2/Let’s start with L1. L1 radiates to the groin. I remember that b/c the number 1 is, well, um…phallic. So the phallic number 1 radiates to the groin.
3/Let’s skip to L3 for a second. I remember L3 is to the knee—easy, it rhymes!
4/Ok, back to L2. Two is the number between 1 and 3, so the distribution of L2 is between the distributions of L1 and L3—and between the groin and knee is the thigh. L2 radiates to the thigh. It’s not the catchiest way to remember it, but it works.
5/L4 radiates to the calf. I remember this bc the number 4 looks like the calf, with the top part of the 4 looking like a bulging gastroc & the bottom part of the four is the rest of the calf connecting to the ankle. Don’t we all wish we had bulging gastrocs like the number 4!
6/L5 radiates to the big toe. So I have the little rhyme “Five is to the big guy!” L5 is also foot drop. So I remember big guys are heavy, and heavy gravity = drop. If I hear the history “foot drop,” I never stop looking until I have traced out the entire L5 nerve root.
7/Finally, S1 radiates to the side of the foot. I remember this bc both S1 & Side start w/S.
So now you know where in the lumbar spine to look when a patient says the pain radiates down the leg & hopefully remembering the lumbar radicular distributions won’t cause you any pain!
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1/My hardest thread yet! Are you up for the challenge?
How stroke perfusion imaging works!
Ever wonder why it’s Tmax & not Tmin?
Do you not question & let RAPID read the perfusion for you? Not anymore!
2/Perfusion imaging is based on one principle: When you inject CT or MR intravenous contrast, the contrast flows w/blood & so contrast can be a surrogate marker for blood.
This is key, b/c we can track contrast—it changes CT density or MR signal so we can see where it goes.
3/So if we can track how contrast gets to the tissue (by changes in CT density or MR signal), then we can approximate how BLOOD is getting to the tissue.
And how much blood is getting to the tissue is what perfusion imaging is all about.
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
1/”I LOVE spinal cord syndromes!” is a phrase that has NEVER, EVER been said by anyone.
Do you become paralyzed when you see cord signal abnormality?
Never fear—here is a thread on all the incomplete spinal cord syndromes to get you moving again!
2/Spinal cord anatomy can be complex. On imaging, we can see the ant & post nerve roots. We can also see the gray & white matter. Hidden w/in the white matter, however, are numerous efferent & afferent tracts—enough to make your head spin.
3/Lucky for you, for the incomplete cord syndromes, all you need to know is gray matter & 3 main tracts. Anterolaterally, spinothalamic tract (pain & temp). Posteriorly, dorsal columns (vibration, proprioception, & light touch), & next to it, corticospinal tracts—providing motor