Deliberate release of the laryngeal adductor reflex via microdroplet impulses: Development of a device

The laryngeal adductor reflex (LAR), a reflexive vocal fold closing mechanism, includes an early, probably di- or oligosynaptic ipsilateral LAR1- and a late ipsilateral and contralateral LAR2 polysynaptic component. In a clinical evaluation of dysphagia the LAR can be triggered by air pulses or tactile stimuli and typically assessed only qualitatively. The development and construction of a device that can selectively shoot very small water droplets (microdroplet impulse testing MIT). The MIT device has a water reservoir with an infinitely adjustable pressure. The opening period of the piezo-electrically operated valve determines the droplet size. With a high-speed camera system, the change in the airspeed of the drop can be determined, depending on the set water reservoir pressure. With the knowledge of the droplet size, the shooting speed and the estimation of the distance between the valve and laryngeal mucosa or airspeed can be determined the muzzle energy. By mounting the MIT device to a high speed glottography system, the time between the impact of the droplet on the laryngeal mucosa and the start of the laryngeal adduction, the LAR latency can be determined using an image by image evaluation. In dysphagia with penetration or aspiration it is presumed that the protective function of the larynx is no longer adequately ensured. The MIT-LAR device provides a valid and reliable method to assess LAR quantitatively. Furthermore, it holds the promise of being a simple to handle method that can be used clinically for routine diagnostics.