In mild cases youngsters are often known as being " double jointed " and can be symptom-free.
Some of these patients may have two to three symptom-free days between the minor illness and the major illness, but the symptoms often appear without any previous minor illness.
Since carriers are symptom-free, very few people know if they are carriers unless there is a family history of the disease.
They point out that although the disease may have symptom-free periods if the diet is not followed, silent damage continues to occur.
If the person sustains a second concussion of any severity that same day, he or she should not be allowed to continue contact sports until he or she has been symptom-free, during both rest and activity, for one week.