Various blood products on Axial MRI of an intraparenchymal hemorrhage.
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Causes & Locations of Intracerebral Hemorrhage
overview
Intraparenchymal hemorrhage (aka Intracerebral hemorrhage (ICH))
- Intraparenchymal hemorrhage refers bleeding within the cerebrum, itself.
- It has a 30-day mortality risk of ~ 50%, half of those patients will die in first 24 hours.
Important modifiable risk factors for ICH:
- Hypertension
- Alcohol & Drug Use
- Atherosclerosis
- Anticoagulants
ICH Pathophysiology:
- In hypertensive vaculopathy, there are microscopic degenerative changes in the walls of small vessels over time that eventually result in hemorrhage.
- Cerebral amyloid angiopathy is a disease of the elderly in which amyloid-beta peptide lines the walls of small vessels and leads to rupture.
Most common ICH location:
- Basal Ganglia.
Detailed Review
Common ICH Locations
Most common locations
- Deep
- Basal ganglia (especially the putamen)
- Thalamic
- Lobar (cerebral lobes)
Less common locations
- Cerebellum
- Brainstem, especially the pons
Causes of Intracranial Hemorrhage: Detailed List
Hypertension
- The most common cause of ICH.
- Pathophysiology: microscopic degenerative changes in the walls of small vessels eventually leads to vessel rupture.
Cerebral amyloid angiopathy
- A common cause of ICH in the elderly.
- Pathophysiology: amyloid-beta peptide lines the walls of small vessels and leads to rupture.
- Tends to cause lobar hemorrhages and incidental microhemorrhages.
Vascular malformations
- Arteriovenous malformations
- Pathogenesis: direct arterial to venous connections form without an intervening capillary network (think: arterial pressure).
- MRI characteristics: extra blood vessels with an associated nidus (abnormal flow voids).
- AVMs are the most lethal form of vascular malformation.
- The overall annual risk of ICH for a typical AVM is 2.3% per year over 10 years. Ruptured AVMs have a higher risk of recurrence than unruptured AVMs. (Derdeyn et al., 2017)
- Decision to treat (eg, surgical excision, radiosurgery, endovascular therapy) depends on multiple factors: ruptured AVM is a strong indicator to treat.
- Cavernous malformations
- Comprise dilated, thin walled capillaries, thus they cause less severe hemorrhages than AVMs because they comprise venous blood (whereas AVMS contain high pressure arterial blood).
- MRI characteristics: popcorn-shaped lesions with varying signal intensities secondary to different ages of blood products (see: MRI: Heme Products).
- Familial cerebral cavernous malformations results from three different gene mutations, which can all be remembered by the "CCM" designation: KRIT1 (aka CCM1), CCM2, and PDCD10 (aka CCM3).
- Surgical resection is performed when the cavernous malformation is accessible and is causing intractable seizures, progressive neurologic deficits, or recurrent hemorrhages.
- Developmental venous anomalies and capillary telangiectasias represent the other forms of vascular malformations; they are generally considered incidental findings and are NOT a major cause of hemorrhage.
Hemorrhagic infarction (ie, hemorrhagic conversion of an ischemic stroke)
- Typically asymptomatic and occur regularly in ischemic stroke: ~35% of ischemic strokes undergo hemorrhagic conversion (based on radiographic criteria). (Acute Ischemic Stroke: New Concepts of Care)
- Occur secondary to reperfusion when the full pressure of arterial blood results in a migration of red blood cells into the hypoxic capillaries of the stroke bed.
Endocarditis
- Septic emboli can infect the vessel wall and cause rupture and/or cause mycotic aneurysm.
- Mycotic aneurysms (aneurysmal dilations secondary to infection) can cause infarct or hemorrhage (especially subarachnoid hemorrhage).
Coagulopathies
- Congenital deficiencies
- Acquired factor deficiencies (eg, secondary to liver disease)
- Lymphoproliferative disorders
Meningoencephalitis
- Herpes simplex encephalitis is an especially important infectious cause of ICH.
Brain tumors
- ICH most commonly occurs in hematologic malignancies (eg, acute myelogenous leukemia) and in other malignancies that involve coagulation factor deficiencies.
- Thrombocytopenia is a key cause of ICH in lymphoma, multiple myeloma, and solid tumors.
- Venous infarct (sinus thrombosis or superficial venous thrombosis) is important cause of ICH in malignancy, in general.
- When ICH is the presenting cause of brain tumor, it may obscure the radiographic imaging of the tumor, itself.
- Brain METs that commonly cause ICH include lung cancer, melanoma, and germ cell tumors.
- Radiographic clues to brain METS as a cause of ICH: atypical location, non?hemorrhagic tissue within the ICH, uneven distribution of ICH, significant edema, and additional enhancing sites. (Grisold et al., 2009)
Moyamoya
- Moyamoya causes proliferation of fragile capillaries and aneurysms that are prone to hemorrhage.
Vasculitis
- Typically manifests with cerebrovascular ischemia secondary to accumulation of inflammatory infiltrates with association destruction and/or occlusion but these changes may also lead to hemorrhage.
Illicit Drugs
- Cocaine, heroin, and amphetamines (including methamphetamine and Ecstasy (methylenedioxymethylamphetamine)) are commonly abused illicit drugs that can result in ICH.
Antithrombotic agents
- Patients taking oral anticoagulants constitute 12% to 20% of patients with ICH.
- Antiplatelets are commonly used and increase ICH risk.
- Of note, two randomized controlled trials are ongoing to evaluate the effectiveness of platelet transfusion in ICH patients taking antiplatelet agents.
- Thrombolytic therapy can cause ICH.
Low cholesterol (possible risk factor)
- The risk of low cholesterol as a cause of intracranial hemorrhage is currently in debate.
- The SPARCL trial showed a worrisome rate of intracranial hemorrhage with high-intensity statin therapy but significant data to the contrary has also been published. (Hemphill et al., 2015)
Risk Factors for ICH Recurrence
Most common causes of ICH recurrence
- Hypertension is a key cause of initial and recurrent ICH.
- Older age is also a key cause of initial and recurrent ICH.
- Key age-related factors are cerebral amyloid angiopathy (CAA), antithrombotic medications, and medical comorbidities.
- Small vessel lacunar strokes portend a higher risk of recurrent ICH.
- Cerebral microbleeds (especially lobar), likely related to cerebral amyloid angiopathy (CAA), indicate a high risk of ICH recurrence.
- Carriers of the apolipoprotein E ?2 or ?4 alleles are known to have a higher ICH recurrence risk. (Hemphill et al., 2015)
References