Intraparenchymal Hemorrhage

Slide 1 · Intraparenchymal Hemorrhage

Etiology • vascular pathology • morphology • clinical correlation

Cerebrovascular pathology

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Classify intraparenchymal bleeds by their anatomical distribution.

Explain vessel-wall injury in hypertensive hemorrhage and cerebral amyloid angiopathy.

Recognize the morphologic evolution and secondary consequences of a hematoma.

Differentiate major acquired and inherited causes using clinicopathologic clues.

Slide 3 · Definition: Blood within the brain parenchyma

Primary intraparenchymal hemorrhage follows rupture of a vessel within brain tissue.

Blood collects inside parenchyma rather than solely in meningeal compartments.

The presentation can be abrupt, producing a focal neurologic stroke syndrome.

Slide 4 · Hemorrhage compartments are anatomically distinct

Compartment

Principal distinction

Epidural

Between skull and dura; usually traumatic

Subdural

Between dura and arachnoid; usually traumatic

Subarachnoid

Within CSF-containing subarachnoid space

Intraparenchymal

Within brain substance; often vascular disease

A compartment-based classification precedes etiologic classification.

Slide 5 · Primary bleeding versus hemorrhagic transformation

Primary hemorrhage

Initial event: Intraparenchymal vessel rupture

Forms a hematoma within brain tissue

Deep or lobar pattern offers etiologic clues

Secondary hemorrhagic transformation

Preceded by an ischemic infarct

Hemorrhage occurs within injured/infarcted tissue

May appear as punctate cortical bleeding

Different initiating event

Slide 6 · Clinical onset commonly resembles stroke

Symptoms often begin suddenly, reflecting abrupt bleeding into the parenchyma.

The focal deficit depends primarily on the region of brain affected.

Extensive hemorrhage or ventricular extension can cause especially severe injury.

Slide 7 · Who develops spontaneous hemorrhage?

Spontaneous intraparenchymal hemorrhage predominantly in middle to late adult life.

An incidence peak around 60 years.

Anatomical distribution and associated vascular pathology are more discriminating than age alone.

Slide 8 · Two major distribution patterns

Deep

Lobar

Schematic anatomy — not a clinical scan

Morphologic interpretation

Deep/ganglionic: Basal ganglia and thalamus

Lobar: Superficial cerebral hemisphere

Typical associations: Hypertension versus CAA

Slide 9 · Interpretation begins with location

Find the hemorrhage compartment

Determine deep versus lobar center

Integrate vascular risk and pathology

Consider less common causes

Location is a clue, not independent proof of a single cause.

Slide 10 · Nontraumatic intraparenchymal bleeding: Etiologies

Major association

Other contributors

Hypertension

Deep small-vessel disease

Cerebral amyloid angiopathy

Superficial/lobar vessel disease

Systemic coagulation disorders

Hemostatic susceptibility

Neoplasms, vasculitis, aneurysms

Local lesion or vessel injury

Vascular malformations

Abnormal vascular structure

Slide 11 · Hypertension is dominant in deep hemorrhage

Chronic hypertension is the most prominent association with deep intraparenchymal bleeding.

More than half of clinically significant hemorrhages to hypertension.

The pathological substrate is altered vessel walls, particularly within deep brain regions.

Slide 12 · The putamen is a frequent origin

Deep focus

Schematic anatomy — not a clinical scan

Morphologic interpretation

Putaminal origin in 50–60% of hypertensive intraparenchymal hemorrhages.

The lesion is centered in deep gray matter.

Large hematomas can extend beyond the site of origin.

Slide 13 · Additional hypertensive hemorrhage sites

Deep focus

Schematic anatomy — not a clinical scan

Morphologic interpretation

Thalamus: Deep hemispheric site

Pons: Brainstem location

Cerebellar hemisphere: Posterior fossa location

Slide 14 · Hypertension damages vessels by caliber

Large arteries may show accelerated atherosclerosis.

Small arteries and arterioles undergo hyaline arteriolosclerosis.

Severe vascular injury can produce proliferative changes and arteriolar necrosis.

Slide 15 · Normal small artery versus hyaline arteriolosclerosis

Normal arteriole

Hyaline-thickened wall

Cross-sectional schematic; Not histology

Pathological interpretation

Normal: Compliant wall with patent lumen

Hyalinosis: Wall thickening and increased rigidity

Rigidity predisposes damaged arterioles to rupture

Slide 16 · Hyaline arteriolosclerosis: Defining change

The arteriolar wall becomes thicker because of hyaline/fibrotic material.

Although thickened, the vessel is mechanically abnormal rather than protected.

Basal ganglia and subcortical white-matter vessels.

Slide 17 · Pathogenesis of hypertensive hemorrhage

Chronic hypertension

Hyaline small-vessel wall change

Rigid, rupture-prone arteriole

Deep parenchymal hematoma

Mechanistic sequence summarized from the Robbins discussion.

Slide 18 · Why thickening does not equal strength

Normal arteriole

Hyaline-thickened wall

Cross-sectional schematic; Not histology

Pathological interpretation

Pathological thickening reduces normal wall compliance.

Rigid vessel walls are more vulnerable to rupture.

Microscopic wall disease produces macroscopic parenchymal hemorrhage.

Slide 19 · Spectrum of hypertensive vasculopathy

Affected structure

Source-described alteration

Larger arteries

Accelerated atherosclerosis

Small arteries / arterioles

Hyaline arteriolosclerosis

Severely injured arterioles

Proliferation and frank necrosis

These are distinct vessel lesions, not synonymous processes.

Slide 20 · One diseased arteriole, two major outcomes

Rupture

Wall fragility predominates

Blood enters brain parenchyma

A primary hemorrhagic lesion forms

Occlusion

Vessel lumen becomes blocked

Small territory becomes ischemic

A lacunar infarct may develop

Rupture ≠ occlusion

Slide 21 · Lacunar infarction is an ischemic counterpart

Hyaline arteriolosclerosis to both hemorrhage and lacunar infarction.

When a small affected artery is occluded, its dependent tissue undergoes infarction.

A lacune is not equivalent to an old intraparenchymal hematoma.

Slide 22 · Extension into the ventricular system

Deep ganglionic hematoma

Disruption of adjacent parenchyma

Possible ventricular breakthrough

More extensive intracranial involvement

The Robbins illustration depicts ganglionic bleeding entering a lateral ventricle.

Slide 23 · Cerebral amyloid angiopathy: Clinical association

Cerebral amyloid angiopathy (CAA) is particularly associated with lobar hemorrhages.

Its defining lesion is amyloid deposition in small- and medium-caliber brain vessels.

Involved vessels are structurally weakened and prone to hemorrhage.

Slide 24 · CAA: Deposition in a vessel wall

Reference vessel

Aβ-laden vessel

Cross-sectional schematic; Not histology

Pathological interpretation

Amyloid β is deposited within the vessel wall.

The vessel is rigid and may fail to collapse during histologic sectioning.

Unlike hypertensive hyalinosis, the deposited material is amyloid.

Slide 25 · The key CAA protein is amyloid β

The vascular peptide as amyloid β (Aβ).

The same amyloidogenic peptide class is linked to Alzheimer disease.

CAA describes vascular amyloid deposition; It is not simply a synonym for parenchymal Alzheimer plaques.

Slide 26 · CAA preferentially targets surface vessels

Superficial focus

Schematic anatomy — not a clinical scan

Morphologic interpretation

Leptomeningeal and cortical vessels are prominent sites of disease.

Cerebellar vessels can also be involved.

This distribution is distinct from the deep-vessel predominance of hypertension.

Slide 27 · CAA and the cerebellum

CAA can affect vessels within the cerebellum as well as cerebral cortical vessels.

Its association with lobar hemorrhage reflects predominance in superficial cerebrovascular territories.

Distribution should be interpreted alongside other etiologic evidence.

Slide 28 · Routine H&E: Two hyaline-appearing lesions

Hypertensive arteriolosclerosis

Fibrotic/hyaline thickening

Prominent in basal ganglia / white matter

Often produces deep hemorrhage

CAA

Aβ deposition in vessel wall

Prominent in cortex / leptomeninges

Often produces lobar hemorrhage

Deposited substance differs

Slide 29 · CAA: Pathological confirmation requires specificity

H&E may show a thickened, hyaline-appearing vessel wall.

The deposited material is amyloid rather than ordinary collagenous hyaline.

Aβ immunohistochemistry demonstrating vascular deposits.

Slide 30 · Aβ deposition can be localized by immunostaining

Reference vessel

Aβ-laden vessel

Conceptual stain localization

Cross-sectional schematic; Not histology

Pathological interpretation

Vascular Aβ labeling as evidence of the deposited peptide.

A labeled vascular wall localizes disease to the vasculature.

A positive tissue stain must be interpreted in anatomical context.

Slide 31 · CAA progression to hemorrhage

Vascular Aβ deposition

Wall distortion and rigidity

Mechanical weakening of vessel

Lobar hemorrhage and/or microbleeds

Schematic causal model; Not a quantitative temporal pathway.

Slide 32 · Lobar hemorrhage may reach the subarachnoid space

Superficial focus

Schematic anatomy — not a clinical scan

Morphologic interpretation

CAA-associated hematomas often involve subcortical white matter.

Large lobar bleeds may dissect toward the cortical surface.

The Robbins gross image shows extension into subarachnoid space.

Slide 33 · Microbleeds reflect smaller vessel failures

CAA may produce numerous small hemorrhages, not only a single large hematoma.

Robbins calls these deposits of blood “microbleeds.”

The source notes that microbleeds can be demonstrated using imaging techniques.

Slide 34 · CAA and Alzheimer pathology share Aβ

CAA

Deposits localized in vessel walls

Weakens vessel integrity

Associated with hemorrhage

Alzheimer-related Aβ pathology

Aβ is also involved in Alzheimer disease

Shared peptide does not imply identical lesion

Different compartment and clinical expression

Same peptide, different location

Slide 35 · APOE alleles modify bleeding risk in CAA

The APOE gene encodes apolipoprotein E.

Both ε2 and ε4 alleles as associated with increased CAA bleeding risk.

Genetic association is a susceptibility factor, not a stand-alone diagnosis.

Slide 36 · APP mutations can cause hereditary CAA

Some autosomal dominant CAA forms arise from APP mutations.

APP encodes the precursor protein from which amyloid β peptides are generated.

A mutation can favor amyloidogenic vascular deposition and hemorrhagic disease.

Slide 37 · Hypertension versus CAA: High-yield distinctions

Feature

Hypertension

CAA

Typical center

Deep/ganglionic

Lobar/subcortical

Characteristic vessels

Basal ganglia, white matter

Cortical, leptomeningeal

Wall lesion

Hyaline arteriolosclerosis

Vascular Aβ deposition

Additional feature

May cause lacunar infarcts

May cause microbleeds

Slide 38 · Cortical versus deep vessel distribution matters

A thickened vessel wall on H&E is not sufficient to distinguish CAA from hyalinosis.

Assess the affected vascular territory: Cortex/leptomeninges versus deep nuclei.

Use amyloid-specific evidence when making a tissue diagnosis of CAA.

Slide 39 · When a case does not fit hypertension or CAA

Consider hereditary cerebral small-vessel disorders.

Consider systemic bleeding predispositions, vascular malformations, tumors, and vasculitis.

Location and the accompanying pathology guide the next etiologic hypothesis.

Slide 40 · Hereditary small-vessel disorders

Disorder

Major gene

Prominent clinical expression

Hereditary CAA

APP

Amyloid-associated hemorrhage

CADASIL

NOTCH3

Small-vessel strokes; often infarcts

COL4A1-related disease

COL4A1

Hemorrhage and systemic findings

Slide 41 · CADASIL is a NOTCH3-associated arteriopathy

CADASIL is an autosomal dominant hereditary small-vessel disease.

Pathogenic NOTCH3 mutations lead to misfolding of the receptor’s extracellular domain.

It primarily causes small-vessel strokes and progressive neurologic disease.

Slide 42 · CADASIL: Molecular defect to phenotype

NOTCH3 mutation

Misfolded receptor domain

Cerebral small-vessel disease

Recurrent strokes and dementia

Infarcts more often than hemorrhages.

Slide 43 · CADASIL: White-matter abnormalities come early

The earliest detectable imaging changes in cerebral white matter.

Changes may be identified around age 35 and progress with time.

The prominent presentation is recurrent small-vessel ischemia rather than lobar hemorrhage.

Slide 44 · CADASIL versus CAA

CADASIL

NOTCH3; Autosomal dominant

White-matter imaging changes

Infarcts are more common than hemorrhages

CAA

Vascular Aβ; APP in rare familial cases

Cortical/leptomeningeal vessel disease

Lobar bleeds and microbleeds

Different vascular pathology

Slide 45 · COL4A1 affects the vascular basement membrane

COL4A1 encodes a collagen component of the basement membrane.

Pathogenic variants can cause an inherited cerebral small-vessel disorder.

COL4A1-related disease with intracerebral hemorrhage.

Slide 46 · COL4A1 disease extends beyond the brain

The source lists cataract, hematuria, and epilepsy among its additional findings.

The multisystem phenotype reflects a basement-membrane component defect.

An associated systemic feature may support an inherited vascular disorder.

Slide 47 · Inherited disease: Discriminator table

Clue

Consider

Vascular Aβ and familial lobar bleeding

APP-associated CAA

Early white-matter disease and recurrent infarcts

CADASIL / NOTCH3

Hemorrhage with cataract or hematuria

COL4A1-related disease

These are teaching clues, not stand-alone diagnostic criteria.

Slide 48 · Systemic disorders of coagulation

Systemic coagulation disorders can cause or contribute to spontaneous parenchymal bleeding.

A bleeding tendency may act alongside pre-existing cerebral vessel pathology.

Systemic hemostatic dysfunction in the etiologic differential.

Slide 49 · Hemorrhage associated with neoplasia

Primary high-grade gliomas may bleed into their tumor parenchyma.

Melanoma, choriocarcinoma, and renal-cell carcinoma metastases.

A neoplastic lesion is an alternative to primary hypertensive or amyloid vasculopathy.

Slide 50 · Local nonhypertensive causes

Category

Reason for inclusion

Vasculitis

Inflammatory damage to vascular walls

Aneurysm

Focal vascular lesion can rupture

Vascular malformation

Structurally abnormal vascular channels

Neoplasm

Bleeding within primary or metastatic tumor

Slide 51 · Traumatic contusions have a characteristic setting

Intraparenchymal hemorrhage may result from trauma rather than spontaneous vessel disease.

Contusions preferentially affect gyral crests that contact the inner skull.

Frontal and temporal tips and orbitofrontal surfaces as susceptible.

Slide 52 · Hemorrhagic infarction is not primary ICH

Punctate hemorrhages can occur in brain tissue previously injured by ischemia.

The source describes hemorrhagic conversion along the cortical ribbon.

Distinguish this pattern from a primary, space-occupying hematoma.

Slide 53 · Three major intraparenchymal bleeding patterns

Pattern

Characteristic context

Primary deep hematoma

Hypertensive arteriolar disease

Primary lobar hematoma

CAA, among other causes

Hemorrhagic transformation

Bleeding superimposed on ischemic infarction

Contusion

Trauma at vulnerable brain surfaces

Slide 54 · Acute gross morphology of primary hemorrhage

Small vessel ruptures

Central core of clotted blood

Compression of surrounding brain

Secondary tissue ischemia / edema

Schematic sequence based on the Robbins morphology box.

Slide 55 · The hematoma compresses adjacent brain

The acute lesion contains a central clot.

Expanding blood compresses local neural tissue and small vessels.

Surrounding parenchymal compression contributes to secondary infarction.

Slide 56 · Perihematomal injury is not just blood loss

Core

Edema / compression zone

Schematic anatomy — not a clinical scan

Morphologic interpretation

Blood clot: Physical space occupation

Adjacent brain: Compression and edema

Parenchymal response: Secondary ischemic damage

Slide 57 · Microscopic consequences of compression

Perihematomal ischemia causes anoxic changes in neurons.

Glial cells are also affected by the secondary injury.

Edema compounds disruption of surrounding brain tissue.

Slide 58 · Organized response: Blood breakdown and cleanup

As the acute phase resolves, macrophages accumulate.

Macrophages may contain hemosiderin from blood breakdown.

Lipid-laden macrophages accompany the removal of injured tissue.

Slide 59 · Astroglial reaction marks tissue injury

Reactive astrocytes proliferate at the lesion periphery.

The cellular progression parallels repair after cerebral infarction.

Gliosis demarcates the boundary between destroyed and surviving brain.

Slide 60 · Morphologic evolution of a hematoma

Acute

Clotted blood; Edema; Compression

Organizing

Macrophages; Hemosiderin; Gliosis

Remote

Cavity with brownish rim

Phases qualitatively; No exact hemorrhage-specific time intervals are asserted.

Slide 61 · Remote hemorrhage leaves destructive sequelae

Old hematomas may form a cavity after loss of brain parenchyma.

A peripheral brown discoloration reflects residual blood breakdown products.

Irreversible cavitary loss differs from simple reabsorption without tissue injury.

Slide 62 · Outcome depends on location and extent

A large bleed can be devastating because substantial brain tissue is directly disrupted.

Extension into the ventricular system is another adverse anatomic feature.

Smaller focal bleeds may be silent or resemble ischemic infarcts clinically.

Slide 63 · Hematoma clearance can permit improvement

Blood and necrotic material may be removed gradually over weeks to months.

Some neurologic improvement may accompany hematoma resolution.

Clinical recovery remains constrained by the amount and location of permanent tissue damage.

Slide 64 · Clinicopathologic reasoning pathway

Confirm an intraparenchymal collection

Localize: Deep, lobar, or other

Distinguish primary from secondary / trauma

Correlate vascular and systemic causes

Anatomic localization is the organizing principle.

Slide 65 · Applied case: Ganglionic hemorrhage

Clinical stem

A 61-year-old with chronic hypertension has sudden focal neurologic deficits and a hematoma centered in the putamen.

Question

Which vascular lesion is the strongest pathological correlate?

Answer

Hyaline arteriolosclerosis of deep small vessels.

Pathological reasoning

Robbins relates chronic hypertension, deep ganglionic hemorrhage, and rigid hyalinized arterioles.

Slide 66 · Applied case: Superficial hemorrhage

Clinical stem

An older adult has a spontaneous hematoma in subcortical white matter with extension toward the cortical surface.

Question

Which vascular disorder is a leading etiologic consideration?

Answer

Cerebral amyloid angiopathy.

Pathological reasoning

CAA damages cortical and leptomeningeal vessels and is strongly associated with lobar bleeding.

Slide 67 · Applied case: Recurrent infarcts and dementia

Clinical stem

An adult with an autosomal dominant history has progressive white-matter abnormalities, recurrent small-vessel strokes, and cognitive decline.

Question

Which gene-associated small-vessel disease fits best?

Answer

CADASIL associated with NOTCH3.

Pathological reasoning

The textbook contrasts recurrent small-vessel infarcts in CADASIL with CAA-associated lobar hemorrhage.

Slide 68 · Applied morphology: Remote lesion

Clinical stem

A remote intraparenchymal lesion shows a cavity and a brown-tinged peripheral zone.

Question

What does this morphology indicate?

Answer

An old hemorrhage with cavitary parenchymal destruction and residual hemosiderin.

Pathological reasoning

Macrophage-mediated cleanup and reactive gliosis accompany long-term posthemorrhagic changes.

Slide 69 · Diagnostic synthesis: Pattern to mechanism

Finding

Most pertinent pathological explanation

Deep ganglionic bleed

Hyaline arteriolosclerosis

Lobar bleed / cortical microbleeds

Amyloid β angiopathy

White-matter disease with mostly infarcts

NOTCH3 small-vessel disease

Hemorrhage plus cataract / hematuria

COL4A1 basement-membrane disease

Cavity + brown rim

Remote parenchymal hemorrhage

Slide 70 · Core teaching messages

Deep and lobar hemorrhage distributions reflect different predominant vessel diseases.

Hypertension injures deep arterioles; CAA deposits Aβ in cortical/leptomeningeal vessels.

A hematoma causes compression, edema, secondary infarction, macrophage cleanup, and reactive gliosis.

Always distinguish spontaneous primary bleeding from trauma and hemorrhagic transformation.

Slide 71 · Reference and source boundaries

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. (2026). Chapter 28, “Intraparenchymal Hemorrhage,” pp. 1139–1141.

Associated source material: “Intracranial Hemorrhage” introductory section and Table 28.1.

Original schematics are conceptual teaching drawings, not patient images or histologic specimens.

Clinical algorithms, acute therapy and externally updated diagnostic criteria are outside this source-grounded lecture.