A<unk>  is an apparent increased attenuation on CT scans within the basal cisterns that mimics a true subarachnoid hemorrhage. This occurs in cases of severe cerebral edema, such as by cerebral hypoxia. It may also occur due to intrathecally administered contrast material, leakage of high-dose intravenous contrast material into the subarachnoid spaces, or in patients with cerebral venous sinus thrombosis, severe meningitis, leptomeningeal carcinomatosis, intracranial hypotension, cerebellar infarctions, or bilateral subdural hematomas. In a true subarachnoid hemorrhage, there is higher attenuation on CT scans of the basal cisterns, and blood that has leaked from a vessel or formed a hematoma is more highly attenuated due to the absorption of plasma.<unk> s have been observed in as much as 20% of patients resuscitated from non-traumatic cardiopulmonary arrest. Patients with<unk> s may have worse prognoses than those with true subarachnoid hemorrhages because of underlying disease processes and decreased cerebral perfusion with elevated intracranial pressure. The identification of a<unk>  as opposed to a true subarachnoid hemorrhage may therefore change a patient's treatment plan.
Pseudosubarachnoid hemorrhage
Duret haemorrhages
ROSAH syndrome
Cerebral venous sinus thrombosis
Splinter hemorrhage
Subdural empyema
Subarachnoid hemorrhage
Subdural hematoma