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Difficulty: EasyNeurosurgery

Match the following types of intracranial hemorrhage with their classic presentation on a noncontrast head computed tomography (CT) scan.

  • Epidural hematomaBiconvex (lens-shaped) hyperdensity that does not cross cranial suture lines
  • Subdural hematomaCrescent-shaped hyperdensity that can cross suture lines but is limited by dural reflections
  • Subarachnoid hemorrhageHyperdensity filling the basal cisterns and tracking along the cerebral sulci
  • Intraparenchymal hemorrhageHyperdensity localized deep within the brain tissue, such as the basal ganglia or thalamus

Answer

Epidural hematoma matches with the biconvex (lens-shaped) hyperdensity; Subdural hematoma matches with the crescent-shaped hyperdensity; Subarachnoid hemorrhage matches with hyperdensity in the cisterns/sulci; Intraparenchymal hemorrhage matches with localized deep hyperdensity in the basal ganglia.
Each type of intracranial hemorrhage has a distinct anatomic space that dictates its appearance on noncontrast CT. The firm attachment of the dura to the skull sutures causes arterial epidural bleeds to form a biconvex shape. Venous subdural bleeds spread over the hemisphere as a crescent. Subarachnoid blood fills the pre-existing CSF spaces (cisterns and sulci), and intraparenchymal blood pools directly within brain tissue, typically in deep structures like the basal ganglia due to hypertension.

Step-by-Step Solution

1
Evaluate the anatomy and bleeding source of an epidural hematoma.
Identify that arterial bleeding between the skull and dura creates a localized, high-pressure biconvex (lens) shape limited by cranial sutures.
This structural limitation dictates its distinct radiographic appearance on CT.
2
Evaluate the anatomy and bleeding source of a subdural hematoma.
Identify that venous bleeding between the dura and arachnoid spreads out, forming a crescent shape that can cross sutures but is stopped by dural folds.
Venous pressure is lower, allowing blood to diffuse over a larger hemispheric area.
3
Evaluate the distribution of subarachnoid hemorrhage.
Identify that blood mixes with CSF in the subarachnoid space, appearing as hyperdensity outlining the sulci and basal cisterns.
Bleeding is occurring on the surface of the brain inside the fluid-filled spaces.
4
Evaluate the location of intraparenchymal hemorrhage.
Identify that this type of bleeding occurs inside the brain parenchyma, classically in deep structures like the basal ganglia.
It is often caused by hypertensive vasculopathy affecting deep penetrating arteries.

Key Concept

Radiographic appearance and anatomic boundaries of intracranial hemorrhages
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Topics

Neurosurgery

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