Re: Looking for MRI experts.

[Guest guest]

Hi Shayne,

I have a few thoughts on your e-mail question.  In medical textbooks and such,

Chiari is defined as a herniation of the tonsils 5mm or more through the foramen

magnum.  With the experience gained over the years since MRI was implemented,

NSGs who have experience with Chiari have found that the degree of herniation is

not so important.  For example there are sometimes cases with large herniations

(20 mm or more) and a person may have few symptoms and there are also cases of 0

mm herniation and a person has many symptoms.

I think one of the tools often used by NSGs who are familiar with Chiari is the

Cine-MRI.  That's where the CSF flow is assessed via MRI at the area of

suspected occlusion.  If the CSF flow is obstructed, there is a potential of

symptoms (even without a measurable herniation.)

May you find answers,

Ann

[Guest guest]

That was supposed to be a ?

Sent from my iPhone

> Hey all,

> I guessing a few of you might be MRI experts by now. I have 2 questions that

would be great if answered.

> I am booked in to see a Neuro in a few weeks. I have had a c.t. scan the first

time and MRI a few weeks later due to reoccurring symptoms.

> The c.t. scan showed one image of my tonsils herniated 4.7mm. It was mentioned

on the forums that c.t scans can be inaccurate in measuring. I had my MRI and

was given a copy on disc to take to my nuro appointment. So I worked out how to

use the software that was installed on the disc and measured the herniation on

the MRI.

>

> What I found was looking at the side view of the brain cutting through

sections is that the herniation is least in the very middle or center photo of

the brain. Like 4mm or so. Interestingly the photo before the center line

measures 9mm and the next photo after the center measures 8mm. For a diagnosis

does anyone know if only the middle image is taken into consideration or the

side images of the photos?

> Ok next question. Looking at your MRI from top view can you tell if how much

space you have between the tonsils and the spinal cord to tell if you have fluid

restrictions or you tonsils may be irritating the spinal cord?

> Also can we attach MRI to theses posts for comparisons sakes?

> Cheers

> Shayne

>

>

[Guest guest]

The best MRI for this purpose is probably of the cranio-cervical junction,

preferably CINE. Did you have a full spine MRI to check for syringomyelia!

Barbara

Sent from my iPhone

> Hey all,

> I guessing a few of you might be MRI experts by now. I have 2 questions that

would be great if answered.

> I am booked in to see a Neuro in a few weeks. I have had a c.t. scan the first

time and MRI a few weeks later due to reoccurring symptoms.

> The c.t. scan showed one image of my tonsils herniated 4.7mm. It was mentioned

on the forums that c.t scans can be inaccurate in measuring. I had my MRI and

was given a copy on disc to take to my nuro appointment. So I worked out how to

use the software that was installed on the disc and measured the herniation on

the MRI.

>

> What I found was looking at the side view of the brain cutting through

sections is that the herniation is least in the very middle or center photo of

the brain. Like 4mm or so. Interestingly the photo before the center line

measures 9mm and the next photo after the center measures 8mm. For a diagnosis

does anyone know if only the middle image is taken into consideration or the

side images of the photos?

> Ok next question. Looking at your MRI from top view can you tell if how much

space you have between the tonsils and the spinal cord to tell if you have fluid

restrictions or you tonsils may be irritating the spinal cord?

> Also can we attach MRI to theses posts for comparisons sakes?

> Cheers

> Shayne

>

>

[Guest guest]

Be sure to find a surgeon that bases the dx on measurements of the skull rather

than the herniation. Remember, the herniation is really just another symptom of

the real problem, not the problem itself! Cortney

[Guest guest]

Peer response to Shayne (and anyone else wondering about measuring tonsils),

The observation you made corresponds to the anatomy of the cerebellum. The two

cerebellar tonsils are like pudgy little tails, one on the bottom of each of the

two hemispheres of the cerebellum. They descend lower than the rest of the

cerebellum, but they are supposed to stay inside the skull. There is a small

space between them unless they are really tightly packed and squished.

When sagittal MRI images are taken, there is one midsagittal (central) slice

that attempts to capture a view of the center of the brain and spinal cord. It

often shows the space between the tonsils (but not always, because people aren't

all that symmetrical, so one tonsil could be partly in there.) That central view

also shows the bony landmarks by which measurements and comparisons are made.

The slices before and after the midsagittal slice show more of the length of the

tonsils. They might show the full length if the slice happens to line up with

the longest part of a tonsil, but that's not a given.

Sometimes people think their herniation length has changed because their

subsequent MRI reports estimate the lengths differently.

Some reasons for variations in appearance from one scan to the next (in the same

person) are: it's not easy to get the head in the exact same position each time;

the slice thicknesses can differ depending on the orders; slices happen to

capture or not capture views of the longest part of each tonsil. So maybe one

report says 4mm and the next one says 6mm, but they're the same tonsil with no

change.

Also remember that measurements are given in millimeters, which are so tiny that

it takes 25 of them to make an inch. So there is no real difference between 4mm

and 6 mm anyway.

The emphasis on herniation length is not state of the science, because it

doesn't tell whether the tissue is blocking fluid flow. There could be plenty of

room, even with a long tonsil. It's better to look for disturbances in CSF

flow. A cine' MRI can do that if it is read by a Chiari- knowledgeable

radiologist or neurosurgeon. (or maybe experienced patients - lol).

Hope this helps a bit...