ORIGINAL ARTICLE. The Yung Percutaneous Mastoid Vent. middleearcanleadtovariouspathologicconditions,

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1 The Yung Percutaneous Mastoid Vent A Medium-Term Follow-up Study Matthew Man-Wah Yung, PhD, FRCS, DLO ORIGINAL ARTICLE Background: I designed a percutaneous mastoid vent to provide permanent ventilation to the middle ear. The vent consists of an outer titanium tube that osseointegrates with the mastoid bone and an inner Teflon tube that protrudes into the mastoid antrum. Objective: To follow up all patients who had the mastoid vent inserted since Study Design and Setting: Retrospective study of 14 patients with mastoid vents inserted at the ear, nose, and throat clinic of a district general hospital. Patients: All patients had ventilation problems of the ear that failed to respond to conventional treatment. Three patients had persistent otitis media ; 10 had completely collapsed eardrums; and 1 had failed tympanoplasty with recollapsed eardrum. Intervention and Outcome Measure: The mastoid vent extrusion rate, surrounding skin reaction, patency of the vent, and functional results were assessed with a follow-up period of 9 to 36 months. Results: Only 1 vent was extruded in a patient who had a previous cortical mastoidectomy. There was no dermatitis around any of the vents. All vents remained patent, and 9 of the 14 ears underwent successful ventilation. Four ears had adhesions within the mastoid antrum, mainly due to a previous cortical mastoidectomy. Six of 8 ears with intact ossicles also had improved hearing. Conclusion: The percutaneous mastoid vent can provide medium-term ventilation to the middle ear. Arch Otolaryngol Head Neck Surg. 1999;125: From the Ipswich Hospital NHS Trust, Ipswich, Suffolk, England. NEGATIVE pressure in the middleearcanleadtovariouspathologicconditions, such as otitis media with effusion (OME), atelectasis,orcholesteatoma. 1 Todate,themaintreatment is still insertion of a ventilating tube through the tympanic membrane. However, these tubes often extrude from the ear and need to be replaced repeatedly if there is a long-term ventilation problem of the middle ear. Numerouslong-stayingventilatingtubes can provide long-term ventilation to the middle ear. However, these tubes also have a high rate of extrusion from the ear. 2 Moreover, conventional ventilating tubes are situated in the ear canal and have the same risk of the tube being blocked by crust and the inconvenience of having to keep water away from the ear. I designed the Yung percutaneous mastoid vent with Nobel Biocare in 1994 to provide permanent ventilation to the middle ear cleft without having to put a tube through the tympanic membrane. 3 The vent is a percutaneous device that can be inserted into the mastoid antrum, allowing air to get into the middle ear through the aditus and epitympanum. The vent consists of an outer titanium tube and an inner Teflon tube. The outer titanium tube is inserted through the skin into the mastoid antrum using the established technique of osseointegration and hence becomes truly permanent. 4 The inner Teflon tube protrudes beyond the bottom end of the titanium tube into the mastoid antrum and keeps the system patent by preventing the lining of the mastoid antrum from growing over the bottom of the mastoid vent (Figure 1). The inner tube can be removed for cleaning purposes and replaced easily. It has an outer flange to prevent it from sliding too deep into the lumen of the outer titanium tube. The outer titanium tube has an internal thread that allows it to be connected to external devices so that extra air or pressure can be delivered into the middle ear cleft if required. Patients can still enjoy water sports by simply capping the vent at the outer end. This article is a report of more than 9 months of follow-up of patients I treated since

2 PATIENTS, MATERIALS, AND METHODS The new treatment of percutaneous mastoid ventilation was approved by the East Suffolk District Research Ethics Committee in Between 1995 and 1997, I performed 14 Yung mastoid vent operations on patients aged 8 to 67 years. Three operations were performed on ears with persistent OME, despite repeated ventilating tube insertions; 10 were for a completely collapsed eardrum; and 1 was for failed tympanoplasty that was judged to be due to persistent eustachian tube blockage, which resulted in a retraction of the eardrum and extrusion of the ossicular prosthesis. INSERTION TECHNIQUE A preoperative computed tomographic scan of the temporal bone was obtained to assess the level of dura and size of the mastoid antrum. Extreme care was taken during the insertion of the vent if low dura was identified on the scan. A needle dipped in methylene blue was used to make a tattoo mark on the mastoid bone underneath the desired site of skin penetration; in all cases the conchal area just below the crura of the antihelix. A postauricular incision was made, and an inferiorly based periosteal flap was elevated to expose the underlying mastoid bone. Any necessary tympanoplasty was performed before the vent was inserted. A 2-mm cutting burr was used initially to create a bony tunnel from the surface of the mastoid bone (at the methylene blue tattooed mark) into the mastoid antrum. Care was taken to not damage the dura and sigmoid sinus. The bony tunnel was then enlarged to a 3-mm diameter using a 3-mm spiral burr. Vigorous irrigation with saline was performed during the drilling procedure to prevent heat damage to the bone. 5 A 2.7-mm, 30 rigid endoscope was inserted into the bony tunnel to inspect the mastoid antrum. At low-speed, tapping (threading of the bony tunnel) was performed with a titanium screw tap, again accompanied by saline irrigation. The Yung mastoid vent was then inserted using a specially designed hand tool (Figure 2). Care was taken to not overtighten the mastoid vent in order to avoid damage to the bony threads. To ensure a permanent reaction-free skin penetration, the conchal cartilage and soft tissue under the skin at the conchal region adjacent to the penetration site were removed. A small cuff of skin at the site of the skin penetration was excised to allow the mastoid vent to pass through. The skin penetration site should be just beneath the crura of the antihelix at the conchal region. The inner Teflon tube was then inserted to prevent blood from clogging the outer tube during the postoperative period. POSTOPERATIVE CARE During the postoperative period, the patients or their parents were given instructions to keep the implant site clean, similar to the advice given for patients with boneanchored hearing aids. 6 The inner tube was replaced, and the patients were provided with a fine-bore catheter connected to a pipette bulb to allow them to aspirate any mucus or blood that was trapped in the inner tube. Five of the patients had a previous cortical mastoidectomy, and hence it was not possible for the Yung mastoid vent to be inserted through a proper bony tunnel. Instead, the vent was inserted through a bony groove, with bone surrounding at least three quarters of the circumference of the titanium tube. All patients were included in the study group, even those who had a previous cortical mastoidectomy, and were followed up for 9 to 36 months. Any mobility or extrusion of the vent and skin reaction around the vent were noted. The patients were asked about the discomfort level and cosmetic acceptability of the vent. The patency of the Yung mastoid vent was confirmed by putting air through the vent and observing either a movement of the eardrum or an escape of air through the eustachian tube the air insufflation test. For each patient, the appearance of the eardrum and hearing level before and after the treatment were also documented. Figure 1. The Yung vent, with outer titanium and inner Teflon tubes. RESULTS The indication of operation, history of mastoidectomy, ossicular status, length of follow-up, middle ear ventilation, and complications for each patient are illustrated in Table 1. Results of the Yung mastoid vent operation can be summarized as follows. Figure 2. Special hand tool for inserting the Yung mastoid vent. MOBILITY OR EXTRUSION OF THE IMPLANTED VENT Of the 14 vents inserted, 1 extruded after 6 months in a patient who had a previous cortical mastoidectomy and hence had inadequate bone surrounding the vent. All other vents were stable and immobile. 965

3 Table 1. Indication for the Yung Mastoid Vent Operation, Length of Follow-up, Ossicular Status, Functional Result, and Complications in Each Patient Patient No. Age, y Follow-up Period, mo Indication for Operation Otitis media History of Cortical Mastoidectomy Ossicular Status Ventilation of Middle Ear No Intact Yes None Complication Atelectasis No Intact Yes None Atelectasis No Intact Yes Subcutaneous tissue overgrowth Atelectasis No Intact Yes None Atelectasis No Intact Yes None Atelectasis Yes Intact No Subcutaneous tissue overgrowth; adhesive otitis media Otitis media Yes Intact No None Otitis media Yes Intact No Extruded at 6 mo Atelectasis Yes Incus eroded Yes None Failed tympanoplasty; atelectasis Yes Incus and Yes 1 Episode of discharge (transient) Atelectasis No Incus and No Subcutaneous tissue overgrowth Atelectasis No Incus eroded Yes None Atelectasis No Incus eroded Yes None Atelectasis No Incus and No None SKIN REACTION There was no dermatitis or excoriation of skin around any Yung mastoid vent. However, 3 patients (2 children and 1 adult) had skin prolapsed over the outer end of the vent due to inadequate soft-tissue removal during the initial operation, requiring further reduction of the subcutaneous tissue around the vent. There was no perichondritis in any patient. OTITIS MEDIA There was 1 episode of discharge through the vent in a patient following an upper respiratory tract infection. This resolved quickly with oral antibiotics, and the vent remained patent after the inner tube was changed. ACCEPTANCE BY PATIENTS AND PARENTS The vents were well accepted by all patients and their parents regarding their aesthetic appearance and discomfort (Figure 3). PATENCY OF THE YUNG MASTOID VENT The patency of only 13 of 14 vents was assessed since 1 vent extruded after 6 months. All vents were patent. However, only 9 vents were functioning, which was confirmed by the entry of air from the vent into the middle ear. The other 4 ears had fibrous adhesions within the mastoid antrum, which was confirmed on surgical exploration of the ears. Of these 4 ears, 2 had a previous cortical mastoidectomy, which could explain the fibrous adhesions within the mastoid antrum. FUNCTIONAL RESULTS Eight of the 9 functioning vents were on ears with a previously collapsed eardrum, and were reinflated following the operation and remained so throughout follow-up (Figure 4 and Figure 5). The other functioning vent was on an ear with persistent OME, which did not recur after the Yung mastoid vent was inserted. Six of the 14 ears in this study also had an ossicular defect that required ossiculoplasty at the time of vent insertion. Therefore, it was inappropriate to present these hearing results since they also depend on the outcome of ossiculoplasty. Hence, only the hearing results of 8 ears that had intact ossicular chains are presented (Table 2). Six of these 8 ears had an improvement of hearing, mainly from the resolution of the OME or reinflation of the collapsed eardrum. The patient whose vent extruded has since had a recurrence of OME. One patient had a further deterioration of hearing due to adhesive otitis media after the operation. COMMENT The Yung mastoid vent is not designed to replace conventional ventilation tubes. These simple-to-use tubes should always be used first. However, there are some patients who cannot benefit from a conventional tube, such as those with atrophic and collapsed eardrums that cannot keep a conventional tube in place. The vent might 966

4 Figure 5. Same ear that appears in Figure 4, nine months after insertion of the Yung vent. The collapsed eardrum is reinflated. Table 2. Hearing Results Following the Yung Mastoid Vent Operation on 8 Ears That Had Intact Ossicular Chains Figure 3. Ear with the Yung vent inserted 16 months previously. Figure 4. Ear with a completely collapsed eardrum. be a useful treatment in these cases. It has the advantage over a conventional long-staying tube in that it osseointegrates with bone and can be connected to external devices. Not only would it work as a permanent vent, but it also opens up many diagnostic and therapeutic potentials. The vent could act as a channel through which middle-ear gas content and pressure can be sampled and measured. It can even allow a microendoscope to pass through to examine the mastoid antrum. Furthermore, extra air or pressure can be delivered to the middle ear to reinflate a collapsed eardrum. Patient No. Follow-up Period, mo Preoperative Hearing Level, db* Postoperative Hearing Level, db* *Four tone average at 0.5, 1, 2, and 3 khz. This vent was extruded after 6 months. The Yung mastoid vent detailed in this study is a second prototype. The first prototype consisted of just the outer titanium tube without an inner Teflon tube. It was used on 4 patients, but the tubes were all blocked at the bottom end since titanium is so biocompatible that it allows fibroblasts to grow over its surface. The inner Teflon tube was subsequently incorporated into this second prototype, which keeps the system patent and easily replaceable to overcome any blockage from crust or old blood trapped inside. However, for the vent to provide adequate ventilation to the mesotympanum, the channel between the mesotympanum and the mastoid antrum, including the aditus, epitympanum, and tympanic isthmus, must be patent. Therefore, any adhesions or blockage in these areas, which occurred in 4 patients in this study, could affect the efficacy of the vent. Three patients in this study required further reduction of the subcutaneous tissue around the Yung mastoid vent because of inadequate removal during the initial operation. These patients were enrolled in the early part of the study, and such a problem was not encountered with subsequent patients. Similar to users of bone anchor hearing aids, it is essential that the skin around the vent be kept clean by the patient to avoid crusting and dermatitis. It was also observed that mucus often accumulates inside the inner tube, and hence regular aspiration was necessary to maintain its patency. 967

5 Any permanent device needs to stand the test of time. This article represents a medium-term follow-up of patients in whom all conventional treatments had failed. The conventional treatment of a completely collapsed eardrum has been particularly disappointing. It has been reported that more than 50% of completely atelectatic eardrums will eventually recollapse. 7 Hence, the most encouraging result of this study is that all atelectatic eardrums were reinflated. I regard the Yung mastoid vent as effective only if it can remain patent and provide long-term ventilation to the middle ear. The air insufflation test is considered a reliable assessment. The impedance test was not as useful since most ears in this study had a reenforcement tympanoplasty using cartilage, which can result in a thick eardrum and a flat impedance curve. So far, the results of using the Yung mastoid vent seem encouraging. However, a longer follow-up period involving a multicenter trial is warranted. Accepted for publication January 25, I thank Patrik Johannson, MSc, and Lennart Carlsson, MSc, of the Department of Research and Development, Nobel Biocare AB, Sweden, for providing support and help in the design and supply of the Yung mastoid vent. Reprints: Matthew Man-Wah Yung, PhD, FRCS, DLO, The Ipswich Hospital NHS Trust, Heath Road, Ipswich, Suffolk IP5 4PD, England ( yung@doctors.net.uk). REFERENCES 1. Cohen-Boulakia J, Hadas E, Sade J, et al. Intra-tympanic gas-pressure in cases of SOM and atelectasis. Acta Otolaryngol. 1981;93: Matt BH, Miller RL, Meyers RM, et al. Incidence of perforation with Goode T- tube. Int J Pediatr Otorhinolaryngol. 1991;21: Yung MW. Permanent mastoid vent: a new treatment for persistent Eustachian tube blockage. Clin Otolaryngol. 1998;23: Branemark PI, Adell R, Breine U, et al. Intra-osseous anchorage of dental prosthesis, I: experimental studies. Scand J Plast Reconstr Surg. 1969;3: Eriksson RA, Albrektsson T. The effect of heat on bone regeneration: an experimental study in the rabbit using the bone growth chamber. J Oral Maxillofac Surg. 1984;42: Holgers KM, Tjellstrom A, Erlandsson BE, et al. Soft tissue reactions around percutaneous implants: a clinical study of soft tissue conditions around skinpenetrating titanium implants for bone-anchored hearing aids. Am J Otol. 1988; 9: Yung, MW. Retraction of the pars tensa: long term results of surgical treatment. Clin Otolaryngol. 1997;22: