Risk Factors for Hemorrhagic Stroke
Hemorrhagic stroke accounts for approximately 5–15% of all acute stroke events worldwide, with its two most common subtypes being intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH). Each of these hemorrhagic stroke subtypes accounts for 5–10
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Risk Factors for Hemorrhagic Stroke Alessandro Biffi
2.1
isk Factors for Intracerebral R Hemorrhage
2.1.1 Pathophysiology and Risk Factors for Primary Intracerebral Hemorrhage Intracerebral hemorrhage (ICH) is the acute manifestation of a chronic progressive disease of the cerebral vessels [1]. The underlying vessel disease can be a mass, vascular malformation or other macroscopic abnormalities. However, for patients over the age of 55 years, the overwhelming majority of ICH cases occur in the presence of cerebral small vessel disease [2]. A number of pathology correlates have been identified, including (1) prominent degeneration of the arteriolar media and smooth muscles and (2) fibrinoid necrosis of the subendothelium with micro-aneurysms and focal dilatations. ICH is routinely classified according to the region of the brain in which it occurs: the thalamus, basal ganglia, brain stem, cerebellum (“deep” or “non-lobar” ICH), or at the junction of the cortical gray matter and subcortical white matter (“lobar” ICH). Pathological studies demonstrate that ICH location frequently A. Biffi Divisions of Stroke, Memory Disorders and Behavioral Neurology, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA e-mail: [email protected]
correlates with different underlying small vessel diseases. Arteriolosclerosis leads to non-lobar ICH due to rupture of vessels damaged by long-standing, uncontrolled hypertension. Lobar ICH is more often associated with cerebral amyloid angiopathy (CAA), a degenerative disorder characterized by deposition of β-amyloid at capillaries, arterioles, and small- and medium-sized arteries in the cerebral cortex, leptomeninges, and cerebellum [3]. CAA is associated with sporadic ICH, preferentially lobar in location and affecting elderly individuals. From an epidemiological standpoint, CAA-related ICH is associated with higher risk of recurrence than non-lobar, hypertensive ICH [4]. This section will present risk factors for ICH and existing evidence supporting their role in increasing ICH risk, as also summarized in Fig. 2.1.
2.1.2 F amily History and Genetic Risk Factors From a genetic epidemiological standpoint, ICH syndromes can be characterized as either (1) familial, with an easily identifiable hereditary transmission pattern within families with multiple affected individuals, or (2) sporadic, with no overt evidence of familial inheritance [5].
2.1.2.1 Familial ICH Multiple familial ICH syndromes, manifesting only in selected families with highly consistent phenotypes and a clear autosomal dominant
© Springer Science+Business Media Singapore 2018 S.-H. Lee (ed.), Stroke Revisited: Hemorrhagic Stroke, Stroke Revisited, https://doi.org/10.1007/978-981-10-1427-7_2
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A. Biffi
8 Strength of available evidence Strong
Effect size
Moderate
Weak
Substantial (>100% risk modification)
Family history Race / ethnicity APOE gene Age Hypertension Alcohol consumption Oral anticoagulation
Sympathomimetic drugs
Modest (50–99% risk modifi
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