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Management of surgical difficulties during cochlear implant with inner ear anomalies
International Journal of Pediatric Otorhinolaryngology 92 (2017) 45e49
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: http://www.ijporlonline.com/
Management of surgical difficulties during cochlear implant with inner ear anomalies Ahmad M. Aldhafeeri a, Abdulrahman A. Alsanosi b, * a
Fellow in Otology-Neurotology, King Saud University Fellowship, King Abdullah Ear Specialist Centre, King Saud University Medical City, Riyadh, Saudi Arabia b King Abdullah Ear Specialist Centre, King Saud University Medical City, P.O. Box 245, Riyadh, 11411, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 17 August 2016 Received in revised form 29 October 2016 Accepted 1 November 2016 Available online 3 November 2016
Objective: To review the difficulties that can occur during cochlear implant surgery in patients with inner ear abnormalities and the management thereof. Methods: A retrospective chart review of 316 patients who received cochlear implants was conducted. The data collected included the types of inner ear anomalies, intraoperative findings, and the clinical management strategies. A review of the literature was also performed. Results: A total of 24 patients with inner ear malformations who underwent 28 total cochlear implant procedures were identified. The anomalies included isolated large vestibular aqueducts in 8 (33.3%) patients, isolated semicircular canal dysplasia in 8 (33.3%) patients, classical Mondini malformation in 7 (29.1%) patients, and cochlear hypoplasia in 1 (4.1%) patient. Four (14.2%) patients exhibited intraoperative cerebrospinal fluid (CSF) gushers. One patient experienced delayed facial nerve paralysis, and an electrode was partially inserted into one patient. In 2 (7.14%) cases, the surgeries were aborted because of difficulties. Conclusion: Cochlear implantation for inner ear anomalies can be performed safely. Special attention should be given to preoperative imaging to anticipate the potential intraoperative risks that can occur in inner ear anomaly cases. Every surgery should be planned with a safe approach and specific requirements, e.g., regarding electrode type, and the surgeries must be performed by experienced surgeons who are capable of modifying their technique according to the surgical findings. © 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Anomaly Cochlear implant Difficulty Risk Surgical Management
1. Introduction Cochlear implants are the treatment modality of choice for patients with profound cochlear hearing loss, particularly patients who have experienced minimal or no benefit from hearing aids. Cochlear implants were first utilised in the 1980s following the introduction of single-channel devices [1] and the subsequent introduction of multi-channel devices [2]. These devices were implanted to restore the sense of audition and became the standard of care for cochlear hearing loss. Until the last decade, many cochlear implant centres refused to implant devices in children with anomalous inner ears because of concerns related to surgical difficulties and performance expectations [3]. Over time, however,
as the experience of the surgeons who performed these surgeries increased, a greater number of children with inner ear anomalies were considered as candidates for surgery. Operating on a patient with an inner ear anomaly is associated with greater risks of surgical complications, such as facial nerve injury, labyrinthine fistula, and cerebrospinal fluid (CSF) gushers. Moreover, few reports have addressed the surgical risks and complications encountered during cochlear implantation in patients with inner ear anomalies in our region. Therefore, the purpose of this study was to evaluate the surgical aspects of cochlear implantation, including the intraoperative findings, surgical difficulties and post-operative complications, and to review the management of these cases. 2. Materials and methods
* Corresponding author. E-mail addresses: [email protected] (A.M. Aldhafeeri), sanosi@hotmail. com (A.A. Alsanosi). http://dx.doi.org/10.1016/j.ijporl.2016.11.001 0165-5876/© 2016 Elsevier Ireland Ltd. All rights reserved.
A retrospective chart review was conducted at the Department of Otolaryngology and Head and Neck Surgery of King Abdul-Aziz University Hospital in Riyadh from January 2009 to January 2013
46
A.M. Aldhafeeri, A.A. Alsanosi / International Journal of Pediatric Otorhinolaryngology 92 (2017) 45e49
after obtaining IRB approval from the ethics committee at king Saud university Medical City. The patients' ages ranged from 12 months to 15 years. A total of 316 patients were included. All of the patients underwent a preoperative evaluation that included high-resolution computed tomography (HRCT) scans of the temporal bone and magnetic resonance imaging (MRI). Patients with identified inner ear anomalies were included in the study. The surgical data were reviewed for the following intraoperative findings: any difficulties encountered during surgery (e.g., perilymph gusher, abnormal facial nerve anatomy and the number of inserted electrodes). Patients with incomplete data were excluded. In total, 24 patients with inner ear malformations who underwent 28 total cochlear implant procedures were included. 3. Results Twenty-four patients with inner ear malformations were identified. Their ages ranged from 12 months to 15 years; the mean age was 4.02 years. The anomalies included semicircular canal (SCC) dysplasia in 8 (33.3%) patients, large vestibular aqueducts (LVAs) in 8 (33.3%) patients, Mondini malformation in 7 (29.1%) patients, and cochlear hypoplasia in 1 (4.1%) patient. A total of 28 cochlear implantations were performed. Twenty patients underwent unilateral cochlear implants, and 4 patients underwent bilateral cochlear implants (1 of these 4 procedures was performed in a single stage, and 3 were performed sequentially). The standard facial recess approach was used in 20 (71.4%) of the cochlear implantations. Five (17.8%) cochlear implants were performed using transaditus approaches (i.e., the anterior tympanotomy and a transantral approach without an open facial recess). Three (10.7%) of the cochlear implantations were performed with a combined approach (i.e., the anterior tympanotomy and facial recess approach, i.e., the combined technique) because of limited facial recess exposure. One of these patients exhibited dehiscence of the tympanic part of the facial nerve (Fig. 1). Nineteen (67.8%) of the surgeries were uneventful. Four (14.2%) patients exhibited intraoperative CSF gushers (1 patient had an LVA, and 3 patients had incomplete partition type II (IP-II) Mondini malformations), and the insertion of the electrode was incomplete in one patient (Fig. 2). Three of the procedures were associated with surgical difficulties. In one patient, the cochleostomy to the scala tympani did not allow the insertion of the electrode because of fibrosis; thus, the cochleostomy was widened superiorly to the
scala vestibuli, and the electrode was fully inserted. Two surgeries were aborted because intraoperative difficulties related to identifying the round window or performing the cochleostomy with distorted anatomy; revisions were performed by the senior otologist and were uneventful. In these cases, the initial difficulty with the procedures could be explained by the previous surgeons' lack of experience with unusual anatomy. 4. Discussion Cochlear implants in patients with inner ear anomalies carry a risk of intraoperative difficulty and possible complications. Such complications can occur because of abnormal landmarks and anatomy. Cochlear implants were previously contraindicated for patients with cochleovestibular anomalies [3], and prior to advancements in radiological imaging technologies, many programmes only identified inner ear anomalies incidentally after the implanted patients experienced acceptable outcomes [4]. Cochlear implantation is a challenging operation, particularly when associated with inner ear anomalies, which increase the risk of potential perioperative complications [5] and surgical difficulty. Therefore, special attention must be paid to unexpected situations, such as the intraoperative identification of abnormalities, and the surgical technique must be altered accordingly. 4.1. Surgical approach The standard facial recess approach can be used in the majority of cases with inner ear anomalies, and we used this approach in 71% (20 cochlear implants) of our cases. Three (11%) cochlear implant procedures were performed with a combined facial recess and anterior tympanotomy approach because of the presence of narrow facial recesses and increased cochleostomy difficulty caused by limited exposure. Five (18%) surgeries utilised a combined approach that involved the transaditus approach (as opposed to the facial recess approach). This approach was used in one case because the patient had a high jugular bulb above the round window; in the other 4 cases, this approach was the surgeon's preference. According to the literature, the facial recess approach is the primary approach used for cochlear implantations. However, a variety of approaches can be used when facing difficulties. These other approaches began to be reported in the early 2000s with the introduction of several modifications, such as the total transcanal
Fig. 1. The different surgical approaches used.
A.M. Aldhafeeri, A.A. Alsanosi / International Journal of Pediatric Otorhinolaryngology 92 (2017) 45e49
47
Fig. 2. Intraoperative findings.
approach by open tunnel [6] or closed tunnel [7], the suprameatal approach [8], the combined transmeatal approach with posterior tympanotomy [9] and the combined transaditus approach [10]. All of these approaches have been reported on, and each presents certain advantages and disadvantages [6e10]. These alternative approaches can be helpful in cases in which there is limited exposure through the facial recess or a high jugular bulb or when the round window faces inferiorly. For example, if a high jugular bulb approaches the middle ear from the attic, the combined transaditus approach (used in five of our cases) can be helpful, as can the combined suprameatal approach. The combined transaditus approach involves a cortical mastoidectomy with a transmeatal approach (i.e., not a facial recess approach). The electrode is passed through the mastoid to the aditus, where it can be reached from the external auditory canal and inserted into the round window via a cochleostomy. This approach avoids the difficulties of a limited facial recess or can even bypass the normal route because it is safer than drilling near the facial nerve. The suprameatal approach is similar to the transaditus approach, with the exception that it makes use of a limited opening by forming a tunnel to the attic; it has the advantage of avoiding unnecessary mastoid manipulation. In comparison, the transaditus approach has the advantage of using a familiar procedure (i.e., a cortical mastoid operation) and has more landmarks. Consequently, this approach makes it easier to avoid injuring the dura or the 2nd genu of the facial nerve and/or causing ossicular trauma. A transmastoid labyrinthotomy may be applicable in situations in which facial nerve injuries are a concern, as when a common cavity presents a high risk of an abnormally placed facial nerve [11]. A labyrinthotomy opening is created at the site where the lateral semicircular canal is normally situated. This procedure can avoid risking facial nerve damage and avoids the facial recess. In addition, this approach lowers the risk of an improperly directed cochleostomy that enters the internal carotid artery. Sennaroglu [12] mentions such a situation, in which the difficult anatomy of the facial nerve prevents the creation of a facial recess. In this situation, a canal wall down with blind sac closure can be performed to permit better visualisation of the oval window, round window and promontory. However, we believe that the previously mentioned alternative approaches are safer and more conservative than performing extensive work that may increase the risk of complication and the unnecessary loss of material. These different approaches decrease the complication rate because they can be altered
intraoperatively when exposure of the target region is limited or when it is difficult to proceed. These approaches also permit presurgical planning when certain anomalies are identified based on imaging results.
4.2. CSF/perilymph gushers The majority (64%) of the cochlear implantations that were reviewed in this study were uneventful (19 implants; Fig. 2). Perilymph leaks or gushers are frequently encountered in the presence of inner ear malformations; indeed, they are the most common intraoperative complication and have been reported in up to 50% of patients with an inner ear anomaly [13]. The incidence of this complication depends on the type of malformation. In our series, this complication was encountered in 14% of cases. The majority of perilymph leaks/gushers are easily controlled by elevating the head and sealing the cochleostomy with a small piece of fascia around the electrode. Several features of inner ear anomalies on radiologic images are correlated with an increased risk of perilymph leak/ gusher and may lead to sequela, such as continued post-operative CSF leaks and meningitis [14]. Certain anomalies are associated with a high risk of perilymph gushing, e.g., when the modiolus is absent or there is a defect of the internal auditory canal or an LVA malformation [12,15]. However, this complication can be managed using the fascia or muscle to form a seal around the electrode. Some authors have used glue on top of the graft that is placed around the electrode. Alternatively, one can use a “cork” stopper electrode to seal the opening [16]. When a gusher occurs, a wide cochleostomy is preferred for better insertion of the fascia or muscle and better sealing [17]. A lumbar drain is an extra measure that can be added in cases of uncontrolled CSF gushers or when the plug dislodges because of an uncooperative candidate [18]; however, such drains are rarely needed. In cases of contentious uncontrolled CSF leakage despite all measures, a blind sac closure may be used to obliterate the middle ear, mastoid, and Eustachian tube (ET) and to close the external auditory canal [14,17]. With respect to the blind sac procedure, a crucial step is required before the ET is obliterated; specifically, peritubal air cells can bypass the obliteration and drain to the ET medially, causing a continuous CSF leak through nasopharynx. To overcome over this potential complication, the ET should be drilled and all air cells should be removed prior to obliteration.
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4.3. Facial nerve An abnormal course of the facial nerves was not observed intraoperatively in any the patients described herein. One patient had an enlarged labyrinthine segment on a computed tomography (CT) scan, and another patient exhibited dehiscence of the tympanic and 2nd genu segments; both of these cases were IP type II. An aberrant course of the facial nerves has been reported in 9%e 16% of cases with inner ear anomalies [3,19,20]. Typically, facial nerve anomalies involve anterior displacement, and when such displacement is encountered, the cochleostomy should be changed to be anterior to the facial nerve promontory. Many case reports of facial nerve anomalies have reported accompanying abnormalities in the structure of the stapes, which can later be used to help position the nerve normally [21]. Certain patients are likely to present more facial nerve abnormalities, such as those with a common cavity, cochlear hypoplasia, and craniofacial anomalies [20]. In the current review, we observed one case with delayed facial nerve paralysis on the 3rd post-operative day and a House-Brackmann score of 4. The patient was reassured and was managed with oral steroids for one week and then tapered in the 2nd week as an outpatient. No antiviral medication was used. The patient fully recovered in two months. 4.4. Round window/cochleostomy The opening to the cochlea for electrode insertion was provided via cochleostomy in 71.4% (20 patients) of cases and via the round window in 28.6% (8 patients) of cases (Fig. 3). Havenith et al. [22] performed a systematic review to compare cochleostomy with the round window approach for hearing preservation surgeries and found no differences between the two techniques. However, the methodology was questionable because no studies that directly compared these techniques were included in the analysis. In the present study, one patient had an opened scala vestibuli caused by fibrosis of the scala tympani, which extended the cochleostomy superiorly and allowed for the insertion of the electrode in the scala vestibuli; full insertion was achieved without resistance. In situations in which the scala tympani is obliterated, the scala vestibuli often remains patent [21]. Therefore, when the scala tympani is obliterated and surgical drill-out does not reveal a patent lumen,
the electrode array may be placed into the scala vestibuli by performing a cochleostomy close to the oval window [23]. Revisions were performed in two cases in which the surgeries were aborted. In one case, another institution attempted cochlear implantation but failed because of the patient's abnormal anatomy. This patient exhibited an iatrogenic labyrinthine fistula; therefore, after one month, we performed a cochlear implantation in the same ear that was uneventful. In the second case, which was treated at our institution, the cochleostomy was difficult to perform because of the dense bone of the promontory. The decision was made to abort the surgery. Fifteen days later, the same patient received a cochlear implant on the same side, and the operation was performed by a senior colleague; this surgery was uneventful. Given these unexpected difficulties and cases with abnormal anatomy, we recommend that the images of any patient receiving a cochlear implant be reviewed carefully to identify any potential malformations of the inner ear. In addition, we recommend that the operation be performed by an experienced surgeon who can modify the approach and technique and make the correct choices when necessary. 4.5. Electrode choice The length of the human cochlea ranges from 20 to 30 mm, and the nerve endings of the spiral ganglion cells are distributed along this length. Because this length is altered in patients with anomalous structures, the characteristics of each case vary, and these variations affect the choice of the electrode array. In cases of cochlear malformation, attempting to achieve full insertion may lead to the misdirection of the electrode array towards the internal auditory canal through a deficient modiolus [18]. Electrode arrays with different designs, including different arrangements, lengths, stiffnesses, and flexibilities, are now available on the market. When a mildly malformed cochlea is expected, insertion of the full length can be expected if a soft and flexible array is used. When severe cochlear hypoplasia or a common cavity is present and in cases involving severe gushers, short arrays are preferred because standard electrodes may be misdirected into the internal auditory canal. Many choices of electrodes that are better suited to cochlear implants for patients with inner ear anomalies are now available [24]. In cases of common cavities and severe incomplete partition
Fig. 3. Types of electrode insertion techniques.
A.M. Aldhafeeri, A.A. Alsanosi / International Journal of Pediatric Otorhinolaryngology 92 (2017) 45e49
type I (IP-I) malformations, Chadha et al. [25] overcame the risk of a misdirected insertion into the internal auditory canal by using a straight electrode array that was gently pushed against the promontory prior to insertion into the cochleostomy to create a slight curvature over the first 3 to 5 electrodes. These authors believe that this procedure allows for the steering of the electrode array towards the modiolus to prevent misplacement into the internal auditory canal [25]. Intraoperative images are occasionally used to evaluate the position of the electrode if its proper placement is in doubt. This imaging is performed using an intraoperative x-ray. In rare cases, CT scans can be performed on the second day when further evaluation is required. Intraoperative imaging confirmation is indicated when a severely malformed cochlea is present or when there is a loss of the bone separating the base of the cochlea from the internal auditory canal. These conditions occur in many inner ear anomalies, such as a common cavity, cochlear hypoplasia, and an incomplete partition. In these cases, or when the surgeon is in doubt during the surgery, a periorbital x-ray can be performed to evaluate the orientation of the electrode before waking the patient from anaesthesia [14]. Fishman et al. [26] suggested the use of fluoroscopy-assisted insertion for the accurate introduction of the electrode into a malformed cochlea.
[3]
[4]
[5]
[6]
[7]
[8]
[9] [10]
[11]
5. Conclusion [12]
This study reviewed surgical difficulties during cochlear implantation. The results indicated that cochlear implantation can be safely performed in patients with inner ear anomalies. However, imaging results must be carefully evaluated preoperatively, and any anomaly associated with increased intraoperative risks should be given particular attention. In addition, the surgeries must be performed by experienced surgeons who are capable of modifying their technique according to the surgical findings. The transmastoid facial recess approach can be used in the majority of cases, and CSF gushers represent the most common type of intraoperative finding.
[13] [14] [15] [16]
[17]
Funding
[18]
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
[19]
Conflicts of interest
[20]
None.
[21]
Acknowledgements [22]
None. Appendix A. Supplementary data
[23]
Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.ijporl.2016.11.001.
[24] [25]
References [1] W.M. Luxford, W.F. House, Cochlear implants in children: medical and surgical considerations, Ear Hear 6 (1985) 20Se203, http://dx.doi.org/10.1097/ 00003446-198505001-00005. [2] G.M. Clark, P.J. Blamey, P.A. Busby, R.C. Dowell, B.K. Franz, G.N. Musgrave, T.G. Nienhuys, B.C. Pyman, S.A. Roberts, Y.C. Tong, R.L. Webb, J.A. Kuzma,
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D.K. Money, J.F. Patrick, P.M. Seligman, A multiple-electrode intracochlear implant for children, Arch. Otolaryngol. Head Neck Surg. 113 (1987) 825e828, http://dx.doi.org/10.1001/archotol.1987.01860080031010. C.A. Buchman, B.J. Copeland, K.K. Yu, C.J. Brown, V.N. Carrasco, H.C. Pillsbury, Cochlear implantation in children with congenital inner ear malformations, Laryngoscope 114 (2004) 309e316, http://dx.doi.org/10.1097/00005537200402000-00025. P.L. Mangabeira-Albernaz, The mondini dysplasiadfrom early diagnosis to cochlear implant, Acta Otolaryngol. 95 (1983) 627e631, http://dx.doi.org/ 10.3109/00016488309139454. M.N. Pakdaman, B.S. Herrmann, H.D. Curtin, J. Van Beek-King, D.J. Lee, Cochlear implantation in children with anomalous cochleovestibular anatomy: a systematic review, Otolaryngol. Head Neck Surg. 146 (2012) 180e190, http://dx.doi.org/10.1177/0194599811429244. €usler, Cochlear implantation without mastoidectomy: the pericanal R. Ha electrode insertion technique, Acta Otolaryngol. 122 (2002) 715e719, http:// dx.doi.org/10.1080/00016480260349773. T. Kiratzidis, ‘Veria operation’: cochlear implantation without a mastoidectomy and a poaterior tympanotomy. A new surgical technique, in: C.S. Kim, S.O. Chang, D. Li (Eds.), Updates in Cochlear Implantations. Adv. Otorhinolaryngol, vol. 57, Basel Karger, New York, 2000, pp. 127e130. J. Kronenberg, L. Migirov, T. Dagan, Suprameatal approach: new surgical approach for cochlear implantation, J. Laryngol. Otol. 115 (2001) 283e285, http://dx.doi.org/10.1258/0022215011907451. L. Lavinsky, M. Lavinsky, Combined approach technique to cochlear implantation, Otolaryngol. Head Neck Surg. 135 (2006) 258e259. A. Al Sanosi, Trans-aditus approach: an alternative technique for cochlear implantation, Indian J. Otolaryngol. Head Neck Surg. 64 (2012) 142e144, http://dx.doi.org/10.1007/s12070-011-0403-7. J.T. Mcelveen, V.N. Carrasco, R.T. Miyamoto, F.H. 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Neurotol. 23 (2002) 181e186, http://dx.doi.org/ 10.1097/00129492-200203000-00013. S. Havenith, M.J. Lammers, R.A. Tange, F. Trabalzini, A. Della Volpe, G.J. van der Heijden, W. Grolman, Hearing preservation surgery: cochleostomy or round window approach? A systematic review, Otol. Neurotol. 34 (2013) 667e674, http://dx.doi.org/10.1097/MAO.0b013e318288643e. T.P. Nikolopoulos, K. Kiprouli, Cochlear implant surgery in challenging cases, Cochlear Implants Int. 5 (Suppl 1) (2004) 56e63, http://dx.doi.org/10.1179/ cim.2004.5.Supplement-1.56. Z. Kabatova, M. Profant, L. Simkova, M. Groma, D. Nechojdomova, Cochlear implantation in malformed inner ear, Bratisl. Lek. Listy 110 (2009) 609e613. N.K. Chadha, A.L. James, K.A. Gordon, S. Blaser, B.C. Papsin, Bilateral cochlear implantation in children with anomalous cochleovestibular anatomy, Arch. Otolaryngol. Head Neck Surg. 135 (2009) 903e909, http://dx.doi.org/10.1001/ archoto.2009.120. A.J. Fishman, J.T. Roland, G. Alexiades, J. 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Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: http://www.ijporlonline.com/
Management of surgical difficulties during cochlear implant with inner ear anomalies Ahmad M. Aldhafeeri a, Abdulrahman A. Alsanosi b, * a
Fellow in Otology-Neurotology, King Saud University Fellowship, King Abdullah Ear Specialist Centre, King Saud University Medical City, Riyadh, Saudi Arabia b King Abdullah Ear Specialist Centre, King Saud University Medical City, P.O. Box 245, Riyadh, 11411, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 17 August 2016 Received in revised form 29 October 2016 Accepted 1 November 2016 Available online 3 November 2016
Objective: To review the difficulties that can occur during cochlear implant surgery in patients with inner ear abnormalities and the management thereof. Methods: A retrospective chart review of 316 patients who received cochlear implants was conducted. The data collected included the types of inner ear anomalies, intraoperative findings, and the clinical management strategies. A review of the literature was also performed. Results: A total of 24 patients with inner ear malformations who underwent 28 total cochlear implant procedures were identified. The anomalies included isolated large vestibular aqueducts in 8 (33.3%) patients, isolated semicircular canal dysplasia in 8 (33.3%) patients, classical Mondini malformation in 7 (29.1%) patients, and cochlear hypoplasia in 1 (4.1%) patient. Four (14.2%) patients exhibited intraoperative cerebrospinal fluid (CSF) gushers. One patient experienced delayed facial nerve paralysis, and an electrode was partially inserted into one patient. In 2 (7.14%) cases, the surgeries were aborted because of difficulties. Conclusion: Cochlear implantation for inner ear anomalies can be performed safely. Special attention should be given to preoperative imaging to anticipate the potential intraoperative risks that can occur in inner ear anomaly cases. Every surgery should be planned with a safe approach and specific requirements, e.g., regarding electrode type, and the surgeries must be performed by experienced surgeons who are capable of modifying their technique according to the surgical findings. © 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Anomaly Cochlear implant Difficulty Risk Surgical Management
1. Introduction Cochlear implants are the treatment modality of choice for patients with profound cochlear hearing loss, particularly patients who have experienced minimal or no benefit from hearing aids. Cochlear implants were first utilised in the 1980s following the introduction of single-channel devices [1] and the subsequent introduction of multi-channel devices [2]. These devices were implanted to restore the sense of audition and became the standard of care for cochlear hearing loss. Until the last decade, many cochlear implant centres refused to implant devices in children with anomalous inner ears because of concerns related to surgical difficulties and performance expectations [3]. Over time, however,
as the experience of the surgeons who performed these surgeries increased, a greater number of children with inner ear anomalies were considered as candidates for surgery. Operating on a patient with an inner ear anomaly is associated with greater risks of surgical complications, such as facial nerve injury, labyrinthine fistula, and cerebrospinal fluid (CSF) gushers. Moreover, few reports have addressed the surgical risks and complications encountered during cochlear implantation in patients with inner ear anomalies in our region. Therefore, the purpose of this study was to evaluate the surgical aspects of cochlear implantation, including the intraoperative findings, surgical difficulties and post-operative complications, and to review the management of these cases. 2. Materials and methods
* Corresponding author. E-mail addresses: [email protected] (A.M. Aldhafeeri), sanosi@hotmail. com (A.A. Alsanosi). http://dx.doi.org/10.1016/j.ijporl.2016.11.001 0165-5876/© 2016 Elsevier Ireland Ltd. All rights reserved.
A retrospective chart review was conducted at the Department of Otolaryngology and Head and Neck Surgery of King Abdul-Aziz University Hospital in Riyadh from January 2009 to January 2013
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A.M. Aldhafeeri, A.A. Alsanosi / International Journal of Pediatric Otorhinolaryngology 92 (2017) 45e49
after obtaining IRB approval from the ethics committee at king Saud university Medical City. The patients' ages ranged from 12 months to 15 years. A total of 316 patients were included. All of the patients underwent a preoperative evaluation that included high-resolution computed tomography (HRCT) scans of the temporal bone and magnetic resonance imaging (MRI). Patients with identified inner ear anomalies were included in the study. The surgical data were reviewed for the following intraoperative findings: any difficulties encountered during surgery (e.g., perilymph gusher, abnormal facial nerve anatomy and the number of inserted electrodes). Patients with incomplete data were excluded. In total, 24 patients with inner ear malformations who underwent 28 total cochlear implant procedures were included. 3. Results Twenty-four patients with inner ear malformations were identified. Their ages ranged from 12 months to 15 years; the mean age was 4.02 years. The anomalies included semicircular canal (SCC) dysplasia in 8 (33.3%) patients, large vestibular aqueducts (LVAs) in 8 (33.3%) patients, Mondini malformation in 7 (29.1%) patients, and cochlear hypoplasia in 1 (4.1%) patient. A total of 28 cochlear implantations were performed. Twenty patients underwent unilateral cochlear implants, and 4 patients underwent bilateral cochlear implants (1 of these 4 procedures was performed in a single stage, and 3 were performed sequentially). The standard facial recess approach was used in 20 (71.4%) of the cochlear implantations. Five (17.8%) cochlear implants were performed using transaditus approaches (i.e., the anterior tympanotomy and a transantral approach without an open facial recess). Three (10.7%) of the cochlear implantations were performed with a combined approach (i.e., the anterior tympanotomy and facial recess approach, i.e., the combined technique) because of limited facial recess exposure. One of these patients exhibited dehiscence of the tympanic part of the facial nerve (Fig. 1). Nineteen (67.8%) of the surgeries were uneventful. Four (14.2%) patients exhibited intraoperative CSF gushers (1 patient had an LVA, and 3 patients had incomplete partition type II (IP-II) Mondini malformations), and the insertion of the electrode was incomplete in one patient (Fig. 2). Three of the procedures were associated with surgical difficulties. In one patient, the cochleostomy to the scala tympani did not allow the insertion of the electrode because of fibrosis; thus, the cochleostomy was widened superiorly to the
scala vestibuli, and the electrode was fully inserted. Two surgeries were aborted because intraoperative difficulties related to identifying the round window or performing the cochleostomy with distorted anatomy; revisions were performed by the senior otologist and were uneventful. In these cases, the initial difficulty with the procedures could be explained by the previous surgeons' lack of experience with unusual anatomy. 4. Discussion Cochlear implants in patients with inner ear anomalies carry a risk of intraoperative difficulty and possible complications. Such complications can occur because of abnormal landmarks and anatomy. Cochlear implants were previously contraindicated for patients with cochleovestibular anomalies [3], and prior to advancements in radiological imaging technologies, many programmes only identified inner ear anomalies incidentally after the implanted patients experienced acceptable outcomes [4]. Cochlear implantation is a challenging operation, particularly when associated with inner ear anomalies, which increase the risk of potential perioperative complications [5] and surgical difficulty. Therefore, special attention must be paid to unexpected situations, such as the intraoperative identification of abnormalities, and the surgical technique must be altered accordingly. 4.1. Surgical approach The standard facial recess approach can be used in the majority of cases with inner ear anomalies, and we used this approach in 71% (20 cochlear implants) of our cases. Three (11%) cochlear implant procedures were performed with a combined facial recess and anterior tympanotomy approach because of the presence of narrow facial recesses and increased cochleostomy difficulty caused by limited exposure. Five (18%) surgeries utilised a combined approach that involved the transaditus approach (as opposed to the facial recess approach). This approach was used in one case because the patient had a high jugular bulb above the round window; in the other 4 cases, this approach was the surgeon's preference. According to the literature, the facial recess approach is the primary approach used for cochlear implantations. However, a variety of approaches can be used when facing difficulties. These other approaches began to be reported in the early 2000s with the introduction of several modifications, such as the total transcanal
Fig. 1. The different surgical approaches used.
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47
Fig. 2. Intraoperative findings.
approach by open tunnel [6] or closed tunnel [7], the suprameatal approach [8], the combined transmeatal approach with posterior tympanotomy [9] and the combined transaditus approach [10]. All of these approaches have been reported on, and each presents certain advantages and disadvantages [6e10]. These alternative approaches can be helpful in cases in which there is limited exposure through the facial recess or a high jugular bulb or when the round window faces inferiorly. For example, if a high jugular bulb approaches the middle ear from the attic, the combined transaditus approach (used in five of our cases) can be helpful, as can the combined suprameatal approach. The combined transaditus approach involves a cortical mastoidectomy with a transmeatal approach (i.e., not a facial recess approach). The electrode is passed through the mastoid to the aditus, where it can be reached from the external auditory canal and inserted into the round window via a cochleostomy. This approach avoids the difficulties of a limited facial recess or can even bypass the normal route because it is safer than drilling near the facial nerve. The suprameatal approach is similar to the transaditus approach, with the exception that it makes use of a limited opening by forming a tunnel to the attic; it has the advantage of avoiding unnecessary mastoid manipulation. In comparison, the transaditus approach has the advantage of using a familiar procedure (i.e., a cortical mastoid operation) and has more landmarks. Consequently, this approach makes it easier to avoid injuring the dura or the 2nd genu of the facial nerve and/or causing ossicular trauma. A transmastoid labyrinthotomy may be applicable in situations in which facial nerve injuries are a concern, as when a common cavity presents a high risk of an abnormally placed facial nerve [11]. A labyrinthotomy opening is created at the site where the lateral semicircular canal is normally situated. This procedure can avoid risking facial nerve damage and avoids the facial recess. In addition, this approach lowers the risk of an improperly directed cochleostomy that enters the internal carotid artery. Sennaroglu [12] mentions such a situation, in which the difficult anatomy of the facial nerve prevents the creation of a facial recess. In this situation, a canal wall down with blind sac closure can be performed to permit better visualisation of the oval window, round window and promontory. However, we believe that the previously mentioned alternative approaches are safer and more conservative than performing extensive work that may increase the risk of complication and the unnecessary loss of material. These different approaches decrease the complication rate because they can be altered
intraoperatively when exposure of the target region is limited or when it is difficult to proceed. These approaches also permit presurgical planning when certain anomalies are identified based on imaging results.
4.2. CSF/perilymph gushers The majority (64%) of the cochlear implantations that were reviewed in this study were uneventful (19 implants; Fig. 2). Perilymph leaks or gushers are frequently encountered in the presence of inner ear malformations; indeed, they are the most common intraoperative complication and have been reported in up to 50% of patients with an inner ear anomaly [13]. The incidence of this complication depends on the type of malformation. In our series, this complication was encountered in 14% of cases. The majority of perilymph leaks/gushers are easily controlled by elevating the head and sealing the cochleostomy with a small piece of fascia around the electrode. Several features of inner ear anomalies on radiologic images are correlated with an increased risk of perilymph leak/ gusher and may lead to sequela, such as continued post-operative CSF leaks and meningitis [14]. Certain anomalies are associated with a high risk of perilymph gushing, e.g., when the modiolus is absent or there is a defect of the internal auditory canal or an LVA malformation [12,15]. However, this complication can be managed using the fascia or muscle to form a seal around the electrode. Some authors have used glue on top of the graft that is placed around the electrode. Alternatively, one can use a “cork” stopper electrode to seal the opening [16]. When a gusher occurs, a wide cochleostomy is preferred for better insertion of the fascia or muscle and better sealing [17]. A lumbar drain is an extra measure that can be added in cases of uncontrolled CSF gushers or when the plug dislodges because of an uncooperative candidate [18]; however, such drains are rarely needed. In cases of contentious uncontrolled CSF leakage despite all measures, a blind sac closure may be used to obliterate the middle ear, mastoid, and Eustachian tube (ET) and to close the external auditory canal [14,17]. With respect to the blind sac procedure, a crucial step is required before the ET is obliterated; specifically, peritubal air cells can bypass the obliteration and drain to the ET medially, causing a continuous CSF leak through nasopharynx. To overcome over this potential complication, the ET should be drilled and all air cells should be removed prior to obliteration.
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4.3. Facial nerve An abnormal course of the facial nerves was not observed intraoperatively in any the patients described herein. One patient had an enlarged labyrinthine segment on a computed tomography (CT) scan, and another patient exhibited dehiscence of the tympanic and 2nd genu segments; both of these cases were IP type II. An aberrant course of the facial nerves has been reported in 9%e 16% of cases with inner ear anomalies [3,19,20]. Typically, facial nerve anomalies involve anterior displacement, and when such displacement is encountered, the cochleostomy should be changed to be anterior to the facial nerve promontory. Many case reports of facial nerve anomalies have reported accompanying abnormalities in the structure of the stapes, which can later be used to help position the nerve normally [21]. Certain patients are likely to present more facial nerve abnormalities, such as those with a common cavity, cochlear hypoplasia, and craniofacial anomalies [20]. In the current review, we observed one case with delayed facial nerve paralysis on the 3rd post-operative day and a House-Brackmann score of 4. The patient was reassured and was managed with oral steroids for one week and then tapered in the 2nd week as an outpatient. No antiviral medication was used. The patient fully recovered in two months. 4.4. Round window/cochleostomy The opening to the cochlea for electrode insertion was provided via cochleostomy in 71.4% (20 patients) of cases and via the round window in 28.6% (8 patients) of cases (Fig. 3). Havenith et al. [22] performed a systematic review to compare cochleostomy with the round window approach for hearing preservation surgeries and found no differences between the two techniques. However, the methodology was questionable because no studies that directly compared these techniques were included in the analysis. In the present study, one patient had an opened scala vestibuli caused by fibrosis of the scala tympani, which extended the cochleostomy superiorly and allowed for the insertion of the electrode in the scala vestibuli; full insertion was achieved without resistance. In situations in which the scala tympani is obliterated, the scala vestibuli often remains patent [21]. Therefore, when the scala tympani is obliterated and surgical drill-out does not reveal a patent lumen,
the electrode array may be placed into the scala vestibuli by performing a cochleostomy close to the oval window [23]. Revisions were performed in two cases in which the surgeries were aborted. In one case, another institution attempted cochlear implantation but failed because of the patient's abnormal anatomy. This patient exhibited an iatrogenic labyrinthine fistula; therefore, after one month, we performed a cochlear implantation in the same ear that was uneventful. In the second case, which was treated at our institution, the cochleostomy was difficult to perform because of the dense bone of the promontory. The decision was made to abort the surgery. Fifteen days later, the same patient received a cochlear implant on the same side, and the operation was performed by a senior colleague; this surgery was uneventful. Given these unexpected difficulties and cases with abnormal anatomy, we recommend that the images of any patient receiving a cochlear implant be reviewed carefully to identify any potential malformations of the inner ear. In addition, we recommend that the operation be performed by an experienced surgeon who can modify the approach and technique and make the correct choices when necessary. 4.5. Electrode choice The length of the human cochlea ranges from 20 to 30 mm, and the nerve endings of the spiral ganglion cells are distributed along this length. Because this length is altered in patients with anomalous structures, the characteristics of each case vary, and these variations affect the choice of the electrode array. In cases of cochlear malformation, attempting to achieve full insertion may lead to the misdirection of the electrode array towards the internal auditory canal through a deficient modiolus [18]. Electrode arrays with different designs, including different arrangements, lengths, stiffnesses, and flexibilities, are now available on the market. When a mildly malformed cochlea is expected, insertion of the full length can be expected if a soft and flexible array is used. When severe cochlear hypoplasia or a common cavity is present and in cases involving severe gushers, short arrays are preferred because standard electrodes may be misdirected into the internal auditory canal. Many choices of electrodes that are better suited to cochlear implants for patients with inner ear anomalies are now available [24]. In cases of common cavities and severe incomplete partition
Fig. 3. Types of electrode insertion techniques.
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type I (IP-I) malformations, Chadha et al. [25] overcame the risk of a misdirected insertion into the internal auditory canal by using a straight electrode array that was gently pushed against the promontory prior to insertion into the cochleostomy to create a slight curvature over the first 3 to 5 electrodes. These authors believe that this procedure allows for the steering of the electrode array towards the modiolus to prevent misplacement into the internal auditory canal [25]. Intraoperative images are occasionally used to evaluate the position of the electrode if its proper placement is in doubt. This imaging is performed using an intraoperative x-ray. In rare cases, CT scans can be performed on the second day when further evaluation is required. Intraoperative imaging confirmation is indicated when a severely malformed cochlea is present or when there is a loss of the bone separating the base of the cochlea from the internal auditory canal. These conditions occur in many inner ear anomalies, such as a common cavity, cochlear hypoplasia, and an incomplete partition. In these cases, or when the surgeon is in doubt during the surgery, a periorbital x-ray can be performed to evaluate the orientation of the electrode before waking the patient from anaesthesia [14]. Fishman et al. [26] suggested the use of fluoroscopy-assisted insertion for the accurate introduction of the electrode into a malformed cochlea.
[3]
[4]
[5]
[6]
[7]
[8]
[9] [10]
[11]
5. Conclusion [12]
This study reviewed surgical difficulties during cochlear implantation. The results indicated that cochlear implantation can be safely performed in patients with inner ear anomalies. However, imaging results must be carefully evaluated preoperatively, and any anomaly associated with increased intraoperative risks should be given particular attention. In addition, the surgeries must be performed by experienced surgeons who are capable of modifying their technique according to the surgical findings. The transmastoid facial recess approach can be used in the majority of cases, and CSF gushers represent the most common type of intraoperative finding.
[13] [14] [15] [16]
[17]
Funding
[18]
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
[19]
Conflicts of interest
[20]
None.
[21]
Acknowledgements [22]
None. Appendix A. Supplementary data
[23]
Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.ijporl.2016.11.001.
[24] [25]
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