Su1974 Classification of Cyclic Vomiting Syndrome Patients in Inter-Episodic Phase From Healthy Controls Using Cortical Resting State Functional Connectivity

Abstract

Background/Aims: Anecdotal clinical evidence supports the use of carbonated liquids in reducing the likelihood of aspiration in dysphagic patients (Bulow et al,Acta Radiol 2003; Sdravou et al, Dysphagia 2011). Repetitive transcranial magnetic stimulation (rTMS) delivered at 1-Hz can induce transient focal suppression of pharyngeal motor cortex (Mistry S., et al. J Physiol, 2007). Here we investigated whether swallowing of carbonated water can reverse the inhibitory effects of a virtual lesion to pharyngeal motor cortex, compared to still water and saliva swallowing. Methods: In 9 healthy subjects (5 male, mean age 33.7 ± 14.34(SD)) pharyngeal electromyographic responses were recorded using an intraluminal catheter after the application of Transcranial Magnetic Stimulation (TMS) over pharyngeal motor cortex, as a measure of cortico-bulbar excitability. On 3 randomised visits, subjects were cued by a visual feedback software to perform a total of 40 swallows over 10 minutes (swallows every 15 s) of either carbonated water or still water vs. 10 minutes of saliva swallowing ad libitum (control), before and after an unilateral 1-Hz virtual lesion of the pharyngeal motor cortex. Cortical excitability (presented as mean ± SEM) was then reassessed bilaterally for 60 minutes post-interventions and analysed with two-way ANOVA (SPSS 14). Results: Compared to saliva swallowing (control), swallowing of carbonated water appeared to increase cortical excitability bilaterally (lesioned pharyngeal motor cortex: 68 ± 38% at 30 minutes post intervention, and to the unlesioned: 60 ± 24%, at 15 minutes post), not seen with still water swallowing. However, using a 2-way ANOVA, only the effects over the ipsilateral (lesioned) pharyngeal motor projection were statistical significant for carbonation (F1,8=6.2, p=0.037, Figure 1). Conclusion: Carbonation reverses the effects of a unilateral virtual lesion with significant increases in cortical excitability limited to the lesioned hemisphere. These data support the notion that chemesthetic solutions of carbonation may provide the required peripheral sensory information that can influence greater neuronal activity compared to still water swallowing. These data provides the platform for considering the use of carbonation as facilitating stimuli in dysphagic patients who aspirate thin liquids.