Otology & Neurotology 35:662Y666 Ó 2014, Otology & Neurotology, Inc.
Anomalous Facial Nerve in Congenital Stapes Fixation *Yun Suk An, †Jeong Hyun Lee, and *Kwang-Sun Lee *Department of Otolaryngology, and ÞDepartment of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Objective: The aim of this article was to assess the prevalence and influence of anomalous facial nerves in patients undergoing surgery for congenital stapes anomalies. Patients: The medical records of all patients who underwent surgery for congenital stapes fixation between January 1999 and December 2012 were retrospectively reviewed. An abnormal facial nerve was found in 7 ears in 5 patients (from a total of 62 ears). Main Outcome Measures: The patients’ temporal bone computed tomography results, operation records, video clips, and preoperative and postoperative hearing tests were reviewed. Results: Oval window atresia was found in all 7 ears, and the facial nerves in all 7 ears ran inferior medially over the atretic oval window niche. The atretic plate was fenestrated into the vestibule in the superior margin of the facial nerve. A piston
wire was anchored to the long process of the incus in 3 ears, to the handle of the malleus in 3 ears, and attached to the tympanic membrane in 1 ear. The postoperative ABG at long-term followup was 13.1 dB (SD, 4.6 dB; range, 8.8Y18.3 dB). No patient had postoperative facial weakness. Conclusion: An anomalous facial nerve was found in 11.2% of ears in patients undergoing surgery for congenital stapes fixation. Despite the anomalous course of facial nerves in these patients, vestibular fenestration was successful without facial nerve damage. The audiometric outcome at long-term follow-up was serviceable hearing for all cases. Key Words: Congenital stapes fixationVFacial nerveVIncudostapedotomyVMalleostapedotomyV Tympanic membrane stapedotomy.
Conductive hearing loss secondary to congenital stapes malformations is rare with a reported occurrence of 0.5% to 1.2% (1Y3). Congenital stapes ankylosis represents 20% to 35% of ossicular malformations, secondary only to fixation of the peripheral lamina stapedialis to the annular ligament (3,4). Some extent of dehiscence of the horizontal segment of the facial canal is commonly observed during middle ear surgery, and it is considered a normal variation (5). Baxter (6) reported dehiscence of some portion of the intratemporal facial nerve in 55% of the 535 human temporal bones that were subjected to histopathologic analysis. However, an anomalously coursing dehiscent facial nerve either covering the oval window niche or running inferior to it over the promontory is rare. An aberrant course of the facial nerve has been associated with congenital middle ear malformations (7,8), occasionally leading to abandonment of the planned surgery.
An aberrant course of the facial nerve in stapes surgery is challenging to the otologist, requiring advanced diagnostic skills and a flexible surgical technique. The aim of this study was to review the prevalence of facial nerves with an aberrant course in patients undergoing surgery for congenital stapes fixation and to report on the surgical technique and audiometric outcomes for these patients.
Otol Neurotol 35:662Y666, 2014.
MATERIALS AND METHODS Study Subjects The medical records of 121 patients (175 ears) underwent stapes surgery between 1999 and 2012 were retrospectively reviewed. All patients had undergone a preoperative workup comprising audiometric tests and high-resolution temporal bone computed tomography (TBCT). Age at onset, bilaterality, sex, age at surgery, and intraoperative findings including configuration of the malformed ossicles, the course of the facial nerve, and the presence of oval window atresia were analyzed using operation records and video clips. This study was approved by the institutional review board of Asan Medical Center.
Address correspondence and reprint requests to Kwang-Sun Lee, M.D., Ph.D., Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Republic of Korea; E-mail: [email protected] The authors disclose no conflicts of interest.
Surgical Methods All surgeries were performed under general anesthesia. An endomeatal approach with an ear canal speculum was used in
662
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CONGENITAL STAPES FIXATION 5 ears, and an endoaural incision was used in 2 ears because of narrow external auditory canals. After elevation of the tympanomeatal flap, a small osteotome was used to remove the bony annulus over the incudostapedial joint (ISJ). After identifying the displaced facial nerve that was prolapsed inferior medially over the atretic oval window niche, a small slit was made in the atretic plate along the superior margin of the facial nerve. Using a 0.5-mm Skeeter drill burr (Medtronic ENT, Jacksonville, FL, USA), an approximately 0.6 mm fenestration was made for insertion of the piston prosthesis. Routinely, a Fisch-type polytetrafluoroethylene piston wire prosthesis (Medtronic ENT, Jacksonville, FL, USA) was used. When the long process of the incus was present, it was used as the attachment point for the piston wire (incudostapedotomy, Fig. 1B and Fig. 2F); however, when absent, the piston wire was attached to the handle of the malleus just inferior to the short process of the malleus (malleostapedotomy, Fig. 2D). In 1 ear, where the long process of the incus was absent and the head of the malleus was fixed, the prosthesis was attached to the tympanic membrane with soft tissue attached to the wire and the piston inserted into the fenestra (tympanic membrane stapedotomy, Fig. 3B).
Audiometric Evaluation Audiometric data recorded at approximately 3 months and 1 year after surgery and at long-term follow-up were compared with preoperative data. Preoperative and postoperative air conduction (AC) and bone conduction (BC) at 0.5, 1, 2, and 3 kHz were included in the analysis. When a 3 kHz test was not performed, the mean value of the 2 and 4 kHz tests was substituted. The air-bone gap (ABG) was calculated only for those patients who had BC and AC values collected at the same time.
663
Intraoperative and TBCT Findings Ossicular chain anomalies were noted in all 7 ears: aplasia or dysplasia of the stapes in 7 ears, absence of the long and lenticular process of the incus in 5 ears, and fixation of the malleus in 1 ear. An absence of the stapes superstructure was found in 5 ears, and incus anomalies were found in 5 ears; absences of long process of the incus were found in 2 ears, a fibrous band of the ISJ in 2 ears, and an absence of the lenticular process of the incus in 1 ear (Table 1). All 7 ears had inferior medially prolapsed facial nerves running over the atretic oval window niche (Figs. 1Y3). Audiometric Results The mean preoperative AC was 54.5 dB (SD, 13.4 dB), and the mean preoperative ABG was 39.3 dB (SD, 12.6 dB). Audiometric data were obtained for all ears at approximately 3 months (mean, 1.6; range 0.9Y4.5) after surgery. The mean postoperative 3-month AC was 26.1 dB (range, 20Y33.8), and the average residual ABG was 12.0 dB (range, 5Y23.3). At approximately 1 year (mean, 11.2; range, 9.4Y13.2 mo) after surgery (n = 6), the mean AC was 25.6 dB (range, 18.8Y31.3), and the average residual ABG was 14.0 dB (range, 8.8Y21.3). The mean long-term follow-up duration (n = 6) was 37.9 months (range, 28.8Y94.3), the mean AC was 27.1 dB (range, 17.5Y31.3), and the average residual ABG was 13.1 dB (range, 8.8Y18.3) (Table 2). The preoperative and postoperative speech discrimination scores were 100% in all patients.
RESULTS
DICUSSION
Among 175 ears that underwent stapes surgery, congenital stapes fixation was diagnosed in 62 ears (35.4%). Among 62 ears, an anomalous facial nerve in the middle ear cavity was found in 7 ears (11.2%).There were 4 male subjects (5 ears) and 1 female subjects (2 ears), and the mean age at the time of surgery was 16.6 years (SD, 11.9). Two patients underwent surgery in both ears (Table 1).
Embryologically, the stapes develops in the fifth to sixth week from the second branchial arch (Reichert’s cartilage), forming a ring around the stapedial artery (9). Between the seventh and ninth weeks, a depression forms in the otic capsule, deep to the stapes footplate, at the site of the future oval window. This tissue finally fuses with the stapes to form the labyrinthine side of the footplate
FIG. 1. Patient 1, Left Ear. A, An anomalous dehiscent tympanic segment of the facial nerve (black arrows) was noted over the atretic oval window niche. B, A fenestration into the vestibule was made in the middle of the atretic footplate superior to the dehiscent facial nerve. A polytetrafluoroethylene piston was inserted into the vestibule through the fenestrum. The asterisk represents the chorda tympani nerve, and the filled circle represents the incus long process. Otology & Neurotology, Vol. 35, No. 4, 2014
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FIG. 2. Patient 3. Axial (A) and coronal CT scans (B) show an inferior medially located facial nerve (black arrow) over the atretic oval window niche. C and D, Left ear, an abnormally dehiscent tympanic segment of the facial nerve (thin arrows) runs over the oval window niche. A vestibulostomy site was showed as the posterior margin of the atretic oval window niche (thick arrow). A 6-mm polytetrafluoroethylene piston (asterisk) was inserted into the vestibule and anchored to the handle of the malleus. E and F, Right ear, an abnormally dehiscent tympanic segment of the facial nerve (black arrows) runs over the oval window niche. A vestibulostomy was made at the posterior margin of the atretic plate of the oval window (asterisk) along the superior margin of the facial nerve. The eroded incus long process is shown by the filled circle. A polytetrafluoroethylene piston was inserted into the vestibule (asterisk), and the wire was crimped to the long process of the incus.
(lamina stapedius). The facial nerve canal develops from the otic capsule and Reichert’s cartilage at approximately the same time as the stapes. The common origin of the facial nerve and stapes from the second branchial arch could explain the frequent combination of an aberrant facial nerve and a malformed stapes (7). Congenital stapes fixation with facial nerve malposition has been previously reported (7,10Y13). Despite the
rarity of facial nerve displacement, the otologist must consider the possibility of facial nerves overlying the oval window niche or coursing downward to the oval window so that an iatrogenic injury can be avoided. The course of the facial nerve should be carefully reviewed with highresolution TBCT before surgery (14Y17). Hearing aids are alternative option for the hearing loss in children, and hearing aids should be tried before
Otology & Neurotology, Vol. 35, No. 4, 2014
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CONGENITAL STAPES FIXATION
665
FIG. 3. Patient 4, Right Ear. A, Anomalous dehiscent tympanic segment of the facial nerve (black arrows) over the atretic oval window niche. B, The fenestration into the vestibule was made medial to superior margin of the facial nerve (black arrows). A 6-mm soft tissue attached polytetrafluoroethylene piston was inserted into the fenestra, and the soft tissue attached wire placed to the posterior superior quadrant of the tympanic membrane. C, Soft tissue from the posterior surface of the ear lobule attached to the wire of the prosthesis. D, Whitish area (asterisk) in the posterior tympanum is a place where the soft tissue piston wire prosthesis attached to the tympanic membrane.
offering surgery. Surgery should be delayed until the patient is free of recurrent otitis media until at least 5 years of age (10,12). Massey et al. (11) reported 2 cases in which surgery was not performed because in 1 case, the facial nerve was blocking the oval window, and in the other, the facial nerve position over the oval window precluded reconstruction. Martin et al. (13) reported good long-term results after platinotomy or vestibulotomy in 2 cases of congenital stapes fixation or oval window absence, despite
TABLE 1.
the presence of a deviated facial nerve course. Hasegawa et al. (18) reported excellent long-term results after fenestration of the scala vestibuli below the facial nerve in 3 cases of oval window absence with facial nerve anomalies. Vestibulotomy is a feasible treatment for an absent oval window (15). To our knowledge, attachment of the piston wire with soft tissue to the tympanic membrane has not been previously reported. This technique, although technically challenging, was successfully implemented for the patient
Intraoperative and high-resolution temporal bone CT findings Ossicular anomaly
Patient no. 1 2 3 4 5
Site
Stapes
Incus
Malleus
PW method
Length of PW (mm)
L R R L R L R
Malformed shape Ant crura and foot plate absent Suprastructure absent Suprastructure absent Suprastructure absent Suprastructure absent Suprastructure absent
Normal Normal ISJ fibrous band ISJ fibrous band Abscent Abscent ISJ abscent
Normal Normal Normal Normal Fix & Ant. displacement Normal Normal
Incudostapedotomy Incudostapedotomy Incudostapedotomy Malleostapedotomy TM anchored PW Malleostapedotomy Malleostapedotomy
5 4.5 5.2 6 5.3 6.2 5.5
R indicates right; L, left; ISJ, incudostapedial joint; Fix, fixation; Ant, anterior; PW, piston wire; TM, tympanic membrane. Otology & Neurotology, Vol. 35, No. 4, 2014
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TABLE 2.
Patients’ charateristics and preoperative and 1-year postoperative audiometry Preoperative audiometry
Postoperative audiometry
Patient BC no. Sex Age Site (dB)
AC (dB)
ABG (dB)
BC (dB)
AC (dB)
ABG (dB)
1 2 3
58.75 58.75 61.25 63.75 27.5 46.25 65
41.75 43.75 38.75 47 15 33.75 55
15a 10.5 10 13 16.25 10 10
20a 21.25 31.25 31.25 28.75 22.5 18.75
5a 10.8 21.3 18.3 12.5 12.5 8.75
4 5
M M F F M M M
5.7 12.4 10.9 11.8 33.3 33.9 8.0
L R R L R L R
17 15 22.5 16.8 12.5 12.5 10
M indicates male; F, female; Age is the age at stapes surgery; R, right; L, left; dB, decibel; BC, bone conduction; AC, air conduction; ABG, airbone gap. a Three-month postoperative audiometry, only this case was lost to follow-up.
with an absent long process of incus and a fixed head of malleus. The ABG at 3 months after tympanic membrane stapedotomy was 23.3 dB; however, it decreased to 12.5 dB at 1 year after surgery and, finally, 8.8 dB at 35.6 months after surgery. We think that the decrease of ABG over time was because the stabilized piston wire was stabilized by the soft tissue connection to the tympanic membrane. The limitations of this Article were a retrospective manner and a relatively small sample in size especially in the tympanic membrane stapedotomy. CONCLUSION An anomalous facial nerve was found in 11.2% of congenital stapes fixation patients. Despite the presence of an anomalous facial nerve, fenestration into the vestibule was successfully performed in all cases without injury to the facial nerve. Incudostapedotomies were performed in 3 ears and malleostapedotomies in 2, and in one ear, the piston wire was attached to the tympanic membrane. The long-term audiometric outcome was serviceable hearing for all cases. Regardless of whether an anomalous course of the facial nerve or an ossicular
anomaly is found during stapes surgery, awareness, careful consideration, and a flexible management can produce successful hearing outcomes. REFERENCES 1. Jahrsdoerfer RA. Congenital malformations of the ear: analysis of 94 operations. Ann Otol 1980;89:348Y52. 2. Kisilevsky VE, Bailie NA, Dutt SN, Halik J I. Hearing results of stapedotomy and malleo-vestibulopexy in congenital hearing loss. Int J Pediatr Otorhinolaryngol 2009;73:1712Y7. 3. Albert S, Roger G, Rouillon I, et al. Congenital stapes ankylosis: study of 28 cases and surgical results. Laryngoscope 2006;116: 1153Y7. 4. Teunissen B, Cremers WR, Huygen PL, Pouwels TP. Isolated congenital stapes ankylosis: surgical results in 32 ears and a review of the literature. Laryngoscope 1990;100:133lY6. 5. Kettel K. Surgery of the facial nerve. Arch Otolaryngol 1963;77: 327Y41. 6. Baxter A. Dehiscence of the Fallopian canal. J Laryngol Otol 1971;85:587Y94. 7. Boone R, Dornhoffer J. Stapedotomy above the facial nerve in a congenitally malformed ear: a case report. Otolaryngol Head Neck Surg 2002;127:342Y5. 8. Jahrsdoerfer RA. The facial nerve in congenital ear malformations. Laryngoscope 1981;91:1217Y25. 9. Larson WJ. Development of the ears. In: Human embryology. New York, NY: Churchill Livingstone, 1993:352Y74. 10. De la Cruz A, Angeli S, Slattery WH. Stapedectomy in children. Otolaryngol Head Neck Surg 1999;120:487Y92. 11. Massey BL, Hillman TA, Shelton C. Stapedectomy in congenital stapes fixation: are hearing outcotnes poorer? Otolaryngol Head Neck Surg 2006;134:816Y8. 12. House JW, Sheehy JL, Antunez JC. Stapedectomy in children. Laryngoscope 1980;90:1804Y9. 13. Martin C, Oletski A, Bertholon P, Prades JM. Abnormal facial nerve course associated with .stapes fixation or oval window absence: report of two cases. Eur Arch Otorhinolaryngol 2006:263:79Y85. 14. Welling DB, Glasscock ME II1, Gantz BJ. Avulsion of the anomalous facial nerve at stapedectomy. Laryngoscope 1992;102: 729Y33. 15. Pou JW. Congenital absence of oval window. Laryngoscope 1963;73:384Y91. 16. Leek JH. An anomalous facial nerve. Laryngoscope 1974;84: 1535Y44. 17. Durcan DJ, Shea JJ, Sleeckx JR Bifurcation of the facial nerve. Arch Otolaryngol 1976;86:619Y31. 18. Hasegawa J, Kawase T, Hidaka H, Oshima T, Kobayashi T. Surgical treatment for congenital absence of the oval window with facial nerve anomalies. Auris Nasus Larynx. 2012;39:249Y55.
Otology & Neurotology, Vol. 35, No. 4, 2014
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Anomalous Facial Nerve in Congenital Stapes Fixation *Yun Suk An, †Jeong Hyun Lee, and *Kwang-Sun Lee *Department of Otolaryngology, and ÞDepartment of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
Objective: The aim of this article was to assess the prevalence and influence of anomalous facial nerves in patients undergoing surgery for congenital stapes anomalies. Patients: The medical records of all patients who underwent surgery for congenital stapes fixation between January 1999 and December 2012 were retrospectively reviewed. An abnormal facial nerve was found in 7 ears in 5 patients (from a total of 62 ears). Main Outcome Measures: The patients’ temporal bone computed tomography results, operation records, video clips, and preoperative and postoperative hearing tests were reviewed. Results: Oval window atresia was found in all 7 ears, and the facial nerves in all 7 ears ran inferior medially over the atretic oval window niche. The atretic plate was fenestrated into the vestibule in the superior margin of the facial nerve. A piston
wire was anchored to the long process of the incus in 3 ears, to the handle of the malleus in 3 ears, and attached to the tympanic membrane in 1 ear. The postoperative ABG at long-term followup was 13.1 dB (SD, 4.6 dB; range, 8.8Y18.3 dB). No patient had postoperative facial weakness. Conclusion: An anomalous facial nerve was found in 11.2% of ears in patients undergoing surgery for congenital stapes fixation. Despite the anomalous course of facial nerves in these patients, vestibular fenestration was successful without facial nerve damage. The audiometric outcome at long-term follow-up was serviceable hearing for all cases. Key Words: Congenital stapes fixationVFacial nerveVIncudostapedotomyVMalleostapedotomyV Tympanic membrane stapedotomy.
Conductive hearing loss secondary to congenital stapes malformations is rare with a reported occurrence of 0.5% to 1.2% (1Y3). Congenital stapes ankylosis represents 20% to 35% of ossicular malformations, secondary only to fixation of the peripheral lamina stapedialis to the annular ligament (3,4). Some extent of dehiscence of the horizontal segment of the facial canal is commonly observed during middle ear surgery, and it is considered a normal variation (5). Baxter (6) reported dehiscence of some portion of the intratemporal facial nerve in 55% of the 535 human temporal bones that were subjected to histopathologic analysis. However, an anomalously coursing dehiscent facial nerve either covering the oval window niche or running inferior to it over the promontory is rare. An aberrant course of the facial nerve has been associated with congenital middle ear malformations (7,8), occasionally leading to abandonment of the planned surgery.
An aberrant course of the facial nerve in stapes surgery is challenging to the otologist, requiring advanced diagnostic skills and a flexible surgical technique. The aim of this study was to review the prevalence of facial nerves with an aberrant course in patients undergoing surgery for congenital stapes fixation and to report on the surgical technique and audiometric outcomes for these patients.
Otol Neurotol 35:662Y666, 2014.
MATERIALS AND METHODS Study Subjects The medical records of 121 patients (175 ears) underwent stapes surgery between 1999 and 2012 were retrospectively reviewed. All patients had undergone a preoperative workup comprising audiometric tests and high-resolution temporal bone computed tomography (TBCT). Age at onset, bilaterality, sex, age at surgery, and intraoperative findings including configuration of the malformed ossicles, the course of the facial nerve, and the presence of oval window atresia were analyzed using operation records and video clips. This study was approved by the institutional review board of Asan Medical Center.
Address correspondence and reprint requests to Kwang-Sun Lee, M.D., Ph.D., Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Republic of Korea; E-mail: [email protected] The authors disclose no conflicts of interest.
Surgical Methods All surgeries were performed under general anesthesia. An endomeatal approach with an ear canal speculum was used in
662
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CONGENITAL STAPES FIXATION 5 ears, and an endoaural incision was used in 2 ears because of narrow external auditory canals. After elevation of the tympanomeatal flap, a small osteotome was used to remove the bony annulus over the incudostapedial joint (ISJ). After identifying the displaced facial nerve that was prolapsed inferior medially over the atretic oval window niche, a small slit was made in the atretic plate along the superior margin of the facial nerve. Using a 0.5-mm Skeeter drill burr (Medtronic ENT, Jacksonville, FL, USA), an approximately 0.6 mm fenestration was made for insertion of the piston prosthesis. Routinely, a Fisch-type polytetrafluoroethylene piston wire prosthesis (Medtronic ENT, Jacksonville, FL, USA) was used. When the long process of the incus was present, it was used as the attachment point for the piston wire (incudostapedotomy, Fig. 1B and Fig. 2F); however, when absent, the piston wire was attached to the handle of the malleus just inferior to the short process of the malleus (malleostapedotomy, Fig. 2D). In 1 ear, where the long process of the incus was absent and the head of the malleus was fixed, the prosthesis was attached to the tympanic membrane with soft tissue attached to the wire and the piston inserted into the fenestra (tympanic membrane stapedotomy, Fig. 3B).
Audiometric Evaluation Audiometric data recorded at approximately 3 months and 1 year after surgery and at long-term follow-up were compared with preoperative data. Preoperative and postoperative air conduction (AC) and bone conduction (BC) at 0.5, 1, 2, and 3 kHz were included in the analysis. When a 3 kHz test was not performed, the mean value of the 2 and 4 kHz tests was substituted. The air-bone gap (ABG) was calculated only for those patients who had BC and AC values collected at the same time.
663
Intraoperative and TBCT Findings Ossicular chain anomalies were noted in all 7 ears: aplasia or dysplasia of the stapes in 7 ears, absence of the long and lenticular process of the incus in 5 ears, and fixation of the malleus in 1 ear. An absence of the stapes superstructure was found in 5 ears, and incus anomalies were found in 5 ears; absences of long process of the incus were found in 2 ears, a fibrous band of the ISJ in 2 ears, and an absence of the lenticular process of the incus in 1 ear (Table 1). All 7 ears had inferior medially prolapsed facial nerves running over the atretic oval window niche (Figs. 1Y3). Audiometric Results The mean preoperative AC was 54.5 dB (SD, 13.4 dB), and the mean preoperative ABG was 39.3 dB (SD, 12.6 dB). Audiometric data were obtained for all ears at approximately 3 months (mean, 1.6; range 0.9Y4.5) after surgery. The mean postoperative 3-month AC was 26.1 dB (range, 20Y33.8), and the average residual ABG was 12.0 dB (range, 5Y23.3). At approximately 1 year (mean, 11.2; range, 9.4Y13.2 mo) after surgery (n = 6), the mean AC was 25.6 dB (range, 18.8Y31.3), and the average residual ABG was 14.0 dB (range, 8.8Y21.3). The mean long-term follow-up duration (n = 6) was 37.9 months (range, 28.8Y94.3), the mean AC was 27.1 dB (range, 17.5Y31.3), and the average residual ABG was 13.1 dB (range, 8.8Y18.3) (Table 2). The preoperative and postoperative speech discrimination scores were 100% in all patients.
RESULTS
DICUSSION
Among 175 ears that underwent stapes surgery, congenital stapes fixation was diagnosed in 62 ears (35.4%). Among 62 ears, an anomalous facial nerve in the middle ear cavity was found in 7 ears (11.2%).There were 4 male subjects (5 ears) and 1 female subjects (2 ears), and the mean age at the time of surgery was 16.6 years (SD, 11.9). Two patients underwent surgery in both ears (Table 1).
Embryologically, the stapes develops in the fifth to sixth week from the second branchial arch (Reichert’s cartilage), forming a ring around the stapedial artery (9). Between the seventh and ninth weeks, a depression forms in the otic capsule, deep to the stapes footplate, at the site of the future oval window. This tissue finally fuses with the stapes to form the labyrinthine side of the footplate
FIG. 1. Patient 1, Left Ear. A, An anomalous dehiscent tympanic segment of the facial nerve (black arrows) was noted over the atretic oval window niche. B, A fenestration into the vestibule was made in the middle of the atretic footplate superior to the dehiscent facial nerve. A polytetrafluoroethylene piston was inserted into the vestibule through the fenestrum. The asterisk represents the chorda tympani nerve, and the filled circle represents the incus long process. Otology & Neurotology, Vol. 35, No. 4, 2014
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
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Y. S. AN ET AL.
FIG. 2. Patient 3. Axial (A) and coronal CT scans (B) show an inferior medially located facial nerve (black arrow) over the atretic oval window niche. C and D, Left ear, an abnormally dehiscent tympanic segment of the facial nerve (thin arrows) runs over the oval window niche. A vestibulostomy site was showed as the posterior margin of the atretic oval window niche (thick arrow). A 6-mm polytetrafluoroethylene piston (asterisk) was inserted into the vestibule and anchored to the handle of the malleus. E and F, Right ear, an abnormally dehiscent tympanic segment of the facial nerve (black arrows) runs over the oval window niche. A vestibulostomy was made at the posterior margin of the atretic plate of the oval window (asterisk) along the superior margin of the facial nerve. The eroded incus long process is shown by the filled circle. A polytetrafluoroethylene piston was inserted into the vestibule (asterisk), and the wire was crimped to the long process of the incus.
(lamina stapedius). The facial nerve canal develops from the otic capsule and Reichert’s cartilage at approximately the same time as the stapes. The common origin of the facial nerve and stapes from the second branchial arch could explain the frequent combination of an aberrant facial nerve and a malformed stapes (7). Congenital stapes fixation with facial nerve malposition has been previously reported (7,10Y13). Despite the
rarity of facial nerve displacement, the otologist must consider the possibility of facial nerves overlying the oval window niche or coursing downward to the oval window so that an iatrogenic injury can be avoided. The course of the facial nerve should be carefully reviewed with highresolution TBCT before surgery (14Y17). Hearing aids are alternative option for the hearing loss in children, and hearing aids should be tried before
Otology & Neurotology, Vol. 35, No. 4, 2014
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
CONGENITAL STAPES FIXATION
665
FIG. 3. Patient 4, Right Ear. A, Anomalous dehiscent tympanic segment of the facial nerve (black arrows) over the atretic oval window niche. B, The fenestration into the vestibule was made medial to superior margin of the facial nerve (black arrows). A 6-mm soft tissue attached polytetrafluoroethylene piston was inserted into the fenestra, and the soft tissue attached wire placed to the posterior superior quadrant of the tympanic membrane. C, Soft tissue from the posterior surface of the ear lobule attached to the wire of the prosthesis. D, Whitish area (asterisk) in the posterior tympanum is a place where the soft tissue piston wire prosthesis attached to the tympanic membrane.
offering surgery. Surgery should be delayed until the patient is free of recurrent otitis media until at least 5 years of age (10,12). Massey et al. (11) reported 2 cases in which surgery was not performed because in 1 case, the facial nerve was blocking the oval window, and in the other, the facial nerve position over the oval window precluded reconstruction. Martin et al. (13) reported good long-term results after platinotomy or vestibulotomy in 2 cases of congenital stapes fixation or oval window absence, despite
TABLE 1.
the presence of a deviated facial nerve course. Hasegawa et al. (18) reported excellent long-term results after fenestration of the scala vestibuli below the facial nerve in 3 cases of oval window absence with facial nerve anomalies. Vestibulotomy is a feasible treatment for an absent oval window (15). To our knowledge, attachment of the piston wire with soft tissue to the tympanic membrane has not been previously reported. This technique, although technically challenging, was successfully implemented for the patient
Intraoperative and high-resolution temporal bone CT findings Ossicular anomaly
Patient no. 1 2 3 4 5
Site
Stapes
Incus
Malleus
PW method
Length of PW (mm)
L R R L R L R
Malformed shape Ant crura and foot plate absent Suprastructure absent Suprastructure absent Suprastructure absent Suprastructure absent Suprastructure absent
Normal Normal ISJ fibrous band ISJ fibrous band Abscent Abscent ISJ abscent
Normal Normal Normal Normal Fix & Ant. displacement Normal Normal
Incudostapedotomy Incudostapedotomy Incudostapedotomy Malleostapedotomy TM anchored PW Malleostapedotomy Malleostapedotomy
5 4.5 5.2 6 5.3 6.2 5.5
R indicates right; L, left; ISJ, incudostapedial joint; Fix, fixation; Ant, anterior; PW, piston wire; TM, tympanic membrane. Otology & Neurotology, Vol. 35, No. 4, 2014
Copyright © 2014 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
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Y. S. AN ET AL.
TABLE 2.
Patients’ charateristics and preoperative and 1-year postoperative audiometry Preoperative audiometry
Postoperative audiometry
Patient BC no. Sex Age Site (dB)
AC (dB)
ABG (dB)
BC (dB)
AC (dB)
ABG (dB)
1 2 3
58.75 58.75 61.25 63.75 27.5 46.25 65
41.75 43.75 38.75 47 15 33.75 55
15a 10.5 10 13 16.25 10 10
20a 21.25 31.25 31.25 28.75 22.5 18.75
5a 10.8 21.3 18.3 12.5 12.5 8.75
4 5
M M F F M M M
5.7 12.4 10.9 11.8 33.3 33.9 8.0
L R R L R L R
17 15 22.5 16.8 12.5 12.5 10
M indicates male; F, female; Age is the age at stapes surgery; R, right; L, left; dB, decibel; BC, bone conduction; AC, air conduction; ABG, airbone gap. a Three-month postoperative audiometry, only this case was lost to follow-up.
with an absent long process of incus and a fixed head of malleus. The ABG at 3 months after tympanic membrane stapedotomy was 23.3 dB; however, it decreased to 12.5 dB at 1 year after surgery and, finally, 8.8 dB at 35.6 months after surgery. We think that the decrease of ABG over time was because the stabilized piston wire was stabilized by the soft tissue connection to the tympanic membrane. The limitations of this Article were a retrospective manner and a relatively small sample in size especially in the tympanic membrane stapedotomy. CONCLUSION An anomalous facial nerve was found in 11.2% of congenital stapes fixation patients. Despite the presence of an anomalous facial nerve, fenestration into the vestibule was successfully performed in all cases without injury to the facial nerve. Incudostapedotomies were performed in 3 ears and malleostapedotomies in 2, and in one ear, the piston wire was attached to the tympanic membrane. The long-term audiometric outcome was serviceable hearing for all cases. Regardless of whether an anomalous course of the facial nerve or an ossicular
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Otology & Neurotology, Vol. 35, No. 4, 2014
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