Erica A. Samuel

Characterization of the upper esophageal sphincter response during cough.

BACKGROUND Vagal reflex initiated by esophageal stimulation and microaspiration can cause chronic cough in patients with gastroesophageal reflux disease (GERD). By raising intraabdominal pressure,cough can, in turn, predispose to GERD. The role of the upper esophageal sphincter (UES)in preventing esophagopharyngeal reflux during coughing is not well known. The aim of this study was to evaluate the UES response during coughing. METHODS We studied 20 healthy young (10 women; age, 27 ± 5 years) and 15 healthy elderly(nine women; age, 73 ± 4 years) subjects. Hard and soft cough-induced pressure changes in the UES, distal esophagus, lower esophageal sphincter, and stomach were determined simultaneously using high-resolution manometry and concurrent acoustic cough recordings. RESULTS Resting UES pressure was significantly higher in the young compared with the elderly subjects (42 ± 14 mm Hg vs 24 ± 9 mm Hg; P < .001). Cough induced a UES contractile response in all subjects. Despite lower UES resting pressures in the elderly subjects, the maximum UES pressure during cough was similar between the young and the elderly subjects (hard cough, 230 ± 107 mm Hg vs 278 ± 125 mm Hg, respectively; soft cough, 156 ± 85 mm Hg vs 164 ± 119 mm Hg, respectively; P not significant for both). The UES pressure increase over baseline during cough was significantly higher than that in the esophagus, lower esophageal sphincter, and stomach for both groups ( P < .001). CONCLUSIONS Cough induces a rise in UES pressure, and this response is preserved in elderly people. A cough-induced rise in UES pressure is significantly higher than that in the esophagus and stomach,thereby providing a barrier against retrograde entry of gastric contents into the pharynx.

Esophageal acid stimulation alters insular cortex functional connectivity in gastroesophageal reflux disease.

The insula plays a significant role in the interoceptive processing of visceral stimuli. We have previously shown that gastroesophageal reflux disease (GERD) patients have increased insular cortex activity during esophageal stimulation, suggesting a sensitized esophago‐cortical neuraxis. However, information regarding the functional connectivity (FC) of the insula during visceral stimulation is lacking. The primary aim of this study was to investigate the FC of insular subregions during esophageal acid stimulation.

Deglutitive Pharyngeal and UES Pressure Phenomena

Deglutitive pressure phenomena within the pharynx is generated by the contraction of pharyngeal constrictors, velum and posterior thrust of the tongue base. Due to axial as well as radial asymmetry, swallow induced pharyngeal pressure at any location varies depending on the radial directions and distance relative to the upper esophageal sphincter. With the recent availability of circumferential recording devices such those used in high resolution manometry, it is now possible to record average pressure at any location within the pharynx and overcome the radial asymmetry. The inherent shortening of the pharynx and the associated oral movement of the upper esophageal sphincter during swallowing poses a significant technical challenge in recognizing manometrically where the pharynx ends and where the UES begins. From a clinical perspective, however concurrent high resolution pharyngo-UES manometry can help ascertain pharyngeal peristalsis and its coordination with the UES relaxation, duration of UES relaxation and its coordination with pharyngeal peristalsis, hypo-pharyngeal intrabolus pressure.

Tu2086 The Endocannabinoid System (ECS) and the Hypothalamic-Pituitary-Adrenal (HPA) Axis in Adults With Cyclic Vomiting Syndrome (CVS)

Background: The most commonly used drug for Parkinson disease (PD) therapy, levodopa (L-dopa) induces delayed gastric emptying (GE) in PD patients and healthy controls. We previously reported that ghrelin could prevent L-dopa-inhibited GE in rats. Rikkunshito is a kampo medicine that increases ghrelin in humans and mice and used clinically in Japan to treat functional and chemotherapy-induced dyspepsia, and post-operative gastric ileus. Aim: To investigate whether rikkunshito mimics ghrelin effect to improve gastric motility in L-dopa-treated rats. Methods: In overnight fasted rats, rikkunshito (Gastroenterology 2008, 143:2004), or vehicle (distilled water) was administered by orogastic gavage (og) 170 min before L-dopa/carbidopa (LD/CD, og), 10 min later followed by a meal (methylcellulose/ phenol red or 40% powder meal in water with 50% glass bead, og), and GE was assessed 20 min (non-nutrient solution) or 60 min (nutrient meal) thereafter. The ghrelin antagonist, D-[Lys3]-GHRP-6 was injected IP at the same time as rikkunshito and GE was determined 20 min after og LD/CD or vehicle. Strain gauge transducer was implanted in the rat antrum. After 6 days, overnight food restricted rats were treated with rikkunshito or vehicle and 170 min later with L-dopa or vehicle (IP) and then 10 min later, the powder meal solution was gavaged and antral motility was recorded for 60 min. Food intake was monitored after rikkunshito and LD/CD gavage in overnight fasted rats. Results: LD/CD (15/1.5, 20/2 and 50/5 mg/kg, og) dose-dependently inhibited GE of nutrient meal (58.1±4.1%, 41.9±5.8%*, 28.9±5.6%* vs. vehicle 72.9±5.2%, respectively, *:p,0.05). In vehicle pretreated rats, LD/ CD (20/2 mg/kg, og) decreased GE of a non-nutrient meal compared to vehicles (12.1±7.4% vs. 49.3±7.0%, p,0.05). Rikkunshito (0.5 or 1.0 g/kg, og) prevented dose-dependently the LD/CD inhibitory effect on GE (36.9±7.4% and 46.6±4.8% respectively, p,0.05 vs. vehicle plus LD/CD) while having no effect alone (56.6±8.5%). Likewise, rikkunshito (1.0 g/kg) blocked LD/CD reduced GE of the nutrient meal (61.4±4.1% vs. 43.0±5.0%, p ,0.05) compared to vehicles (71.5±5.0%). L-dopa (15 mg/kg)-induced reduction of antral motility (motility index 78.3±3.4 vs. vehicle 103.3±6.7, p,0.05) was blocked by rikkunshito (1.0 g/kg; motility index 102.0±5.4). D-[Lys3]-GHRP-6 (1 mg/kg) partially reversed rikkunshito effect on LD/CD-inhibited GE. There was no significant difference in cumulative food intake response to a fast at 1, 2, 4 and 24 h after og rikkunshito (1.0 g/kg) plus LD/CD (20/2 mg/ kg). Conclusions: Rikkunshito exerts a gastroprokinetic effect under conditions of levodopainhibited gastric motor function that may be in part mediated by ghrelin. Rikkunshito may have therapeutic application to improve gastric transit in levodopa treated-PD patients. Supported by Tsumura & Co. and NIDDK 41303 (animal core)

Su2102 Objective Diagnosis of Minimal Hepatic Encephalopathy (MHE) by Analysis of Brain Resting State Functional Connectivity

these significant differences, NERD and ERD groups showed substantial classification with superior classification in the buffer (figure 1C) compared to the acid condition (figure 1D). Conclusions: Interoceptive network functional connectivity responds differently to acid and buffer induced esophageal stimulation in NERD and ERD patients. These differences can be exploited to classify these two groups from each other and from healthy controls.

Su2100 Differences in Resting State Functional Connectivity of Interoceptive and Default Mode Networks in Nerd and Healthy Controls

these significant differences, NERD and ERD groups showed substantial classification with superior classification in the buffer (figure 1C) compared to the acid condition (figure 1D). Conclusions: Interoceptive network functional connectivity responds differently to acid and buffer induced esophageal stimulation in NERD and ERD patients. These differences can be exploited to classify these two groups from each other and from healthy controls.

Su2093 Alterations in the Periaqueductal Gray Matter Resting State Functional Connectivity in Cyclic Vomiting Syndrome

dorsal PCC was identified as a hub, but other hub regions differed. In IBS, right aMCC, pMCC, and supramarginal gyrus were identified as hubs. In HC, identified hubs included the L aINS, R orbital gyrus, and bilateral inferior frontal regions. Conclusions. Regional structural brain network properties differ between IBS and HCs, and when viewed together with findings obtained in other chronic pain conditions, suggest neuroplastic remodeling of the brain in IBS. Future studies will address the correlations between structural and functional brain networks, and the relationship of these changes with clinical symptoms.

661 The Resting and Guided Thinking State Functional Connectivity of the Nausea Network in Cyclic Vomiting Syndrome: The Effect of Emotional Stress

BACKGROUND: Cyclic vomiting syndrome (CVS) is characterized by episodic nausea and vomiting and is often triggered by several factors including emotional stress. With the recent description of neural correlates of nausea (Napadow et al. Cerebral Cortex, 2012) it is now possible to directly study its role in CVS patients. Our AIM was to determine and compare the effect of emotional stress on the resting state functional connectivity of the nausea network between patients with CVS and healthy controls (HC). METHODS: We used guided thinking state fMRI to study the effect of emotional stress on 10 Rome III positive CSV patients (6F, ages 19-49, average length of disease 11 years) in their inter-episodic phase and 10 HC (6F, ages 21-54). Guided thinking state fMRI is an emerging concept where a prior task or induced mood is used to modulate resting state networks. Functional MRI data was acquired during two 10-minute resting state scans (TR 2 s, 3.5 mm isotropic voxels, 64x64 matrix, 240 mm FOV, 3.5 mm slice thickness and 41 contiguous slices) using a 3T MRI scanner with a 32-channel head coil, before and after volunteers were shown 3 minutes of pictures with a negative valence from a standardized picture database. We used Analysis of Functional Neuroimages software and the afni_proc.py python script for analysis. Fourteen four-millimeter radius seeds were dropped using coordinates defined a priori as the nausea network. The average time series were extracted from the seed regions and the Pearson cross correlation coefficient (CC) was calculated to assess the functional connectivity of each of these seeds to the other seeds within the network. Unpaired t-tests were used for comparison and false discovery rate (FDR) was utilized to correct for multiple comparisons. RESULTS: There was no difference in the connectivity of the nausea network between the CVS patients and HC prior to emotional stress. However, after emotional stress there were significant differences observed between the two groups in connections between the right (R) premotor area (PM) and R middle cingulate cortex (MCC) and between the R superior temporal gyrus (STG) and R perigenual anterior cingulate cortex (pgACC) (FIgures 1, 2). In addition, HC but not CVS patients exhibited alterations of the nausea network following emotional stress between the R secondary somatosensory area and the R MCC and between the R PM and R pgACC. CONCLUSIONS: There are significant differences in the functional connectivity of the nausea network between CVS patients and HC following emotional stress. This finding contributes to our understanding of the role of emotional stress in CVS.

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

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.

Reliability and Reproducibility of FMRI Activity in the Cortical Swallowing Network

Background & Aim: Early studies using functional MRI (fMRI) have demonstrated that volitional swallow is associated with activation of a number of cortical areas (middle cingulate gyrus, ventrolateral prefrontal cortex, ventrolateral sensory/motor cortices andmiddle insula), which collectively represent the “cortical swallowing network” (CSN). Although the activation of these regions has been reported in the literature, the reproducibility of these activations has not been systematically studied. The aim of our study is to investigate the reproducibility of the CSN across different fMRI sessions. Methods: We studied 16 young right-handed healthy volunteers utilizing a standard paradigm driven fMRI protocol and analyzed with an event-related analysis technique. Echo-planar images were obtained during two identical nine minute scans across different sessions while twenty-one dry swallows were performed by visual cues in random intervals. Physiologic circulatory and respiratory-related signal changes were removed retrospectively. Functional images were then aligned, registered (12 degrees of freedom), and mapped stereotaxically to the standard coordinate system. Generalized linear model was then used to remove undesirable signal changes correlated with motion, white matter and cerebrospinal fluid. Finally, the second order group random mixed-effect multilevel analysis was performed to identify active cortical regions. Clusters with p<0.01 corrected for multiple comparisons were considered significant. The number of activated voxels (3.75x3.75x4 mm3) along with their average and peak percent signal change within each cluster was reported and compared between the two study sessions in order to determine the correlation co-efficient. Results: All subjects showed significant and clustered activity within the deglutition network during both scans. Activity within the right precuneus and supplementary area were not reproducible. Overall, the percent fMRI signal change and the number of activated voxels were similar between the two studies with correlation co-efficients r=0.88 and r=0.86, respectively (p<0.0001). Activity within the right precuneus and supplementary area were not reproducible. Within the remaining 20 regions of interest (ROI), the overlap of activity maps across both sessions showed that the center of the activated clusters was within 6.3±4.8 mm (less than two voxels). The difference in maximum activated voxel activity was 9.7±5.9 mm. Conclusions: fMRI activity maps as well as percent signal change and number of voxels activated by volitional swallow in the CSN are reproducible between studies.