Helen Yates, Chief Executive of MSRC, commenting on this paper said; "Whilst we are always saddened to hear of MS in the very young, it is very important that the medical profession is becoming increasingly aware that the condition DOES exist in children.  MSRC is working to provide as many resources as possible for young people with MS and their families"

Introduction

Multiple sclerosis (MS) in children is being recognized with increasing frequency.  The first descriptions of MS in children were published by Charcot between 1829 and 1849, though it was not for another 50 years that MS in children was again described in the literature (Hanefeld, 2007).  There are now several national programs focused on the research and clinical management of children with MS.  Recently, an International Pediatric Multiple Sclerosis Study group was constituted with the goal of fostering collaborative efforts (for more information, email: info@ipmssg.org). 

Demographics and Epidemiology of Pediatric Multiple Sclerosis

How common is MS in children?

Analysis suggests that 2% to 5% of all patients with MS are diagnosed before their 16th birthday (Ness et al., 2007).  These estimates, however, are based on retrospective review of established adult MS populations and may underestimate the true prevalence of the disease in the pediatric population.  The annual average incidence of a first demyelinating event in Canadian children is 0.9/100,000, but has been reported as lower in other parts of the world (Banwell et al., 2007; Pohl, 2008).  The incidence of MS diagnosis following an acute demyelinating event is the subject of ongoing research. 

Genetic factors clearly influence the risk of developing MS, as MS can "run" in families.  The risk of developing MS is approximately 30% if you have an identical twin with MS, 5% if you have a first degree relative (parent or non-twin) with MS, but only 0.1% if no one in the family has MS (Sadovnick, Dircks, & Ebers, 1999).  Furthermore, carefully documented family histories reveal that approximately 20% of people with MS will have at least one first degree or distant relative with MS (Sadnovnick, Baird, & Ward, 1988).  Family history data obtained from a large international study of MS demonstrated that 6% to 8% have a positive history of MS (Banwell et al., 2007).  It is important to remember that the first degree relatives of pediatric patients with MS are still young, and may still be at risk to develop MS in the future. 

A female preponderance in MS is well-established in the adult MS population.  In children, however, the Female:Male (F:M) ratio varies depending on age at first presentation.  Males outnumber females when MS onset occurs prior to 10 years of age (F:M ratio, 0.7) (Simone et al., 2002; Ruggieri, Polizzi, Pavone, & Grimaldi, 1999).  A female preponderance is pronounced in adolescence-onset MS (F:M ratio, 2.7 - 4.7) (Ghezzi et al., 2002).  Hormonal contributions to pediatric MS risk in females after puberty require further study. 

In order for the immune system to "attack", it must first recognize the "target." Scientists are very interested in learning what is initially targeted in MS.  Complicating this search, however, is the fact that once the immune system is active, it will not only attack the initial target, but over time will also attack the injured tissue in the brain/spinal cord as well. 

We found that children with MS harbour T-cell populations that proliferate when exposed to myelin proteins (Banwell et al., 2008).  These T-cell findings may reflect the injured tissue response, rather than a primary immune aspect of MS and they represent one of several abnormalities in immune cell regulation in MS (Bar-Or, 2008).