EFFECT OF MENTAL ACTIVITY ON BREATHING IN CONGENITAL CENTRAL HYPOVENTILATION SYNDROME

Congenital central hypoventilation syndrome (CCHS) is associated with hypoventilation during sleep, but breathing can be adequate during wak efulness. It has been assumed that in awake CCHS patients breathing is activated by the forebrain, even voluntarily (i.e. Ondine's Curse). W e tested whether or not an abnormal breathing pattern can be provoked by intense mental concentration in CCHS patients as this would be expe cted to disturb any voluntary control over breathing if present. Breat hing (inductance plethysmography), end-tidal P(CO2) (PET(CO2)), arteri al oxygen saturation (Sa(O2)) and EEG were measured in 5 children with CCHS (aged 8-17 years) and 5 controls during 5 min periods while rest ing; reading; performing mental arithmetic and playing a hand-held ''N intendo'' game. There were no significant differences between controls and CCHS (unpaired t-tests, P>0.05) in mean breath duration, tidal vo lume, ventilation, Sa(O2) or PET(CO2) during REST or the conditions of mental stimulation. Both groups increased ventilation during mental s timulation. Respiratory variability was not greater in CCHS in any con dition. These data provide indirect evidence that CCHS patients do not require voluntary activation of every breath (they do not have Ondine 's Curse) and suggest that mental concentration might stimulate the re spiratory complex as part of a generalised CNS arousal.