Kawasaki syndrome

Having recently cared for a child with this exotic sounding disease, I thought it might be interesting for parents to know a little more about it.

As with many pediatric diseases with unusual names, parents' initial reaction to hearing this diagnostic possibility for their child is immense anxiety--yet another example of fearing that which one does not understand.

In the case of Kawasaki Syndrome (KS), it is not as uncommon as one might think. In the US, the overall incidence is approximately 10 per 100,000. It is the leading cause of acquired pediatric heart disease. KS tends to most commonly affect children under 5 years of age, but is rare in children under about a year old. Now that treatment options are better understood, mortality is low, but many children can become quite ill from this disorder and it may require a prolonged convalescence.

Just what is KS? As one might expect, it was first described in the medical literature by Dr. Kawasaki in Japan. He noticed a group of children who developed coronary artery disease, including some deaths from myocardial infarctions (heart attacks), several weeks after recovering from a flu-like illness. As he looked into it more closely, he realized that many of the children with this illness had very similar signs and symptoms which could not be explained by any other illness.

As doctors around the world learned about this association, they began to pool their experiences, eventually defining specific criteria for making the diagnosis of KS.

To be diagnosed with KS, a child must first have fever for 5 days that is not explained by any other infection. Then, they must have at least four of the following five signs, none of which can be explained by any other infection:

1. Puffiness of the hands and feet

2. A characteristic rash over the trunk and extremities

3. Conjunctivits (inflammation of the whites of the eyes)

4. Redness and swelling of the lips and tongue

5. At least one enlarged neck lymph node.

Obviously, these findings are somewhat nonspecific, so other illness must be eliminated as possible cause before a diagnosis of KS can be made. These include measles, Rocky Mountain Spotted Fever, Scarlet Fever, Toxic Shock Syndrome, Juvenile Rheumatoid Arthritis and Epstein-Barr Virus infection.

Why is the diagnosis of KS so important? This is the crux the matter. If undiagnosed and therefore untreated, there is a 1 in 5 chance that the child will develop an aneurysm (weaknesses in the wall of a vessel that can lead to bulging and even rupture) of one or more of the coronary arteries. This may lead to myocardial infarction and/or death. If instituted in time, the treatment can completely eliminate the possibility of this.

So what is the treatment? There are two phases. One involves the use of aspirin which decrease the fever and inflammation as well as decreasing the "stickiness" of platelets. This component of the blood plays a role in the development of coronary aneurysms.

The parents of the last KS patients I treated with aspirin raised concern over the possibility of Reye's syndrome. This is mainly a theoretic possibility and has not been reported to any significant degree. Besides, the risk of not treating for KS is far greater than the remote possibility of this complication.

The second and perhaps most important phase of treatment involves the use of intravenous gammaglobulin (IVIG) which acts primarily to quiet down what seems to be an out of control immune response. Usually after one, and sometimes two, doses of IVIG, the child's symptoms abate, and the risk of cardiac complications is essentially eliminated.

The exact cause of KS is not yet known, but it is felt to be due to an as yet unidentified infectious agent, an unknown bacteria or virus. The resulting inflammatory response from this infection results in vasculitis (inflammation of the walls of blood vessels) that affects every organ system to some degree. The blood vessels supplying the heart seem to be particularly vulnerable.

So, when your child has a seemingly unrelenting fever for five days, as well as some of the other symptoms listed above, your child's doctor may begin to consider the possibility of Kawasaki Syndrome. Don't be overly alarmed if he does. Although not everything is yet known about this disorder, enough is understood to enable doctors to protect your child from the potential long term ill effects of this curious disease.

John E. Monaco, M.D., is board certified in both Pediatrics and Pediatric Critical Care. He lives and works in Tampa, Florida. He welcomes your comments, suggestions, and criticisms.

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