Difference in Hindbrain Crowding and Tonsil Herniation?

[Guest guest]

I've looked for this answer in the archives and other ACM sites but haven't

found it. Is there a difference in Hindbrain Crowding and Tonsil Herniation?

Is Tonsil Herniation what is measured by mm? And, can you have a short mm

and still have hindbrain crowding?

Thanks!

Sheree

[Guest guest]

Please post any comments to these questions to the group.

Carol

Canada

Difference in Hindbrain Crowding and Tonsil Herniation?

>I've looked for this answer in the archives and other ACM sites but haven't

>found it. Is there a difference in Hindbrain Crowding and Tonsil

Herniation?

> Is Tonsil Herniation what is measured by mm? And, can you have a short

mm

>and still have hindbrain crowding?

>

>Thanks!

>Sheree

>

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[Guest guest]

Sheree.

The problem is that the posterior fossa (hindbrain) in Chiari patients

is usually smaller than nornal, causing crowding from compressive

forces. This causes the cerebellum to be squished somewhat, usually,

but not always, forcing the cerebellar tonsils downwards into the

spinal canal. The forcing of the tonsils downwards is what is referred

to as tonsillar herniation and is usually measured in mm. It's measured

from the level of the foramen magnum (opening of the spinal canal)

downwards to the tips of the tonsils. Sometimes, perhaps many times,

one tonsil is more herniated than the other.

If the tonsils are herniated enough, they will restrict CSF flow at the

foramen magnum. From my understanding, the smaller compartment also

causes CSF cisterns to be compressed posterior and lateral to the

cerebellum, thus impeding normal CSF flow in other areas other than the

foramen magnum. The problem is that these latter cases are often the no

or minimal herniation cases which very few docs are aware of. They have

proper flow at the foramen magnum but restricted flow elsewhere.

My daughter had hindbrain crowding but NO tonsillar herniation. She had

no restriction of CSF flow at the foramen magnum because her tonsils

were not herniated. However, due to the smaller compartment, there was

compression posterior and lateral to the cerebellum. It seems most docs

either don't know how to see this or consider it insignificant.

In fact, during surgery, it was discovered that her cerebellar tonsils

were underdeveloped - they were referred to as " short nubs " and were

protruding into the 4th ventricle. It seems the nubs were restricting

flow through the 4th ventricle too.

Most docs either don't know you can have minimal or no herniation of

the cerebellar tonsils and be symptomatic or they don't believe

it....yet! Hope this was clear.

Eurico

scbpurpl-@... wrote:

original article:/group/chiari/?start=31329

> I've looked for this answer in the archives and other ACM sites but

haven't

> found it. Is there a difference in Hindbrain Crowding and Tonsil

Herniation?

> Is Tonsil Herniation what is measured by mm? And, can you have a

short mm

> and still have hindbrain crowding?

>

> Thanks!

> Sheree