[Autonomic neural functioning in children with the periodic syndrome].

The pathogenesis of periodic syndrome (recurrent abdominal pain, cyclic vomiting, headache and other equivalents of childhood migraine) is often related in the literature to a "neuro-vegetative dysfunction", by which occasional stimuli (environmental, metabolic, emotional) should find a particular somatic expression. The homeostatic role of the autonomic nervous system could be deficient in these cases, but systematic research has never been done to explore this hypothesis. We have evaluated the autonomic nervous function in 38 children (12 M, 26 F) with periodic syndrome, by cardiovascular autonomic function tests. They consist of ortho- and parasympathetic parameters obtained by ECG registration and pressure monitoring during deep breathing, Valsalva manoeuvre, lying to standing postural change, sustained handgrip. In the absence of adequate pediatric references values, we have previously standardized these tests in a population of 198 healthy children (94 M, 104 F), aged 8.3-15.7 years. Results have been compared with our standard reference values, matching them by t-test for independent data: in both sexes, significant differences have been found out in only one of 11 parameters (p < 0.05) of the autonomic tests performed. Children affected by periodic syndrome reveal a reduced heart rate variation in transition from the early orthosympathetic phase to the late parasympathetic one after lying to standing passage, showing a smaller fluctuation of autonomic feedback systems. The physiological meaning of this result is unclear. However, in children with periodic syndrome no prevalence of ortho- or parasympathetic systems is evident.