1. SM Home Page
2. SM Primer Page
3. SM MRI Comp Page
4. CM (Chiari Malformation) Comp Page

1. SM Home Page 

This was once a very rare condition that is much more prevalent since the 1990s--sometimes called the scratching disease as dogs who get this often scratch almost uncontrollably in their neck and shoulder area at times, often not even touching skin. Note though that only 30-40% of Cavaliers with SM actually scratch however!  Here is a short synopsis of what SM is, written by Clare Rusbridge.  

Syringomyelia
Clare Rusbridge BVMS DipECVN MRCVS
https://www.wear-referrals.co.uk/about-us/meet-the-team/neurology/clare-rusbridge
https://www.instagram.com/neurovetclare/
https://veterinary-neurologist.co.uk/frequently-asked-question/?fbclid=IwAR32CFOBGVELwcvSfN-PCOSv5kuFTI9zpzwaaT1j8lvGiV8tjrFAOEJ8Tbk

What is Syringomyelia?
Syringomyelia is a condition whereby fluid filled cavities develop within the spinal cord. Some refer to SM as "neck scratcher's disease" because scratching in the air near the neck is a common sign. 

Click on picture above to go to MRI Primer page

What causes it?
Syringomyelia is a consequence of an obstruction to cerebrospinal fluid (CSF) flow. In the normal mammal, the CSF around the brain shunts back and forth with the arterial pulse [heart beat].  If this rapid efflux and influx is obstructed then the pressure wave is transmitted down the spinal cord distending it immediately below the blockage. This results in the formation of a cavity or syrinx. Syringomyelia can occur from any blockage in the subarachnoid space (space containing CSF around the brain and spinal cord).  However, the most common cause is the cerebellum within the foramen magnum (i.e. the back of the brain poking though the hole at the back of the skull). The cerebellum is pushed (herniated) out the skull because there is not enough space since the bone at the back of the skull (occipital bone) is too small. This condition occurs in many small breeds but is common in the Cavalier King Charles Spaniel (CKCS) (conservative estimates at least 50% of the breed). It is similar to the human condition Chiari malformation (some vets refer to it as Arnold Chiari syndrome which is incorrect and confusing as this original description by Arnold was of syringomyelia associated with spina bifida and this is not the case in the CKCS).

What are the clinical signs of syringomyelia?
By far the most important sign of syringomyelia is pain. This is most commonly localized to the neck region but may be difficult to define or intermittent. Owners often report that their dog is worse at night; when first getting up; during hot or cold temperature extremes; when excited; or related to posture e.g. preferring to sleep with their head raised. They may seem to be overly sensitive to touch on one side of the neck / ear / shoulder / sternum.  In addition, affected dogs often scratch at one area of the shoulder, ear, neck or sternum. This is typically on one side only, while the dog is moving and sometimes without making skin contact Some dogs, more commonly younger patients, develop a scoliosis (twisted spine). Some severe cases may have other neurological deficits such as fore and hindlimb weakness and ataxia (wobbliness). Facial nerve paralysis and deafness have also been associated with the condition.

What age of dog is affected?
Clinical signs of syringomyelia secondary to occipital hypoplasia are usually recognized between 6 months and 3 years of age. However, dogs of any age may be presented and dogs with more severe disease tend to be presented before two years of age.

Do the signs get worse?
Progression of the disease is quite variable. Some dogs have the tendency to scratch with mild pain only and other neurological signs, such as paresis, never or very slowly develop. Others can be severely disabled by pain and neurological deficits within 12 months of the first signs developing. Mild syringomyelia may also be found as an incidental finding, with no recognized clinical signs, in the investigation of another neurological disease.

Are there any diseases with similar signs to syringomyelia?
The main diseases to rule out are other causes of neck pain e.g. disc disease (uncommon in dogs less than two years of age); CNS inflammatory diseases and other malformations. If scratching or face rubbing is the main sign then skin disease should be eliminated.

How do I know if my dog has Syringomyelia?
The only way to confirm a diagnosis is by MRI (Magnetic Resonance imaging). This is essentially a picture of the water content of the body presented in a series of slices (like a loaf of bread). Nervous tissue, which contains a lot of water, is not imaged by x-rays but is shown in great detail by MRI.  The syringomyelia can be easily-visualized as a pocket of fluid within the spinal cord. In severe cases the syrinx is so wide that only a thin rim of spinal cord remains.