For the most part, bleeding in the brain (intracranial hemorrhage) is a pretty bad thing. Though like most things in medicine, there are varying degrees of badness, all with different mechanisms that help us sort of why we really wouldn’t want something to happen.
Intracranial hemorrhages are categorized into 5 subtypes, and are given obvious sounding names depending on where the bleed is in the brain and in relation to the layers of the meninges.
- Epidural (above the dura, right under the skull)
- Subdural (below the dura, above the arachnoid)
- Subarachnoid (below the arachnoid, above the brain)
- Intraventricular (in the ventricles)
- Intraparenchymal (in the meat* of brain)
* The brain is not meaty, “parenchyma” means the functional part of the organ
The poor pia mater did not get any hemorrhage named after it, but if you want you can think of intraparenchymal as “subpial” just so it doesn’t feel left out.
Telling them apart
The most confusing thing, and thing that likes to get asked the most on exams, is the difference between epidural and subdural hematomas.
| Epidural | Subdural | Subarachnoid |
| Above the dura | Below the dura | Below the arachnoid |
| Respects suture lines | Doesn’t respect suture lines | No respect for anything |
| High force trauma | Low force trauma | Aneurysm rupture or high force trauma |
| Arterial blood (commonly the middle meningeal artery) | Venous (from venous plexus) | Arterial from the circle of Willis |
| Lentiform (lens-shaped) or biconcave on CT | Cresent (banana-shaped) on CT | Lining surface, going into fissures and sulci and sella (death-star) |
| Acute presentation | May be insidious (worsening headache over days) | Acute presentation (thunderclap headache) |
The reason intraventricular and intraparenchymal aren’t included in the table as they each have a bunch of causes, but for both of them trauma is a potential cause as well as hypertension and stroke. It’s good to remember that premature infants are at a much higher risk of intraventricular hemorrhages.
Blood on CTs
- New blood: bright white
- 1-2 weeks: isodense
- Old blood (2-3 weeks): dark grey
I really love your drawings and your site. Thanks for doing these, I’m having a year out at the moment on maternity leave and it helps me to keep some medical stuff in my brain, while only taking up a few minutes to look at it. I hope they keep coming, thanks again.
I’m about to enter my second year of medical school and I can’t believe I just found your site now. It’s amazing and would have been super helpful all of last year. I’ll be sure to utilize it from now on though. It’s really helping me to work on my retention. It will also be an awesome study tool for Step 1 when I get so sick of my First Aid book I want to dropkick it across my room. Thank you!
I can’t thank you enough for this website. I am in my second year of nursing. I will use this website when I am studying for my pathotherapeutic classes. Your sketches are great for people like me who are visual learners.
Thanks heaps for all your drawings! :) I’m in my second last year of med, coming up to the exams that will essentially determine intern position. This site is awesome to just pick a page and do a quick 2 minutes of revision of a topic I mightn’t have thought about for awhile. Keep it up :)
Love your site!! I’m an anatomy instructor and it’s great to give myself refreshers on material as well as learn stuff I didn’t know! I’m a visual learner, so these images are way better than reading 15 pages of text, and I get most of the same info!
These are GREAT. The only way I got through tests was drawing everything out.