Spasmodic croup in the adult.

Recurrent inspiratory stridor, for which there appears to be no organic basis, can present a serious medical problem. We measured the changes in cross-sectional area of the glottic aperture during the respiratory cycle in a patient with recurrent inspiratory stridor when she was well, during a spontaneous attack, and during one induced with histamine aerosol. The glottis was visualized using a fiberoptic bronchoscope passed transnasally and attached to a video camera and tape recorder. During stridor there was marked constriction of the glottis on inspiration and phase reversal of the normal movements of the vocal cords with respect to respiration. Intermittent positive pressure ventilation (IPPV) and continuous positive airway pressure (CPAP) applied during stridor, in the absence of inspiratory effort, reversed the glottic narrowing. Pulmonary resistance (RL) on inspiration was elevated during stridor and returned to normal during IPPV and CPAP. Expiratory RL was normal throughout. Our results show that stridor in this patient was due to dynamic inspiratory constriction of the vocal cords. Glottic constriction could be induced by histamine aerosol and reversed when lung inflation was unaccompanied by inspiratory effort during IPPV and CPAP. Recognition and appropriate management of this condition may avoid potentially dangerous therapeutic interventions.