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This is an MRI of the brain

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performed for routine surveillance

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in a five-year-old patient

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with neurofibromatosis type 1.

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We can see some hyperintense signal

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on T2-weighted image in the anterior

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aspect of the medial portion

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of the right thalamus.

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If we scroll to the brainstem,

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we see some asymmetric hyperintense

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signal in the right aspect

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of the tegmentum.

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In the pons,

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we can see to the left and midline

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some hyperintense signal that's

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slightly expansile subjacent to

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the left facial colliculus.

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So, this bump here on the posterior

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aspect of the pons would be the

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floor of the fourth ventricle.

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This is the facial colliculus.

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Subjacent to that is actually,

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despite the name facial colliculus,

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is actually the location of the abducens nucleus,

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the 6th nerve nucleus.

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It gets its name, the facial colliculus,

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because the motor nucleus of the

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7th nerve is anterior to that.

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But the motor fibers of the

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7th nerve cross around it,

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around the 6th nerve nucleus.

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So a lesion in this location

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potentially can cause a 6th and 7th nerve palsy.

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I mentioned it's the motor nucleus

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of the 7th nerve because that is

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separate from the superior solitary nucleus

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and solitary tract nuclei of the facial nerve,

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which their fibers join the motor fibers

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after the motor fibers pass around

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the abducens nucleus at the level

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of the facial colliculus.

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We can see in this patient also

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multiple areas of hyperintense

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signal or myelin vacuolization in the

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deep cerebellar white matter and

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deep cerebellar gray matter

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in the region of the dentate nuclei.

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That's a common pattern in

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neurofibromatosis type 1.

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Now, a few years later,

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on follow-up examination,

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we can see this lesion

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in the midbrain has increased in size.

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We can see it here on this coronal image.

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So an increased size of a lesion is

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always something we want to be

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aware of and characterize.

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This lesion does not enhance,

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so you can have suspicious lesions

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that don't enhance,

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and in neurofibromatosis type 1,

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you can actually have non neoplastic

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lesions that enhance and eventually go away.

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So the lack of enhancement alone

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doesn't fully characterize the lesion.

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But it's one more level of comfort

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that this is something that,

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while we're going to keep a close eye on,

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is likely and hopefully not going

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to be anything worrisome.

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It's important to treat each lesion

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in neurofibromatosis type 1 like this.

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Ideally, instead of just seeing a bunch

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of different areas of myelin vacuolation

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and saying, "Oh, they have NF 1."

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But try and put these comparison

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studies side by side,

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find the lesion that stands

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out as being different.

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Sometimes it's bigger,

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sometimes it's smaller,

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sometimes it goes away,

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sometimes it's new.

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But that's what we want to do.

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That's the type of care we want

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to provide to these patients,

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because we don't know which one

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of these lesions, if any, might eventually become

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a worrisome lesion.

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The best way to figure that out is

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to look at each one, compare them,

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and if there's something suspicious,

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we can find it.

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One additional thing.

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So, on this patient,

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the optic nerves are symmetric in caliber.

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I don't see any focal signal abnormality,

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but this right optic nerve is more

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tortuous than the left.

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Now, you can have a tortuous optic nerve

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just from eye position.

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Sometimes it can be normal.

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Usually, tortuosity of the optic nerves

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doesn't happen in young children,

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and usually, it's going to be symmetric

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when it does occur.

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In the setting of neurofibromatosis type 1,

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any degree of tortuosity has

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to be followed closely.

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And even in the absence of signal

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abnormality or abnormal enhancement,

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you have to wonder or worry about

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this possibly being early signs of

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an optic pathway glioma.

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Now, how do we convey this information?

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Well, the thing not to say is that there's

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optic nerve tortuosity.

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Please clinically correlate.

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That doesn't help anyone.

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In particular, it doesn't help the patient.

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What you can say, which is,

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I think a very valid thing,

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is saying there's tortuosity

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of the right optic nerve.

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While no discrete lesion is seen,

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in the setting of neurofibromatosis type 1,

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this could represent an early

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or subtle glioma,

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and close attention to this on

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follow-up examination is warranted.

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That's helpful because it lets them

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know, well, it could be something,

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but at least in your eyes,

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this is something to more keep an eye on.

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That will likely get the patient to

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the ophthalmologist to do more detailed eye exams.

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It will also mean that at the follow-up exams,

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they will hopefully get a dedicated

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orbital imaging in addition,

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where you get thinner sections and

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you have multiple planes of high

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resolution to compare to.

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That's the type of thing that's value added.

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Sometimes there's a propensity from

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insurance companies to not approve

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dedicated orbital imaging in

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neurofibromatosis type 1 patients,

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and I think that does the patients a disservice.

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I think neurofibromatosis type 1 patient surveillance

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is best, typically brain and orbital imaging.

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Now, there's dedicated guidelines out there.

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They may not need dedicated orbital

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imaging on every single study,

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but that is a way to be able to find

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subtle tumors before they become a problem

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and to be able to follow them closely.

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Fortunately, even if this is an optic pathway glioma,

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they will just follow it.

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So, they're not going to intervene.

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They're not going to do surgery

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on this at this point,

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they're not going to do radiation therapy,

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but they want to know about it.

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They need to know about it,

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and that's what we can help them with.