Incus Footplate Assembly: Indication and Surgical Outcome

Transcription

1 The Laryngoscope VC 2016 The American Laryngological, Rhinological and Otological Society, Inc. Incus Footplate Assembly: Indication and Surgical Outcome Mina Park, MD; Sungjun Han, MD; Byung Yoon Choi, MD, PhD; Sun O Chang, MD, PhD; Chong Sun Kim, MD, PhD; Ja-Won Koo, MD, PhD Objectives/Hypothesis: To review surgical findings and hearing outcomes of incus footplate assembly (IFA) for the patients with conductive hearing loss due to missing stapes superstructure with a mobile stapes footplate. Study Design: Retrospective case review and survey. Methods: Pre- and postoperative audiometric data and intraoperative findings were reviewed. Postoperative air-bone gap () and closure (postoperative air-conduction threshold preoperative bone-conduction threshold) were analyzed. Results: The causes of missing stapes superstructure and conductive hearing loss were congenital ossicular (n 5 5), chronic otitis media (n 5 2), and congenital cholesteatoma (n 5 1). The prosthesis was designed to fit between the medial side of the incus and stapes footplate and had a mean length of mm. The mean pre- and postoperative were and db, respectively. The postoperative at frequencies of 0.25, 0.5, 1.0, 2.0, 3.0, and 4.0 khz were , , , , , and db, respectively. The mean closure was 9.5 db (range, db). Seven cases obtained the best results (mean closure 10 db). In the remaining patient, the mean closure was 9.5 db until 6 months after surgery, but was 35.8 db 1 year after surgery. Conclusions: IFA seems to be a reasonable surgical option in patients with missing the stapes superstructure, but with a mobile footplate in which the long process of incus is preserved. Key Words: Conductive hearing loss, ossicular replacement, ossicular, surgery, indication. Level of Evidence: 4 Laryngoscope, 126: , 2016 INTRODUCTION The goals of an exploratory tympanotomy in conductive hearing loss are to check for ossicular chain disruption or fixation limiting ossicular mobility, and then to reconstruct the ossicular chain to restore functional hearing with a minimal air-bone gap (). 1,2 Once any pathology causing a conductive component is found in the middle ear, the ossicular chain can be reconstructed after removing the diseased ossicles or releasing any ossicular fixation. 3,4 When a stapes superstructure is missing but the remaining footplate mobility is intact, a total ossicular replacement prosthesis (TORP) is frequently used as a Additional Supporting Information may be found in the online version of this article. From the Department of Otorhinolaryngology Head and Neck Surgery and Healthcare Research Institute (M.P.), Seoul National University Hospital, Healthcare System Gangnam Center, Seoul, Korea; Department of Translational Biomedical Research (M.P.), Seoul National University College of Medicine, Seoul, Korea; Department of Otorhinolaryngology Head and Neck Surgery (S.H., B.Y.C., C.S.K., J.-W.K.), Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea; Department of Otorhinolaryngology Head and Neck Surgery (S.O.C.), Sungkyunkwan University School of Medicine, Seoul, Korea. Editor s Note: This Manuscript was accepted for publication January 12, The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Ja-Won Koo, MD, Department of Otorhinolaryngology Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. jwkoo99@snu.ac.kr DOI: /lary malleus footplate assembly or long collumelization depending on the status of the malleus handle. 5 7 The remaining incus is usually removed during the surgery, because the long process of incus is frequently eroded or absent. However, ossicular chain reconstruction in cases with an intact incus and absent stapes superstructure is rare, and has not been reviewed or discussed in detail. This study reviewed our surgical cases of incus footplate assembly (IFA) and hearing outcome and proposed indications for this procedure. MATERIALS AND METHODS Subjects From January 2005 to December 2014, IFA was performed in eight patients by four surgeons affiliated with Seoul National University Healthcare (four men; age range, years) (Table I). This retrospective study was approved by the institutional review board of the Clinical Research Institute of Seoul National University Bundang Hospital (No. B ). Surgical Procedures of IFA The operation was done via an endaural approach under local or monitored anesthesia care (MAC) (n 5 4) or general anesthesia (n 5 4). The middle ear cavity and ossicles were exposed following tympanomeatal flap elevation. The shape of the ossicles was inspected, and the mobility of the malleus and incus was evaluated by gentle palpation. In these eight cases, the stapes superstructure was missing, but the remaining stapes footplate was mobile. After measuring the distance from the medial side of the incus to the stapes footplate, the height of the prosthesis for the IFA was tailored accordingly. 2569

2 TABLE I. Patient Summary of the Eight Patients Included in the Study. Case Sex/Age, yr Diagnosis Operative Finding Graft Material (Before) (After 1 Year) Closure 1 Male/57 Congenital ossicular 2 Male/19 Congenital cholesteatoma 3 Female/35 Chronic otitis media 4 Female/11 Congenital ossicular 5 Male/20 Congenital ossicular 6 Female/18 Congenital ossicular 7 Female/61 Chronic otitis media 8 Male/13 Congenital ossicular SS: absent, FP: mobile TORP SS: absent, FP: mobile TORP TM: central moderate perforation, ISJ: loss of continuity, SS : present (removed) FP: mobile Homologous ossicle SS: absent, FP: mobile PWP SS: absent, FP: mobile PWP SS: absent, FP: mobile PWP TM: small perforation, M: hypomobile, I: fixed, S: fixed due to tympanosclerosis around stapes! IS separation and SS removal, FP: mobile PWP SS: absent, FP: mobile PWP air-bone gap; FP 5 footplate; I 5 incus; ISJ 5 incudostapedial joint; M 5 malleus; PWP 5 piston wire prosthesis; S 5 stapes; SS 5 stapes superstructure; TM 5 tympanic membrane; TORP 5 total ossicular replacement prosthesis. Commercially available hydroxyapatite prosthesis or homologous incus was sculptured and designed using a surgical drill and then adjusted between the incus and footplate for earlier cases as illustrated in Figure 1A and 1B. However, because it was difficult for the bulky TORP to be fitted in the space between the incus and footplate, piston-wire prostheses (PWP) for stapes surgery were used for the interposition between the incus and stapes footplate in the later cases (Fig. 1C,D). These prostheses were positioned under or anchored to the incus, and the round window reflex was checked by palpating the incus. After repositioning the tympanomeatal flap with Gelfoam support, the ear canal was packed with nylon strips and cotton wicks. In two patients, the tympanic membrane was perforated, and a myringoplasty was performed simultaneously with IFA. Audiometric Evaluations The preoperative, 6-month, and 1-year postoperative audiograms were analyzed based on the guidelines suggested by the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology Head and Neck Surgery. 8 The thresholds at 0.5, 1, 2, and 3 khz were used to calculate the pure-tone average (PTA). Hearing outcomes were evaluated using the pre- and postoperative and closure (postoperative air-conduction threshold, preoperative bone-conduction threshold). closure within 10 db was regarded as the best results. Postoperative differences in the bone-conduction threshold >10 db for each of six frequencies were regarded as significant. 9 The postoperative for each frequency (i.e., 0.25, 0.5, 1.0, 2.0, 3.0, and 4.0 khz) was also reviewed. RESULTS The patients characteristics are summarized in Table I. After removing any pathological structures (congenital cholesteatoma in case 2, partially eroded stapes superstructure in case 3, and tympanosclerotic plaque surrounding the stapes in case 7), the malleus, incus, and stapes footplate were mobile and showed no or minimal erosion, although the stapes superstructure was missing. IFA could be performed to reconstruct the ossicular chain in all cases. The diagnoses of middle ear pathology were congenital ossicular (n 5 5), chronic otitis media (n 5 2), and congenital cholesteatoma (n 5 1). The materials used for IFA were a TORP (case 1 and case 2), homologous incus (case 3), and PWP prosthesis (in the remaining five patients). The individual pre- and postoperative audiograms are compared in Supporting Figure 1 in the online version of this article. Also, the minimal dataset in the standardized reporting format is shown in Supporting Table 1 in the online version of this article. The mean pre- and postoperative values were and db, respectively. The postoperative values at frequencies of 0.25, 0.5, 1.0, 2.0, 3.0, and 4.0 khz were , , , , , and db, respectively (Fig. 2). The mean closure for all eight patients was 9.5 db (range, 21.3 to 35.8). In seven (87.5%) of the eight patients, the closure 1-year postoperatively corresponded to the best results. In case 4, the 2570

3 Fig. 1. Schematic illustrations of the incus footplate assembly. A total ossicular replacement prosthesis is placed between the incus and footplate (A, B), or a piston wire prosthesis (C, D) is anchored to the long process of the incus. closure was improved to 9.5 db at 6 months postoperatively, but worsened again to 35.8 db at 1-year postoperatively (Table II) (Supporting Fig. 1H,I in the online version of this article). The mean differences in boneconduction thresholds 1-year postoperatively (i.e., postoperative bone conduction preoperative bone-conduction) at 0.25, 0.5, 1.0, 2.0, 3.0, and 4.0 khz were , , , , , and db, respectively. Description of an Index Case: Congenital Ossicular Anomaly Case 5 was a 20-year-old man who had hearing difficulty since childhood. The tympanic membrane was normal. The stapes shadow was not visible, but it was otherwise free on temporal bone computed tomography (CT) (see Supporting Fig. 2, upper panel, in the online version of this article). Audiometry showed a 50 db (see Supporting Fig. 1J in the online version of this article). To explore the cause of the conductive hearing loss, an exploratory tympanotomy was performed under MAC anesthesia. The stapes was hypoplastic, and the anterior and posterior crura were missing. The hypoplastic remnant stapes was removed (see Supporting Video 1 in the online version of this article). The length of the PWP was adjusted to match the distance from incus medial side to the footplate (4.0 mm). After the prosthesis was positioned on the footplate and anchored to the incus, the round window reflex was present on manipulating the incus. Description of an Index Case: Tympanosclerosis Around the Stapes Superstructure Case 7 was a 61-year-old woman referred for hearing loss. The tympanic membrane showed a healed perforation with a pinpoint perforation. There was also tympanosclerotic plaque on the tympanic membrane. Temporal bone CT showed a soft tissue density with calcification around the stapes (see Supporting Fig. 2, lower panel, in the online version of this article). PTA showed conductive hearing loss with an of approximately 35 db (see Supporting Fig. 1N in the online version of this article). While exploring the middle ear, the mobility of the ossicular chain was found to be limited by tympanosclerotic plaque over the fallopian canal of the tympanic segment of the facial nerve and Fig. 2. The air-bone gap at each frequency tested 1 year postoperatively. 2571

4 TABLE II. The Postoperative Closure After Incus Footplate Assembly. Closure, db 6 Month, No. (%) 1 Year, No. (%) 10 7 (87.5) 7 (87.5) (12.5) 0 (0.0) (0.0) 31 1 (12.5) Total 8 (100.0) 8 (100.0) 5 air-bone gap. stapes. After separating the incudostapedial joint, the pathology involving the stapes superstructure was removed using a CO 2 laser, as is done in a stapedotomy for otosclerosis. Because the malleus, incus, and stapes footplate were intact and mobile, IFA was considered instead of stapedotomy. The length of the PWP was adjusted to match the distance from incus medial side to the footplate (3.6 mm) (see Supporting Video 2 in the online version of this article). DISCUSSION The goal of an ossiculoplasty is to reestablish the transfer of induced vibratory energy from the tympanic membrane to the stapes footplate, maximizing the postoperative hearing gain. 10 Although potential causes of defective conduction can be identified before surgery from the patient s medical history and high-resolution temporal bone CT, the definitive plan on how to reconstruct the ossicular chain should be based on a careful assessment of the mobility and integrity of the remaining ossicles during surgical exploration. 10 Many techniques have been suggested for dealing with a missing stapes superstructure. 5 7 Fisch and Schmid reported the hearing outcomes in cases with the footplate only (i.e., without the stapes suprastructure). 5 They found that the Spandrel II (Xomed-Trace, Jacksonville, FL), which consists of two parts (i.e., the shoe and the head with the shaft), improved sound conduction when the wire core contacted the stapes footplate directly, and recommended it as the best choice for ossicular chain reconstruction in the absence of a stapes suprastructure. Mills showed the superiority of hearing outcomes with the malleus handle and stapes footplate assembly compared to the tympanic membrane and stapes footplate assembly in ears without a stapes suprastructure. 6 Chole and Skarada suggested reconstruction methods when the incus and stapes suprastructure were absent, classifying them into wide- and narrow-oval window niches, and recommended using a presculpted cartilage TORP and Goldenberg TORP for the respective niches. 7 The postoperative after malleus footplate assembly typically ranges from 3 to 31 db. 6 This range in results likely arises from a number of factors, including the middle ear aeration, type of combined mastoidectomy, appropriateness of the length and position of the interposed TORP, and the surgeon s skill. 5,7,11 14 Postoperative at 4 khz was 23.1 db in this series, which was much larger than those at other frequencies. Postoperative at 4 khz was compared depending on the presence of preoperative Carhart notch (Table III) (see Supporting Fig. 1 in the online version of this article). Interestingly, all patients without preoperative Carhart notch (cases 1, 4, and 5) showed complete closure of at 4 khz after surgery, whereas patients with preoperative Carhart notch (cases 2, 3, 6, 7, and 8) showed variable improvement of at 4 khz. Preoperative Carhart notch might indicate the presence of ossicular fixation other than the discontinuity between the incus and the stapes footplate. However, it was not definite enough to be recognized on manual palpation, and thus could not be resolved by surgery. The fixation might be caused by inflammation (case 2, 3, and 7) or congenital etiology (cases 6 and 8). Therefore, it seems important to check the mobility of individual ossicles and footplate more carefully, especially in patients showing Carhart notch in the preoperative audiometry. Stapes surgery could be an option in some cases of our series based on this speculation since focal subclinical fixation of footplate which might not be definitely demonstrated by manual palpation of the footplate. Stapedotomy is a familiar surgical procedure for most expert otology surgeons and doing stapedotomy instead of IFA may resolve such concern 15 but the disadvantage is the chance of inner ear damage by handling the mobile footplate using a microdrill or perforator. 15,16 Published techniques mostly describe methods to reestablish sound conduction from the handle of the malleus or tympanic membrane to the stapes footplate in caseswithanabsentstapessuperstructure. 5 7 However, we found no study describing an ossiculoplasty in an intact incus without the stapes superstructure. Considering the ratio of the malleus handle to incus (1.31:1), which contributes 2.3 db to the sound amplification mechanics, 12,17,18 it would be better theoretically to reestablish the ossicular chain while preserving the original incus, instead of using the malleus footplate assembly after removing the incus, as long as the long process of the incus is intact. As seen in our series, the surgical outcome of IFA was excellent. closure within 10 db was achieved in seven of eight patients and closure within 20 db in all of the patients at 6 months, although one patient had an of 35 db at the 1-year follow-up. TABLE III. Hearing Result Depending on the Presence of Carhart Notch. Carhart Notch, Preoperative Case No. at 1 khz/2 khz/3 khz, Preoperative, db at 4 khz, Pre-/ Postoperative, db Absent 1 30/40/45 60/0 4 35/45/40 50/0 5 45/40/35 50/0 Present 2 50/35/25 45/ /20/25 30/ /40/20 55/ /30/25 35/ /35/30 55/25 5 air-bone gap. 2572

5 The timing of incus removal during ossiculoplasty should also be emphasized. Several cases with persistent conductive hearing loss after ossiculoplasty have been referred to us, in which stapes fixation was not recognized during initial surgery. Because the incus had been removed, malleostapedotomy was the only option to restore functional hearing in these patients. As also seen in our series, stapes mobility was limited in case 7 due to massive tympanosclerosis between the tympanic segment of the facial nerve and stapes. The stapes superstructure with the tympanosclerosis was removed carefully using a CO 2 laser, which exposed the stapes footplate so that we could attempt a stapedotomy. After removing the tympanosclerosis and stapes superstructure, IFA was possible instead of a stapedotomy, because the stapes footplate was mobile and the incus long process was intact. Therefore, any decision regarding incus removal should be reserved until the status of the stapes is confirmed. In case 4, the postoperative was 10 db until 6 months, but fell to 32 db at the 1-year follow-up. Temporal bone CT and reexploration were recommended to determine the cause of the conductive component, but this patient was lost to follow-up. Potential causes of decreased hearing and displacement of the prosthesis include poor tubal function, vigorous activity, and head trauma. 10,19 Others studies have also reported a wide range of hearing outcomes after pediatric ossiculoplasty CONCLUSION IFA may be indicated in patients with an intact incus long process, absent stapes superstructure, and mobile footplate. In our series, the majority of cases had congenital conductive hearing loss. Although candidate cases might be very limited in clinical practice, IFA is an ideal surgical option for reestablishing the original ossicular chain, if possible. BIBLIOGRAPHY 1. Nemati S, Ebrahim N, Kaemnejad E, Aghjanpour M, Abdollahi O. Middle ear exploration results in suspected otosclerosis cases: are ossicular and footplate area anomalies rare? Iran J Otorhinolaryngol 2013;25: Ng M. Exploratory tympanotomy. Medscape website. Available at: emedicine.medscape.com/article/ overview. Published November 12, Accessed April 26, Slater PW, Rizer FM, Schuring AG, Lippy WH. Practical use of total and partial ossicular replacement prostheses in ossiculoplasty. Laryngoscope 1997;107: Park M, Song JJ, Chang MY, Lee JH, Oh SH, Chang SO. Malleostapedotomy revisited: the advantages of malleus neck-anchoring malleostapedotomy. Otol Neurotol 2014;35: Fisch U, Schmid S. Total reconstruction of the ossicular chain. Otolaryngol Clin North Am 1994;27: Mills RP. Hearing results in tympanic membrane footplate and malleus-footplate assemblies. Clin Otolaryngol Allied Sci 1995;20: Chole RA, Skarada DJ. Middle ear reconstructive techniques. Otolaryngol Clin North Am 1999;32: Monsell EM. New and revised reporting guidelines from the Committee on Hearing and Equilibrium. Otolaryngol Head Neck Surg 1995;113: Fisch U, Acar GO, Huber AM. Malleostapedotomy in revision surgery for otosclerosis. Otol Neurotol 2001;22: Adams ME, El-Kashlan HK. Tympanoplasty and ossiculoplasty. In: Niparko JK, ed. Cummings Otolaryngology Head and Neck Surgery. 5th ed. Chicago IL: Mosby; 2011: Kartush JM, Balough BJ. Contemporary ossiculoplastic options. Curr Opin Otolaryngol Head Neck Surg 2001;9: Javia LR, Ruckenstein MJ. Ossiculoplasty. Otolaryngol Clin North Am 2006;39: Yung M. Long-term results of ossiculoplasty: reasons for surgical failure. Otol Neurotol 2006;27: Vartiainen E, Nuutinen J. Long-term hearing results of one-stage tympanoplasty for chronic otitis media. Eur Arch Otorhinolaryngol 1992;249: Gerlinger I, Bako P, Piski Z, et al. KTP laser stapedotomy with a selfcrimping, thermal shape memory Nitinol piston: follow-up study reporting intermediate-term hearing. Eur Arch Otorhinolaryngol 2014;271: Yavuz H, Caylakli F, Ozer F, Ozluoglu LN. Reliability of microdrill stapedotomy: comparison with pick stapedotomy. Otol Neurotol 2007;28: Anatomy and physiology of hearing. University of Vermont website. Available at: Published August 16, Accessed March 15, Goode RL, Ball G, Nishihara S, Nakamura K. Laser Doppler Vibrometer (LDV) a new clinical tool for the otologist. Otol Neurotol 1996;17: Cushing SL, Papsin BC. The top 10 considerations in pediatric ossiculoplasty. Otolaryngol Head Neck Surg 2011;144: Daniels RL, Rizer FM, Schuring AG, Lippy WL. Partial ossicular reconstruction in children: a review of 62 operations. Laryngoscope 1998;108: Murphy TP. Hearing results in pediatric patients with chronic otitis media after ossicular reconstruction with partial ossicular replacement prostheses and total ossicular replacement prostheses. Laryngoscope 2000; 110: Michael P, Fong J, Raut V. Kurz titanium prostheses in paediatric ossiculoplasty short term results. Int J Pediatr Otorhinolaryngol 2008;72: