Non-traumatic intracranial hemorrhage is a type of stroke caused by the spontaneous rupture of a blood vessel within the skull. This bleeding originates from underlying medical conditions affecting the brain’s vascular system. It is a medical emergency where blood accumulates inside the skull, increasing pressure that can compress and damage brain tissue. This event accounts for about 10-15% of all strokes and is a cause of disability and mortality.
Types and Locations of Bleeding
The classification of non-traumatic intracranial hemorrhage depends on where the bleeding occurs. The main types are distinguished by their location relative to the brain tissue. One major type is an intraparenchymal hemorrhage, which involves bleeding directly into the brain’s functional tissue, the parenchyma. These bleeds most frequently happen in deep brain structures like the basal ganglia, thalamus, cerebellum, and pons.
A second primary category is the subarachnoid hemorrhage. This refers to bleeding in the subarachnoid space, which is the area between the brain and the thin tissues that cover it.
A related event is an intraventricular hemorrhage, where bleeding extends into the brain’s ventricles. This is often a complication or extension of a nearby intraparenchymal or subarachnoid hemorrhage, not a primary event. The location of the initial bleed is a strong indicator of its underlying cause.
Primary Causes and Risk Factors
The most common cause of bleeding directly into the brain tissue is chronic high blood pressure (hypertension). Over many years, elevated pressure weakens the walls of small, deep-penetrating arteries in the brain, which can eventually rupture. In contrast, the leading cause of subarachnoid hemorrhage is a ruptured cerebral aneurysm. A cerebral aneurysm is a weak, bulging spot on the wall of a larger artery, often located at the base of the brain in a formation called the circle of Willis.
Another cause is an arteriovenous malformation (AVM), an abnormal tangle of arteries and veins where high-pressure arterial blood flows directly into low-pressure veins, making them prone to rupture. AVMs are a notable cause of hemorrhage, especially in younger individuals.
Other factors also contribute to the risk. Cerebral amyloid angiopathy (CAA) is a condition where an abnormal protein builds up in the walls of brain arteries, making them brittle and prone to bleeding. This condition is a leading cause of lobar hemorrhages, which occur in the outer lobes of the brain, particularly in the elderly. Blood clotting disorders and the use of anticoagulant medications also increase the risk of bleeding.
Signs and Symptoms
The onset of an intracranial hemorrhage is sudden and dramatic. The most distinctive symptom, particularly for a subarachnoid hemorrhage, is a severe headache that reaches its maximum intensity within seconds, often described as the “worst headache of my life.” This pain results from blood irritating the meninges, the protective layers covering the brain.
Other symptoms appear rapidly and can include:
- Nausea and vomiting, occurring in about 40-50% of cases due to increased pressure inside the skull.
- A change in consciousness, which can range from lethargy and confusion to a complete loss of consciousness or coma.
- Sudden weakness, numbness, or paralysis, often affecting one side of the body.
- Difficulty speaking or understanding language (aphasia).
- Vision loss, or a loss of balance and coordination.
- Seizures, which can be triggered by the irritation to brain tissue.
Diagnosis and Immediate Management
Suspected intracranial hemorrhage requires immediate medical evaluation. The primary diagnostic tool is a non-contrast computed tomography (CT) scan of the head. A CT scan is fast and effective at detecting acute bleeding, which appears as a bright area on the image, allowing physicians to confirm the diagnosis and identify the hematoma’s location and size.
Once a hemorrhage is confirmed, further imaging is often required to determine the cause. A CT angiogram (CTA) is frequently performed to look for aneurysms, AVMs, or other vascular abnormalities. An MRI scan may also be used, as it provides more detailed pictures of the brain tissue and can detect issues like cavernous malformations.
Immediate management focuses on stabilizing the patient and preventing further brain injury. A primary goal is to control blood pressure, and if the patient is on anticoagulant medications, treatments are administered to reverse their effects. Intracranial pressure (ICP) is also monitored, as swelling can cause dangerous pressure elevations.
Definitive Treatment and Recovery
After a patient is stabilized, treatment shifts to addressing the specific cause of the hemorrhage. For a ruptured aneurysm, the goal is to prevent it from bleeding again. This is achieved through endovascular coiling, a minimally invasive technique where a catheter guides tiny platinum coils into the aneurysm to block blood flow, or surgical clipping, which involves a craniotomy to place a small metal clip across the neck of the aneurysm.
If the hemorrhage was caused by an arteriovenous malformation (AVM), treatment options include surgical removal, embolization to block blood flow to the AVM, or stereotactic radiosurgery, which uses focused radiation to close off the vessels. When a large blood clot is causing significant pressure, a surgeon may perform a craniotomy to surgically evacuate the blood.
The recovery process following a hemorrhage is highly variable and depends on the bleed’s severity. Some patients recover fully, while others have lasting neurological deficits. Rehabilitation is a component of recovery and involves physical therapy for strength, occupational therapy for daily activities, and speech therapy for communication. The greatest recovery typically occurs within the first six months.