Clinical and epidemiological characteristics of acute flaccid myelitis cases in children registered in the Russian Federation in 2015–2019

Acute flaccid myelitis is a syndrome characterized as the development of acute flaccid paralysis of one or more limbs due to lesions of the anterior horns of the spinal cord, which occurs against the background of a viral infection. More than 300 acute flaccid paralysis cases are registered in the Russian Federation annually, most of them are of a non-infectious etiology. In some cases, patients develop a complex of symptoms similar to poliomyelitis, but without isolation of polioviruses from stool samples. Clinical characteristics of such cases include acute onset, fever, persistent peripheral asymmetric paresis/paralysis of predominantly proximal parts of the limbs, and absence of pathological reflexes, pelvic disturbances, or pyramidal symptoms. In literature, such complex of symptoms is referred as acute flaccid myelitis. We provide an analysis of 18 cases of acute flaccid myelitis detected in the Russian Federation in the period from 2015 to 2019. A clear seasonality of the disease from July to November was noted. Studies of faecal samples, cerebrospinal fluid and blood samples did not reveal the pathogen. In all patients, regardless of therapy, there was a positive trend, but complete recovery was not achieved: paresis of varying severity persisted, mainly in the proximal extremities Therefore, acute flaccid myelitis cases as acute flaccid paralysis cases of unknown etiology require an additional observation and an expanded algorithm of laboratory investigation aimed to finding a possible pathogen.