Thread by @teachplaygrub

1/Time is brain! But what time is it?

If you don’t know the time of stroke onset, are you able to deduce it from imaging?

Here’s a thread to help you date a stroke on MRI!

2/Strokes evolve, or grow old, the same way people evolve or grow old

The appearance of stroke on imaging mirrors the life stages of a person—you just have to change days for a stroke into years for a person

So 15 day old stroke has features of a 15 year old person, etc.

3/Initially (less than 4-6 hrs), the only finding is restriction (brightness) on diffusion imaging (DWI)

You can remember this bc in the first few months, a baby does nothing but be swaddled or restricted

So early/newly born stroke is like a baby, only restricted

4/Next, at 4-6 hours, you see bright signal on FLAIR imaging

You can remember this bc after a few months, a baby starts to develop some personality or flair

So after a few hours, the stroke gets some flair as well. So if you see FLAIR, stroke is old enough to have personality

5/Next stage in life is when you go off to school to “enhance” your education beyond just your parents/family at home

This can be early, i.e. preschool (at like 3yrs) but usually its kindergarten (5 yrs)

So most strokes start to enhances at 5 days, but can be a bit earlier

6/It’s not until you’re about 10 that your parents give you a little independence (loosen restrictions), liking letting you go away by yourself to camp

Same w/strokes, at about 10 days restricted diffusion ends—so if there’s no restriction, kid’s gotta be older than about 10

7/At about 15 is when you go through your rebellious phase.

You start doing this like dyeing the tips of your hair.

Same w/strokes—you start to see T1 bright signal along the tips of the cortex at about 15 days—called cortical laminar necrosis

8/Enhancement ends from 15 to 40 days, very variable

It’s when you get tired of education/enhancement in life. For some it’s in their teens but others (doctors!) it’s not until later

But if you’re still in education/enhancement at age 50—it’s unusual & consider more imaging

9/Finally, the last stage is encephalomalacia—where you lose volume.

And everyone knows that things start to go downhill after 40

Just like people lose volume & shrivel up as they age, so do strokes

Any stroke showing volume loss/encephalomalacia is always chronic

10/So now you know how to date a stroke on imaging, but using it’s imaging features to see what stage of life it is at

Now when a stroke w/unknown onset comes it, you’ll be ready—right in the nick of time!