Causes of Intraventricular Hemorrhage
Primary Etiologic Classification
Intraventricular hemorrhage occurs through two distinct mechanisms: secondary IVH (most common), which represents extension from an intracerebral hemorrhage, and primary IVH, which is confined to the ventricles without associated parenchymal hemorrhage. 1, 2
Adult Population: Etiologies
Most Common Cause
- Hypertensive intracerebral hemorrhage is the predominant etiology, occurring in approximately 45% of patients with spontaneous ICH, typically involving the basal ganglia and thalamus with subsequent extension into the ventricular system 1, 2
Vascular Malformations
- Arteriovenous malformations, dural arteriovenous fistulas, and cavernous malformations can rupture into the ventricular system 2
- Cerebral aneurysm rupture causing subarachnoid hemorrhage with secondary intraventricular extension 3
Cerebrovascular Conditions
- Cerebral amyloid angiopathy, particularly in elderly patients with lobar hemorrhages 2
- Cerebral venous thrombosis, including isolated cortical vein thrombosis 2, 4
- Moyamoya disease 2
Coagulopathy-Related Causes
- Anticoagulant use (warfarin, direct oral anticoagulants) 2, 3
- Antiplatelet agents 2
- Inherited or acquired clotting disorders 3
When Etiology is Unclear
- Additional workup including cerebral angiography, MRI/MRA, and toxicology screening should be performed when the underlying cause is not immediately apparent from history and initial imaging 2, 3
- Coagulation studies (prothrombin time, partial thromboplastin time) are essential to identify coagulopathy-related causes 2, 3
Neonatal/Premature Infant Population: Distinct Pathophysiology
Germinal Matrix Hemorrhage
- IVH in premature infants originates from the germinal matrix, a richly vascularized collection of neuronal-glial precursor cells in the developing brain 1, 5
- Occurs predominantly in infants born before 37 weeks' estimated gestational age, with highest risk in those born earlier and with lower birth weights 1
Vascular Fragility Mechanisms
- Intrinsic fragility of germinal matrix vasculature due to abundance of immature angiogenic blood vessels with paucity of pericytes, immature basal lamina, and deficiency of glial fibrillary acidic protein (GFAP) in ensheathing astrocyte endfeet 5, 6
- High VEGF and angiopoietin-2 levels activate rapid angiogenesis, creating unstable vessels 5
- Relative hypoxia of the germinal matrix from high metabolic activity and oxygen consumption of neural progenitor cells 5
Hemodynamic Factors
- Fluctuation in cerebral blood flow is a critical contributor to hemorrhage in the fragile germinal matrix vasculature 5, 6
Clinical Significance and Prognostic Impact
- The presence of IVH dramatically worsens prognosis, with mortality increasing from 20% in ICH without IVH to 51% in ICH with IVH 1, 2, 4
- IVH is an independent predictor of poor functional outcome regardless of the underlying cause 1, 7, 8
Pathophysiological Mechanisms of Injury
Four distinct mechanisms explain the clinical deterioration associated with IVH 7:
- Acute obstructive hydrocephalus from mechanical blockage of CSF pathways
- Mass effect from the intraventricular blood clot
- Neurotoxicity from blood breakdown products on adjacent brain parenchyma
- Chronic hydrocephalus development from inflammation and fibrosis of CSF absorption pathways
Common Pitfalls
- Do not assume all IVH is secondary to hypertension—in younger patients or those without hypertension history, aggressive workup for vascular malformations and other etiologies is mandatory 2, 3
- Premature infants and adults have completely different etiologies—germinal matrix hemorrhage is unique to the neonatal population and should not be confused with adult IVH 1, 5
- Coagulopathy must be assessed before any invasive procedures (such as external ventricular drain placement) to minimize procedural hemorrhage risk 1, 3