- Email: [email protected]
Influence of head rotation on upper esophageal sphincter pressure evaluated by high-resolution manometry system
Otolaryngology–Head and Neck Surgery (2010) 142, 214-217
ORIGINAL RESEARCH–LARYNGOLOGY AND NEUROLARYNGOLOGY
Influence of head rotation on upper esophageal sphincter pressure evaluated by high-resolution manometry system Kenji Takasaki, MD, Hiroshi Umeki, MD, Hidetaka Kumagami, MD, and Haruo Takahashi, MD, Nagasaki, Japan No sponsorships or competing interests have been disclosed for this article. ABSTRACT OBJECTIVES: This study aimed to quantify the effects of head rotation on upper esophageal sphincter (UES) pressure in healthy subjects using a novel high-resolution manometry (HRM) system. STUDY DESIGN: Prospective study. SETTING: Nagasaki University Hospital. SUBJECTS AND METHODS: Eighteen asymptomatic Japanese male adult volunteers were studied. A solid-state HRM was positioned to record resting UES pressure. After endoscopically confirming on which side of the pyriform sinus the manometric sensor was positioned within the hypopharynx, we measured the maximum and mean values of the resting UES pressure and the length of the zone of the UES along the esophagus with the patients in the following positions: 1) neutral and straightforward head position (NSF), 2) turning the head in the direction of the side in which the sensor was positioned (HSS), and 3) turning the head in the opposite direction of the side with sensor (HOS). RESULTS: The maximum and mean values of the resting UES pressure were statistically higher in HSS than in NSF (P ⫽ 0.0001 and P ⬍ 0.0001, respectively), and were statistically lower in HOS than in NSF (P ⬍ 0.0001 and P ⬍ 0.0001, respectively). The length of the zone of the UES was statistically shorter in HOS than in NSF (P ⬍ 0.0001), but there was no significant difference in resting UES pressure along the esophagus between HSS and NSF (P ⫽ 0.3024). CONCLUSION: The present study provided us with physiological information regarding normal UES pressure in relation to head rotation. This data will be of aid to future clinical and investigative swallowing studies. Additionally, the current study provides evidence of the safety and usefulness of the head rotation maneuver for dysphagic patients. © 2010 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved.
T
he head rotation maneuver is known as a useful technique to facilitate safe swallowing for dysphagic patients.1,2 Logemann et al1 reported that the head rotation
swallow causes the bolus to lateralize away from the direction of the head turn and also causes a significant drop in upper esophageal sphincter (UES) pressure. Ohmae et al2 stated that the head rotation swallow in normal subjects not only alters the bolus pathway but also has a useful effect on both pharyngeal clearance and UES dynamics. However, in these reports, UES pressure was measured using conventional manometry. Because the elevation of the larynx during swallowing causes a spike-like movement along the upper esophagus, it is extremely difficult to detect the exact pressure at a specific point by analyzing the values with conventional manometry because there are only a few sensors widely spaced (about 2 cm or more apart). To solve this problem, we previously reported on the feasibility of a novel high-resolution manometry (HRM) system for evaluating normal swallowing function and mechanism. We obtained data on swallowing along the velopharynx and upper esophagus of normal Japanese adults and demonstrated that this HRM can overcome the disadvantages of conventional manometric methods.3,4 The purpose of the current study was to quantify the effects of head rotation on UES pressure in healthy subjects using the HRM system, and to evaluate the feasibility of the head rotation maneuver as a rehabilitative procedure for dysphagic patients.
Methods Subjects We studied 18 healthy Japanese male volunteers with no history of dysphagia, gastrointestinal symptoms, previous upper gastrointestinal tract surgery, or other significant medical condition. Their ages ranged from 23 to 28 years. The study protocol was approved by the institutional review board committee of Nagasaki University Hospital, and written informed consent was obtained from each participant.
Received August 14, 2009; revised September 28, 2009; accepted October 22, 2009.
0194-5998/$36.00 © 2010 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved. doi:10.1016/j.otohns.2009.10.033
Takasaki et al
Influence of head rotation on upper . . .
215 from NSF to HSS and from NSF to HOS, respectively. All results measured in the present study are demonstrated in Figures 4, 5, and 6. The maximum and mean values, respectively, of the RUESP (mm Hg) were 138.5 ⫾ 79.1 and 56.8 ⫾ 23.5 (mean ⫾ standard deviation) in HSS, 55.8 ⫾ 20.0 and 32.3 ⫾ 9.2 in NSF, and 28.9 ⫾ 15.0 and 17.8 ⫾ 5.9 in NSF. The RUESPL (cm) was 3.8 ⫾ 0.7 in HSS, 3.6 ⫾ 0.7 in NSF, and 2.4 ⫾ 1.0, in HOS. The maximum and mean values of the RUESP were statistically higher in HSS than in NSF (degree of freedom [df] ⫽ 17; t ⫽ 4.960 and t ⫽ 5.615, and P ⫽ 0.0001 and P ⬍ 0.0001, respectively), and were statistically lower in HOS than in NSF (df ⫽ 17; t ⫽ 7.781 and t ⫽ 8.798, and P ⬍ 0.0001 and P ⬍ 0.0001, respectively). The RUESPL was statistically shorter in HOS than in NSF (df ⫽ 17; t ⫽ 6.148, P ⬍ 0.0001), but there was no significant difference in RUESPL between HSS and NSF (df ⫽ 17; t ⫽ 1.063, P ⫽ 0.3024).
Figure 1 Nasal endoscopy showing that the manometric sensor (arrow) was located on the left side of the pyriform sinus in this case.
Measurement Using HRM The protocol using the HRM system (ManoScan, Sierra Scientific Instruments Inc., Los Angeles, CA) was described in detail in our previous report.3,4 In brief, after administering local anesthesia in the nasal cavity, the catheter was inserted and fixed by taping at the nostril with the patient in a natural supine position. The UES pressure changes were recorded above the cricopharyngeus muscle. The location of the manometric sensor in the pyriform sinuses was endoscopically confirmed (Fig 1). The resting UES pressure (not swallowing pressure [RUESP]) was examined in relation to each of the following three head positions: 1) neutral and straightforward head position (NSF), 2) turning the head in the direction of the side with the sensor (HSS), and 3) turning the head in the opposite direction of the side with the sensor (HOS). Manometric data were analyzed using ManoView analysis software (Sierra Scientific Instruments Inc.). Parameters measured in this study were the maximum and mean value of the RUESP, and the length of the zone of the RUESP along the esophagus (RUESPL). The zone of the RUESP was defined as the zone along the esophagus having an RUESP of 10 mm Hg or higher in each arbitrary minute during the period of the measurements (Fig 2) for each of the three head positions. Statistical analysis was performed using the paired Student’s t test, and P values ⬍0.01 (2-tailed) were regarded as significant.
Discussion Kahrilas et al5 emphasized that there are two components to the deglutive pharyngeal contraction; one is longitudinal and the other is lumen-obliterating horizontal contraction. To date, the former has been measured using conventional manometry, and the latter using the videofluorography.1,2 Because conventional manometry relies on a small number of sensors widely spaced (about 2 cm or more apart), we could not measure the longitudinal component of the pharyngeal contraction using it. Advances in computer technology allow a large volume of data to be acquired and presented in real time by HRM, not only as conventional line plots, but also as twodimensional spatiotemporal plots (sometimes referred to as contour or topographic plots) that display the direction and force of pharyngeal and esophageal pressure activity in 1-mm and 1-mm Hg units.3,6 This novel HRM system enabled us to measure both longitudinal and lumen-obliterating horizontal contraction pharyngeal swallowing
Results Figures 3A and B show typical changes of the color-graphic patterns indicating the RUESP when the head was rotated
Figure 2 Using ManoView analysis software, all parameters are demonstrated in a selected area (dotted line).
216
Otolaryngology–Head and Neck Surgery, Vol 142, No 2, February 2010
Figure 3 Typical changes of the color-graphic patterns were demonstrated. White arrows and red arrows show the moment when the head was rotated.
function.3 In the present study, we measured the maximum and mean value of the RUESP as an index of the lumen-obliterating horizontal contraction and the RUESPL as an index of the longitudinal contraction in each of the three head positions. In the present study, the RUESP was statistically lower in HOS than in NSF and statistically higher in HSS than in NSF. Also, the RUESPL was statistically shorter in HOS than in NSF. These results suggest that the head rotation may produce changes in UES resistance and UES-pharynx coordination. A low RUESP and shortened RUESPL in HOS are likely to facilitate bolus passage in this segment, while high RUESP in HSS may impede it. There were several reports demonstrating the benefit of the head rotation swallow in patients with unilateral neuralgic or structural damage to the pharynx and larynx.1,7 Our present results support these clinical phenomena, and appear to cast evidence of the feasibility and usefulness of the head-rotation maneuver as a rehabilitative tool for dysphagic patients. Tsukamoto et al8 demonstrated, on CT images of a patient with lateral medullary syndrome, that the hypopharyngeal cavity above the pyriform sinus was occupied by shifted soft tissue, leaving no air space in HSS. They
speculated that head rotation may act to stretch out the hypopharyngeal wall of the opposite side, and that dilation of the opposite hypopharyngeal cavity can help more food move into the pyriform sinus on the intact side. Tsunoda et al9 also reported that during head rotation in endoscopy, the anatomical structures on the opposite side of the hypopharynx are easy to observe, and that such a head rotation technique is simple and very effective for laryngeal and hypopharyngeal observation. However, there is no report providing detail about the anatomical change of the pharynx during head rotation in normal subjects. We speculate that head rotation may cause changes in the anatomical relationship between the laryngeal cartilages and the hypopharyngeal wall, resulting in differences in the size of the pyriform sinus between both sides. However, we do not know whether the change in the RUESP was homogenous throughout the UES region or variable. To answer this question, we think that we must measure the RUESP using both the HRM and some type of imaging (CT, for example). Finally, we could not evaluate age- or sex-related differences regarding the effects of head rotation on RUESP because we studied only young, healthy, Japanese male volunteers.
Figure 4 Results of the maximum value of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Figure 5 Results of the mean value of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Takasaki et al
Influence of head rotation on upper . . .
217
Author Contributions Kenji Takasaki, main writer, study design, data collection; Hiroshi Umeki, study design, data collection; Hidetaka Kumagami, writer, study design; Haruo Takahashi, writer, study design.
Disclosures Competing interests: None. Sponsorships: None.
References Figure 6 Results of the length of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Conclusion The present study provided us with physiological information regarding normal UES pressure in head rotation that will be of aid to future clinical and investigative swallowing studies. Additionally, the study provided evidence of the safety and usefulness of the head rotation maneuver for dysphagic patients.
Author Information From the Department of Otolaryngology–Head and Neck Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. Corresponding author: Kenji Takasaki, MD, Department of Otolaryngology–Head and Neck Surgery, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1, Sakamoto, Nagasaki 852-8501, Japan. E-mail address: [email protected].
1. Logemann JA, Kahrilas PJ, Kobara M, et al. The benefit of head rotation on pharyngoesophageal dysphagia. Arch Phys Med Rehabil 1989;70:767–71. 2. Ohmae Y, Ogura M, Kitahara S, et al. Effects of head rotation on pharyngeal function during normal swallow. Ann Otol Rhinol Laryngol 1998;107:344 – 8. 3. Takasaki K, Umeki H, Enatsu K, et al. Investigation of pharyngeal swallowing function using high-resolution manometry. Laryngoscope 2008;118:1729 –32. 4. Umeki H, Takasaki K, Enatsu K, et al. Effects of a tongue-holding maneuver during swallowing evaluated by high-resolution manometry. Otolaryngol Head Neck Surg 2009;141:119 –22. 5. Kahrilas PJ, Logemann JA, Lin S, et al. Pharyngeal clearance during swallowing: a combined manometric and videofluoroscopic study. Gastroenterology 1992;103:128 –36. 6. Fox MR, Bredenoord AJ. Oesophageal high-resolution manometry—moving from research into clinical practice. Gut 2008;57:405–23. 7. Ertekin C, Keskin A, Kiylioglu N, et al. The effect of head and neck positions on oropharyngeal swallowing: a clinical and electrophysiologic study. Arch Phys Med Rehabil 2001;82:1255– 60. 8. Tsukamoto Y. CT study of closure of the hemipharynx with head rotation in a case of lateral medullary syndrome. Dysphagia 2000;15:17– 8. 9. Tsunoda A, Ishihara A, Kishimoto S, et al. Head torsion technique for detailed observation of larynx and hypopharynx. J Laryngol Otol 2007; 121:489 –90.
ORIGINAL RESEARCH–LARYNGOLOGY AND NEUROLARYNGOLOGY
Influence of head rotation on upper esophageal sphincter pressure evaluated by high-resolution manometry system Kenji Takasaki, MD, Hiroshi Umeki, MD, Hidetaka Kumagami, MD, and Haruo Takahashi, MD, Nagasaki, Japan No sponsorships or competing interests have been disclosed for this article. ABSTRACT OBJECTIVES: This study aimed to quantify the effects of head rotation on upper esophageal sphincter (UES) pressure in healthy subjects using a novel high-resolution manometry (HRM) system. STUDY DESIGN: Prospective study. SETTING: Nagasaki University Hospital. SUBJECTS AND METHODS: Eighteen asymptomatic Japanese male adult volunteers were studied. A solid-state HRM was positioned to record resting UES pressure. After endoscopically confirming on which side of the pyriform sinus the manometric sensor was positioned within the hypopharynx, we measured the maximum and mean values of the resting UES pressure and the length of the zone of the UES along the esophagus with the patients in the following positions: 1) neutral and straightforward head position (NSF), 2) turning the head in the direction of the side in which the sensor was positioned (HSS), and 3) turning the head in the opposite direction of the side with sensor (HOS). RESULTS: The maximum and mean values of the resting UES pressure were statistically higher in HSS than in NSF (P ⫽ 0.0001 and P ⬍ 0.0001, respectively), and were statistically lower in HOS than in NSF (P ⬍ 0.0001 and P ⬍ 0.0001, respectively). The length of the zone of the UES was statistically shorter in HOS than in NSF (P ⬍ 0.0001), but there was no significant difference in resting UES pressure along the esophagus between HSS and NSF (P ⫽ 0.3024). CONCLUSION: The present study provided us with physiological information regarding normal UES pressure in relation to head rotation. This data will be of aid to future clinical and investigative swallowing studies. Additionally, the current study provides evidence of the safety and usefulness of the head rotation maneuver for dysphagic patients. © 2010 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved.
T
he head rotation maneuver is known as a useful technique to facilitate safe swallowing for dysphagic patients.1,2 Logemann et al1 reported that the head rotation
swallow causes the bolus to lateralize away from the direction of the head turn and also causes a significant drop in upper esophageal sphincter (UES) pressure. Ohmae et al2 stated that the head rotation swallow in normal subjects not only alters the bolus pathway but also has a useful effect on both pharyngeal clearance and UES dynamics. However, in these reports, UES pressure was measured using conventional manometry. Because the elevation of the larynx during swallowing causes a spike-like movement along the upper esophagus, it is extremely difficult to detect the exact pressure at a specific point by analyzing the values with conventional manometry because there are only a few sensors widely spaced (about 2 cm or more apart). To solve this problem, we previously reported on the feasibility of a novel high-resolution manometry (HRM) system for evaluating normal swallowing function and mechanism. We obtained data on swallowing along the velopharynx and upper esophagus of normal Japanese adults and demonstrated that this HRM can overcome the disadvantages of conventional manometric methods.3,4 The purpose of the current study was to quantify the effects of head rotation on UES pressure in healthy subjects using the HRM system, and to evaluate the feasibility of the head rotation maneuver as a rehabilitative procedure for dysphagic patients.
Methods Subjects We studied 18 healthy Japanese male volunteers with no history of dysphagia, gastrointestinal symptoms, previous upper gastrointestinal tract surgery, or other significant medical condition. Their ages ranged from 23 to 28 years. The study protocol was approved by the institutional review board committee of Nagasaki University Hospital, and written informed consent was obtained from each participant.
Received August 14, 2009; revised September 28, 2009; accepted October 22, 2009.
0194-5998/$36.00 © 2010 American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved. doi:10.1016/j.otohns.2009.10.033
Takasaki et al
Influence of head rotation on upper . . .
215 from NSF to HSS and from NSF to HOS, respectively. All results measured in the present study are demonstrated in Figures 4, 5, and 6. The maximum and mean values, respectively, of the RUESP (mm Hg) were 138.5 ⫾ 79.1 and 56.8 ⫾ 23.5 (mean ⫾ standard deviation) in HSS, 55.8 ⫾ 20.0 and 32.3 ⫾ 9.2 in NSF, and 28.9 ⫾ 15.0 and 17.8 ⫾ 5.9 in NSF. The RUESPL (cm) was 3.8 ⫾ 0.7 in HSS, 3.6 ⫾ 0.7 in NSF, and 2.4 ⫾ 1.0, in HOS. The maximum and mean values of the RUESP were statistically higher in HSS than in NSF (degree of freedom [df] ⫽ 17; t ⫽ 4.960 and t ⫽ 5.615, and P ⫽ 0.0001 and P ⬍ 0.0001, respectively), and were statistically lower in HOS than in NSF (df ⫽ 17; t ⫽ 7.781 and t ⫽ 8.798, and P ⬍ 0.0001 and P ⬍ 0.0001, respectively). The RUESPL was statistically shorter in HOS than in NSF (df ⫽ 17; t ⫽ 6.148, P ⬍ 0.0001), but there was no significant difference in RUESPL between HSS and NSF (df ⫽ 17; t ⫽ 1.063, P ⫽ 0.3024).
Figure 1 Nasal endoscopy showing that the manometric sensor (arrow) was located on the left side of the pyriform sinus in this case.
Measurement Using HRM The protocol using the HRM system (ManoScan, Sierra Scientific Instruments Inc., Los Angeles, CA) was described in detail in our previous report.3,4 In brief, after administering local anesthesia in the nasal cavity, the catheter was inserted and fixed by taping at the nostril with the patient in a natural supine position. The UES pressure changes were recorded above the cricopharyngeus muscle. The location of the manometric sensor in the pyriform sinuses was endoscopically confirmed (Fig 1). The resting UES pressure (not swallowing pressure [RUESP]) was examined in relation to each of the following three head positions: 1) neutral and straightforward head position (NSF), 2) turning the head in the direction of the side with the sensor (HSS), and 3) turning the head in the opposite direction of the side with the sensor (HOS). Manometric data were analyzed using ManoView analysis software (Sierra Scientific Instruments Inc.). Parameters measured in this study were the maximum and mean value of the RUESP, and the length of the zone of the RUESP along the esophagus (RUESPL). The zone of the RUESP was defined as the zone along the esophagus having an RUESP of 10 mm Hg or higher in each arbitrary minute during the period of the measurements (Fig 2) for each of the three head positions. Statistical analysis was performed using the paired Student’s t test, and P values ⬍0.01 (2-tailed) were regarded as significant.
Discussion Kahrilas et al5 emphasized that there are two components to the deglutive pharyngeal contraction; one is longitudinal and the other is lumen-obliterating horizontal contraction. To date, the former has been measured using conventional manometry, and the latter using the videofluorography.1,2 Because conventional manometry relies on a small number of sensors widely spaced (about 2 cm or more apart), we could not measure the longitudinal component of the pharyngeal contraction using it. Advances in computer technology allow a large volume of data to be acquired and presented in real time by HRM, not only as conventional line plots, but also as twodimensional spatiotemporal plots (sometimes referred to as contour or topographic plots) that display the direction and force of pharyngeal and esophageal pressure activity in 1-mm and 1-mm Hg units.3,6 This novel HRM system enabled us to measure both longitudinal and lumen-obliterating horizontal contraction pharyngeal swallowing
Results Figures 3A and B show typical changes of the color-graphic patterns indicating the RUESP when the head was rotated
Figure 2 Using ManoView analysis software, all parameters are demonstrated in a selected area (dotted line).
216
Otolaryngology–Head and Neck Surgery, Vol 142, No 2, February 2010
Figure 3 Typical changes of the color-graphic patterns were demonstrated. White arrows and red arrows show the moment when the head was rotated.
function.3 In the present study, we measured the maximum and mean value of the RUESP as an index of the lumen-obliterating horizontal contraction and the RUESPL as an index of the longitudinal contraction in each of the three head positions. In the present study, the RUESP was statistically lower in HOS than in NSF and statistically higher in HSS than in NSF. Also, the RUESPL was statistically shorter in HOS than in NSF. These results suggest that the head rotation may produce changes in UES resistance and UES-pharynx coordination. A low RUESP and shortened RUESPL in HOS are likely to facilitate bolus passage in this segment, while high RUESP in HSS may impede it. There were several reports demonstrating the benefit of the head rotation swallow in patients with unilateral neuralgic or structural damage to the pharynx and larynx.1,7 Our present results support these clinical phenomena, and appear to cast evidence of the feasibility and usefulness of the head-rotation maneuver as a rehabilitative tool for dysphagic patients. Tsukamoto et al8 demonstrated, on CT images of a patient with lateral medullary syndrome, that the hypopharyngeal cavity above the pyriform sinus was occupied by shifted soft tissue, leaving no air space in HSS. They
speculated that head rotation may act to stretch out the hypopharyngeal wall of the opposite side, and that dilation of the opposite hypopharyngeal cavity can help more food move into the pyriform sinus on the intact side. Tsunoda et al9 also reported that during head rotation in endoscopy, the anatomical structures on the opposite side of the hypopharynx are easy to observe, and that such a head rotation technique is simple and very effective for laryngeal and hypopharyngeal observation. However, there is no report providing detail about the anatomical change of the pharynx during head rotation in normal subjects. We speculate that head rotation may cause changes in the anatomical relationship between the laryngeal cartilages and the hypopharyngeal wall, resulting in differences in the size of the pyriform sinus between both sides. However, we do not know whether the change in the RUESP was homogenous throughout the UES region or variable. To answer this question, we think that we must measure the RUESP using both the HRM and some type of imaging (CT, for example). Finally, we could not evaluate age- or sex-related differences regarding the effects of head rotation on RUESP because we studied only young, healthy, Japanese male volunteers.
Figure 4 Results of the maximum value of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Figure 5 Results of the mean value of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Takasaki et al
Influence of head rotation on upper . . .
217
Author Contributions Kenji Takasaki, main writer, study design, data collection; Hiroshi Umeki, study design, data collection; Hidetaka Kumagami, writer, study design; Haruo Takahashi, writer, study design.
Disclosures Competing interests: None. Sponsorships: None.
References Figure 6 Results of the length of the resting UES pressure in HSS, NSF, and HOS. Black solid circles are mean values. Bars represent standard deviations.
Conclusion The present study provided us with physiological information regarding normal UES pressure in head rotation that will be of aid to future clinical and investigative swallowing studies. Additionally, the study provided evidence of the safety and usefulness of the head rotation maneuver for dysphagic patients.
Author Information From the Department of Otolaryngology–Head and Neck Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. Corresponding author: Kenji Takasaki, MD, Department of Otolaryngology–Head and Neck Surgery, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1, Sakamoto, Nagasaki 852-8501, Japan. E-mail address: [email protected].
1. Logemann JA, Kahrilas PJ, Kobara M, et al. The benefit of head rotation on pharyngoesophageal dysphagia. Arch Phys Med Rehabil 1989;70:767–71. 2. Ohmae Y, Ogura M, Kitahara S, et al. Effects of head rotation on pharyngeal function during normal swallow. Ann Otol Rhinol Laryngol 1998;107:344 – 8. 3. Takasaki K, Umeki H, Enatsu K, et al. Investigation of pharyngeal swallowing function using high-resolution manometry. Laryngoscope 2008;118:1729 –32. 4. Umeki H, Takasaki K, Enatsu K, et al. Effects of a tongue-holding maneuver during swallowing evaluated by high-resolution manometry. Otolaryngol Head Neck Surg 2009;141:119 –22. 5. Kahrilas PJ, Logemann JA, Lin S, et al. Pharyngeal clearance during swallowing: a combined manometric and videofluoroscopic study. Gastroenterology 1992;103:128 –36. 6. Fox MR, Bredenoord AJ. Oesophageal high-resolution manometry—moving from research into clinical practice. Gut 2008;57:405–23. 7. Ertekin C, Keskin A, Kiylioglu N, et al. The effect of head and neck positions on oropharyngeal swallowing: a clinical and electrophysiologic study. Arch Phys Med Rehabil 2001;82:1255– 60. 8. Tsukamoto Y. CT study of closure of the hemipharynx with head rotation in a case of lateral medullary syndrome. Dysphagia 2000;15:17– 8. 9. Tsunoda A, Ishihara A, Kishimoto S, et al. Head torsion technique for detailed observation of larynx and hypopharynx. J Laryngol Otol 2007; 121:489 –90.