Asymmetrical changes in cerebral blood oxygenation induced by an active standing test in children with postural tachycardia syndrome.

Near-infrared spectroscopy enables recognition of various brain conditions based on certain factors, such as oxygenated hemoglobin (oxy-Hb). Since July 2012, we have been trying to determine the mechanisms of autonomic function in Japanese children with orthostatic intolerance (also called orthostatic dysregulation) in Nihon University Itabashi Hospital in Tokyo, Japan. A total of 23 children aged 7-16 years diagnosed with postural tachycardia syndrome (POTS), a subtype of orthostatic dysregulation, were enrolled in the study. We evaluated the relation between asymmetry in frontal cortex activity and the automatic nervous system and compared oxy-Hb changes in the right and left frontal cortices during an active standing test. We observed that during active standing oxy-Hb decreased in the frontal cortex. The oxy-Hb changes were asymmetrical, with a significantly larger decrease in the left frontal cortex than in the right frontal cortex, suggesting that tachycardia during active standing in POTS patients might be caused by activation of the right frontal cortex, which induces sympathetic nervous system activity.