Laryngeal spasm: a neurophysiologic redefinition.

Within the limits of standard neurophysiologic techniques, we have attempted to redefine laryngeal spasm as distinct from the glottic closure reflex. This distinction is based upon the observation that laryngeal spasm is solely mediated by the superior laryngeal nerve. Stimulation of other afferent nerves, capable of eliciting the glottic closure reflex, produces little adductor after-discharge activity that is characteristic of laryngeal spasm. In this regard, modification of output function from the adductor motoneuron aggregate by means of temporal and spatial summation of sensory input data has been described, and its characteristics further defined in response to varying ventilatory states and barbiturate levels.