1/CSF leaks are controversial. Some say they are overdiagnosed, others underdiagnosed. How can you make sure you aren’t under or overdiagnosing?
Are you Bern-ing to know when you should suspect a CSF leak? Here’s a thread about an easy brain MRI score for suspected CSF leaks
2/In CSF leaks, everyone knows about brain sagging. But this can happen w/other dz, 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 1 findings = 1 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.
4/Not surprisingly, they found the best signs for CSF leaks is the classic pachymeningeal enhancement. While not always seen, it was seen in more than 4 out of 5 leak patients. Therefore, this sign is worth 2 points on the scoring system
5/Classically, subdural collections are also associated, these are seen less commonly (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 associated w/leaks is rounding of the transverse sinus. Dural venous 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 points
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.
11/Here is the summary of the points awarded to each finding. The scoring system is classified as follows:
High suspicion >/= 5 (>90% sensitive & specific)
Intermediate suspicion =3-4
Low suspicion </= 2
12/ So next time you are looking at a brain MRI for intracranial hypotension, you can feel confident in classifying whether or not you suspect there is a CSF leak. As they say in Billions, you are not uncertain
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