Medical Care: ADEM is often treated with high-dose intravenous corticosteroids, to which it appears to be responsive (Pasternak, 1980). One common protocol is 20 mg/kg/d of methylprednisolone (maximum dose of 1 g/d) for 3-5 days. Improvement may be observed within hours but usually requires several days. An oral taper for 3 weeks or some other interval is sometimes appended. The chief alternative therapy is intravenous immune globulin (IVIG) (Kleiman, 1995; Hahn, 1996; Nishikawa, 1999). It is administered as 2 g/kg intravenously for 2-3 days. IVIG may be preferable in instances where meningo-encephalitis cannot be excluded based upon the hypothesis that corticosteroids might worsen the course of infection (Nishikawa, 1999).
Available published information concerning efficacy is inadequate to accurately assess much concerning the impact of either form of therapy, although it appears likely that both forms of therapy increase the pace of initial recovery. Whether these forms of therapy influence times to final outcome or extent of final recovery is not known.
Theoretically, very high-dose corticosteroids (30-50 mg/kg) administered intravenously at presentation to patients with transverse myelitis may be advantageous from the vantage point of its capacity to close the blood-brain barrier and limit swelling. Marked cord swelling may account for poor outcome in some cases of transverse myelitis because of circulatory impairment and cord infarction. The same argument may hold true for severe cerebral ADEM such as tends to arise in some young children (<3 y old) who also may have marked permanent neurologic impairments after severe ADEM.
There is as yet no convincing evidence that treatment with the combination of intravenous corticosteroids and IVIG confers any advantage in such cases, although this approach is employed by some clinicians.
Severe ADEM has also been treated, apparently successfully, with such alternative approaches as (1) combination of intravenous corticosteroids and IVIG, (2) cyclosporin, (3) cyclophosphamide, or (4) plasma exchange/plasmapheresis (Stricker, 1992; Kanter, 1995). Greater understanding of trimolecular complex regulation, adhesion molecules, and inflammatory cytokines may permit development of more specific and effective ADEM therapies. The polymorphism of the human major histocompatibility complex and apparent heterogeneity of T cell response to autoantigens render this a daunting project (Miller, 1991), although anticytokines represent an intriguing avenue of therapeutic research (Sugita, 1993).
Taper-related recurrence occurs in as many as 3-5% of cases and usually responds to prolongation of taper. Similar phenomena occur in other postinfectious diseases, such as Guillain-BarrΓ© syndrome or opsoclonus-myoclonus. A subset of patients manifest repeated recurrences that prevent discontinuation of corticosteroids or necessitate changing to various steroid-sparing treatments such as cyclophosphamide or beta-interferons. This rare and interesting subgroup tends to have onset of disease before 6 years of age, and despite recurrence, these children do not manifest evidence for CSF immune profile (ie, IgG index, IgG synthetic rate, oligoclonal bands) abnormality. The relationship of this group to patients with ADEM or MS or some other form of inflammatory CNS illness remains unclear.
Nonβtaper-related recurrences occur in as many as 5% of children with ADEM. In such instances most children have just a single recurrence, although some prepubertal children manifest 2 or even 3 recurrences within a year or two of the initial bout but then manifest no further recurrences for follow-up intervals as long as 18 years. Although it has been suggested that IVIG administered in treatment of a single recurrence may prevent further recurrence, the evidence for this remains inconclusive because most children with a single recurrence of ADEM that are treated with corticosteroids also have no further recurrences.
Surgical Care: Surgical treatment for severely elevated intracranial pressure has been undertaken for cases of AHLE, hemorrhagic brain purpura, and non-Reye syndrome, examples of what have been termed obscure encephalopathies of infancy. Some of these cases were likely examples of hyperacute ADEM. Surgical interventions have ranged from placement of pressure bolts to decompression of the intracranial fossae by unroofing of the cranium. Outcome of such interventions was mixed.
Although such severe cases were regularly noted in the medical literature from the 1920s until the mid 1970s, few examples have been noted since that time. Prevalence clearly has dramatically decreased. Because these severe cases often followed measles, mumps, and other diseases for which effective vaccines have been developed and because the disappearance of such cases has followed the availability and use of such vaccines (earlier disappearance in the United States and Western Europe, subsequent disappearance in Asia and the Middle East), this change in prevalence likely reflects the removal of pathogens that are provocative of such severe forms of ADEM.