How are head bleeds classified by anatomic location, mechanism, and timing?

Head Bleed Classifications

Head bleeds are classified into distinct anatomical compartments and further stratified by mechanism (spontaneous vs. traumatic) and coagulation status, with the four primary clinical categories being: noncoagulopathic spontaneous ICH, coagulopathic spontaneous ICH, noncoagulopathic traumatic intracranial hemorrhage, and coagulopathic traumatic intracranial hemorrhage. 1

Primary Anatomical Classification

Intracranial hemorrhage encompasses any bleeding within the cranial vault, with blood accumulating in specific anatomical compartments that determine clinical presentation and prognosis 2, 3:

Intraparenchymal Hemorrhage (IPH)

• Bleeding within the brain parenchyma or brainstem tissue itself 2
• Accounts for approximately 10% of all strokes 3
• Subdivided by specific location:
  • Deep/ganglionic: Basal ganglia, thalamus (most common hypertensive locations) 4, 5
  • Lobar: Subcortical white matter, cortical regions 4, 3
  • Cerebellar: Cerebellar hemispheres 4, 3
  • Brain stem: Primarily pontine 4, 5

Intraventricular Hemorrhage (IVH)

• Isolated bleeding within the ventricular system, not secondary to intraparenchymal or subarachnoid extension 2
• Often occurs as secondary extension from deep hemorrhages 1

Subarachnoid Hemorrhage (SAH)

• Bleeding into the subarachnoid space between the arachnoid and pia mater 6
• Seizures develop in 6-26% of patients with aneurysmal SAH 7

Subdural Hemorrhage (SDH)

• Bleeding between the dura and arachnoid membranes 6
• Present in approximately 30% of traumatic brain injury patients 6
• Risk of expansion requiring craniotomy ranges from 6-22% within 12-24 hours 1

Epidural Hemorrhage (EDH)

• Bleeding between the skull and dura mater 6
• Present in approximately 22% of traumatic brain injury patients 6

Classification by Mechanism and Timing

Spontaneous vs. Traumatic

The tempo and pathobiology differ fundamentally between these mechanisms 1:

Spontaneous ICH:

• Hyperacute bleeding window 1
• Hematoma growth occurs in 38% of patients scanned within 3 hours of onset 1
• More frequent expansion with deep than lobar location 1

Traumatic intracranial hemorrhage:

• Prolonged bleeding window extending 12 hours to 3-4 days post-injury 1
• Approximately 50% of cerebral contusions experience hemorrhagic progression 1

Coagulopathic vs. Noncoagulopathic

Anticoagulation dramatically affects risk, magnitude, and mechanism of bleeding, necessitating separate classification 1:

• Coagulopathic hemorrhages should specify the causative agent (vitamin K antagonists, antiplatelet agents, antithrombin agents, fibrinolytics, anti-factor Xa agents) 1, 4
• Risk of progressive bleeding is greater when coagulopathy is present regardless of hemorrhage type 1

Etiologic Subclassification

Hypertensive Hemorrhages

• Typical locations: basal ganglia, thalamus, pons, cerebellum 4, 5
• Result from structural changes in small perforating vessels 5
• Should be documented as "intraparenchymal hemorrhage due to hypertensive vasculopathy" 4

Amyloid-Related Hemorrhages

• Predominantly lobar location in elderly patients 1, 5
• Distinguished from hypertensive deep hemorrhages 1

Other Etiologies

• Vascular malformations (predominantly young patients, lobar) 5
• Intracranial tumors 5
• Vasculitis 8
• Venous sinus thrombosis 8
• Sympathomimetic drug use 5

Clinical Significance by Location

Lobar Hemorrhages

• Highest seizure risk at 28-31% of patients, especially with cortical surface contact 7
• Early seizures (within 72 hours) occur in 4.2% overall, rising to 8.1% within 30 days 7
• Electrographic seizures detected in 28% during continuous EEG monitoring in the first 72 hours 7

Size-Based Prognostic Classification

• Volumes >30 mL in supratentorial locations indicate higher mortality risk 4
• Volumes >3 cm in cerebellar locations indicate higher mortality risk 4
• Large hemorrhages (regardless of location) carry substantially higher mortality than small bleeds 6
• Odds ratios for mortality comparing large vs. small: SDH 3.41, IPH 3.47, EDH 2.86 6

Critical Terminology Distinctions

"Hemorrhage" indicates active bleeding, whereas "hematoma" describes the resulting blood collection 2. The term "intracerebral hemorrhage (ICH)" specifically includes both intraparenchymal and intraventricular hemorrhage, while "intracranial hemorrhage" is the umbrella term for all bleeding within the skull 2, 3.

The term "hemorrhagic stroke" should be avoided in favor of precise anatomical terminology to prevent ambiguity 2.