There is no traumatic injury on the head CT, but the head CT is very abnormal.
The abnormality is hydrocephalus. In the ED, we are accustomed to seeing hydrocephalus (due to atrophy) on brain CTs, even in younger patients. A normal CT in a young person will show small ventricles and no sulci / gyri. When we see large ventricles on a CT, it is usually in the context of aging, and you see appearance of sulci / gyri as well.
Whenever you see large lateral ventricles on a head CT, look at the other ventricles (third, fourth). If the third and fourth ventricles appear normal, the patient may have obstructing hydrocephalus.
In this patient, the lateral ventricles are huge, but the third and fourth ventricles are relatively normal (figures), suggestive of obstructing hydrocephalus.
There’s a big difference between obstructing and non-obstructing hydrocephalus. Obstructing hydrocephalus may be fatal in a few hours, if not minutes.
This is the equivalence of finding a brain tumor when you’re looking for head trauma. It’s an important incidental finding. The difference is that now you have an incidental finding that may kill the patient in the near future. The need for further investigation is more urgent.
The most common cause of obstructing hydrocephalus that I see (by far) is neurocysticercosis. It’s a neurosurgical emergency. I was pretty sure that this was a congenital finding. I asked a few questions – prior imaging, baseline function, history of headaches, birthplace, travel, etc.
The patient had an emergent MRI and a neurosurgical consult. It was a congenital finding (apparently they can see a flap… it was a “House” moment for sure). He was discharged with follow-up.
This looked a good web reference…
https://www.radiologymasterclass.co.uk/tutorials/ct/ct_brain_anatomy/ct_brain_anatomy_ventricles
