Intracranial Hemorrhage: The Four Types Compared

What intracranial hemorrhage means

"Intracranial" means inside the skull. The brain is wrapped in three membranes: the tough dura mater next to the skull, the delicate arachnoid, and the pia on the brain surface. Where blood collects relative to these layers determines the type of hemorrhage, its usual cause, how fast it develops, and how it is treated.

Because the skull is a closed box, any blood takes up space. As a bleed grows, pressure inside the skull rises (increased intracranial pressure), squeezing the brain and reducing its blood supply. That is why some bleeds cause headache and vomiting followed by drowsiness and coma.

Types of intracranial hemorrhage

Epidural and subdural bleeds are called hematomas because blood pools in a pocket. Subarachnoid and intracerebral hemorrhages that happen without injury are forms of hemorrhagic stroke, covered in more depth on our brain hemorrhage page.

Epidural vs subdural hematoma

Both usually follow trauma, but they behave differently. An epidural hematoma is usually arterial, grows fast, and is common in young adults after a blow to the side of the head. A subdural hematoma is usually venous and can grow slowly. Brain shrinkage with age and alcohol stretches the bridging veins, so older adults can develop a chronic subdural after a trivial bump they may not remember.

Symptoms

Symptoms depend on the type, size and location:

• Sudden or worsening headache
• Nausea and repeated vomiting
• Drowsiness, confusion or loss of consciousness
• Weakness on one side, facial droop or numbness
• Slurred or confused speech
• Vision changes, including double vision
• Seizures
• Stiff neck and sensitivity to light (subarachnoid)
• Unequal pupils, slow breathing and posturing in severe cases

Causes and risk factors

• Head injury: falls, assaults, car and bike crashes, sports. See traumatic brain injury.
• High blood pressure: the leading cause of spontaneous bleeding into the brain.
• Blood thinners and antiplatelet drugs, and bleeding disorders.
• Ruptured brain aneurysm or arteriovenous malformation.
• Cerebral amyloid angiopathy: fragile vessels in older adults, causing bleeds near the brain surface.
• Other: brain tumors, heavy alcohol use, cocaine and amphetamines, liver disease, and prematurity in newborns.

Diagnosis

• Non-contrast CT head scan: fast and very sensitive for fresh blood. It is the first test in the ER.
• CT or MR angiography: looks for aneurysms or abnormal vessels.
• MRI: better for small, older bleeds and for finding causes such as amyloid angiopathy or tumors.
• Lumbar puncture: if a subarachnoid hemorrhage is suspected but the CT is normal.
• Blood tests: clotting, platelet count and kidney function.

Treatment

Emergency measures

• Protect breathing and circulation
• Reverse blood thinners quickly with specific antidotes or clotting factor concentrates
• Lower very high blood pressure carefully
• Treat seizures, raise the head of the bed, and manage raised pressure

Surgery and procedures

• Craniotomy: opening the skull to remove a large epidural or acute subdural hematoma. Epidural hematomas often need surgery within hours.
• Burr hole drainage: for many chronic subdural hematomas. Middle meningeal artery embolization lowers recurrence in selected people.
• Aneurysm coiling or clipping: to prevent rebleeding after subarachnoid hemorrhage.
• External ventricular drain: relieves blocked fluid and pressure.
• Observation: small bleeds in alert patients are often watched with repeat scans.

Outlook and recovery

Outcomes vary widely. Small subdural and epidural bleeds treated promptly can lead to full recovery. Large intracerebral and subarachnoid hemorrhages carry significant risk of death and disability. Recovery often involves rehabilitation with physical, occupational and speech therapy over months. Controlling blood pressure is the most effective way to prevent a recurrence.

Frequently asked questions

What are the 4 types of intracranial hemorrhage?

They are epidural hematoma (between skull and dura), subdural hematoma (between dura and arachnoid), subarachnoid hemorrhage (in the fluid around the brain) and intracerebral hemorrhage (inside brain tissue). Intraventricular hemorrhage, into the fluid spaces, is sometimes listed as a fifth.

Is an intracranial hemorrhage the same as a stroke?

Some are. Intracerebral and non-traumatic subarachnoid hemorrhages are types of hemorrhagic stroke. Epidural and subdural hematomas from injury are usually classed as traumatic brain injuries instead. All need emergency care and a CT scan.

Can you survive a bleed on the brain?

Yes, many people do, especially with smaller bleeds and fast treatment. Survival and recovery depend on the type, size and location of the bleed, the person's age and health, and how quickly pressure is relieved and bleeding stopped.

How long after a head injury can a brain bleed occur?

Epidural bleeds usually show within hours. Acute subdural bleeds appear within about 3 days, but chronic subdural hematomas can develop over weeks to months, particularly in older adults and those on blood thinners. New headache, confusion or unsteadiness weeks after a fall needs a medical review.

What is the most common cause of intracranial hemorrhage?

Head injury is the most common cause overall. Among bleeds that happen without injury, long-standing high blood pressure is the leading cause of bleeding into the brain, and a ruptured aneurysm is the main cause of non-traumatic subarachnoid hemorrhage.