is characterized and studied; it is not a basis for diagnosis or treatment of an individual, which depends on clinical assessment, imaging, and current guidelines and rests with the treating team (Greenberg et al., 2022).

Epidemiology

Intracerebral hemorrhage is a less common stroke subtype than ischemic stroke but carries the highest early case fatality among the major subtypes, with substantial disability among survivors (Feigin et al., 2009). Incidence rises with age and with the prevalence of hypertension; cerebral amyloid angiopathy is an important contributor to lobar hemorrhage in older adults.

Evidence & guidelines

Acute approaches and the biology of hematoma expansion are reviewed by Cordonnier et al. (2018). Management is summarized in successive AHA/ASA guidelines (Hemphill et al., 2015; Greenberg et al., 2022), and the classification of symptomatic parenchymal hemorrhage as a stroke subtype follows the updated definition (Sacco et al., 2013).

History

Intracerebral hemorrhage was long understood chiefly as a complication of hypertension affecting deep brain structures. Recognition of cerebral amyloid angiopathy clarified why many lobar hemorrhages occur in normotensive older adults, and computed tomography made it possible to study hematoma size, location, and early expansion directly, reshaping how prognosis and acute management are conceived (Cordonnier et al., 2018; Hemphill et al., 2015).

Debates

What is the role of surgery in spontaneous intracerebral hemorrhage?

Whether and when hematoma evacuation benefits patients has been studied across varied locations and techniques with mixed results, and the indications for surgical versus medical management remain an area of active investigation.

Key figures

• Charlotte Cordonnier
• Steven M. Greenberg
• Craig S. Anderson
• J. Claude Hemphill

Seminal works

• sacco-2013
• hemphill-2015
• cordonnier-2018

Frequently asked questions

How is intracerebral hemorrhage different from subarachnoid hemorrhage?

Intracerebral hemorrhage is bleeding into the brain tissue itself, forming a parenchymal hematoma, whereas subarachnoid hemorrhage is bleeding into the cerebrospinal-fluid-filled subarachnoid space, most often from a ruptured aneurysm.

Why is early hematoma expansion important?

The hematoma can enlarge in the hours after onset, increasing mass effect and tissue injury. Because expansion is associated with worse outcomes, it is a focus of research on prognosis and acute management.