Bilateral Isodense/Hyperdense Subdural Hematomas
Findings:
Axial noncontrast CT images show medial displacement
of the gray/white junction bilaterally, associated with bilateral mostly
isodense extraaxial collections, with slight dependent hyperdensity.
Differential Diagnosis:
Subdural hematoma is the only reasonable diagnosis in
this case. "En plaque" meningioma could be considered if the extraaxial
abnormality were unilateral, and contrast would help in that case if the
clinical history was inconsistent with trauma. This patient had recurrent
subdural hemorrhages of varying ages due to repeated falls.
Discussion:
-attenuation characteristics: hyperdense
<3days, isodense 3 days up to 3 weeks, then hypodense
-viewing with intermediate window width
may be more sensitive
-overall mortality up to 90% (usually from
underlying or associated injuries)
-more common with falls/assaults than MVA,
may occur in the absence of direct impact
-bilateral more common in infants- child
abuse
-etiology: tear of bridging veins
-location: supratentorial along convexity
or along tent/falx, rare anterior and middle fossa, retroclival