Pathogenesis (disease development)
The brain is enveloped by three densely packed meninges (meninges; layers of connective tissue). They protect and stabilize the brain. The dura mater is the outermost and thickest layer. It is directly adjacent to the skull. The middle meninges are called arachnoid mater (cobweb skin). The pia mater (delicate meninges) is the innermost meninges and lies directly on top of the brain. The two inner layers are also called or combined as the soft meninges. Between the meninges run blood vessels and is the cerebrospinal fluid (CSF).
The subdural hemorrhage is localized between the dura mater and the arachnoid mater. The origin of the hemorrhage is in ruptured (rupturing) bridging veins that run through the subdural space.With age, there is external atrophy of the brain (brain volume reduction), which increases the pull on the bridging veins and increases the risk for rupture. The hemorrhages may become encapsulated by a neomembrane. The capillaries (fine blood vessels) of the neomembranes are very permeable (permeable), so rebleeding can occur repeatedly. Brain atrophy is not only seen in the elderly, but also in alcoholics.Acute subdural hematomas are usually localized on one side, while chronic ones are usually bilateral (especially with anticoagulant/anticoagulant therapy).
Etiology (causes)
Acute subdural hematoma
- In the setting of severe traumatic brain injury (TBI): blow or impact to the head, traffic accidents
Chronic subdural hematoma
Behavioral causes
- Consumption of stimulants
- Alcohol abuse (alcohol dependence)
Causes related to disease
- Diabetes mellitus – promotes the development of subdural hematoma due to vascular damaging effects.
- Hypertension (high blood pressure) – favors the development of subdural hematoma due to vascular damaging effects.
- Coagulopathies – disorder of blood clotting.
Medication
- Anticoagulants (anticoagulants).
Other causes
- In the context of mild to moderate traumatic brain injury (TBI) – minor trauma, such as from falls (especially in the elderly), sports accidents.
- Changes in intracranial pressure – e.g., during pressure relief in epileptic seizures (convulsions), hydrocephalus (pathological expansion of the liquid-filled fluid spaces (ventricles) of the brain / obsolete “hydrocephalus”), cerebrospinal fluid drainage (for the drainage of cerebrospinal fluid), lumbar puncture (cerebrospinal fluid puncture)
