Eur Arch Otorhinolaryngol DOI 10.1007/s00405-014-2993-7
Otology
Evaluation of a minimally invasive surgical fixation technique for young children with the Concerto Pin cochlear implant system Johannes Schnabl · Astrid Wolf‑Magele · Stefan Marcel Pok · Christoph Url · Patrick Zorowka · Georg Sprinzl
Received: 4 December 2013 / Accepted: 1 March 2014 © Springer-Verlag Berlin Heidelberg 2014
Abstract In 2011, Med-El (Innsbruck, Austria) introduced a new cochlear implant system, designed to require a minimally invasive surgical technique and allow greater positional flexibility for its fixation on the skull. The Concerto Pin implant system is a good option for patients with thinner bone, such as children and elderly. The aim of this study was to investigate the implant’s stability in children using our minimally invasive surgical technique. This was a prospective, longitudinal study with a single-subject, repeated-examination design. Six children, implanted with a Concerto Pin using our minimally invasive surgical technique between October 2011 and September 2012, were assessed 1, 3 and 6 months after surgery. In each case, the implant remained in a stable position and no adverse events or problems with healing were observed at any time during the investigation. The minimally invasive technique and the method of implant fixation that bypass drilling a deep
J. Schnabl (*) · A. Wolf‑Magele · S. M. Pok · G. Sprinzl (*) Department of Otorhinolaryngology, Karl Landsteiner University Hospital St. Pölten, Propst Führer‑Straße 4, 3100 St. Pölten, Austria e-mail: [email protected] G. Sprinzl e-mail: [email protected] J. Schnabl · G. Sprinzl Karl Landsteiner Institut für Implantierung elektronischer Hörsysteme, St. Pölten, Austria C. Url Department of Otorhinolaryngology, Medical University Innsbruck, Innsbruck, Austria P. Zorowka Department of Hearing, Speech and Voice Disorders, Medical University Innsbruck, Innsbruck, Austria
implant bed constitute a good option for patients with thinner bone, such as children. This clinical study shows the safety and stability of the Concerto Pin implant system using a minimally invasive surgical technique. Keywords Cochlear implant · Minimally invasive surgery · Concerto Pin · Children
Introduction Since the introduction of cochlear implants (CI) for patients suffering from severe to profound hearing loss, there have been great strides made in the devices themselves as well as the surgical techniques. These days, cochlear implantation is considered to be a safe procedure, with many different surgical techniques in use [1, 2]. Usually, the implant receiver is anchored in a deep implant bed on the temporal bone and fixed with tie-down sutures. When drilling a deep implant bed and the holes for the sutures, the dura mater can be damaged, especially in children and older adults due to their thinner skull bone. This population is, therefore, more vulnerable to dural injury [1, 3]. More and more, less invasive and less time-consuming surgical techniques are being developed [2–5], and alternative fixation methods, such as the use of titanium screws and different types of meshes instead of sutures, have been established [6–8]. In a multicenter study evaluating a fixation system with titanium screws, Guevara et al. [9] concluded that the usage of these screws was safe and would not increase the risk of implant dislocation or be significantly time-consuming. The usage of only a periosteal pocket with no sutures or drilled holes without any dislocation observed has also been described in the literature [4, 10–13]. However, since children have higher activity levels
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Eur Arch Otorhinolaryngol
Fig. 1 The Concerto Pin cochlear implant system with dimensions in millimeters. a Frontal view, b side view, c pins
and more frequent head traumas, the risk of implant dislocation increases with these techniques [14]. In an evidencebased review of literature, Varebeke et al. [15] concluded that it seems fair to define good practice as the creation of at least a bony well and/or (bony) sutures. In 2011, Med-El (Innsbruck, Austria) introduced a new cochlear implant system (the Concerto Pin) that requires a minimally invasive surgical technique and uses pins to give more stability to the implant receiver. In a former anatomical study [16] we demonstrated the mechanical stability of the Concerto Pin attachment system. The authors concluded that this method of fixation provides a secure attachment to the skull with a direct mechanical connection between implant and bone. In addition, this fixation method requires less drilling and no tie-down sutures, which makes the surgery quicker and less invasive. The aim of this study was to assess the safety of the Concerto Pin cochlear implant system for children using our minimally invasive surgical technique.
Materials and methods This study has been planned as a prospective, medium-term follow-up study with a single-subject, repeated-examination design. The data acquisition was conducted within the scope of the Concerto and Concerto Pin post-marketing study. The study was approved by the responsible ethical committee. Concerto Pin cochlear implant system The Concerto Pin cochlear implant system (Fig. 1) is a part of the Maestro cochlear implant system and is a further development of the Sonata system (Med-El, Innsbruck, Austria). The implant was designed for minimally
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invasive surgical techniques and is one of the smallest and lightest implants available (7.6 g without electrode). The implant is available in a large variety of electrode arrays for every cochlear anatomy. Furthermore, the implant was designed for increased positional flexibility on the skull for individual variation in skull anatomy. The implant has an integrated reference electrode for reduced risk and shorter surgery time (no need for surgical placement of a reference electrode). Minimally invasive surgical technique Figure 2a–f demonstrates our minimally invasive surgical technique on a right ear. Figure 2a demonstrates the way the templates for the Concerto Pin are marked on the patient’s skin. The processor template is positioned behind the ear. The Concerto Pin template should be positioned in such a way that the implant will be located on an area of the scalp containing hair. The lower part of the stimulator should be close to the temporal line, at an angle of 45°. The surgeon then performs a retroauricular incision. This should be no more than 4 cm long and should be placed 1–2 cm in front of the implant to ensure that the scar will not lie directly over the implant body. Figure 2b demonstrates the precise preparation of the double-layer flap. After the incision is made, the wound is held open by retractors. The first flap contains the skin and the subcutis. The second, U-shaped flap consists of the muscle and the periosteum and is performed with an electric scalpel and then freed from the surface of the bone. A double-layer skin flap may reduce the chance of infection and may allow for better healing. After drilling a mastoidectomy and a posterior tympanotomy, a periosteal pocket for the implant is prepared using a periosteal elevator.
Eur Arch Otorhinolaryngol
Fig. 2 Illustration of the minimally invasive surgical technique with the Concerto Pin cochlear implant system. a Marked templates on the patient’s skin, b preparation of the double-layer flap, c drilling the holes for the fixation pins with the support of the drilling guide, d
a bony channel to give additional stability to the implant and protect the electrode lead. The holes for the fixation pins are circled, e the final position of the stimulator and the electrode lead after the cochlear implantation, f bone pâté for additional fixation
The implant template is used to mark the correct position of the stimulator. A minimal implant bed for the titanium housing only and a ramp to ensure sufficient immobilization of the stimulator is then created using a diamond burr with a maximum depth of 2–3 mm at the anterior edge. The holes of the fixation pins are drilled into the skull at a distance and depth of 1.4 mm with the support of the drilling guide (Fig. 2c). To give additional stability to the implant and protect the electrode lead, a bony channel is drilled towards the mastoidectomy (Fig. 2d). During all this drilling, the middle ear cavity is protected from bone dust contamination by closing it with medical gauze. Drilling should also be completed before the cochlea is opened.
Figure 2e demonstrates the position of the stimulator and the electrode lead after the cochlear implantation. Tiedown sutures are not used. For additional fixation, the stimulator, the small implant bed and the bony channel are covered with bone pâté (Fig. 2f). A CBCT (Cone beam computed tomography) scan is performed postoperatively to determine the position of the implant (Fig. 3). Patient population Between October 2011 and September 2012, 6 children aged 2–12 (mean: 6.2 years, range 2–12 years) were implanted
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Eur Arch Otorhinolaryngol
skin flap reactions, device extrusion or electrode extrusion, and no re-insertions were necessary. Altogether, no adverse event was registered.
Discussion
Fig. 3 CBCT scan of the mastoid and position of the implant in a minimally deep implant bed 1 day after implantation
with 8 Concerto Pin cochlear implants (N = 8). Two children were implanted bilaterally in a single stage. Four CIs were implanted on the right side and four on the left. Five patients suffered from bilateral congenital hearing loss and one patient had unilateral hearing loss after a trauma. All patients had no significant outer or middle ear pathology and were in excellent general, medical, and psychological health. All patients were implanted using the previously described minimally invasive technique. Patients were examined by a study investigator (not the surgeon but a member of the otologic team) at intervals of 1, 3 and 6 months after the implantation. The following issues were analyzed: stability (whether or not there was any shifting or rocking), adverse reactions to the implant (allergic reaction, chronic infection, tissue reaction, skin irritation, other issues), problems with skin flap healing (skin flap infection, extrusion of the device, re-insertion of the device due to skin flap infection, extrusion of the electrode in the mastoid cavity region, other issues), other adverse events. The issues were analyzed using anamnestic questions and clinical examination. The stability was additionally checked by the investigator moving and pushing the implant during the examination.
Results The implant was found to be in a stable position in all cases, with no shifting or rocking observed at the time of investigation. No unwanted or adverse reactions to the implant were noticed. There were also no problems with skin flap healing in any of the patients. We did not see any
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This clinical study demonstrates the safety of the Concerto Pin implant and fixation system with our minimally invasive surgical technique under everyday life conditions in children, and verifies the stability that was demonstrated in a prior anatomical study [16]. Our surgical technique is a minimally invasive one. A pre-operative CT scan is done to evaluate the bony structures, particularly the structures of the middle and inner ear and the topography of the facial nerve and sinus sigmoideus. The pre-operative evaluation of the thickness of the temporal bone is secondary, because all the burring is performed under good visual conditions. The retroauricular incision should be no longer than 3–4 cm. This is consistent with other minimally invasive techniques described in the literature [2, 13]. As additional protection, we use a double-layer flap. After the incision of the cutis and subcutis, a musculo-periosteal, U-shaped flap is prepared. As described also by other authors [2, 13, 17], we create a tight periosteal pocket for fixation of the implant. In addition, we burr a minimally deep implant well for the titanium housing and a ramp to ensure sufficient stimulator immobilization with a maximum depth of 2 mm at the anterior edge. The holes for the pins have a depth of 1.4 mm. Due to this shallow depth and the fact that the surgeon has a clear view while drilling the holes, dural injury or sigmoid sinus puncture is very improbable. To give additional stability to the implant and protect the electrode lead, a bony channel is drilled towards the mastoid cavity, and then the stimulator, the small implant bed and the bony channel are covered with bone pâté similar as described by Loh et al. [17]. No tie-down sutures are used; therefore, the implant is held in place by the pins at its base and the retaining forces of the periosteal pocket. The implant well, the channel for the electrode lead and coverage with bone dust provide additional stability. Omitting tie-down sutures and drilling a minimally deep implant bed reduce surgery time and possible injury to the dura mater. Figure 4 shows a diagram of the implanted Concerto Pin implant system using the minimally invasive technique. Several implant fixation techniques have been described. Lane and Carrasco [18] fixed the implant in the bony well, overlaid with Gore-Tex micro-mesh which was secured with titanium screws. They were also able to reduce the length of the surgery using the standard suturing technique. O’Donoghue et al. [19] described a minimal access technique
Eur Arch Otorhinolaryngol Fig. 4 Schematic picture of the implanted Concerto Pin cochlear implant system with a small implant bed/ramp
in which they made a small incision below the hairline without shaving any hair. They then drilled a bony well inside a small subperiosteal pocket, where the implant is held tightly in place. They stated better psychological acceptance by the patient, reduced operation time and only minor complications (postauricular swelling). Campisi et al. [20] used the Mitek QuickAnchor fixation system (holes are drilled in the walls of the recessed well and a tightening suture is passed through bony holes) in children with thick cortical bone. This proved to be an effective minimal access technique for this group of children. Black [21] described a keyhole surgery using a 15–18 mm C-incision on the back side of the auricle. In this technique, the implant is retained in a tight pericranial pocket without a bony well. He concluded that current implant designs should be modified for better adaption to the cranial contours. Jethanamest et al. [22] described a fixation method using a tight subperiosteal pocket without the usage of either sutures or a bony recess. In a median follow-up period of 32.6 months, no complications and no cases of migration were identified. Boscolo-Rizzo et al. [23] described an alternative and safe non-sutured fixation technique to secure the receiver-stimulator of the cochlea implant to the skull with a special tailored flap of periosteum. As stated in our study group’s former preclinical study [16], our results demonstrate that the pins hold the implant in place even if it is exposed to an impact such as those happening often in daily children circumstances. When an impact occurs, it is split between a perpendicular force which presses the implant against the skull and inhibits the pins from being displaced from their fixation points and a tangential force which is compensated by the pins. No screws, transcortical holes or foreign materials are used. A very small implant bed/ramp can be considered, but may not be necessary if the bone in this area is only flattened. An X-ray is usually sufficient to evaluate the postoperative electrode position [24]. However, in some specific cases, a CBCT scan is recommended to obtain a detailed evaluation of the position of the implant itself as well as the
electrode, due to its low sensitivity to metallic artifacts. In addition, this type of scan is especially useful in children since it has a low radiation dose [25]. Eight Concerto Pin CIs were implanted in six patients. Although the “data assessment” was based on subjective experience and it was not possible to quantify the pins’ ability to hold the implant in place, we nevertheless observed no implant migration such as shifting or rocking in any of the patients. This outcome is comparable to the results described by Cuda [2], who also employed a minimally invasive surgical technique in children using the Concerto CI (Med-El, Innsbruck, Austria). Furthermore, no unwanted or adverse reactions to the implant such as an allergic reaction, chronic infection, tissue reaction or skin irritation were observed. There were also no problems with skin flap healing.
Conclusion In conclusion, our minimally invasive surgical technique for implantation of the Concerto Pin results in a safe and stable implant system for children in everyday life conditions. In this technique, no transcortical holes, screws, or foreign materials are used. The implant is held in place by the pins after a small incision is made, with the creation of a minimal implant bed/ramp if necessary. Conflict of interest All authors declare that the manuscript has not been published previously or under review by another journal. The paper has not been presented to any professional society. Furthermore, all authors declare that no financial interest, commercial financial support or personal relationship with other people or organizations that could influence this work exist.
References 1. Alexander NS, Caron E, Woolley AL (2011) Fixation methods in pediatric cochlear implants: retrospective review of an evolution of 3 techniques. Otolaryngol Head Neck Surg 144:427–430
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2. Cuda D (2013) A simplified fixation of the new thin cochlear implant receiver-stimulators in children: long term results with the “back-pocket” technique. Int J Pediatr Otorhinolaryngol 77:1158–1161 3. Adunka OF, Buchman CA (2007) Cochlear implant fixation in children using periosteal sutures. Otol Neurotol 28:768–770 4. Cuda D (2009) Cochlear implantation with Pulsar Med El: a novel small incision technique. Acta Otorhinolaryngol Ital 29:76–78 5. Dalchow CV, Werner JA (2005) A new instrument for minimal access surgery in cochlear implantation. Otol Neurotol 26:678–679 6. Davis BM, Labadie RF, McMenomey SO, Haynes DS (2004) Cochlear implant fixation using polypropylene mesh and titanium screws. Laryngoscope 114:2116–2118 7. Molony TB, Giles JE, Thompson TL, Motamedi KK (2010) Device fixation in cochlear implantation: is bone anchoring necessary? Laryngoscope 120:1837–1839 8. Djalilian HR, King T, Faust RA, Smith S, Levine SC (2001) Securing cochlear implants to the skull: two alternate methods. Ear Nose Throat J 80:171–173 9. Guevara N, Sterkers O, Bebear JP, Meller R, Magnan J, Mosnier I, Amstutz I, Lerosey Y, Triglia JM, Roman S, Gahide I (2010) Multicenter evaluation of the digisonic SP cochlear implant fixation system with titanium screws in 156 patients. Ann Otol Rhinol Laryngol 119:501–505 10. Gekeler J, Luers JC, Lang-Roth R, Beutner D (2013) Cochlear implant fixation: are sutures really necessary? Eur Arch Otorhinolaryngol 270:483–487 11. Guldiken Y, Orhan KS, Yigit O, Basaran B, Polat B, Gunes S, Acoglu E, Deger K (2011) Subperiosteal temporal pocket versus standard technique in cochlear implantation: a comparative clinical study. Otol Neurotol 32:987–991 12. Costain N, Cavanagh J, Bance M, Morris DP, Hong P (2013) A musculoperiosteal flap cochlear implant device fixation technique: our experience in one hundred and seventy nine patients. Clin Otolaryngol 38:86–89 13. Balkany TJ, Whitley M, Shapira Y, Angeli SI, Brown K, Eter E, Van De Water T, Telischi FF, Eshraghi AA, Treaba C (2009) The temporalis pocket technique for cochlear implantation: an anatomic and clinical study. Otol Neurotol 30:903–907
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Eur Arch Otorhinolaryngol 14. James AL, Papsin BC (2004) Device fixation and small incision access for pediatric cochlear implants. Int J Pediatr Otorhinolaryngol 68:1017–1022 15. de Varebeke SP, Govaerts P, Cox T, Deben K, Ketelslagers K, Waelkens B (2012) Fixation of cochlear implants: an evidencebased review of literature. B-ENT 8:85–94 16. Schnabl J, Markl A, Hormann R, Wolf-Magele A, Schartinger V, Sprinzl G (2012) Concerto Pin: a novel concept of cochlear implant fixation. Otol Neurotol 33:1525–1529 17. Loh C, Jiang D, Dezso A, Fitzgerald O’Connor A (2008) Nonsutured fixation of cochlear implants using a minimally-invasive approach. Clin Otolaryngol 33:255–264 18. Otto RA, Lane AP, Carrasco VN (1999) A new technique for securing cochlear implants. Otolaryngol Head Neck Surg 120:897–898 19. O’Donoghue GM, Nikolopoulos TP (2002) Minimal access surgery for pediatric cochlear implantation. Otol Neurotol 23:891–894 20. Campisi P, Hayward L, Papsin B (2005) Mitek QuickAnchor fixation of cochlear implants using a minimal access technique. Int J Pediatr Otorhinolaryngol 69:1655–1658 21. Black B (2009) Keyhole cochlear implantation surgery. Cochlear Implants Int 10:150–159 22. Jethanamest D, Channer GA, Moss WJ, Lustig LR, Telischi FF (2013) Cochlear implant fixation using a subperiosteal tight pocket without either suture or bone-recess technique. Laryngoscope. doi:10.1002/lary.24426 23. Boscolo-Rizzo P, Muzzi E, Barillari MR, Trabalzini F (2011) Non-sutured fixation of the internal receiver-stimulator in cochlear implantation. Eur Arch Otorhinolaryngol 268:961–965 24. Dirr F, Hempel JM, Krause E, Muller J, Berghaus A, Ertl-Wagner B, Braun T (2013) Value of routine plain X-ray position checks after cochlear implantation. Otol Neurotol 34:1666–1669 25. Bremke M, Luers JC, Stenner M, Bovenschulte H, Dorn F, Unkel C, Hollering J, Beutner D (2013) Radiologic examinations in human temporal bone specimens using digital volume tomography and high-resolution computed tomography after implantation of middle ear prosthesis and cochlear implant electrode array. Otol Neurotol 34:1321–1328
Otology
Evaluation of a minimally invasive surgical fixation technique for young children with the Concerto Pin cochlear implant system Johannes Schnabl · Astrid Wolf‑Magele · Stefan Marcel Pok · Christoph Url · Patrick Zorowka · Georg Sprinzl
Received: 4 December 2013 / Accepted: 1 March 2014 © Springer-Verlag Berlin Heidelberg 2014
Abstract In 2011, Med-El (Innsbruck, Austria) introduced a new cochlear implant system, designed to require a minimally invasive surgical technique and allow greater positional flexibility for its fixation on the skull. The Concerto Pin implant system is a good option for patients with thinner bone, such as children and elderly. The aim of this study was to investigate the implant’s stability in children using our minimally invasive surgical technique. This was a prospective, longitudinal study with a single-subject, repeated-examination design. Six children, implanted with a Concerto Pin using our minimally invasive surgical technique between October 2011 and September 2012, were assessed 1, 3 and 6 months after surgery. In each case, the implant remained in a stable position and no adverse events or problems with healing were observed at any time during the investigation. The minimally invasive technique and the method of implant fixation that bypass drilling a deep
J. Schnabl (*) · A. Wolf‑Magele · S. M. Pok · G. Sprinzl (*) Department of Otorhinolaryngology, Karl Landsteiner University Hospital St. Pölten, Propst Führer‑Straße 4, 3100 St. Pölten, Austria e-mail: [email protected] G. Sprinzl e-mail: [email protected] J. Schnabl · G. Sprinzl Karl Landsteiner Institut für Implantierung elektronischer Hörsysteme, St. Pölten, Austria C. Url Department of Otorhinolaryngology, Medical University Innsbruck, Innsbruck, Austria P. Zorowka Department of Hearing, Speech and Voice Disorders, Medical University Innsbruck, Innsbruck, Austria
implant bed constitute a good option for patients with thinner bone, such as children. This clinical study shows the safety and stability of the Concerto Pin implant system using a minimally invasive surgical technique. Keywords Cochlear implant · Minimally invasive surgery · Concerto Pin · Children
Introduction Since the introduction of cochlear implants (CI) for patients suffering from severe to profound hearing loss, there have been great strides made in the devices themselves as well as the surgical techniques. These days, cochlear implantation is considered to be a safe procedure, with many different surgical techniques in use [1, 2]. Usually, the implant receiver is anchored in a deep implant bed on the temporal bone and fixed with tie-down sutures. When drilling a deep implant bed and the holes for the sutures, the dura mater can be damaged, especially in children and older adults due to their thinner skull bone. This population is, therefore, more vulnerable to dural injury [1, 3]. More and more, less invasive and less time-consuming surgical techniques are being developed [2–5], and alternative fixation methods, such as the use of titanium screws and different types of meshes instead of sutures, have been established [6–8]. In a multicenter study evaluating a fixation system with titanium screws, Guevara et al. [9] concluded that the usage of these screws was safe and would not increase the risk of implant dislocation or be significantly time-consuming. The usage of only a periosteal pocket with no sutures or drilled holes without any dislocation observed has also been described in the literature [4, 10–13]. However, since children have higher activity levels
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Eur Arch Otorhinolaryngol
Fig. 1 The Concerto Pin cochlear implant system with dimensions in millimeters. a Frontal view, b side view, c pins
and more frequent head traumas, the risk of implant dislocation increases with these techniques [14]. In an evidencebased review of literature, Varebeke et al. [15] concluded that it seems fair to define good practice as the creation of at least a bony well and/or (bony) sutures. In 2011, Med-El (Innsbruck, Austria) introduced a new cochlear implant system (the Concerto Pin) that requires a minimally invasive surgical technique and uses pins to give more stability to the implant receiver. In a former anatomical study [16] we demonstrated the mechanical stability of the Concerto Pin attachment system. The authors concluded that this method of fixation provides a secure attachment to the skull with a direct mechanical connection between implant and bone. In addition, this fixation method requires less drilling and no tie-down sutures, which makes the surgery quicker and less invasive. The aim of this study was to assess the safety of the Concerto Pin cochlear implant system for children using our minimally invasive surgical technique.
Materials and methods This study has been planned as a prospective, medium-term follow-up study with a single-subject, repeated-examination design. The data acquisition was conducted within the scope of the Concerto and Concerto Pin post-marketing study. The study was approved by the responsible ethical committee. Concerto Pin cochlear implant system The Concerto Pin cochlear implant system (Fig. 1) is a part of the Maestro cochlear implant system and is a further development of the Sonata system (Med-El, Innsbruck, Austria). The implant was designed for minimally
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invasive surgical techniques and is one of the smallest and lightest implants available (7.6 g without electrode). The implant is available in a large variety of electrode arrays for every cochlear anatomy. Furthermore, the implant was designed for increased positional flexibility on the skull for individual variation in skull anatomy. The implant has an integrated reference electrode for reduced risk and shorter surgery time (no need for surgical placement of a reference electrode). Minimally invasive surgical technique Figure 2a–f demonstrates our minimally invasive surgical technique on a right ear. Figure 2a demonstrates the way the templates for the Concerto Pin are marked on the patient’s skin. The processor template is positioned behind the ear. The Concerto Pin template should be positioned in such a way that the implant will be located on an area of the scalp containing hair. The lower part of the stimulator should be close to the temporal line, at an angle of 45°. The surgeon then performs a retroauricular incision. This should be no more than 4 cm long and should be placed 1–2 cm in front of the implant to ensure that the scar will not lie directly over the implant body. Figure 2b demonstrates the precise preparation of the double-layer flap. After the incision is made, the wound is held open by retractors. The first flap contains the skin and the subcutis. The second, U-shaped flap consists of the muscle and the periosteum and is performed with an electric scalpel and then freed from the surface of the bone. A double-layer skin flap may reduce the chance of infection and may allow for better healing. After drilling a mastoidectomy and a posterior tympanotomy, a periosteal pocket for the implant is prepared using a periosteal elevator.
Eur Arch Otorhinolaryngol
Fig. 2 Illustration of the minimally invasive surgical technique with the Concerto Pin cochlear implant system. a Marked templates on the patient’s skin, b preparation of the double-layer flap, c drilling the holes for the fixation pins with the support of the drilling guide, d
a bony channel to give additional stability to the implant and protect the electrode lead. The holes for the fixation pins are circled, e the final position of the stimulator and the electrode lead after the cochlear implantation, f bone pâté for additional fixation
The implant template is used to mark the correct position of the stimulator. A minimal implant bed for the titanium housing only and a ramp to ensure sufficient immobilization of the stimulator is then created using a diamond burr with a maximum depth of 2–3 mm at the anterior edge. The holes of the fixation pins are drilled into the skull at a distance and depth of 1.4 mm with the support of the drilling guide (Fig. 2c). To give additional stability to the implant and protect the electrode lead, a bony channel is drilled towards the mastoidectomy (Fig. 2d). During all this drilling, the middle ear cavity is protected from bone dust contamination by closing it with medical gauze. Drilling should also be completed before the cochlea is opened.
Figure 2e demonstrates the position of the stimulator and the electrode lead after the cochlear implantation. Tiedown sutures are not used. For additional fixation, the stimulator, the small implant bed and the bony channel are covered with bone pâté (Fig. 2f). A CBCT (Cone beam computed tomography) scan is performed postoperatively to determine the position of the implant (Fig. 3). Patient population Between October 2011 and September 2012, 6 children aged 2–12 (mean: 6.2 years, range 2–12 years) were implanted
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skin flap reactions, device extrusion or electrode extrusion, and no re-insertions were necessary. Altogether, no adverse event was registered.
Discussion
Fig. 3 CBCT scan of the mastoid and position of the implant in a minimally deep implant bed 1 day after implantation
with 8 Concerto Pin cochlear implants (N = 8). Two children were implanted bilaterally in a single stage. Four CIs were implanted on the right side and four on the left. Five patients suffered from bilateral congenital hearing loss and one patient had unilateral hearing loss after a trauma. All patients had no significant outer or middle ear pathology and were in excellent general, medical, and psychological health. All patients were implanted using the previously described minimally invasive technique. Patients were examined by a study investigator (not the surgeon but a member of the otologic team) at intervals of 1, 3 and 6 months after the implantation. The following issues were analyzed: stability (whether or not there was any shifting or rocking), adverse reactions to the implant (allergic reaction, chronic infection, tissue reaction, skin irritation, other issues), problems with skin flap healing (skin flap infection, extrusion of the device, re-insertion of the device due to skin flap infection, extrusion of the electrode in the mastoid cavity region, other issues), other adverse events. The issues were analyzed using anamnestic questions and clinical examination. The stability was additionally checked by the investigator moving and pushing the implant during the examination.
Results The implant was found to be in a stable position in all cases, with no shifting or rocking observed at the time of investigation. No unwanted or adverse reactions to the implant were noticed. There were also no problems with skin flap healing in any of the patients. We did not see any
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This clinical study demonstrates the safety of the Concerto Pin implant and fixation system with our minimally invasive surgical technique under everyday life conditions in children, and verifies the stability that was demonstrated in a prior anatomical study [16]. Our surgical technique is a minimally invasive one. A pre-operative CT scan is done to evaluate the bony structures, particularly the structures of the middle and inner ear and the topography of the facial nerve and sinus sigmoideus. The pre-operative evaluation of the thickness of the temporal bone is secondary, because all the burring is performed under good visual conditions. The retroauricular incision should be no longer than 3–4 cm. This is consistent with other minimally invasive techniques described in the literature [2, 13]. As additional protection, we use a double-layer flap. After the incision of the cutis and subcutis, a musculo-periosteal, U-shaped flap is prepared. As described also by other authors [2, 13, 17], we create a tight periosteal pocket for fixation of the implant. In addition, we burr a minimally deep implant well for the titanium housing and a ramp to ensure sufficient stimulator immobilization with a maximum depth of 2 mm at the anterior edge. The holes for the pins have a depth of 1.4 mm. Due to this shallow depth and the fact that the surgeon has a clear view while drilling the holes, dural injury or sigmoid sinus puncture is very improbable. To give additional stability to the implant and protect the electrode lead, a bony channel is drilled towards the mastoid cavity, and then the stimulator, the small implant bed and the bony channel are covered with bone pâté similar as described by Loh et al. [17]. No tie-down sutures are used; therefore, the implant is held in place by the pins at its base and the retaining forces of the periosteal pocket. The implant well, the channel for the electrode lead and coverage with bone dust provide additional stability. Omitting tie-down sutures and drilling a minimally deep implant bed reduce surgery time and possible injury to the dura mater. Figure 4 shows a diagram of the implanted Concerto Pin implant system using the minimally invasive technique. Several implant fixation techniques have been described. Lane and Carrasco [18] fixed the implant in the bony well, overlaid with Gore-Tex micro-mesh which was secured with titanium screws. They were also able to reduce the length of the surgery using the standard suturing technique. O’Donoghue et al. [19] described a minimal access technique
Eur Arch Otorhinolaryngol Fig. 4 Schematic picture of the implanted Concerto Pin cochlear implant system with a small implant bed/ramp
in which they made a small incision below the hairline without shaving any hair. They then drilled a bony well inside a small subperiosteal pocket, where the implant is held tightly in place. They stated better psychological acceptance by the patient, reduced operation time and only minor complications (postauricular swelling). Campisi et al. [20] used the Mitek QuickAnchor fixation system (holes are drilled in the walls of the recessed well and a tightening suture is passed through bony holes) in children with thick cortical bone. This proved to be an effective minimal access technique for this group of children. Black [21] described a keyhole surgery using a 15–18 mm C-incision on the back side of the auricle. In this technique, the implant is retained in a tight pericranial pocket without a bony well. He concluded that current implant designs should be modified for better adaption to the cranial contours. Jethanamest et al. [22] described a fixation method using a tight subperiosteal pocket without the usage of either sutures or a bony recess. In a median follow-up period of 32.6 months, no complications and no cases of migration were identified. Boscolo-Rizzo et al. [23] described an alternative and safe non-sutured fixation technique to secure the receiver-stimulator of the cochlea implant to the skull with a special tailored flap of periosteum. As stated in our study group’s former preclinical study [16], our results demonstrate that the pins hold the implant in place even if it is exposed to an impact such as those happening often in daily children circumstances. When an impact occurs, it is split between a perpendicular force which presses the implant against the skull and inhibits the pins from being displaced from their fixation points and a tangential force which is compensated by the pins. No screws, transcortical holes or foreign materials are used. A very small implant bed/ramp can be considered, but may not be necessary if the bone in this area is only flattened. An X-ray is usually sufficient to evaluate the postoperative electrode position [24]. However, in some specific cases, a CBCT scan is recommended to obtain a detailed evaluation of the position of the implant itself as well as the
electrode, due to its low sensitivity to metallic artifacts. In addition, this type of scan is especially useful in children since it has a low radiation dose [25]. Eight Concerto Pin CIs were implanted in six patients. Although the “data assessment” was based on subjective experience and it was not possible to quantify the pins’ ability to hold the implant in place, we nevertheless observed no implant migration such as shifting or rocking in any of the patients. This outcome is comparable to the results described by Cuda [2], who also employed a minimally invasive surgical technique in children using the Concerto CI (Med-El, Innsbruck, Austria). Furthermore, no unwanted or adverse reactions to the implant such as an allergic reaction, chronic infection, tissue reaction or skin irritation were observed. There were also no problems with skin flap healing.
Conclusion In conclusion, our minimally invasive surgical technique for implantation of the Concerto Pin results in a safe and stable implant system for children in everyday life conditions. In this technique, no transcortical holes, screws, or foreign materials are used. The implant is held in place by the pins after a small incision is made, with the creation of a minimal implant bed/ramp if necessary. Conflict of interest All authors declare that the manuscript has not been published previously or under review by another journal. The paper has not been presented to any professional society. Furthermore, all authors declare that no financial interest, commercial financial support or personal relationship with other people or organizations that could influence this work exist.
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