- < 6 hours:
hyperacute haemorrhage, significant hypodense component due to unclotted blood.
- 6 hours to 3 days:
homogeneously hyperdense, if there is ongoing active bleeding may see the swirl sign
- 3 days to 3 weeks:
isodense to cerebral parenchyma
- chronic haemorrhage:
hypodense to brain and may looks like CSF
- bilateral hypodense areas in the lentiform nuclei (“owls eyes” in the basal ganglia)
Elevated Intracranial Pressure
- effacement of the basal cisterns
- loss of grey-white differentiation
- loss of sulci
- midline shift
- herniation of cerebellar tonsils into foramen magnum
- uncal herniation (shift of brainstem and distortion of adjacent cisterns, dilation of contralateral temporal horn, compression of the posterior cerebral artery as it crosses the tentorium -> posterior cerebral artery territory infarct)
- small, deep subcortical infarcts less than 1.5cm in size
- usually involve: basal ganglia, thalamus, internal capsule, corona radiate and brainstem
- cortical border zone infarctions between the territories supplied by anterior, middle and posterior cerebral arteries
- internal border zone infarctions between the territory of the penetrating arteries arising form the superficial pial plexus and territories of the deep penetrating arteries arising from the basal cerebral arteries (corona radiate and centrum semiovale adjacent to the lateral ventricles)
- uncal transtentorial herniation: the uncinate process of the temporal lobe herniates into the anterior part of the opening of the tentorium cerebelli.
- central tentorial herniation: there is symmetrical downward movement of the thalamic region through the opening of the tentorium cerebelli
- subfalcine herniation: displacement of the cingulated gyrus under the falx and across the midline.
- foraminal herniation: there is downward herniation of the cerebellar tonsils into the foramen magnum.
Rim contrast enhancing lesions
- infections (toxoplasmosis)
References and Links
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.