The Laryngoscope C 2014 The American Laryngological, V
Rhinological and Otological Society, Inc.
Visualization of the Eustachian Tube Lumen With Valsalva Computed Tomography Muaaz Tarabichi, MD; Murtaza Najmi, MD Objectives/Hypothesis: Assess the feasibility of using the Valsalva maneuver to visualize the cartilaginous eustachian tube lumen with computed tomography (CT) in subjects with no ear disease. Study Design: Prospective case series study. Methods: Thirty-eight consecutive patients undergoing CT of the sinuses for nose-related complaints with normal radiographic findings consented for a CT of the temporal bone while performing the Valsalva maneuver. Multiplanar reconstruction was performed along the axis of the tube. Images were assessed for visualization of the whole length of lumen of the tube, or partial visualization with ratio of visualized to nonvisualized segments. Results: The Valsalva maneuver allowed visualization of the whole length of the tube in 27/76 (35%) ears examined. It consistently visualized the distal one-third of the cartilaginous tube in 71/76 (94%) ears. Paradoxical collapse of the eustachian tube was present in three ears along with evidence of poor Valsalva technique. Conclusions: Valsalva CT consistently allows visualization of the lumen of the distal one-third of the eustachian tube in a majority of patients with no eustachian tube–related complaints. This technique might be helpful in localizing eustachian tube pathology in patients with obstructive tube symptoms. Key Words: Cholesteatoma, chronic ear surgery, eustachian tube dysfunction, computed tomography, Valsalva, imaging of eustachian tube. Level of Evidence: 4. Laryngoscope, 00:000–000, 2014
INTRODUCTION
MATERIALS AND METHODS
There has been increased interest lately in revisiting diagnostic and surgical approaches to the eustachian tube.1–4 Multiple methods have long been devised to evaluate the eustachian tube’s main function of ventilating the middle ear cleft.5 However, there is lack of consensus on the most accurate method of accomplishing that evaluation.6 Despite the tremendous advances in imaging of the temporal bone structures and related disease with CT and magnetic resonance imaging (MRI), the eustachian tube lumen and structure have remained a black box and could not be visualized in imaging studies. The tube’s soft tissue structure and the physiologic collapse of the cartilaginous eustachian tube have rendered CT useless in evaluating its structure and patency. This study attempted to look at the ability of the Valsalva maneuver to increase the visualization of the lumen of the cartilaginous tube in patients who have no ear-related complaints, no identifiable ear pathology, and no radiographic evidence of sinus disease.
We asked patients who had undergone CT of the sinuses for sinus-related complaints and who had no ear symptoms, no previous ear surgery, and normal findings on the sinus CT to participate in the study. Given the lack of ear symptoms or findings, audiological testing was not performed. After obtaining consent, CT of the temporal bone was performed while the patient was actively performing the Valsalva maneuver (concurrent with the maneuver). The technician was instructed to ask the patient to perform forceful exhalation against a closed nose. Individual patient instruction was done by the technician just prior to CT. Thirty-eight consecutive patients were enrolled and underwent CT of the temporal bone while performing the Valsalva maneuver. Primary image acquisition was made in the supine in the helical mode. Overlapping, 0.67 mm (thickness) 3 0.5 mm (increment), axial dataset was obtained. Multiplanar reconstruction of the images in the axis of the eustachian tube was performed. This was done by utilizing image reconstruction proprietary software on the CT scanner workstation (Phillips Brilliance 64; Philips Healthcare, Best, the Netherlands). The following methodology was applied: the rotation center (crosshair) was positioned at the fundus of the nasopharyngeal end of the eustachian tube on axial sections. Looking at the sagittal view, the axial plane was then tilted anteroinferiorly until the whole length of the tube was visualized. Further attempts were made by minor adjustments of all the planes to get the longest segment of the dilated/visualized cartilaginous tube. Images were then examined for visualization of the full length of the tube (Fig. 1). CT images of patients with partial visualization were examined and compared to the pre- Valsalva images obtained on the sinus CT. Measurements were obtained of the dilated and visualized segment and of the collapsed and nonvisualized cartilaginous segment. The anterior limit of the tube was considered to be the lateral lip of the nasopharyngeal orifice. The posterior limit was
From the Department of Otolaryngology, American Hospital Dubai, Dubai, United Arab Emirates. Editor’s Note: This Manuscript was accepted for publication September 29, 2014. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Muaaz Tarabichi, MD, American Hospital Dubai, P.O. Box 5566, Oud Mehta Rd., Dubai, United Arab Emirates. E-mail: [email protected] DOI: 10.1002/lary.24979
Laryngoscope 00: Month 2014
Tarabichi and Najmi: Valsalva Computed Tomography
1
Fig. 1. Screenshot of computed tomography workstation with full visualization of the whole length of the Eustachian tube on multiplanar reconstruction. Multiplanar reconstruction of the images in the axis of the tube: the rotation center (X) was positioned at the fundus of the nasopharyngeal end of the tube on axial sections. Looking at the sagittal view, the axial plane was then tilted anteroinferiorly until the whole length of the tube was visualized. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] that of the starting point of the bony segment of the tube (Fig. 2). To obtain the measurements from a single image as evident in Figure 2, the image needed to incorporate three landmarks: the most proximal point of the dilated tube, the lateral lip of the nasopharyngeal orifice, and the starting point of the bony segment. This was possible in the vast majority of patients. However, in very few patients, these three points could not be visualized on the same image. For these patients, the two measurements were taken individually from two different images. The first image was obtained through multiplanar reconstruction by incorporating the most proximal point of the dilated tube along with the lateral lip of the distal orifice to measure the dilated segment. The second image was obtained by multiplanar reconstruction that incorporates the most proximal point of the dilated tube along with the starting point of the bony tube to measure the collapsed segment of the tube. Careful attention was paid to reproduce similar image plane placement for measurements in the pre-Valsalva and the Valsalva CT so that the effect of Valsalva maneuver could be accurately assessed. The ratio of the visualized to the nonvisualized segment was calculated. The same measurements and calculations were made of the pre-Valsalva sinus CT, and both were compared. These measurements were only obtained in the group of patients with partial visualization of the tube.
Laryngoscope 00: Month 2014
2
The ethics committee at our institution approved the study.
RESULTS Thirty-eight patients were enrolled in the study. There were 16 males and 22 females. The patients’ ages ranged from 22 to 67 years, with a mean age of 42 years. The ears were evaluated individually, and each ear was considered independently as a single data point. The Valsalva maneuver resulted in clear visualization on CT of the whole length of the eustachian tube in 27/76 (35%) of the ears examined (Fig. 1). This finding was bilateral in 12 patients and unilateral in three patients who had partial visualization on the other side. In the remaining 49 ears, the average ratio of dilated and visualized segment of the tube to the nonvisualized segment was 1.26 6 0.40 when the Valsalva maneuver was performed compared with an average ratio of 0.40 6 0.24 before the Valsalva maneuver (Fig. 3). The ratio of the visualized to nonvisualized segment was higher than 0.50 in all but five of the subjects tested with Valsalva. Tarabichi and Najmi: Valsalva Computed Tomography
Fig. 2. Measurements obtained of the dilated visualized segment and the undilated nonvisualized cartilaginous segment. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
There were three ears that showed a decrease in that ratio during the Valsalva maneuver, and it occurred in two subjects with clear evidence of poor Valsalva on CT. These findings included ballooning of the buccal area, closing of the nasopharynx, and positioning of the tongue away from the palate (Fig. 4).
DISCUSSION The eustachian tube has been the focus of attention for almost 300 years. Its related dysfunction accounts for a very substantial number of patient–physician encounters in otolaryngology. Its obstruction is thought to be a major contributor to chronic ear disease and treatment failure.7 The routine use of endoscopes in otolaryngology has resulted in increased access and a rekindling of interest in the evaluation and treatment of eustachian tube dysfunction. Much of the attention has been focused on the endoscopically accessible nasopharyngeal end of the tube.1,2 The preponderance of evidence seem to indicate that the cartilaginous tube and its distal segment harbor most of the sites of obstruction.8–10 However, it stands to reason that there is a degree of variability in the site of Laryngoscope 00: Month 2014
obstruction, and that some patients do have obstruction in a more proximal location in the eustachian tube, in close proximity to the tympanic cavity, and recurrent inflammatory processes within it. Linstrom et al. described their experience in using fiberoptic flexible miniscopes introduced through the ear during ear surgery for chronic conditions to evaluate the patency of the eustachian tube. Their results indicated that much of the obstruction existed in the protympanic segment of the eustachian tube.11 However, it should be pointed out that the quality of the images obtained with the fiberoptic device they used is very limited, which can lead to an inaccurate assessment of the images. In contrast, endoscopic ear surgery with rigid scopes allows highresolution evaluation and instrumentation of the protympanic segment of the tube, and provides opportunities for surgical intervention in that area.12,13 Delineating the exact site of the obstructions seems like a first logical step in any attempt to address the pathology. Much of the testing methods that have been devised for eustachian tube function are not anatomically based, and indirect methods do not locate the site of obstruction.6 Indirect evidence of the tube status on CT is usually derived from the status Tarabichi and Najmi: Valsalva Computed Tomography
3
Fig. 3. Plotting of all of the ratios of the visualized to nonvisualized segments of the cartilaginous tube before and after the Valsalva maneuver. The y-axis ratio value of 0.5 indicates visualization of the distal one-third of the cartilaginous tube. A value of 1.00 indicates visualization of the distal half of the eustachian tube. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
Laryngoscope 00: Month 2014
4
and pneumatization of the middle ear cleft. There has been some success at MRI visualization of eustachian tube structure and related muscles, as well as the depiction of submucosal tumors, but the lumen and physical obstruction can not be visualized in the naturally collapsed tube.14 In normal physiologic conditions, the eustachian tube opens up as a result of a combination of direct muscle action and indirect action by increased nasopharyngeal pressure beyond the opening pressure of the tube.15 Improved CT technology with spiral CT has resulted in very short imaging time, which allows the patient to maintain the Valsalva maneuver throughout the examination. The only previous report on Valsalva CT in the literature looked at this modality when evaluating patulous tubes.16 As a first step in establishing this technique as a possible tool in diagnosing obstruction, we wanted to establish the findings of Valsalva CT in the normal population. We also wanted to know whether the observed dilatation and visualization is a consistent finding in normal subjects. Visualization of the whole length of the cartilaginous tube with the Valsalva maneuver was observed in almost one-third of the examined population. This tended to be a bilateral phenomenon in patients who had it. In the rest of the group, the Valsalva technique further extended the visualized area in all tested patients, except for three ears where there was paradoxical further closing of the distal end of the tube. This occurred in two patients, one unilaterally and the other bilaterally. In these two patients, we had documented poor Valsalva technique with ballooning of the buccal area, closing of the nasopharynx, and positioning of the tongue away from palate (Fig. 4). We hypothesize that the poor Valsalva technique, with tensing of the associated muscles without building up nasopharyngeal pressure, would result in this phenomenon. Although no active ear disease or ear-related complaints were present in the study group, a childhood history of frequent ear infections was not solicited, and that might be a contributing reason of the variation of the visualization identified in this study. In 71/76 (94%) ears examined, the Valsalva technique increased the length of the visualized segment and extended it to include the distal one-third of the tube. The clinical utility of this diagnostic test would require years to establish with the collective wisdom of the global otolaryngology community. Most of our patients undergoing chronic ear surgery are routinely undergoing CT examination, and asking the patient to perform a Valsalva maneuver does not add to the cost and can produce more information on the status of the eustachian tube, especially its distal segment. We believe that transcanal endoscopic ear surgery can possibly provide a route for safe access to the proximal segment of the cartilaginous eustachian tube for possible interventions.13 Demonstrating anatomic patency or obstruction of the eustachian tube with Valsalva CT does not translate into normal function or dysfunction of the eustachian tube, because the tube is a dynamic structure with active mechanisms that are essential for its normal function. Tarabichi and Najmi: Valsalva Computed Tomography
Fig. 4. Computed tomography findings associated with poor Valsalva technique: ballooning of the buccal area, closing of the nasopharynx, and a tongue position away from the palate. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
This study represents an initial report on this technique, but there remains significant opportunity to enhance the inflation, and therefore visualization, of the tube by optimizing the methods and timing of the Valsalva maneuver during the imaging process. There is an opportunity in the future to enhance the technique by performing the CT in the upright position using cone-beam CT, because the patency of the tube is affected by the position of the patient.17 Furthermore, opportunities exist for standardizing the pressure delivery to the nasopharyngeal opening of the tube by multiple devices.
dilated and visualized on CT with the Valsalva maneuver in a majority of the normal population.
BIBLIOGRAPHY 1. Ockermann T, Reineke U, Upile T, et al. A clinical study: balloon dilatation eustachian tuboplasty (BET). Laryngoscope 2010;120:1411–1416. 2. McCoul ED, Anand VK, Christos PJ. Validating the clinical assessment of eustachian tube dysfunction: the eustachian tube dysfunction questionnaire (ETDQ- 7). Laryngoscope 2012;122:1137–1141. 3. Poe DS, Grimmer JF, Metson R. Laser eustachian tuboplasty: two-year results. Laryngoscope 2007;117:231–237. 4. Poe DS, Silvola J, Pyykk€o I. Balloon dilation of the cartilaginous eustachian tube. Otolaryngol Head Neck Surg 2011;144:563–569. 5. McBride TP, Derkay CS, Cunningham MJ, Doyle WJ. Evaluation of noninvasive eustachian tube function tests in normal adults. Laryngoscope 1988;98:655–658.
CONCLUSION In a normal population of patients without any ear or sinus disease, the Valsalva maneuver is able to dilate the naturally collapsed segment of the eustachian tube and allow visualization on CT of the whole length of the eustachian tube in one-third of the population. The distal one-third of the cartilaginous tube is consistently Laryngoscope 00: Month 2014
6. Todd NW. There are no accurate tests for eustachian tube function. Arch Otolaryngol Head Neck Surg 2000;126:1041–1042. 7. Sato H, Hajime N, Iwao H, Masahiko H. Eustachian tube function in tympanoplasty. Acta Otolaryngol 1990;110:9–12. 8. Takahashi H, Fujita A, Honjo I. Site of eustachian tube dysfunction in patients with otitis media with effusion. Am J Otolaryngol 1987;8:361– 363. 9. Edelstein DR, Magnan J, Parisier C. Microfiberoptic evaluation of the middle ear cavity. Am J Otol 1994;15:50–55.
Tarabichi and Najmi: Valsalva Computed Tomography
5
10. Takahashi H, Honjo I, Fujita A. Endoscopic findings at the pharyngeal orifice of the Eustachian tube in otitis media with effusion. Eur Arch Otorhinolaryngol 1996;253:42–47. 11. Linstrom CJ, Carol AS, Arie R, Lawrence ZM. Eustachian tube endoscopy in patients with chronic ear disease. Laryngoscope 2000;110:1884–1889. 12. Tarabichi M. Endoscopic management of limited attic cholesteatoma. Laryngoscope 2004;114:1157–1162. 13. Tarabichi M. Transcanal endoscopic management of cholesteatoma. Otol Neurotol 2010;31:580–588.
Laryngoscope 00: Month 2014
6
14. Leuwer R, Schubert R, Kucinski T. Muscular Compliance of the auditory tube. A model based survey. Laryngoscope 2002;112:1791–1795. 15. Elner A, Ingelstedt S, Ivarsson A. The normal function of the Eustachian tube. Acta Otolaryngol (Stockh) 1971;72:320–328. 16. Kikuchi T, Oshima T, Ogura M. Three-dimensional computed tomography imaging in the sitting position for the diagnosis of patulous eustachian tube. Otol Neurotol 2007;28:199–203. 17. Leclerc JE, Doyle WJ, Karnavas W. Physiological modulation of Eustachian tube function. Acta Otolaryngol 1987;104:500–510.
Tarabichi and Najmi: Valsalva Computed Tomography
Rhinological and Otological Society, Inc.
Visualization of the Eustachian Tube Lumen With Valsalva Computed Tomography Muaaz Tarabichi, MD; Murtaza Najmi, MD Objectives/Hypothesis: Assess the feasibility of using the Valsalva maneuver to visualize the cartilaginous eustachian tube lumen with computed tomography (CT) in subjects with no ear disease. Study Design: Prospective case series study. Methods: Thirty-eight consecutive patients undergoing CT of the sinuses for nose-related complaints with normal radiographic findings consented for a CT of the temporal bone while performing the Valsalva maneuver. Multiplanar reconstruction was performed along the axis of the tube. Images were assessed for visualization of the whole length of lumen of the tube, or partial visualization with ratio of visualized to nonvisualized segments. Results: The Valsalva maneuver allowed visualization of the whole length of the tube in 27/76 (35%) ears examined. It consistently visualized the distal one-third of the cartilaginous tube in 71/76 (94%) ears. Paradoxical collapse of the eustachian tube was present in three ears along with evidence of poor Valsalva technique. Conclusions: Valsalva CT consistently allows visualization of the lumen of the distal one-third of the eustachian tube in a majority of patients with no eustachian tube–related complaints. This technique might be helpful in localizing eustachian tube pathology in patients with obstructive tube symptoms. Key Words: Cholesteatoma, chronic ear surgery, eustachian tube dysfunction, computed tomography, Valsalva, imaging of eustachian tube. Level of Evidence: 4. Laryngoscope, 00:000–000, 2014
INTRODUCTION
MATERIALS AND METHODS
There has been increased interest lately in revisiting diagnostic and surgical approaches to the eustachian tube.1–4 Multiple methods have long been devised to evaluate the eustachian tube’s main function of ventilating the middle ear cleft.5 However, there is lack of consensus on the most accurate method of accomplishing that evaluation.6 Despite the tremendous advances in imaging of the temporal bone structures and related disease with CT and magnetic resonance imaging (MRI), the eustachian tube lumen and structure have remained a black box and could not be visualized in imaging studies. The tube’s soft tissue structure and the physiologic collapse of the cartilaginous eustachian tube have rendered CT useless in evaluating its structure and patency. This study attempted to look at the ability of the Valsalva maneuver to increase the visualization of the lumen of the cartilaginous tube in patients who have no ear-related complaints, no identifiable ear pathology, and no radiographic evidence of sinus disease.
We asked patients who had undergone CT of the sinuses for sinus-related complaints and who had no ear symptoms, no previous ear surgery, and normal findings on the sinus CT to participate in the study. Given the lack of ear symptoms or findings, audiological testing was not performed. After obtaining consent, CT of the temporal bone was performed while the patient was actively performing the Valsalva maneuver (concurrent with the maneuver). The technician was instructed to ask the patient to perform forceful exhalation against a closed nose. Individual patient instruction was done by the technician just prior to CT. Thirty-eight consecutive patients were enrolled and underwent CT of the temporal bone while performing the Valsalva maneuver. Primary image acquisition was made in the supine in the helical mode. Overlapping, 0.67 mm (thickness) 3 0.5 mm (increment), axial dataset was obtained. Multiplanar reconstruction of the images in the axis of the eustachian tube was performed. This was done by utilizing image reconstruction proprietary software on the CT scanner workstation (Phillips Brilliance 64; Philips Healthcare, Best, the Netherlands). The following methodology was applied: the rotation center (crosshair) was positioned at the fundus of the nasopharyngeal end of the eustachian tube on axial sections. Looking at the sagittal view, the axial plane was then tilted anteroinferiorly until the whole length of the tube was visualized. Further attempts were made by minor adjustments of all the planes to get the longest segment of the dilated/visualized cartilaginous tube. Images were then examined for visualization of the full length of the tube (Fig. 1). CT images of patients with partial visualization were examined and compared to the pre- Valsalva images obtained on the sinus CT. Measurements were obtained of the dilated and visualized segment and of the collapsed and nonvisualized cartilaginous segment. The anterior limit of the tube was considered to be the lateral lip of the nasopharyngeal orifice. The posterior limit was
From the Department of Otolaryngology, American Hospital Dubai, Dubai, United Arab Emirates. Editor’s Note: This Manuscript was accepted for publication September 29, 2014. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Muaaz Tarabichi, MD, American Hospital Dubai, P.O. Box 5566, Oud Mehta Rd., Dubai, United Arab Emirates. E-mail: [email protected] DOI: 10.1002/lary.24979
Laryngoscope 00: Month 2014
Tarabichi and Najmi: Valsalva Computed Tomography
1
Fig. 1. Screenshot of computed tomography workstation with full visualization of the whole length of the Eustachian tube on multiplanar reconstruction. Multiplanar reconstruction of the images in the axis of the tube: the rotation center (X) was positioned at the fundus of the nasopharyngeal end of the tube on axial sections. Looking at the sagittal view, the axial plane was then tilted anteroinferiorly until the whole length of the tube was visualized. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] that of the starting point of the bony segment of the tube (Fig. 2). To obtain the measurements from a single image as evident in Figure 2, the image needed to incorporate three landmarks: the most proximal point of the dilated tube, the lateral lip of the nasopharyngeal orifice, and the starting point of the bony segment. This was possible in the vast majority of patients. However, in very few patients, these three points could not be visualized on the same image. For these patients, the two measurements were taken individually from two different images. The first image was obtained through multiplanar reconstruction by incorporating the most proximal point of the dilated tube along with the lateral lip of the distal orifice to measure the dilated segment. The second image was obtained by multiplanar reconstruction that incorporates the most proximal point of the dilated tube along with the starting point of the bony tube to measure the collapsed segment of the tube. Careful attention was paid to reproduce similar image plane placement for measurements in the pre-Valsalva and the Valsalva CT so that the effect of Valsalva maneuver could be accurately assessed. The ratio of the visualized to the nonvisualized segment was calculated. The same measurements and calculations were made of the pre-Valsalva sinus CT, and both were compared. These measurements were only obtained in the group of patients with partial visualization of the tube.
Laryngoscope 00: Month 2014
2
The ethics committee at our institution approved the study.
RESULTS Thirty-eight patients were enrolled in the study. There were 16 males and 22 females. The patients’ ages ranged from 22 to 67 years, with a mean age of 42 years. The ears were evaluated individually, and each ear was considered independently as a single data point. The Valsalva maneuver resulted in clear visualization on CT of the whole length of the eustachian tube in 27/76 (35%) of the ears examined (Fig. 1). This finding was bilateral in 12 patients and unilateral in three patients who had partial visualization on the other side. In the remaining 49 ears, the average ratio of dilated and visualized segment of the tube to the nonvisualized segment was 1.26 6 0.40 when the Valsalva maneuver was performed compared with an average ratio of 0.40 6 0.24 before the Valsalva maneuver (Fig. 3). The ratio of the visualized to nonvisualized segment was higher than 0.50 in all but five of the subjects tested with Valsalva. Tarabichi and Najmi: Valsalva Computed Tomography
Fig. 2. Measurements obtained of the dilated visualized segment and the undilated nonvisualized cartilaginous segment. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
There were three ears that showed a decrease in that ratio during the Valsalva maneuver, and it occurred in two subjects with clear evidence of poor Valsalva on CT. These findings included ballooning of the buccal area, closing of the nasopharynx, and positioning of the tongue away from the palate (Fig. 4).
DISCUSSION The eustachian tube has been the focus of attention for almost 300 years. Its related dysfunction accounts for a very substantial number of patient–physician encounters in otolaryngology. Its obstruction is thought to be a major contributor to chronic ear disease and treatment failure.7 The routine use of endoscopes in otolaryngology has resulted in increased access and a rekindling of interest in the evaluation and treatment of eustachian tube dysfunction. Much of the attention has been focused on the endoscopically accessible nasopharyngeal end of the tube.1,2 The preponderance of evidence seem to indicate that the cartilaginous tube and its distal segment harbor most of the sites of obstruction.8–10 However, it stands to reason that there is a degree of variability in the site of Laryngoscope 00: Month 2014
obstruction, and that some patients do have obstruction in a more proximal location in the eustachian tube, in close proximity to the tympanic cavity, and recurrent inflammatory processes within it. Linstrom et al. described their experience in using fiberoptic flexible miniscopes introduced through the ear during ear surgery for chronic conditions to evaluate the patency of the eustachian tube. Their results indicated that much of the obstruction existed in the protympanic segment of the eustachian tube.11 However, it should be pointed out that the quality of the images obtained with the fiberoptic device they used is very limited, which can lead to an inaccurate assessment of the images. In contrast, endoscopic ear surgery with rigid scopes allows highresolution evaluation and instrumentation of the protympanic segment of the tube, and provides opportunities for surgical intervention in that area.12,13 Delineating the exact site of the obstructions seems like a first logical step in any attempt to address the pathology. Much of the testing methods that have been devised for eustachian tube function are not anatomically based, and indirect methods do not locate the site of obstruction.6 Indirect evidence of the tube status on CT is usually derived from the status Tarabichi and Najmi: Valsalva Computed Tomography
3
Fig. 3. Plotting of all of the ratios of the visualized to nonvisualized segments of the cartilaginous tube before and after the Valsalva maneuver. The y-axis ratio value of 0.5 indicates visualization of the distal one-third of the cartilaginous tube. A value of 1.00 indicates visualization of the distal half of the eustachian tube. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
Laryngoscope 00: Month 2014
4
and pneumatization of the middle ear cleft. There has been some success at MRI visualization of eustachian tube structure and related muscles, as well as the depiction of submucosal tumors, but the lumen and physical obstruction can not be visualized in the naturally collapsed tube.14 In normal physiologic conditions, the eustachian tube opens up as a result of a combination of direct muscle action and indirect action by increased nasopharyngeal pressure beyond the opening pressure of the tube.15 Improved CT technology with spiral CT has resulted in very short imaging time, which allows the patient to maintain the Valsalva maneuver throughout the examination. The only previous report on Valsalva CT in the literature looked at this modality when evaluating patulous tubes.16 As a first step in establishing this technique as a possible tool in diagnosing obstruction, we wanted to establish the findings of Valsalva CT in the normal population. We also wanted to know whether the observed dilatation and visualization is a consistent finding in normal subjects. Visualization of the whole length of the cartilaginous tube with the Valsalva maneuver was observed in almost one-third of the examined population. This tended to be a bilateral phenomenon in patients who had it. In the rest of the group, the Valsalva technique further extended the visualized area in all tested patients, except for three ears where there was paradoxical further closing of the distal end of the tube. This occurred in two patients, one unilaterally and the other bilaterally. In these two patients, we had documented poor Valsalva technique with ballooning of the buccal area, closing of the nasopharynx, and positioning of the tongue away from palate (Fig. 4). We hypothesize that the poor Valsalva technique, with tensing of the associated muscles without building up nasopharyngeal pressure, would result in this phenomenon. Although no active ear disease or ear-related complaints were present in the study group, a childhood history of frequent ear infections was not solicited, and that might be a contributing reason of the variation of the visualization identified in this study. In 71/76 (94%) ears examined, the Valsalva technique increased the length of the visualized segment and extended it to include the distal one-third of the tube. The clinical utility of this diagnostic test would require years to establish with the collective wisdom of the global otolaryngology community. Most of our patients undergoing chronic ear surgery are routinely undergoing CT examination, and asking the patient to perform a Valsalva maneuver does not add to the cost and can produce more information on the status of the eustachian tube, especially its distal segment. We believe that transcanal endoscopic ear surgery can possibly provide a route for safe access to the proximal segment of the cartilaginous eustachian tube for possible interventions.13 Demonstrating anatomic patency or obstruction of the eustachian tube with Valsalva CT does not translate into normal function or dysfunction of the eustachian tube, because the tube is a dynamic structure with active mechanisms that are essential for its normal function. Tarabichi and Najmi: Valsalva Computed Tomography
Fig. 4. Computed tomography findings associated with poor Valsalva technique: ballooning of the buccal area, closing of the nasopharynx, and a tongue position away from the palate. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.]
This study represents an initial report on this technique, but there remains significant opportunity to enhance the inflation, and therefore visualization, of the tube by optimizing the methods and timing of the Valsalva maneuver during the imaging process. There is an opportunity in the future to enhance the technique by performing the CT in the upright position using cone-beam CT, because the patency of the tube is affected by the position of the patient.17 Furthermore, opportunities exist for standardizing the pressure delivery to the nasopharyngeal opening of the tube by multiple devices.
dilated and visualized on CT with the Valsalva maneuver in a majority of the normal population.
BIBLIOGRAPHY 1. Ockermann T, Reineke U, Upile T, et al. A clinical study: balloon dilatation eustachian tuboplasty (BET). Laryngoscope 2010;120:1411–1416. 2. McCoul ED, Anand VK, Christos PJ. Validating the clinical assessment of eustachian tube dysfunction: the eustachian tube dysfunction questionnaire (ETDQ- 7). Laryngoscope 2012;122:1137–1141. 3. Poe DS, Grimmer JF, Metson R. Laser eustachian tuboplasty: two-year results. Laryngoscope 2007;117:231–237. 4. Poe DS, Silvola J, Pyykk€o I. Balloon dilation of the cartilaginous eustachian tube. Otolaryngol Head Neck Surg 2011;144:563–569. 5. McBride TP, Derkay CS, Cunningham MJ, Doyle WJ. Evaluation of noninvasive eustachian tube function tests in normal adults. Laryngoscope 1988;98:655–658.
CONCLUSION In a normal population of patients without any ear or sinus disease, the Valsalva maneuver is able to dilate the naturally collapsed segment of the eustachian tube and allow visualization on CT of the whole length of the eustachian tube in one-third of the population. The distal one-third of the cartilaginous tube is consistently Laryngoscope 00: Month 2014
6. Todd NW. There are no accurate tests for eustachian tube function. Arch Otolaryngol Head Neck Surg 2000;126:1041–1042. 7. Sato H, Hajime N, Iwao H, Masahiko H. Eustachian tube function in tympanoplasty. Acta Otolaryngol 1990;110:9–12. 8. Takahashi H, Fujita A, Honjo I. Site of eustachian tube dysfunction in patients with otitis media with effusion. Am J Otolaryngol 1987;8:361– 363. 9. Edelstein DR, Magnan J, Parisier C. Microfiberoptic evaluation of the middle ear cavity. Am J Otol 1994;15:50–55.
Tarabichi and Najmi: Valsalva Computed Tomography
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