Long-term clinical follow-up and sequential imaging by MRI are normally required to confirm a diagnosis of ADEM. Should there be a development of a relapse with new lesions, it is not compatible with a diagnosis of monophasic ADEM, and depending on the clinical and imaging features, it likely suggests the correct diagnosis being either multiphasic ADEM or MS. Though there is no consensus, some physicians recommend that children receive follow-up MRIs for a period of up to five years to ensure that there is no new inflammatory activity after the initial ADEM attack; i.e., to confirm that the diagnosis is not MS.