ADEM (Acute Disseminated Encephalomyelitis)
What is ADEM?
ADEM (acute disseminated encephalomyelitis) is a rare condition that affects the brain and the spinal cord. It is characterised by inflammation, which causes damage to the myelin, the fibres that surround the nerves. This condition is most commonly found in children under the age of 10 years old.
Experts believe that ADEM is an autoimmune condition, which means that the body’s defence mechanism, the immune system, attacks itself, causing harm to healthy cells in the brain. As the symptoms of ADEM are often similar to MS (multiple sclerosis), it can be difficult to differentiate between the two. However, it is uncommon to develop a relapse of ADEM and therefore if an individual has recurrent bouts of symptoms, this would indicate that they are likely to have MS.
What are the signs and symptoms of ADEM?
Symptoms of ADEM tend to develop very quickly and include stiffness in the neck, headaches, tiredness and drowsiness and encephalopathy, which affects your awareness. In severe cases, ADEM may also cause seizures and loss of consciousness. There may also be neurological symptoms similar to those linked to MS, and include impaired balance, inflammation of the optic nerve and troubles with standing still and walking. Additional signs may include a feeling of weakness in the upper and lower limbs, tingling, impaired speech and changes in bowel habits.
Typically, the symptoms of ADEM tend to last just a few days and can usually be remedied very effectively with treatment. In serious cases, symptoms may last longer, sometimes up to a few months.
Doctors usually make a diagnosis of ADEM based on the patient’s symptoms and an MRI scan. Occasionally, a lumbar puncture may also be used to analyse the spinal cord fluid. As patients with ADEM tend to have symptoms such as a high temperature, it is common for patients to receive antiviral treatment or antibiotics.
Who is affected by ADEM?
ADEM is rare and some studies conducted outside of the UK suggest that the disease affects fewer than 4 in every million children. ADEM is more common in children than adults, but the exact number of cases in the UK is unknown.
What are the causes of ADEM?
The cause of ADEM is largely unknown. Sometimes, symptoms develop following vaccination or after a viral infection. This may be due to an over-reaction of the body’s immune system, rather than the result of damaged to the nerve cells caused by the infection itself.
Treatment for ADEM
The aim of treatment for ADEM is reducing inflammation in the brain and the most common course of treatment is steroid medication. Most commonly, patients are given a 3-5 day course of methylprednisolone, which is administered via a drip. This may be followed by a course of oral steroids, which would gradually decrease in strength. Other treatment options that may be used include plasma therapy and immunoglobulin therapy, which is also given by drip. After treatment, physiotherapy can help to build up strength and improve coordination and balance.
What is the prognosis?
The prognosis for ADEM is good; around 85 per cent of people who are diagnosed with ADEM make a full recovery. Sometimes, recovery can be long and may take several weeks or months.
In rare cases, where the patient doesn’t make a full recovery, there may be mild cognitive and behavioural issues remaining, but these can usually be vastly improved with speech and language therapy, physiotherapy and psychological support. It is important that children receive the necessary support to aid their recovery and they will be cared for by a multi-disciplinary team where appropriate.
In extremely rare cases, ADEM can cause serous complications and even prove fatal. Studies suggest that adults are likely to experience more severe symptoms.
Can ADEM affect people more than once?
It is very uncommon for an individual to have ADEM more than once; around 80 per cent of people will only ever have ADEM once. In cases where symptoms recur, further tests may be used to check for MS.