Abstract
Background
Balloon catheter dilation of diseased sinus ostia has recently demonstrated efficacy and safety in the treatment of chronic sinus disease with 2 years of follow-up. Similar to sinus surgery, initial studies of partial resection of inflamed mucosa from within the cartilaginous eustachian tube (ET) have demonstrated efficacy and safety in the treatment of medically refractory otitis media with effusion. Therefore, balloon dilation of the cartilaginous ET was investigated as a possible treatment modality for otitis media.
Methods
A protocol for sinus balloon catheter dilation was evaluated in each of the cartilaginous ETs in 8 fresh human cadaver heads. Computed tomographic scans and detailed endoscopic inspections with video or photographic documentation were performed pre- and posttreatment, and gross anatomical dissections were done to analyze the effects of treatment and to look for evidence of undesired injury.
Results
Catheters successfully dilated all cartilaginous ETs without any significant injuries. There were no bony or cartilaginous fractures, and 3 specimens showed minor mucosal tears in the anterolateral or inferior walls. Volumetric measurements of the cartilaginous ET lumens showed a change from an average of 0.16 to 0.49 cm 3 (SD, 0.12), representing an average increase of 357% (range, 20–965%).
Conclusions
Balloon catheter dilation of the nasopharyngeal orifice of the ET was shown to be feasible and without evidence of untoward injury. A significant increase in volume of the cartilaginous ET was achieved. A clinical study is now indicated to determine whether balloon dilation will demonstrate lasting benefits and safety in the treatment of otitis media.
1
Introduction
Advances in technology, combined with expanding knowledge of pathophysiology, are facilitating the development of minimally invasive interventions that are increasingly important and efficacious means of therapy that in most cases also reduce morbidity and expenses. Balloon dilation of stenotic or occluded lumina, although simplistic in concept, has contributed to remarkable advances in the fields of urologic, gastrointestinal, neurologic, vascular, and cardiac procedures with effective and remarkably durable results .
Balloon dilation of sinus ostia and recesses was introduced in 2005 with the hypothesis that it could provide lasting patency of ostia along with the advantages of minimizing tissue trauma, bleeding, and scarring . Using the balloon dilating catheter (Acclarent, Inc, Menlo Park, CA), 1-year patency rates of 91.6% and 2-year patient satisfaction results of 85%, with significant symptom improvement (Sino-Nasal Outcome Test 20 scores reduced from 2.17–0.87) and objective reduction of disease (Lund-MacKay score reduced from 9.66–2.69), have been reported. Revision sinus surgery rates for patients were 9.2% . As of 2008, the rate of major complications in patients treated with balloon sinuplasty technology, with or without accompanying endoscopic sinus surgery, was 0.01% .
It is possible that balloon dilation of the cartilaginous portion of the eustachian tube (ET) could produce similar benefits in the treatment of chronic otitis media with effusion (OME). Under normal circumstances, there is a roughly 8- to 12-mm segment in the middle of the cartilaginous ET that is closed at rest, with mucosal surfaces in apposition, and therefore functioning as a valve. The cartilaginous ET dilates to the open position on demand, particularly with swallows and yawns, because of the action of, first, the levator veli palatini (LVP) muscle, which rotates and maintains the posterior cushion (torus tubarius) medially, followed by tensor veli palatini (TVP) contraction that distracts the anterolateral wall laterally to open the valve for approximately 0.4 seconds . Tubal dilatory dysfunction is most commonly due to mucosal inflammation with swelling that limits or prevents dilation of the valve, causing insufficient ventilation of the middle ear . Partial resection of inflamed luminal mucosa, submucosa, and occasionally bulges in the cartilage, from the posteromedial wall, where the soft tissue is thickest, has been beneficial in approximately 50% of cases with severely persistent OME with 2-year follow-up . In patients with OME and sinus disease, this eustachian tuboplasty technique, combined with endoscopic sinus surgery, was effective in relieving symptoms in 70% . These early results support the concept that enlargement of the valve of the ET may facilitate the dilatory efforts of the TVP muscle and provide effective benefit for chronic OME.
Widening of the tubal valve could be accomplished by balloon dilation. It would be expected to deflect the posterior cushion medially, stretching the cartilaginous “hinge” between the mobile medial cartilaginous lamina, within the posterior cushion, and the roof of the ET, which is firmly fixed to the basisphenoid bone. The balloon would circumferentially compress and stretch the mucosa and submucosa. No attempt would be made to dilate the bony-cartilaginous isthmus because it is usually patent, even when OME is present . Furthermore, the dense temporal bone most likely would not be affected by the balloon; and the internal carotid artery comes to within a millimeter of the mucosa or can even be dehiscent within the bony portion of the ET. The purpose of this study was to investigate the feasibility and safety of performing balloon dilation of the cartilaginous ET before consideration of a human trial.
2
Methods
2.1
Hypothesis/research questions
Sinus balloon dilation catheters could be adapted to safely and effectively dilate the cartilaginous portion of the ET.
2.2
Aims/end points
Sinus balloon catheter technology was applied to human cadaver heads in a prospective acute procedural study with the following aims:
- 1.
To evaluate the feasibility of using the system for dilation of the cartilaginous portion of the ET.
- 2.
To evaluate the safety of the dilation procedure with an analysis of any potential adverse effects.
The primary end point of the study was the success or failure of tubal dilation and the occurrence of any adverse effects from the process.
2.3
Procedure design
Initial feasibility analyses were performed on embalmed human cadaver half heads, sagittally split in the midline, and computed tomography (CT) scans of patients with normal ears, patients with OME, and a fresh cadaver one-half head. From this work, a dilatory procedure was conceived using existing sinus balloon technology through a transnasal approach in which the catheter would be advanced into position over a guide wire. The trial procedures would be done first on one-half head specimens to facilitate postprocedure CT imaging and dissections. The procedure would then be evaluated in whole cadaver heads.
2.4
Procedure methods and study
Six frozen unembalmed adult human cadaver heads were divided in the midline sagittal plane and thawed for the procedure. Initial screening CT scans confirmed the absence of any ear or nasal pathology. Baseline CT scans (CereTom OTOscan; NeuroLogica Corporation, Danvers, MA) were obtained of each one-half head, placing it in the supine position and acquiring images in the axial plane with 0.625-mm slice thickness. Baseline endoscopic photographs of the nasopharyngeal orifice of the ET were obtained. Endoscopic visualization was performed with 0°- and 30°-angled, 4-mm–diameter Hopkins rod endoscopes fitted with a 3-chip CCD video camera (Karl Storz, Tuttlingen, Germany) and observed on a monitor with video and photographic capture capability. Instruments were introduced through the nasal cavity to simulate an actual surgical procedure to the maximum extent possible.
The sinus balloon dilation system (Acclarent, Inc) was used to dilate the cartilaginous portion of each ET. A curved guiding catheter with a tip angle of 70° was passed through the nasal cavity, and the tip was placed into the ET nasopharyngeal orifice. A Relieva Vigor sinus guide wire was inserted through the catheter into the ET lumen; and once engaged within the ET, it was advanced slowly under fluoroscopic guidance using a C-arm (GE OEC 9800, Fairfield, CT) through the bony isthmus approximately 5 mm into the temporal bone portion of the ET. The guiding catheter was removed, and another CT scan was performed with the wire in place to aid with identification of the cartilaginous tubal lumen and postprocedure image reconstruction. A 6- or 7-mm–diameter × 16-mm–length Relieva Solo sinus balloon catheter was slipped over the guide wire into the ET orifice until it reached resistance near the bony-cartilaginous isthmus. The balloon typically protruded from the tubal orifice about 2 to 3 mm. The guide wire was then removed. Once in position, the balloon was inflated to 12 atm for 1 minute, after which it was deflated and removed. In the event that a 7-mm balloon slipped out of the ET orifice into the nasopharynx during inflation, it was replaced with a 6-mm balloon; and the inflation was repeated. Careful endoscopic inspection of the postdilation tubal lumen for any evidence of injury was done with photographic documentation immediately after the procedure, and a CT scan was subsequently performed. The one-half head was then placed in a lateral decubitus position with the ET orifice facing upward; and the orifice was filled with Omnipaque contrast solution, 300 mg I − per milliliter (GE Healthcare, Princeton, NJ), to accurately visualize and quantify the final dilation dimensions and volumes. A final CT scan was obtained in this position.
Each specimen was carefully evaluated for any adverse effects from the dilation. Inspection of the lumen was done with the endoscope; and a complete survey of the mucosa was done, looking for any evidence of injuries. The posterior cushion was manipulated and rotated medially, looking for any unusual flexibility or increase in range of mobility. A careful and systematic gross dissection was performed making a circumferential mucosal incision around the tubal orifice and making a longitudinal cut along the inferior free margin of the medial cartilaginous lamina. Submucosal flaps were elevated extra- and intraluminally to reveal the entire medial and lateral cartilaginous laminae up to the bony-cartilaginous junction. Integrity of the cartilage and soft tissues was noted. Inspection was made of the TVP and LVP muscles, Ostmann fat pad, and pterygoid fossa.
A final feasibility trial of balloon dilation of the cartilaginous ET was performed in 2 unembalmed whole cadaver heads under endoscopic guidance. The dilation procedure was executed on each of the 4 ETs using a protocol modified from that in the one-half heads and without CT scans or postdilation dissections. It was found that it was easiest to place the guide wire into the balloon catheter, such that the wire protruded 5 mm from the distal tip of the catheter, and to introduce them together through the guide catheter. Once in position, the guide wire was removed; and the guide catheter was maintained in position to stabilize the balloon. After dilation, close endoscopic inspection was done to assess for any evidence of adverse effects, including a visual survey of the mucosa and palpation of the posterior cushion to inspect for excessive mobility ( Figs. 1–5 ).
Postprocedure CT scans from the one-half heads were reviewed in extensive detail for any evidence of bony fractures in the temporal bone, basisphenoid, or pterygoid plates. For the cartilaginous portion of the ET, lengths, cross-sectional areas with respective major and minor axis diameters at approximately 4-mm intervals, and volumes were computed using OsiriX software (OsiriX Foundation, Geneva, Switzerland) ( Fig. 6 ). In predilation scans, the ET was identified based on the location of the guide wire, which was left in place for the initial set of predilation scans. Once the location had been determined, measurements were completed on an identical set of predilation scans taken with the wire removed. For the postdilation scans, the ET was identified based on the radiopaque contrast that had been poured into ET orifice. Measurements were also completed on the postdilation scans with the contrast present. For both the pre- and postdilation scans, the midpoint of the ET was identified on each axial slice and tagged in OsiriX. The ET lengths were determined from the anterior-inferior–most point of the posterior cushion (torus tubarius) to the bony isthmus as the ET entered the temporal bone. A curvilinear line representing the longitudinal axis of the ET was created by following the identified midpoints from the orifice to the bony-cartilaginous junction. The curvilinear lines became the basis to create 2-dimensional curved multiplanar reconstructions containing the line, from which the length of the longitudinal axis could be measured, and perpendicular to the line, from which cross-sectional areas and major/minor axes were measured ( Figs. 7 and 8 ). Volumes were calculated by manually outlining a region of interest on each axial slice and using the volume estimation function to interpolate between slices.
Statistical analysis was done with SPSS 16.0 statistical software (Espoo, Finland) with 2-tailed paired-samples tests performed using P < .05 for significance.
2
Methods
2.1
Hypothesis/research questions
Sinus balloon dilation catheters could be adapted to safely and effectively dilate the cartilaginous portion of the ET.
2.2
Aims/end points
Sinus balloon catheter technology was applied to human cadaver heads in a prospective acute procedural study with the following aims:
- 1.
To evaluate the feasibility of using the system for dilation of the cartilaginous portion of the ET.
- 2.
To evaluate the safety of the dilation procedure with an analysis of any potential adverse effects.
The primary end point of the study was the success or failure of tubal dilation and the occurrence of any adverse effects from the process.
2.3
Procedure design
Initial feasibility analyses were performed on embalmed human cadaver half heads, sagittally split in the midline, and computed tomography (CT) scans of patients with normal ears, patients with OME, and a fresh cadaver one-half head. From this work, a dilatory procedure was conceived using existing sinus balloon technology through a transnasal approach in which the catheter would be advanced into position over a guide wire. The trial procedures would be done first on one-half head specimens to facilitate postprocedure CT imaging and dissections. The procedure would then be evaluated in whole cadaver heads.
2.4
Procedure methods and study
Six frozen unembalmed adult human cadaver heads were divided in the midline sagittal plane and thawed for the procedure. Initial screening CT scans confirmed the absence of any ear or nasal pathology. Baseline CT scans (CereTom OTOscan; NeuroLogica Corporation, Danvers, MA) were obtained of each one-half head, placing it in the supine position and acquiring images in the axial plane with 0.625-mm slice thickness. Baseline endoscopic photographs of the nasopharyngeal orifice of the ET were obtained. Endoscopic visualization was performed with 0°- and 30°-angled, 4-mm–diameter Hopkins rod endoscopes fitted with a 3-chip CCD video camera (Karl Storz, Tuttlingen, Germany) and observed on a monitor with video and photographic capture capability. Instruments were introduced through the nasal cavity to simulate an actual surgical procedure to the maximum extent possible.
The sinus balloon dilation system (Acclarent, Inc) was used to dilate the cartilaginous portion of each ET. A curved guiding catheter with a tip angle of 70° was passed through the nasal cavity, and the tip was placed into the ET nasopharyngeal orifice. A Relieva Vigor sinus guide wire was inserted through the catheter into the ET lumen; and once engaged within the ET, it was advanced slowly under fluoroscopic guidance using a C-arm (GE OEC 9800, Fairfield, CT) through the bony isthmus approximately 5 mm into the temporal bone portion of the ET. The guiding catheter was removed, and another CT scan was performed with the wire in place to aid with identification of the cartilaginous tubal lumen and postprocedure image reconstruction. A 6- or 7-mm–diameter × 16-mm–length Relieva Solo sinus balloon catheter was slipped over the guide wire into the ET orifice until it reached resistance near the bony-cartilaginous isthmus. The balloon typically protruded from the tubal orifice about 2 to 3 mm. The guide wire was then removed. Once in position, the balloon was inflated to 12 atm for 1 minute, after which it was deflated and removed. In the event that a 7-mm balloon slipped out of the ET orifice into the nasopharynx during inflation, it was replaced with a 6-mm balloon; and the inflation was repeated. Careful endoscopic inspection of the postdilation tubal lumen for any evidence of injury was done with photographic documentation immediately after the procedure, and a CT scan was subsequently performed. The one-half head was then placed in a lateral decubitus position with the ET orifice facing upward; and the orifice was filled with Omnipaque contrast solution, 300 mg I − per milliliter (GE Healthcare, Princeton, NJ), to accurately visualize and quantify the final dilation dimensions and volumes. A final CT scan was obtained in this position.
Each specimen was carefully evaluated for any adverse effects from the dilation. Inspection of the lumen was done with the endoscope; and a complete survey of the mucosa was done, looking for any evidence of injuries. The posterior cushion was manipulated and rotated medially, looking for any unusual flexibility or increase in range of mobility. A careful and systematic gross dissection was performed making a circumferential mucosal incision around the tubal orifice and making a longitudinal cut along the inferior free margin of the medial cartilaginous lamina. Submucosal flaps were elevated extra- and intraluminally to reveal the entire medial and lateral cartilaginous laminae up to the bony-cartilaginous junction. Integrity of the cartilage and soft tissues was noted. Inspection was made of the TVP and LVP muscles, Ostmann fat pad, and pterygoid fossa.
A final feasibility trial of balloon dilation of the cartilaginous ET was performed in 2 unembalmed whole cadaver heads under endoscopic guidance. The dilation procedure was executed on each of the 4 ETs using a protocol modified from that in the one-half heads and without CT scans or postdilation dissections. It was found that it was easiest to place the guide wire into the balloon catheter, such that the wire protruded 5 mm from the distal tip of the catheter, and to introduce them together through the guide catheter. Once in position, the guide wire was removed; and the guide catheter was maintained in position to stabilize the balloon. After dilation, close endoscopic inspection was done to assess for any evidence of adverse effects, including a visual survey of the mucosa and palpation of the posterior cushion to inspect for excessive mobility ( Figs. 1–5 ).
