Totally mystifying: German researchers dispute that cavaliers have CM

[RodRussell]

In a June 2012 report in Veterinary Radiology & Ultrasound, German neurologists and radiologists Martin J. Schmidt, Martin Kramer, and Nele Ondreka compared the volumes of occipital bones of cavaliers with and without syringomyelia and of French bulldogs. They did not find a reduced volume of the occipital bone of CKCSs, compared to the bulldogs. They concluded:

"These results do not support occipital hypoplasia as a cause for syringomyelia development, challenging the paraxial mesoderm insufficiency theory. This also suggests that the term Chiari-like malformation, a term derived from human studies, is not appropriate in the Cavalier King Charles spaniel."

More details at http://cavalierhealth.org/syringomye...rchers_dispute

[Soushiruiuma]

A reduced volume of occipital bone? Or a reduced volume of occipital space?

So they're saying the foramen magnum isn't bigger in cavaliers (allowing the cerebellum to slip out of the skull)? That could measured directly, why infer it from bone volume? How else might occipital bone volume affect SM?

I'm a little confused on what exactly the significance is?

[RodRussell]

A reduced volume of occipital bone? Or a reduced volume of occipital space?

So they're saying the foramen magnum isn't bigger in cavaliers (allowing the cerebellum to slip out of the skull)? That could measured directly, why infer it from bone volume? How else might occipital bone volume affect SM?

I'm a little confused on what exactly the significance is?

I'm confused, too. They refer to "occipital hypoplasia", which is defined as the displacement of the cerebellum into the area of the foramen magnum and a kinking of the medulla and an indentation of the cerebellum. But I think that definition is subject to dispute in the context of CM. They also "suggest" that "the term Chiari-like malformation ... is not appropriate in the Cavalier King Charles spaniel."

As of now, we only have access to the abstract summary of the entire article. It could be that the abstract lacks the information which is in the article and which we need to see the connection between the research and the conclusions.

[Soushiruiuma]

Is the article available? Or just an abstract published ahead of the article appearing? I can swing into my office tomorrow and see if my university has a subscription to the journal.

Or was it just an abstract from a conference (the science equivalent of blowing smoke)?

[RodRussell]

Is the article available? Or just an abstract published ahead of the article appearing? I can swing into my office tomorrow and see if my university has a subscription to the journal.

Or was it just an abstract from a conference (the science equivalent of blowing smoke)?

I found and obtained the article -- at some expense. The link is
http://onlinelibrary.wiley.com/doi/1...955.x/abstract

I just finished reading it, and it appears to me that these researchers have ignored comparisons of the size of the cavalier's cerebellum with that of other breeds. Their focus is entirely upon the volume of the skull and not that of the brain.

They also seem mired in the pre-2010 definition of Chiari-like malformation. They define it as:

"Chiari-like malformation in the Cavalier King Charles spaniel is characterized by indentation of the occipital (bone) with cerebellar herniation".

Since 2010, Chiari-like malformation has been defined as:

"a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum."

Other than those two variants, their findings are consistent with those of other recent studies, including that there was no significant difference in the size of the median occipital bone between cavaliers with and without SM and French bulldogs.

Their study was of 15 cavaliers with SM, 15 cavaliers without SM (but all with CM), and 13 French bulldogs.

[MomObvious]

Their study was of 15 cavaliers with SM, 15 cavaliers without SM (but all with CM), and 13 French bulldogs.

Just wondering, that seems like a small amount of subjects for a study, is that "normal"? Again I'm not expert but....


Melissa

[Karlin]

Thanks Rod for the further detail and helpful highlights.

Yes, it is a smallish sample. And they are ignoring that they are not really comparing like with like -- indeed the whole reason the group of neurologists and researchers chose the term Chiari-like malformation AND used a term that was not specific to referring to either the skull or the brain, is that it was felt that the term the German researchers are using is potentially anatomically incorrect (as is COMS, so why it continues to be used is a bit strange).

It is worth noting too (as Rod says) that what the paper says is actually not new (if poorly interpreted?)-- other studies have already posited that there isn't a difference in volume. Their main point seems to quibble over terminology...? At any rate all the breeding guidelines focus on actual SYRINXES not just CM. Many know their own dogs without syrinxes have SM-like symptoms with scans that do clearly show hindbrain compression from -- doh! -- a brain that isn't fitting within the space of the skull. Call it CM or call it something else but the scans show brains squished down at the back -- clearly NOT normal. And they improve with neuropathic painkillers like gabapentin. Which indicates a neurological pain problem with the only source on a scan being the tight fit between brain and skull.

A sure sign of the breeders to avoid are the ones who rush to grasp at anything to try to discredit a huge pool of researchers, and repeated studies -- as they again try desperately to minimise SM as a serious problem. A problem, by the way, that many of them still do not scan for before breeding. Some were actually at the neurologists' roundtable discussion where the terms were discussed in some detail, but seem to have conveniently fading memories of that day. And show by their discussions that they don't read other research either (or choose to 'forget' it as well?). Some of these people repeatedly claim to be able to interpret MRIs as well!

Be very worried that these people are running breed clubs, judging , and continuing to breed.

[Karlin]

"Chiari-like malformation in the Cavalier King Charles spaniel is characterized by indentation of the occipital (bone) with cerebellar herniation".

There sometimes isn't herniation, either, so this really is not the correct definition of CM at all.