According to him, several points are worth noting:

- Before age 10, the signs may be those of acute encephalitis with impaired consciousness or those of a brain stem (ataxia, involvement of cranial nerves ...), very different from those seen in young adults ;

- Two images in MRI are predictive of an increased risk of relapse after a first attack: all well-circumscribed lesions and lesions oval perpendicular to the long axis;

- Most pediatric forms evolve by resolvent attacks (relapsing), very few (9% over 5 years) becoming secondary progressive. The space of time between the first two relapses is an average of 15 + / - 20 months, but with very large deviations of up to ten years;

- Treatment with beta interferon, which is effective in children, should be used as soon as possible, as in adults.

Like all autoimmune diseases, the triggering mechanism of MS in children is unknown, but surely "multifactorial," attests Dr. Tardieu, involving genetic and environmental factors.

At the genetic level, 8% of children with MS have a parent also reached a similar percentage is found in the Canadian and Dutch pediatric cohorts, he noted.

"The role of environmental factors is still very poorly understood, both in the weight of each factor in risk in the role of their consumption," said the specialist.

However, he reports, several were particularly investigated as viral infections, vitamin D deficiency (and a lack of sun exposure), passive smoking and vaccinations.

Concerning early viral infections, many works were sometimes contradictory, however, "it is now established that EBV infection is most frequently observed before the first outbreak in a population of children with MS compared to a control population. "

"For our part, informs Dr. Tardieu, we investigated the effect of varicella and a study is submitted for publication."

By comparing 129 children with MS in 1038 witnesses, he says, it has been shown that children's exposure to smoking at home was 62% for cases versus 45.1% for controls, risk on being 2.12 or 2.49 for a longer exposure in older children.

Finally, concerning a possible link between vaccinations, particularly against hepatitis B, and in September, "the bulk of our results shows no correlation," said Marc Tardieu.