Acute Demyelinating Encephalomyelitis [ADEM] in children
Written by Dr Pam Tomlin, Paediatric Neurologist, Royal Preston Hospital

What is it?

This is an acute inflammatory reaction in the brain, and sometimes the spinal cord as well, which mainly affects the nerve coverings in the white matter, though sometimes areas of brain cells [grey matter] are also involved. Very often the child will have a history of an infection of some sort about 2 weeks beforehand. Such illnesses are often quite ordinary and easily forgotten, like a cold or sore throat. The immune system has a kind of delayed over-reaction which starts to inflame nerve coverings affecting their normal function. The peak age of onset is 3 – 10 years, but there is a spread.

The condition was first described 250 years ago by a distinguished English clinician called Clifton. He noticed the clinical picture in some survivors of small pox.

What is the illness like?

It usually starts quite promptly with several symptoms. Headache, vomiting, drowsiness and neck stiffness are all quite common, and the definition of the disorder now requires that some “brain irritation” symptoms are in evidence. Loss of balance and inability to walk or stand may also quickly appear. When the doctor examines the child he/she finds broad ranging signs in the nervous system which often indicate that more than one area of the nervous system is involved. Seizures can occur in the course of the illness in up to one third of children, but the seizures are not usually difficult to control. This contrasts with direct viral infection of the brain when seizures may be very troublesome during the illness.

How common is it?

In this country regional centres for children and adolescents will see several cases a year – but probably less than 10. This means it will not be seen every year in every District hospital. Even so, it is more common in children than in adults.

What happens in hospital?

Affected children are likely to given antibiotics and antiviral treatment straight away through a drip while investigations proceed. This is because the symptoms may mimic those of meningitis or viral encephalitis. Blood tests will be done and a lumbar puncture if the child is well enough, as these are likely to give evidence to support a reactive process and help to exclude an invasive infection. A lumbar puncture is often postponed in a drowsy child because management can go ahead anyway after a scan confirms the diagnosis, and the lumbar puncture will still be helpful a day or two later.

CT brain scans are usually unhelpful. MR scans are usually definitive though very occasionally more than one scan needs to be done before the diagnosis shows up. If the child cannot co-operate for the scan they will require supervised sedation or perhaps a general anaesthetic to achieve it. Most children are cared for without intensive care, but if the site of the brain inflammation affects the breathing pattern, or compromises the safety of the airway, then a period of controlled ventilation in intensive care may be required.

Can it be treated?

Treatments which help to dampen down the inflammatory response help the child’s own repair mechanisms to restore nerve coverings and neurological function. Most often a three day course of an intravenous steroid called methyl prednisolone is sufficient to achieve this. A course of steroids are usually given by mouth for a few weeks, with a tailing off schedule, to sustain the process. There are other therapies that can be tried, but the need for this is not common. They include infusions of immunoglobulins given over a few days.

Will my child get better?

Up to 75% of cases in reported series have a complete recovery. However the time scale for recovery varies in individual cases. By its very nature the nervous system is often slow in its repair processes, so do not become disheartened if your child takes some weeks and sometimes a few months to make that recovery. It can be faster for some.

In about half of cases the MR scan will show persisting evidence of the episode, even when there has been a full recovery. What matters is how well the child does clinically.

Can there be long term consequences?

Reports do suggest that in those children who do not make a full recovery their areas for support are likely to be in the field of learning to a mild degree. This makes it even more important for the child’s care to include interdisciplinary rehabilitation while in hospital and afterwards in his/her own Community services. So follow-up and links are important locally as well as at the original hospital. The team involved is likely to be made up of physical therapists, speech and language therapy, psychology and the teaching service – depending on the individual’s particular needs.

Sometimes parents report behavioural changes which should be thought of in the same context as the learning support needs.

Will it happen again?

Most of these episodes are isolated and do not recur. Doctors and clinical research workers are tightening up on the definition of the diagnosis so that the children and their parents can be given the most reassurance in this regard. However sometimes there is a recurrence, which can present differently, for instance with spinal cord involvement more prominent, or with a different set of neurological symptoms from the first episode. Clinicians now call such an illness MDEM [ multiphasic demyelinating encephalomyelitis].

Is this the same as Multiple Sclerosis?

No. However some recurring cases, especially where the features do not strictly fit the ADEM criteria, have been shown to be at some greater risk of developing MS in later life.

The majority of children make very good recoveries over time, allowing the child and family to put the illness behind them in due course, and look forward confidently once more.

FS 040 Acute Demyelinating Encephalomyelitis [ADEM] in children

Last modified: 18 March 2008