2/ With CSF leaks, everyone knows about brain sagging. But this can happen w/other pathologies, ie Chiari 1. Other findings can be seen on brain MRI in CSF leaks. But what are these findings? Are some findings more suggestive than others? Do more findings = ⬆️suspicion?
3/Dobrocky et al. looked at 9 quantitative & 7 qualitative signs seen on brain MRI in CSF leaks to see which are most important. Depending on type & # of findings, they developed a score to indicate what level of suspicion you should have for a leak. pubmed.ncbi.nlm.nih.gov/30776059/
4/Not surprisingly, they found the best sign for CSF leaks is classic pachymeningeal enhancement. While not always seen, it was seen in > 4 out of 5 leak patients, & almost never in others,unless they had recent LP. Therefore, this sign is worth 2 points on the scoring system
5/Classically, subdural collections are also associated, but these are seen less commonly than pachymeningeal enhancement (~about half of leaks), and other patients may have subdurals for other reasons (ie trauma) and therefore, this is only afforded one point.
6/A newer finding assoc w/leaks is rounding of the transverse sinus. Dural sinuses enlarge to compensate for loss of intracranial CSF in leak pts, & in doing so, their margins go from concave to convex. This was seen in 2/3rds of leak pts & never in others, so it is given 2 pts
7/Another overlooked finding in leak pts is⬇️in the suprasellar cistern around the chiasm. As the hindbrain sinks, eventually the chiasm sinks w/it & the cistern below it is attenuated. If the suprasellar cistern below the chiasm measures less than 4mm, this is worth 2 points.
8/Decrease in the pre-pontine cistern (<5mm) was not commonly seen, but was more than 4x more common in leak patients and was reproducible among readers of the scans, and so it was given 1 point.
9/Similarly, a decrease in the ponto-mammillary distance (<6.5mm between the mammillary bodies and top of the pons on the sagittal images) was also not commonly seen, but 3x more common in leak patients and therefore worth 1 point.
10/Other findings, such as the ponto-mesencephalic angle, attenuation of the quadrigeminal plate cistern, enlargement of the intercavernous sinus, and pituitary contour were not reproducible among readers of the scans and therefore not included in the score.
11/Here is the summary of the points awarded to each finding. The scoring system is classified as follows:
12/ So next time you are looking at a brain MRI for intracranial hypotension, you can feel confident in classifying your suspicion of a CSF leak. Say to them like they say in Billions--you are not uncertain 😉
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1/I always say you can tell a bad read on a spine MR if it doesn’t talk about lateral recesses.
What will I think when I see your read? Do you rate lateral recess stenosis?
Here’s a thread on lateral recess anatomy & a grading system for lateral recess stenosis
2/First anatomy.
Thecal sac is like a highway, carrying the nerve roots down the lumbar spine.
Lateral recess is part of the lateral lumbar canal, which is essentially the exit for spinal nerve roots to get off the thecal sac highway & head out into the rest of the body
3/Exits have 3 main parts.
First is the deceleration lane, where the car slows down as it starts the process of exiting.
Then there is the off ramp itself, and this leads into the service road which takes the car to the roads that it needs to get to its destination
1/Do radiologists sound like they are speaking a different language when they talk about MRI?
T1 shortening what? T2 prolongation who?
Here’s a translation w/an introductory thread to MRI.
2/Let’s start w/T1—it is #1 after all! T1 is for anatomy
Since it’s anatomic, brain structures will reflect the same color as real life
So gray matter is gray on T1 & white matter is white on T1
So if you see an image where gray is gray & white is white—you know it’s a T1
3/T1 is also for contrast
Contrast material helps us to see masses
Contrast can’t get into normal brain & spine bc of the blood brain barrier—but masses don’t have a blood brain barrier, so when you give contrast, masses will take it up & light up, making them easier to see.
1/Does your ability to remember temporal lobe anatomy seem, well, temporary?
Or are you feeling temporally challenged when it comes to this complex region?
Here’s a thread to help you remember the structures of the temporal lobe!
2/Temporal lobe can be divided centrally & peripherally.
Centrally is the hippocampus.
It’s a very old part of the brain & is relatively well preserved going all the way back to rats.
Its main function is memory—getting both rats & us through mazes—including the maze of life
3/Peripherally is the neocortex.
Although rats also have neocortex, theirs is much different structurally than humans.
So I like to think of neocortex as providing the newer (neo) functions of the temporal lobes seen in humans: speech, language, visual processing/social cues