Polio or infantile paralysis claimed many victims until the middle of the last century. Thanks to a vaccine against the poliovirus, it is now rare worldwide. However, in the past 10 years, children with a similar picture have been seen. However, this was caused by viruses other than poliovirus, often enterovirus D68. This condition with sometimes severe paralysis symptoms is now called 'acute flaccid myelitis' (AFM); this regardless of which virus causes the symptoms.
Jelte Helfferich conducted extensive research on AFM and obtained his PhD on 6 September. In 2016, children were seen with it for the first time in the Netherlands. Helfferich: 'In them, severe paralysis of arms and legs developed in a very short time, but sometimes also weakness of the respiratory muscles. Some of them had permanent, severe motor disabilities. Sometimes they also remain dependent on a respirator.' All children were fully vaccinated against polio. Helfferich: 'No poliovirus was found in them. In some, however, enterovirus D68 could be detected in the respiratory tract. This is a virus that usually causes a cold and sometimes pneumonia. In rare cases, it can affect cells in the spinal cord causing paralysis.'
This syndrome is very rare, affecting an average of two children a year in the Netherlands. It is difficult for doctors to recognise AFM and distinguish it from other diseases with acute paralysis symptoms. AFM can be diagnosed on the basis of paralysis symptoms shortly after a respiratory infection, with typical MRI abnormalities in the grey matter of the spinal cord. In addition, an inflammatory reaction in the cerebrospinal fluid is often found in AFM. Enterovirus D68 is found in a proportion of children with AFM. And then mostly not in cerebrospinal fluid, but in resporatory specimens. Helfferich: 'The prerequisite for a proper diagnosis is close cooperation between paediatric neurologist and medical microbiologist/virologist.'
There are more conditions with acute paralysis symptoms. Helfferich says it is essential to make the right diagnosis. 'The treatment, course and prognosis of other conditions can be very different. We found important distinguishing features between the different diseases. For example, an initial study with mice seems to indicate that the usual treatment of myelitis transversa (MT), an autoimmune condition associated with inflammation of the spinal cord, actually has an adverse effect in AFM. That alone is why it is so important to make this distinction in diagnosis.'
Helfferich strongly advocates European cooperation on AFM. 'In the Netherlands, we report new cases to the RIVM; as a result, we have a reasonable picture of how often AFM occurs in the Netherlands. Both in the Netherlands and in many other European countries, however, there is no duty to report. As a result, we do not have a good overview of the number of AFM patients in Europe. Especially since it is such a rare syndrome, only by working together we can develop more
knowledge about this condition.' As far as Helfferich is concerned, this cooperation should lead to faster recognition, better diagnostics and ultimately treatment. Helfferich: 'The latter will then be mainly supportive treatment at first.'
Child neurologist Jelte Helfferich received his doctorate from the University of Groningen on 6 September for his research into the AFM syndrome. His supervisors were paediatric neurologist Prof Oebo Brouwer and virologist Prof Bert Niesters. The title of his PhD thesis is: 'Acute flaccid myelitis and enterovirus D68'. He works as a paediatric neurologist in the UMCG.
