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Intracranial Hemorrhage

Three Neurological Emergencies Involving Bleeding Within the Skull

Jun 6, 2008 Anthony Lee

Epidural hematomas, subdural hematomas, and subarachnoid hemorrhages are types of bleeding that require urgent attention.

In general, intracranial hemorrhage is bleeding that occurs inside the skull. They are serious medical emergencies because of their neurological consequences, both immediate and long-term. The following is an overview of three major types of intracranial hemorrhage.

Epidural Hematoma

The brain is surrounded by several layers of membrane. The outermost layer is a tough membrane called the dura mater, which is attached to the inside of the skull along suture lines. An epidural hematoma is a collection of blood between the dura mater and the skull. In the classic case, there is blunt trauma to the side of the head. As a result, the middle meningeal artery ruptures and bleeds into the epidural space. This leads to pressure on the brain and a rapid loss of consciousness.

When such a patient is rushed to the hospital, the diagnosis of epidural hematoma is made by computed tomography (CT). A CT scan typically demonstates the blood as a bright biconvex abnormality, because the blood fills the epidural space and cannot extend past the skull suture lines where the dura is firmly attached. When the need for treatment is urgent, a neurosurgeon performs a craniotomy, drilling burr holes into the skull to drain the blood and relieve intracranial pressure.

Subdural Hematoma

A subdural hematoma is bleeding that occurs underneath the dura mater. This may occur with head trauma but also with other causes like cerebral aneurysm rupture and overdose of anticoagulant medications. A frequent place for subdural bleeding are bridging veins. They are blood vessels connecting the brain circulation to the sinuses inside the dura that drain blood away from the head.

Patients with subdural hematoma may experience symptoms like headache, loss of consciousness, and motor weakness. The time at which symptoms appear depends on the rate of bleeding. The subdural hematoma can be acute (less than 72 hours old), subacute (between 3 and 20 days old), or chronic (older than 3 weeks). In any case, a CT scan shows a subdural hematoma as a bright crescent-shaped abnormality. If treatment becomes highly necessary, surgical craniotomy is performed as definitive treatment.

Subarachnoid Hemorrhage

While the dura mater surrounds the brain but is fixed along the skull, the pia arachnoid and the pia mater are membranes that intimately cover the brain. A subarachnoid hemorrhage (SAH) occurs under the pia arachnoid, often from ruptured aneurysms of cerebral arteries along the brain and arteriovenous malformations (AVMs). Neurological symptoms can vary and range from subtle to severe.

CT can detect the presence of SAH along the brain if it is large enough. Otherwise, there is the possibility of a false negative, and further studies with magnetic resonance imaging (MRI), cerebral angiography, or lumbar puncture are warranted. SAHs are treated medically with blood pressure control when the pressure inside the head gets too high. When the bleeding needs to be stopped definitively, neurosurgeons can place aneurysm clips or perform other operative measures.

References

The copyright of the article Intracranial Hemorrhage in General Medicine is owned by Anthony Lee. Permission to republish Intracranial Hemorrhage in print or online must be granted by the author in writing.
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