Approximately 3-5% of all individuals with MS experience disease onset before age 16 (Chitnis et al., 2009; Boiko et al., 2002; Duquette et al., 1987). Two recent consensus reports – one by neurologists in the United States and one by the International Pediatric MS Study Group (IPMSSG) – provide helpful insights into the management of MS in the pediatric population.
As is true in adults, children with two discrete demyelinating events separated in time and space meet criteria for a diagnosis of MS. The challenge lies in ruling out other disorders that could be mistaken for MS, and distinguishing between MS and various transient demyelinating syndromes that can occur in children. The Pediatric International Study Group (Krupp et al., 2007) proposed consensus definitions for monophasic acute disseminated encephalomyelitis (ADEM – an essential feature of which is the presence of encephalopathy), variants of ADEM associated with a repeat episode, neuromyelitis optica (NMO), clinically isolated syndrome (CIS), and pediatric MS, and updated those definitions in 2013. The International Study Group has also proposed a minimum diagnostic battery for use in pediatric patients with an initial inflammatory demyelinating event.
This chart (Banwell et al., 2007) demonstrates the decision path for diagnosing a child who has experienced an acute CNS demyelinating event and then experiences a second episode of neurologic dysfunction. Note that a subset of patients with ADEM (which typically follows a self-limited disease course) experience relapses of disease activity. Some of these patients are reclassified as MS based on the nature of the clinical events, laboratory findings, and subsequent MRI changes. While the risk of developing MS following an episode of ADEM in childhood is <10%, the risk following an episode of CIS has been shown to be 26% to 62% in several recent studies using the International Study Group criteria (Dale RC et al, 2007; Neuteboom RF et al, 2008; Alper G et al, 2009; Banwell et al., 2007).
Minimum time on full-dose therapy of 6 months + fully compliant on treatment + one of the following:
- Increase or no reduction in relapse rate, or new T2 or contrast enhancing lesions on MRI from pre-treatment period
- > 2 relapses (clinical or MRI relapses) within a 12-month period
Defining an inadequate treatment response should be individualized for each patient, taking into account a variety of factors, including symptoms, relapse recovery, disease progression, and rapid cognitive decline.