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Non-contrast head CT demonstrating post-operative changes, trapped ventricle, PCA stroke Non-contrast head CT demonstrating post-operative changes, trapped ventricle, PCA stroke

A 30 year-old man with no known medical conditions was found to have a left temporal tumor after undergoing workup for new-onset seizures. He undergoes an asleep craniotomy for subtotal resection and is admitted to the NCCU post-operatively. Three hours after arrival to the ICU, nursing finds him to be more somnolent. On your exam, he has anisocoria (OS > OD) with a decrease in reactivity OS. You look up at the monitor and see that his BP, formerly in the 150s/80s, is now in the 250s/140s. You obtain a non-contrast HCT and notice several abnormalities. There's new hypoattenuation within the left occipital lobe, not present on the immediate post-operative scan. What is the most likely unifying etiology of this new finding?

A. Atrial fibrillation

While the area is within the left PCA territory which can be affected by cardioembolism, there's a better unifying diagnosis. This patient is a young healthy man and just had a brain surgery, so important acute conditions associated with that must be first considered, rather than a secondary cause.

B. Artifact

There's some streak artifact appreciable mainly through the pons in this image, but the occipital hypodensity is a true finding not explained by that.

C. Herniation

Yes! This patient just had a brain tumor resection, but his mental status acutely declined and he became markedly hypertensive. The left pupil has blown, indicating compression of the left midbrain. There was downward, transtentorial herniation that compressed the midbrain and PCA, causing an infarct in this territory.

D. Seizure

While the patient is at risk for having seizures, the large area of hypoattenuation would not be expected to be a result of acute seizures. There is an alternative, more likely etiology for this new finding as well as his marked hypertension and anisocoria.

E. Tumor recurrence

The time interval given is too short for tumor recurrence to occur.