Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Acute Subdural Hematoma


KEY FACTS

Terminology

  • Acute blood between inner border cell layer of dura, arachnoid

Imaging

  • NECT as initial screening study

    • Use both bone, soft tissue algorithms

    • Use both standard brain, wide windows (150 HU)

    • Coronal, sagittal reformatted scans best for detecting small subdural hematomas (SDHs)

  • Crescentic hyperdense extraaxial collection

    • Spreads diffusely over cerebral convexity

    • Often extends along falx, tentorium

  • Inward displacement of cortical veins, sulci

  • May cross sutures, not dural attachments

Top Differential Diagnoses

  • Other subdural fluid collections

    • Mixed SDH (acute on chronic/subacute SDH): Hyperdense foci in pockets of iso-, hypodense fluid

    • Subdural hygroma: Clear CSF, no encapsulating membranes

    • Subdural effusion: Near CSF density

    • Subdural empyema: Peripheral enhancement, hyperintensity on FLAIR; restricted diffusion on DWI

  • Acute epidural hematoma (typically crescentic)

Pathology

  • Common: Tear of bridging cortical veins

  • Nontrauma (spontaneous) more common in elderly

Clinical Issues

  • Mental status & focal neurological changes can have rapid deterioration

Diagnostic Checklist

  • Multiplanar reconstructions, wide windows best for subtle acute SDHs; inform clinician if unsuspected finding

Graphic shows acute subdural hematoma (aSDH)
compressing the left hemisphere and lateral ventricle, resulting in midline shift. Coexisting cortical contusions
and axonal injuries
are common in aSDHs.

Axial NECT in a 58-year-old woman with head trauma shows a classic aSDH
extending over the left convexity and compressing the underlying subarachnoid space
. The subtle hypodense foci
within the hyperdense aSDH represent unclotted blood and risk for rapid hematoma expansion.

Occasionally, aSDHs are isodense to the underlying brain. Note the aSDH
with mass effect, inward displacement of the underlying gray-white interface
, and left-to-right subfalcine herniation of the lateral ventricles
.

More cephalad NECT scan in the same patient again shows the isodense aSDH
. The underlying sulci are completely effaced. Compare this appearance of “absent sulci” with the normal-appearing cerebrospinal fluid-filled sulci
over the right hemisphere.

TERMINOLOGY

Abbreviations

  • Acute subdural hematoma (aSDH)

Definitions

  • Acute blood in or between inner border cell layer of dura and arachnoid

IMAGING

General Features

  • Best diagnostic clue

    • CT: Crescentic, hyperdense, extraaxial collection spread diffusely over affected hemisphere

  • Location

    • Between arachnoid and inner border cell layer of dura

    • Supratentorial convexity > interhemispheric, peritentorial

  • Morphology

    • Crescent-shaped extraaxial fluid collection

    • May cross sutures, not dural attachments

    • May extend along falx, tentorium, and anterior and middle fossa floors

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts