1/Kids now out of school? Headache already?? Usually neuroimaging doesn’t add much in headaches, but in occipital neuralgia MR neurography can add a lot.
2/ There are actually 3 occipital nerves:greater, lesser and least. They arise from the upper cervical nerves and innervate various areas of the dorsal scalp. The greater occipital nerve is the only one large enough to image and it arises from C2
3/The greater occipital nerve is the largest cutaneous nerve in the body and can be traced from its origin at the dorsal ramus of C2 along the scalp in MR neurography
4/Many pathologies can affect the greater occipital nerve, but most commonly, it is compression between muscles, resulting in occipital neuralgia. This is the basis behind Botox treatment for occipital neuralgia. Decompressive surgery can also be used to provide relief
5/Where is it compressed? Usually between the multifidus and semispinalis capitis. We can use MR neurography to rule out other pathologies of the nerve and confirm compressive injury
6/MR neurography can confirm unilateral dz preop or post op neuromas w/persistent pain. This is a pt w/unilateral right dz w/a brighter larger right nerve, indicating Sunderland 1 injury from compression
Not all headaches have to be a diagnostic headache with MR neurography 😉
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@TheAJNR 2/Vascular cognitive impairment, or its most serious form, vascular dementia, used to be called multi-infarct dementia.
It was thought dementia directly resulted from brain volume loss from infarcts, w/the thought that 50-100cc of infarcted related volume loss caused dementia
@TheAJNR 3/But that’s now outdated. We now know vascular dementia results from diverse pathologies that all share a common vascular origin.
It’s possible to lose little volume from infarct & still result in dementia.
So if infarcts are common—which contribute to vascular dementia?
@TheAJNR 2/In the lumbar spine, it is all about the degree of canal narrowing & room for nerve roots.
In the cervical spine, we have another factor to think about—the cord.
Cord integrity is key. No matter the degree of stenosis, if the cord isn’t happy, the patient won’t be either
@TheAJNR 3/Cord flattening, even w/o canal stenosis, can cause myelopathy.
No one is quite sure why.
Some say it’s b/c mass effect on static imaging may be much worse dynamically, some say repetitive microtrauma, & some say micro-ischemia from compression of perforators
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.