Subdural hematoma

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[edit] Discussion of Subdural hematoma

  • Usually occur as a result of trauma.
  • Deceleration injuries are often the cause of subdural bleeding from rupturing of veins via a shearing mechanism.
  • Other etiologies include:
    • Nonaccidental trauma
    • Spontaneous hemorrhages may occur in patients receiving anticoagulants or patients with a coagulopathy condition.

[edit] Imaging Findings of Subdural hematoma

[edit] CT

  • Unlike epidural hematomas, subdural hematomas are not restricted by dural tethering at the cranial sutures.
    • They can cross suture lines and continue along the falx and tentorium.
    • They do not cross the midline because of the meningeal reflections.
  • In the acute phase, subdural hematomas appear as a crescent-shaped extra-axial collection with increased attenuation that, when large enough, causes effacement of the adjacent sulci and midline shift.
  • The attenuation changes as the hematoma ages.
  • Subacute subdural hematomas may be difficult to detect because they may have isoattenuation compared with adjacent gray matter
  • Chronic subdural hematomas have isoattenuation relative to the cerebrospinal fluid.
  • Rebleeding into subdural hematomas also may occur and is depicted as a layer of high-attenuation hemorrhage within a lower attenuation hematoma

[edit] MRI

  • MRI is more sensitive than CT scanning in the detection of subdural hematomas because the multiplanar and superior tissue differentiation of MRI makes detection easier.
  • The shape of the subdural hematoma on axial images is the same crescent-shaped pattern seen on CT scan images.
  • The signal depends on the age of the hemorrhage and follows the signal pattern of intraparenchymal hematomas in acute and subacute cases.
  • Chronic subdural hematomas, which appear as isoattenuation relative to CSF on CT scans, often demonstrate increased signal intensity on T1-weighted images because of the presence of free methemoglobin, though the intensity decreases over time.

[edit] Images

Patient #1

Patient #2

[edit] See Also

[edit] External Links

[edit] References