By Lucy Piper, Senior medwireNews Reporter
Severe enterovirus 71 (EV71) neurological disease in children predominantly involves the spinal cord and brainstem and can be quickly recognised using the World Health Organisation (WHO) classification of clinicoradiological syndromes, study findings suggest.
Among 57 patients aged 0.3 to 5.2 years who survived a 2013 outbreak of EV71 in Sydney, Australia, the WHO syndromes identified were encephalomyelitis in 40% of patients, brainstem encephalitis in 35%, encephalitis in 11%, acute flaccid paralysis in 7% and autonomic dysregulation with pulmonary oedema in 7%.
Brain magnetic resonance images for 38 of the patients confirmed abnormalities in 63% of the patients; these were most consistently seen in the dorsal brainstem. Also, all four patients with pulmonary oedema had dorsal brainstem restricted diffusion suggesting cytotoxic injury.
Spinal cord or nerve root abnormalities were seen in 79% of patients, primarily in those with encephalomyelitis syndromes.
Immunomodulatory treatment was given to about half of the patients – more commonly to those with pulmonary oedema, encephalomyelitis or acute flaccid paralysis than to brainstem encephalitis or encephalitis patients. No adverse effects were observed.
The children most likely to have ongoing motor dysfunction at 12 months were those with acute flaccid paralysis or pulmonary oedema. Focal paresis associated with grey matter in the brainstem or spinal cord, seen in 40% of patients at presentation, was the most common persisting clinical and functional problem, affecting five of six patients with residual symptoms, one of whom required invasive ventilation.
Cranial nerve dysfunction, although only seen in 7% of patients at presentation, was also predictive of morbidity at 12 months.
Researcher Hugo Sampaio (Sydney Children’s Hospital, New South Wales, Australia) and colleagues report, however, that there were no fatalities among the 57 children and prognoses were favourable for 77% of patients at 2 months, with no brainstem or motor dysfunction, increasing to 89% of patients by 12 months.
The researchers point out in JAMA Neurology that despite high rates of central nervous system (CNS) involvement, EV71 was not easily identified from cerebrospinal fluid samples. Better diagnostic yields were obtained from throat, stool or rectal swabs.
“Viral load in the [cerebrospinal fluid] may be low in contrast to continued viral shedding that occurs from the gastrointestinal tract for several weeks after clinical recovery”, the researchers explain. “Consequently, diagnostic assessments should include specimens from multiple sites.”
Sampaio and colleagues note that the response to the 2013 EV71 outbreak was influenced by what they had learnt from an outbreak 10 years previously and heightened awareness of early indicators of severe disease led to close observation and prompt immunotherapy.
As a result, the number of patients and severity of invasive central nervous disease was “greatly diminished”, they say. And given the favourable outcomes for the majority of patients, the management approach used “may have altered the natural history of EV71”, the team suggests.
However, an additional four patients died of fulminant disease and so the team says: “It is critical to further develop evidence-based therapeutic guidelines incorporating factors related to outcome and potential responsiveness to disease-modifying immunotherapy.
“Although vaccination will be an important future preventive strategy, children seen with fulminant CNS disease that leads to permanent disability represent a major diagnostic and therapeutic challenge.”
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