What causes Satellite sign in brain on non-contrast CT?
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Satellite sign represents a small intraparenchymal hyperdense hemorrhagic focus, measuring no more than 10 mm in maximum diameter and separated from the main intracerebral hematoma by no more than 20 mm, seen in spontaneous intracerebral hemorrhage, particularly associated with hypertension and intraventricular hemorrhage; it predicts hematoma expansion and poor functional outcome.
Why is it called so?:
The sign is named for the small secondary hemorrhagic focus resembling a satellite orbiting and separated from the larger primary hematoma, analogous to celestial bodies.
Pathophysiology:
Following the initial hemorrhagic insult, perihematomal tissues develop cytotoxic edema leading to local ischemia and reperfusion injury, which disrupts the blood-brain barrier and causes multifocal active bleeding from peripheral arterioles, manifesting as the discrete satellite hemorrhage.
Alternative names: None
Other associated named signs: Spot sign, black hole sign, swirl sign
Access all radiology signs posted so far: https://radiogyan.com/radiology-signs/
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