Canal atresia reconstruction with dental impression material

Canal Atresia Reconstruction Impression Material

With Dental

Peter C. Weber, MD, Betsy Davis, DMD, MS, and Warren Y Adkins, Jr, MD Medium-density viscosity dental impression material has recently been used after repair of an atretic canal to stent open the newly created external auditory canal for 2 weeks, followed by a hard acrylic stent. This may provide more benefits than traditional packing, but caution must still be used. We recently have used the dental impression material to help in the reconstruction of seven ear canals. The medium-viscosity impression material hardens quickly and provides a solid, nonmobile stent, which usually pulls out without difficulty. The stent that is removed may then be used by our prosthodontist to fashion a hard, acrylic, removable stent to be worn for the next few months. This hard stent is used to prevent further stenosis. As with any technique, complications may arise and, through experience, common mistakes that can hinder a good outcome can be avoided. We will report six cases with illustrated tips on how to avoid complications when using this technique. (Am J Otolat-yngol 1999;20:236-240. Copyright 0 1999 by W.B. Saunders Company)

(Editor’s Comment: The authors demonstrate innovative methods to deal with the complex and difficult issue of recurrent stenosis after reconstruction of the external auditory canal.)

Stenosis or atresia of the external auditory canal (EAC) may be congenital, acquired, or iatrogenic. Congenital EAC atresia or stenosis occurs in 1 in 10,000 to 1 in 20,000 live births, and it may associated with microtia or inner ear abnormalities. It is unilateral three to five times more often than bilateral disease.lj2 Acquired stenosis of the EAC may be due to exostosis, chronic infection, or trauma (such as temporal bone fractures resulting from motor vehicle accidents or gunshot wounds). Depending on the cause, surgical repair of the stenosis/atresia can be successful. The most common complication after surgical repair, however, is restenosis or significant tympanic membrane (TM) lateralization. In congenital atresia cases, Chandrasekhar3 reports a 30% restenosis/lateralization rate, which is similar to other reports.‘f4 Repair of acquired stenosis caused by infection has slightly better success, with a 10% to 20% restenosis rate,5z6a7 From the Department of Otolaryngology, Medical Universitv of South Carolina. 171 Ashlev Ave, Charleston, SC. . Address reorint reauests to Peter C. Weber. MD. Department df Otolaryngology, Medical University of South Carolina. 171 Ashlev Ave. Charleston. SC 29425. Copyright 0~ i 999 by W.fi. Saunders Company 0196-0709/99/2004-0007$10.00/0 236

American

Journal

of Otolaryngology,

Vol20,

but nonetheless, it is still the most common complication. Unfortunately, there appears to be no large series evaluating repair of stenosis due to trauma, but one may assume that restenosis/lateralization is of primary concern. Prevention of restenosis is important in successful atresia/stenosis repair. Thin splitthickness skin grafts (STSG) heal better than full-thickness grafts.8 Stenting or packing materials to keep the EAC open immediately after surgical repair require Merocel (Xomed, Jacksonville, FL) or Ambrose wicks (Xomed),3 Owens silk with cotton balls,7 or NuGauze (Johnson & Johnson, Fort Washington, PA) with Bacitracin (Warner Lambert Consumer, Morris Plains, NJ) ointment.g A thick Silastic button is then placed over the new skingrafted TM to prevent lateralization.2s10 Unfortunately, this still leads to a high restenosis rate. Our experience with restenosis is comparable to that reported in the literature. To decrease this rate, the use of long-term stents was implemented. These stents are hard acrylic made of methyl methacrylate, with an internal opening so that medicated drops can be instilled. To assist the making of the hard stent, a dental molding compound (Reprosil; Henry Schein, Port Washington, NY, medium viscosity) was used to make an impression of the canal. We describe six cases and how we have used the dental impression material and the hard acrylic stents (Table 1). No 4 (July-August),

1999:

pp 236-240

CANAL

ATRESIA

TABLE1. Stents

Were

RECONSTRUCTION

Summary Used

of Seven

Cases

237

in Which

Acrylic

Patient

Reprosil for Impression

Time Acrylic Stent Worn

Postoperative Time With No Recurrence (mo)

1 right 1 left 2 3 4 5 6

Yes Yes Yes No Yes Yes Yes

6mo 6mo 4mo 5mo Days 3mo 3mo

36 24 16 20 None 14 17

Case 1 A 5-year-old girl with bilateral congenital atresia was evaluated for possible EAC reconstructive surgery. Evaluation showed the child to be a good candidate for reconstructive surgery, which she underwent. After securing the STSG on the new TM with a sheet of Silastic, two pieces of Gelfoam were placed, and the STSG was secured laterally with sutures at the new meatus. The dental molding compound, Reprosil (medium viscosity), was then used to stent open the canal (Fig 1) with a cotton applicator stick placed in the middle for firture removal. The Reprosil stent was removed 2 weeks after surgery. It should be noted that the mold was difficult to remove because the meatus had grown over the original opening in such a way that there was a slight bottleneck at the meatus. Although the Reprosil was removed, it was not a comfortable experience for this child. A hard acrylic stent was then fashioned from the Reprosil mold (Fig 2). This stent was worn for approximately 2 to 4 weeks, and the child had a patent canal and a mobile TM. Unfortunately, the EAC restenosed approximately halfway between the meatus and the TM, producing an hourglass appearance of the EAC. This occurred within 2 months after removal of the hard acrylic stent. The patient subsequently underwent a second procedure. This time, NuGauze, soaked with Bacitracin, was used to stent open the EAC. After 2 weeks, this packing was removed, and Reprosil was used to form a mold of the ear canal. This mold was then used as a template for the making of the hard acrylic stent. The child wore this stent for 6 months. Three years later, the EAC was patent with a mobile TM and closure of the air/bone gap. The second ear was operated

on 1 year after the first surgery in a similar manner. After almost 2 years, there has been no restenosis. Case 2 A 3-year-old boy with bilateral atresia, along with unilateral microtia, presented with significant hearing loss as well as poor speech and language development. The child either could not, or would not, wear bone conduction hearing aids. Computed tomography scan demonstrated complete atresia of the EAC on the left, along with the microtia and atresia of the EAC on the right, but an aerated middle ear space, and an aberrant facial nerve course. Although repair is usually deferred until 5 to 6 years of age, we proceeded with surgical correction in this child, with the hope of enhancing hearing and allowing the use of a conventional hearing aid. NuGauze packing with Bacitracin was used to stent the EAC open at the time of surgery. Two weeks later, the pack was re-

Figl. Reprosil is loaded into through the red rubber catheter cotton applicator is broken in instrument with which to pull out

the syringe; it flows out in the ear canal, and a half and used as the the Reprosil.

238

WEBER,

DAVIS,

AND

ADKINS

Fig 2. Hard acrylic stent is used to stent open the EAC.

moved. At that time, Reprosil was inserted into the EAC to make an impression of the canal. The stent served as a template for the formation of a custom acrylic stent of the EAC. Unfortunately, the patient did not wait for the stent to be made in the office, and returned 4 weeks later. On return, the patient had developed some lateralization and mild restenosis. The stent was adjusted for the new dimensions of the canal. He wore this stent for 4 months. Although the TM is slightly lateralized, he is now able to wear a conventional hearing aid, which is helping him with his speech and language development. After 16 months, he has not had any further stenosis but refuses further surgical intervention. Case 3 A g-year-old girl with unilateral congenital EAC atresia underwent repair of congenital atresia and was stented open at the time of surgery with NuGauze packing and a Silastic button over the TM. After removing the NuGauze packing in the office, an acrylic stem was placed. Reprosil was not used to make an impression of her EAC; rather, the size of the stent was just estimated. This took 8 revisions before a suitable stent was produced. Without the use of the dental molding template, the time to manufacture the stent increased, thus requiring extra patience of all involved parties and adding to the final cost. After wearing the stent for 5 months, a patent canal was formed. However, the use of the Reprosil mold would have provided a template, and the stent could have been made more efficiently and less expensively.

Case 4 A 25-year-old man involved in a motor vehicle accident developed a complete EAC stenosis. The repair was facilitated by STSG and was stented open with Reprosil at the time of surgery. The patient returned 2 weeks after surgery for removal of the mold, but when the cotton applicator stick was removed, the Reprosil mold broke in half. This left a portion of the stent lodged in the EAC, which was then removed with great difficulty. Thinking that the EAC was patent, a long-term stent was not placed. However, this patient’s EAC subsequently restenosed, and he had to undergo revision, this time with an acrylic stent. The patient removed the stent on his own after 2 days, and has not returned for follow-up. Case 5 A g-year-old girl was shot in the temporal bone, causing complete stenosis of the EAC as well as other facial injuries. During repair of the facial injuries, the canal was also repaired. Reprosil was used to make a mold of the newly fashioned canal at the time of surgery and was removed immediately in the operating room. The EAC was then packed with NuGauze soaked with Bacitracin. This mold was then used to fashion an acrylic stent, which was placed 2 weeks later, after the packing had been removed in the office. This stent has provided an open EAC for 3 months. The EAC remains patent 14 months after the operation. Case 6 A 39-year-old woman who had a microtia and congenital EAC stenosis that had been

CANAL

ATRESIA

RECONSTRUCTION

repaired unsuccessfully many times in the past presented to us for reconstructive surgery. The remaining auricular cartilage was removed for the positioning of Branemark (Nobel Biocare, Westmont, IL) implants to have a prosthetic ear placed, and the ear canal was then enlarged and stented open with a STSG and Reprosil. The Reprosil mold was removed 2 weeks later, revealing a patent canal. A hard acrylic stent was fashioned and left in place for approximately 3 months, after which it was removed. Her canal has remained patent for the last 17 months. DISCUSSION Preventing restenosis or lateralization after repair of a congenital EAC atresia or an acquired atresia is of paramount importance for success. Many techniques have been used to limit the complication of restenosis, but the rate is still high at 30%.‘s3s4 Because restenosis may occur up to 12 months after surgery,3 long-term stenting was felt to be beneficial in the prevention of restenosis/lateralization. The ear canal cannot be packed shut indefinitely with gauze packing or Merocel wicks, as this would not only lead to poor healing, otitis externa, or an EAC fungal infection, but it would also hamper hearing. Stenting the EAC with a hard acrylic stent, which is hollow and open down the center, was believed to be a good alternative. This allows aeration, the ability to hear, and a conduit for medicated ear drops. In the last 2 years, we have used the stent successfully for EAC stenosis and atresia

239

repair 7 times. In the few cases where restenosis occurred, the acrylic stent was not used at all or not long enough (Cl month). We recommend using the stent for at least 3 and up to 6 months. The stent is removed and cleaned periodically by the physician and, once healing of the canal has occurred, may even be performed by family members. We are fortunate to have access to a prosthodontist, who is able to manufacture the stents. It is helpful to have a template of the EAC in order to make these stents. Reprosil was used not only to facilitate the manufacturing of the acrylic stent, but to also serve as a stent to open the EAC after surgery for the first 2 weeks. We had problems with removing Reprosil after using it in this manner, and we do not recommend this use at this time. The problems occur because, as the impression material is setting, the EAC is able to constrict, thus causing the medial portion of the EAC to be wider than the lateral portion of the EAC. However, using Reprosil either at the time of surgery to make an impression and removing it immediately, or doing it in the office after the removal of the NuGauze packing, has not had any adverse effects on our patients’ care. We have not tried molding compounds other than Reprosil, such as those used to take impressions for hearing aids or thermoplastic impression compound. It is quite possible that they would work just as well. We used medium-viscosity Reprosil. The gun that is used to mix the two compounds to form this is rather bulky and would be difficult to use and

240

squirt the compound into the EAC properly. Thus, we have adapted it with a red rubber catheter on the end, which can fit nicely down into the EAC to the TM (Fig 3). The mixture can then be adequately distributed throughout the EAC. A cotton-tip applicator stick is then placed in the middle of this, to have a handle on the mold making it possible to pull it out. SUMMARY We believe that the use of hard acrylic stents facilitates the prevention of restenosis of the EAC and the Reprosil impressions help our prosthodontist make the correct size/shape stent. REFERENCES 1. Jahrsdoerfer RA: Congenital atresia of the ear. Laryngoscope 8&l-48,1978 (suppl13) 2. De la Cruz A, Chandrasekhar SS: Congenital malformation of the temporal bone, in Brackmann DE, Shelton C,

WEBER,

DAVIS,

AND

ADKINS

Arriaga M (eds): Otologic Surgery. Philadelphia, PA, Saunders, 1994, pp 69-84 3. Chandrasekhar SS, De la Cruz A, Garrido E: Surgery of congenital aural atresia. Am J Otol16:713-717,1993 4. Bauer GP, Wiet RJ, Zappia JJ: Congenital aural atresia. Laryngoscope 104:1219-1X24,1994 6. McDonald TJ, Facer GW, Clark JL: Surgical treatment of stenosis of the external auditory canal. Laryngoscope 96:830-833,1986 6. Tos M, Balle V: Postinflammatory acquired atresia of the external canal: Late results of surgery. Am J Otol 7:365-370,1986 7. Cremers WR, Smeets JH: Acquired atresia of the external auditory canal: Surgical treatment and results. Arch Otolaryngol Head Neck Surg 119:162-164, 1993 8. De la Cruz A, Linthicum FH Jr, Luxford WM: Congenital atresia of the external auditory canal. Laryngoscope 95:421-427,1985 9. Cressman WR, Pensak ML: Surgical aspects of congenital aural atresia. Otolaryngol Clin North Am 27:621633,1994 10. Schuknecht HF: Congenital aural atresia and congenital middle ear cholesteatoma, in Nadol JB, Schuknecht HF (eds): Surgery of the Ear and Temporal Bone. New York, NY, Raven, 1993, pp 263-274