3.4
AVC hemorrágico l: Introdução
Um AVC hemorrágico é um evento neurológico agudo que ocorre quando um vaso sanguíneo cerebral enfraquecido se rompe, permitindo que o sangue se acumul…
Um AVC hemorrágico se desenvolve quando um vaso sanguíneo enfraquecido no cérebro se rompe, causando sangramento no tecido cerebral ao redor.
Esse sangramento forma um hematoma focal e pode levar a complicações adicionais, como hemorragia intraventricular, inchaço cerebral ou compressão de estruturas próximas.
O AVC hemorrágico é classificado em dois tipos principais: hemorragia intracerebral e hemorragia subaracnoideana.
A hemorragia intracerebral ocorre quando um vaso sanguíneo rompe e sangra diretamente para o parênquima cerebral.
É mais frequentemente causada por hipertensão crônica ou enfraquecimento dos vasos sanguíneos relacionado à idade devido à angiopatia amiloide cerebral.
Menos comumente, pode resultar de uma malformação arteriovenosa, um aglomerado emaranhado de vasos sanguíneos anormais. Se uma delas se romper, pode causar sangramento dentro do cérebro.
Uma hemorragia subaracnoidiana ocorre quando o sangue vaza para o espaço entre a aracnoide e a pía mater.
É comumente causada pela ruptura de um aneurisma de bagas, que é um volume semelhante a um balão em um vaso sanguíneo, ou por trauma craniano.
View the full transcript and gain access to JoVE Core videos
Q1: What happens when a blood vessel ruptures in the brain?
When a weakened blood vessel in the brain ruptures, it causes bleeding into surrounding brain tissue, forming a focal hematoma. This bleeding increases intracranial pressure, displaces neural tissue, and can obstruct cerebrospinal fluid pathways. Secondary complications like brain swelling or compression of nearby structures may develop, leading to rapid neurological deterioration.
Q2: What are the two main types of hemorrhagic stroke?
Hemorrhagic stroke is classified into intracerebral hemorrhage and subarachnoid hemorrhage. Intracerebral hemorrhage occurs when a blood vessel ruptures and bleeds directly into the brain parenchyma. Subarachnoid hemorrhage happens when blood leaks into the space between the arachnoid mater and pia mater, typically from a ruptured berry aneurysm.
Q3: What causes intracerebral hemorrhage?
Intracerebral hemorrhage most commonly results from chronic hypertension, which induces degenerative changes in small penetrating arteries, making them prone to rupture. Age-related cerebral amyloid angiopathy is another important cause in older adults, as amyloid deposition weakens cortical vessel walls. Less frequently, arteriovenous malformations can rupture and produce intraparenchymal bleeding.
Q4: What triggers subarachnoid hemorrhage?
Subarachnoid hemorrhage is most commonly caused by rupture of a saccular berry aneurysm located at branch points in the circle of Willis. Head trauma can also cause this type of hemorrhage. When blood enters the subarachnoid space, it spreads through cerebrospinal fluid, irritating the meninges and increasing intracranial pressure.
Q5: How does a focal hematoma affect the brain?
A focal hematoma from hemorrhagic stroke disrupts surrounding neural tissue and impairs perfusion to affected brain regions. The expanding hematoma displaces neural structures and increases intracranial pressure, potentially obstructing cerebrospinal fluid pathways. These effects can rapidly lead to neurological deficits and secondary complications like cerebral edema.
Q6: What risk factors increase the likelihood of hemorrhagic stroke?
Chronic hypertension remains the most significant risk factor for hemorrhagic stroke. Cerebral amyloid angiopathy, use of anticoagulant medications, and smoking further weaken vessel integrity or increase bleeding risk. Age-related vascular changes and structural abnormalities also contribute to hemorrhagic stroke development.
Q7: What complications can develop from subarachnoid hemorrhage?
Subarachnoid hemorrhage carries a high risk of secondary complications. Vasospasm, a narrowing of blood vessels triggered by blood irritation, can reduce cerebral blood flow. Hydrocephalus, an accumulation of cerebrospinal fluid, may also develop, further increasing intracranial pressure and worsening neurological outcomes.