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Monday: 8:30 a.m.-7 p.m.
Tuesday: 8:30 a.m.-7 p.m.
Wednesday: 8:30 a.m.-5 p.m.
Thursday: 8:30 a.m.-7 p.m.
Friday: 8:30 a.m.-7 p.m.
Saturday: 8:30 a.m.-2 p.m.
Sunday: 9:00 a.m-12 p.m.

Chiari syndrome: a newly diagnosed disease

There is a newly diagnosed disease called Chiari syndrome (also known as Chiari malformation) in veterinary medicine. The condition has actually been known for a long time in human medicine.

An Austrian pathologist named Hans Chiari first diagnosed the condition in humans in the late 19th century. The pathology or disease involves both the brain and the portion of the skull where the brain ends and starts to transition into the spinal cord. This area is known as the foramen magnum (which translates as "large hole").

What does this information have to do with veterinary medicine? Well, in 2000 a study discovered this same condition in dogs. The most common breed affected was the adorable Cavalier King Charles spaniel. Other breeds can be affected with this condition (bichon frise, Boston terrier, Brussels griffon, Chihuahua, papillon, pug, shih tzu) but the Cavaliers are by far the most represented with this condition.

What the study found in a nutshell was that their brains were too big for their skulls. One would think this would be an advantage and make them the smartest dogs in the world. Instead this abnormality causes the back end of the brain (the cerebellum and medulla oblongata) to herniate, or poke through that foramen magnum. This not only puts pressure on the spinal cord and the large nerves associated with it, but also affects the flow of cerebrospinal fluid (the fluid that bathes the brain and spinal cord), or CSF. This combination leads to significant problems.

Some dogs with this malformation show no signs of disease. If they do show signs, the initial signs of Chiari syndrome are usually excessive scratching around the neck and ears with no apparent cause (no skin rashes or ear infections). This comes from the pressure on nerves and spinal cord and obstruction of the normal flow of CSF which causes hyperesthesia. Hyperesthesia refers to increased feeling or pain.

The good news is that most veterinary neurologists state that this feeling is more of a tingling sensation rather than something extremely painful and, in some cases, it does not progress. Unfortunately, in the cases where the signs do progress, dogs can develop severe neck pain or deteriorate to the point of paralysis.

Treatment consists of medication to control pain in less severe cases, such as cortisone derivatives and pain killers such as gabapentin, amantadine, and others which are better at controlling neuropathic pain (originating from nerves rather than muscle, skin, etc.).

In severe cases there is a surgical procedure called a foramen magnum decompression to attempt to correct the problem. The procedure widens the foramen magnum to free up the compression of the portions of the brain and spinal cord.

This procedure is considered a little controversial amongst some surgeons and neurologists because there is a possibility of scar tissue developing after surgery leading to strictures or narrowing of the opening the surgeon has just made. That narrowing doesn't help much.

If you have one of the dogs mentioned above and see those symptoms, bring it to your veterinarian's attention because there are options.

Dr. Kearns has been in practice for 14 years.

Author: 
Matthew Kearns, 2011