Cerebellar Motor Learning and Dysphagia

The role of cerebellar motor learning in the swallowing function and dysphagia remains unclear. In this review, I herein present a case of bulbar palsy in which severe dysphagia persisted even after the recovery of the cranial nerve function, and propose the possible involvement of cerebellar motor learning in the underlying pathophysiology. I hypothesized that the internal model learned the motor pattern of failed swallowing during bulbar palsy due to a significant mismatch between the somatosensation predicted from the intended swallowing movement and the somatosensory feedback from the actual movement. As a result, the swallowing reflex circuits in the lower brainstem may have received inhibitory inputs from the Purkinje cells in the cerebellum. Voluntary swallowing remained impaired even after the cranial nerve function recovered, and involuntary reflexive swallowing became possible. While further clinical evidence is needed to substantiate this hypothesis, I highlight the significance of incorporating insights from neuroscience, including motor learning theory, to better understand dysphagia in cases where traditional pathophysiological mechanisms fall short.