SYRINGOMYELIA
(SM)
Skull X-Ray to MRI Comps
(including comparison of heads in the 70s
to today)


Above is shown a comparison of an MRI showing a
full cerebellum vs. the skull X-RAY of a dog with a full cerebellum and a dog
with an MRI showing a crushed cerebellum vs. the skull X-RAY of a dog with a
crushed cerebellum. The cerebellum is circled in red. You can easily
see there is a huge difference in shape of cerebellum between these two
dogs--the one on the left is quite full, the one on the right is severely
crushed.
The
skull x-ray of a dog with a full cerebellum is below that on the left and the
skull x-ray of a dog with a crushed cerebellum is shown on the right. You
can easily see there is a distinct difference in the shape of the back of the
skull between the two and why the cerebellum ends up crushed. The most
distinct difference, besides the fact that the skull on the right is shorter
from front to back, is that the occiput sticks out in the skull x-ray on the
left. In the right, that occiput is still there, but it is more downsloped
and blends in with the back of the skull to the point you can barely see
it--almost like someone took a hammer to the occiput and smashed it
in.
Based on my findings, a study was eventually done to determine if a skull x-ray
could be used to determine amount of CM. The more CM, the more likely
there is to be SM--in most cases. This study did show there was one skull
measurement that did indicate amount of CM. This study has been published
and reference is made to it on Dr. Rusbridge's site.
http://www.veterinary-neurologist.co.uk/ A copy of this
journal article can be purchased from that site. Here is a
comparison of two skull x-rays which show why this particular measurement
indicates amount of CM. The top one is a skull x-ray of a Cavalier with
severe CM (and has SM as well) and the bottom one is a skull x-ray of a Cavalier
with very little to no CM (and no SM).

The line was drawn from right in front of the
'hole' (black spot), center of that curved bone (the 'jaw hinge' area) to where the most
thickened area of the skull ends (and the occipital area begins). In the dog with almost no CM and no SM
you can CLEARLY see there is a lot more lower backskull left behind/below that
line as compared to the dog above--which literally has almost none! This
also happens to be the area where the cerebellum sits so it would be common
sense that the dog in the top x-ray would have much less room for the cerebellum
than the dog on the bottom--and therefore more CM (chiari malformation).
There just isn't any skull left for there to be enough room for the cerebellum.
It appears here that a good skull x-ray may be very useful in determining amount
of CM and therefore breeding towards a goal of less and less CM in future
offspring and thereby lessening the prevalence of SM. A skull x-ray is
much cheaper than an MRI which will enable many more breeders to x-ray for
amount of CM in the future as more information becomes available.
Below
are more side skull xrays of dogs who have also been MRId.
Their diagnosis will be listed below the comps. The
idea is to see if any differences in skull shape could be ascertained from a
simple skull xray. Next to it the MRI was fit into the skull
xray just to see where everything fits in. Below is the result. So
far there appears to be a considerable difference in the shape of the back of
the skull between the dogs with SM and without!
More
xrays are welcome!!!
Below
are Cavaliers WITH SM.

Dog above has moderate to severe malformation and SM with
symptoms

Dog above has moderate malformation and SM with
symptoms

Dog
above has moderate malformation, herniation and syrinxes.

Dog
above has moderate to severe malformation, herniation and syrinxes.

Dog above has mild
malformation, moderate herniation, and syrinxes.

Dog above has moderate malformation and SM with
symptoms and has already has surgery.
You can actually see where the skull was cut away.
Below
are Cavaliers without SM.

Dog above has extremely mild malformation, no SM,
no symptoms
Below are the front and side head pictures of the dog above.


Dog above has extremely mild malformation, no SM,
no symptoms
Below are the front and side head pictures of the dog above. Sorry his
eyes were a bit closed in the front head shot!


Dog above has mild malformation, no SM, no
symptoms

Dog above has mild malformation, no SM, no
symptoms

Dog
above has mild malformation, no SM, no symptoms.

Dog
above has mild malformation, no SM, very slight hydromyelia, no symptoms
Below are many side head
pictures of dogs from the 70s/80s. All were either imports, had one
parent as an import, or all 4 grandparents were imports.
You can easily see the longer and flatter skulls Cavaliers used to have.
Most of these also became CKCSC champions.

Even more head
comps--comparing the heads of the 70s to today.
Quite a difference! The skulls in the
70s were more elongated and flatter
whereas today they are much rounder and more sloped.