What is the prognosis of acute disseminated encephalomyelitis (ADEM)?

Updated: Nov 08, 2018
  • Author: J Nicholas Brenton, MD; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Answer

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  • The outlook for recovery is generally excellent. Although some older series suggest up to a 10% mortality rate, only 1.5% of the author’s (RSR) cases have resulted in mortality due to ADEM-related complications. Other studies present mortalities of 0% in treated ADEM cases. [47, 58, 63, 85] Degree of recovery appears to be unrelated to severity of illness. Complete recovery may be observed even in children who become blind, comatose, and quadriparetic. Recovery is poorest in children younger than 2 years, patients with myelitis, and those who have significant edema of the brain or spinal cord. Whether ultra–high-dose corticosteroid therapy and other treatments for edema might improve the outcome for these groups is not yet known, although limited experience suggests this possibility. In other cases of ADEM, modest visual or motor deficits may persist, as may sphincter abnormalities in patients with spinal cord disease. Disturbances of mood and personality mayoutlastmotordeficits, but they may also wane over ensuing months.

  • The long-term (10-y follow-up) risk of patients with ADEM for development of MS is 25%. Risk for MS is highest in children whose ADEM onset was (1) afebrile, (2) without mental status change, (3) without prodromal viral illness or immunization, (4) without generalized EEG slowing, or (5) associated with an abnormal CSF immune profile. [88]

  • Most patients who experience a bout of ADEM can look forward to complete recovery or the persistence of only mild deficits, such as modestly diminished visual acuity. This excellent outlook even applies to patients who experienced a global low state of function during the acute illness.

  • Whether any available form of treatment has a favorable effect on the time to maximal recovery or the risk for deficits is unknown. Exceptions to the excellent outlook are patients with transverse myelitis and infants younger than 2 years. Cord swelling may account for the high rate of residual paresis and the occasional death of patients with severe acute inflammatory myelitis. Prompt administration of high doses of corticosteroids can possibly improve the outlook for these patients, but no reliable data yet support this hypothesis.

  • The authors have observed children with a typical bout of ADEM in the first decade of life who manifest MS during the second decade, after a symptom-free hiatus of more than 10 years.


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