What are the less common locations of subdural hematomas (SDHs) and how are they identified on CT scans?

Updated: Jul 26, 2018
  • Author: Richard J Meagher, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Subdural hematomas are relatively uncommon in the posterior fossa since the cerebellum undergoes little movement, which is protective of its bridging cortical veins. Subdural hematomas that do occur in that location are usually a result of parenchymal cerebellar injury.

A small acute subdural hematoma may be difficult to appreciate because of the appearance of the overlying skull. Use of the bone window setting may aid in discrimination.

A subdural hematoma may also be located along the falx cerebri (ie, interhemispheric), along the tentorium, or in the posterior fossa. Interhemispheric subdural hematoma causes the falx cerebri to appear thickened and irregular and often is associated with child abuse. [13]

All or part of an acute subdural hematoma may appear hypodense or isodense to brain if the patient’s hematocrit is low, if the clot is hyperacute (eg, < 1 hour old), if the subdural space contains active bleeding, if coagulopathy is present, or if the CSF is creating a dilutional effect.

Detection of an isodense subdural hematoma may require a high index of suspicion; subtle changes in the appearance or position of the cortical sulci may be found. Contrast-enhanced CT or MRI may help to better define the lesion. Interestingly, isodense subdural hematomas may be either hypointense or hyperintense on T2-weighted MRI; this may be a clue to the underlying pathophysiology. [31]

Some degree of midline shift should be present with moderate or large subdural hematomas. Suspect a contralateral mass when midline shift is absent. If midline shift seems excessive, suspect underlying cerebral edema.


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