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Subdural Haematoma

Summary

  • Subdural haematoma (SDH) is a collection of blood between the dura and arachnoid layers of the meninges
  • Typically results from tearing of bridging veins due to trauma or spontaneously in anticoagulated patients
  • Imaging findings vary based on age of haematoma, with characteristic crescent-shaped extra-axial collection on CT/MRI1

Pathophysiology

  • Bridging veins traverse from cortical surface to dural venous sinuses
  • Rupture of these veins leads to bleeding into subdural space
  • Acute SDH: Fresh blood collection
  • Subacute SDH: Liquefaction and breakdown of blood products (3-21 days)
  • Chronic SDH: Encapsulated collection with osmotically driven fluid accumulation (>21 days)

Demographics

  • Bimodal age distribution:
    • Young adults: Often due to trauma
    • Elderly: Increased risk due to brain atrophy and anticoagulation use
  • Male predominance (3:1 male to female ratio)
  • Risk factors:
    • Trauma
    • Anticoagulation therapy
    • Alcohol abuse
    • Coagulopathies

Diagnosis

  • Clinical presentation:
    • Acute: Headache, altered mental status, focal neurological deficits
    • Chronic: Gradual onset of symptoms, cognitive decline, gait disturbances
  • Physical examination:
    • Pupillary abnormalities
    • Hemiparesis
    • Increased intracranial pressure signs
  • Laboratory tests:
    • Coagulation profile
    • Complete blood count

Imaging

  • CT (non-contrast):
    • Acute: Hyperdense crescent-shaped collection
    • Subacute: Isodense to brain parenchyma
    • Chronic: Hypodense collection
    • Mass effect and midline shift may be present
  • MRI:
    • Superior to CT for isodense subacute SDH
    • T1WI:
    • Acute: Isointense to hypointense
    • Subacute: Hyperintense
    • Chronic: Hypointense
    • T2WI:
    • Variable signal intensity based on age
    • FLAIR: Hyperintense in all stages
    • DWI: May show restricted diffusion in acute stage

panels-1

  • 70-year-old patient presented with slurred speech and confusion (although no history of trauma).
  • CT showed a mixed hyper- and hypo-dense crescentic collection over the left cerebral convexity.
  • Mass effect caused distortion of the left lateral ventricle and minimal midline shift.
  • 5 days later, the density of the acute blood decreased.

Treatment

  • Surgical evacuation (burr holes for chronic, craniotomy for acute) with anticoagulation reversal; small collections are observed
  • The crescentic shape that crosses sutures but not the midline distinguishes it from an epidural haematoma; density reflects clot age

Differential diagnosis

Differential Diagnosis Differentiating Feature
Epidural Haematoma Lenticular shape on CT, does not cross suture lines
Subarachnoid Haemorrhage Blood in subarachnoid space, often in basal cisterns
Empyema Rim-enhancing extra-axial collection with restricted diffusion on DWI; no blood products on MRI
Arachnoid Cyst No mass effect, CSF density on CT

  1. Lim et al. Subdural haematoma mimics. 2019. Clinical radiology - Open in new tab. ↩