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.