Modern methods of researching autonomic functions in children with syncope: A literature review

Abstract

The research of autonomic functions in children with non-cardiogenic syncope allows improving differential diagnosis and treatment tactics in children depending on the pathogenetic mechanisms of syncope development. The purpose of the research was to analyse modern scientific achievements in the field of autonomic functions in children with different types of syncope. The review used the full texts of English-language studies published between January 2018 and December 2022 and published in the PubMed Medline and Scopus databases. It has been established that the active orthostasis test, tilt test, circadian blood pressure rhythms and heart rate variability are the most commonly used functional autonomic tests in paediatric practice. They allow evaluating the spectrum of pathological cardiovascular reactions in a standing position; identifying types of orthostatic hypotension and causes of orthostatic intolerance; diagnosing orthostatic hypertension, postural orthostatic tachycardia syndrome, presyncope or syncope; to differentiating between sympathetic and parasympathetic autonomic dysfunctions and psychogenic transient syncope and epilepsy; to recommend orthostatic training as a method of treatment of syncope with an orthostatic mechanism of development. Despite this, there is no consensus on the definition of autonomic disorders and the methodology for conducting functional autonomic tests in children of different ages, considering their gender, body mass index and time of assessment during the day. Thus, functional autonomic tests are additional methods of physical and instrumental examination of the patient that allow effective assessment of the autonomic nervous system and possible mechanisms of syncope development, differentiation of transient loss of consciousness, stratification of future risks and optimisation of treatment and preventive tactics of the child's management based on an individual patient-centred approach