Introducing a Virtual Lesion Model of Dysphagia Resulting from Pharyngeal Sensory Impairment
Background/Aims: Performing neurophysiological and functional imaging studies in severely affected patients to investigate novel neurostimulation techniques for the treatment of neurogenic dysphagia is difficult. Therefore, basic research needs to be conducted in healthy subjects. Swallowing is a motor function highly dependent on sensory afferent input. Here we propose a virtual peripheral sensory lesion model to mimic pharyngeal sensory impairment, which is known as a major contributor to dysphagia in neurological disease. Methods: In this randomized crossover study on 11 healthy volunteers, cortical activation during pneumatic pharyngeal stimulation was measured applying magnetoencephalography in two separate sessions, with and without pharyngeal surface anesthesia. Results: Stimulation evoked bilateral event-related desynchronization (ERD) mainly in the caudolateral pericentral cortex. In comparison to the no-anesthesia condition, topical anesthesia led to a reduction of ERD in beta (13-30 Hz) and low gamma (30-60 Hz) frequency ranges (p<0.05) in sensory but also motor cortical areas. Conclusions: Withdrawal of sensory afferent information by topical anesthesia leads to reduced response to pneumatic pharyngeal stimulation in a distributed cortical sensorimotor network in healthy subjects. The proposed paradigm may serve to investigate the effect of neuromodulatory treatments specifically on pharyngeal sensory impairment as relevant cause of neurogenic dysphagia.