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Chronic Subdural Hematoma


KEY FACTS

Terminology

  • Chronic subdural hematoma (cSDH)

  • Chronic (> 3 weeks to months) subdural blood products

    • Mixed chronic and acute hemorrhage is common

Imaging

  • Crescent-shaped extraaxial collection

    • Spreads diffusely over affected hemisphere

    • Surrounded by enhancing membranes

    • Often septated, loculated, with fluid-fluid levels

    • Recurrent, mixed-age hemorrhage is common and raises suspicion of nonaccidental trauma in children

  • Imaging recommendations

    • NECT is good initial screen

    • Use wide window settings (150-200 HU)

    • MR better demonstrates cSDH

Top Differential Diagnoses

  • Subdural hygroma

  • Subdural effusion

  • Subdural empyema

Pathology

  • Serosanguineous fluid

  • Encapsulated by granulation tissue: “Neomembranes” with fragile capillaries

  • 5% multiloculated with fluid-blood density levels

Clinical Issues

  • Treatment

    • Surgical drainage with resection of membranes

  • Older age, brain atrophy are contributory factors in conversion of traumatic SDH into cSDH

  • Recurrence risk varies with type

    • Separated SDH has highest risk

    • Large > small preoperative collections

    • Residual postoperative volume > 80 mL

Axial graphic depicts pathology of classic chronic subdural hematoma (SDH) with the formation of thin internal
, thicker external
membranes. Note the stretched bridging veins
crossing the SDH, top-to-bottom gradation of fluid from serosanguinous to more proteinaceous contents.

Axial NECT depicts chronic SDH (cSDH) as crescentic hypodense extraaxial fluid collection
over the left hemisphere. Stretched cortical veins
are faintly visible as they cross the SDH.

Axial graphic depicts “mixed” subdural hematoma. Numerous loculations
that contain hemorrhages of multiple ages are present. Note the fluid-fluid levels with mixed acute, subacute blood
. Rehemorrhage into preexisting subacute &/or cSDH is common.

Axial NECT shows classic left-sided “mixed” SDH
. Note the multiple loculations and fluid-fluid levels
formed by acute rehemorrhage into preexisting loculated cSDH.

TERMINOLOGY

Abbreviations

  • Chronic subdural hematoma (cSDH)

Definitions

  • Chronic (> 3 weeks to months) collection of blood products in subdural space

    • May have foci of more acute hemorrhage (“mixed” SDH)

IMAGING

General Features

  • Best diagnostic clue

    • Crescent-shaped, multiseptated, extraaxial collection with enhancing surrounding membranes that spreads diffusely over affected hemisphere

  • Location

    • Potential space between inner layer of dura mater and arachnoid

    • Supratentorial convexity is most common

  • Morphology

    • Crescent-shaped extraaxial fluid collection

    • May cross sutures, not dural attachments

    • May extend along falx and tentorium

    • Compresses and displaces underlying brain surface, cortical vessels, and subarachnoid space fluid

    • Often septated, with internal membranes

    • Calcification in 1-2%

    • Enhancement of encapsulating membranes

    • Recurrent, mixed-age hemorrhage is common and raises suspicion of nonaccidental trauma in children

    • CT density and MR signal intensity vary with age and organization of hemorrhage

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