Acta Otorrinolaringol Esp. 2010;61(2):106−117 ÓRGANO OFICIAL DE LA SOCIEDAD ESPAÑOLA DE OTORRINOLARINGOLOGÍA Y PATOLOGÍA CÉRVICOFACIAL Y DE LA ACADEMIA IBEROAMERICANA DE OTORRINOLARINGOLOGÍA
Acta Otorrinolaringológica Española
Acta Otorrinolaringológica Española
SEORL PCF
Enero-Febrero 2010. Vol. 61. Núm. 1 Parotidectomías en tumores benignos: clasificación «Sant Pau» de la extensión de la resección Resección de tumor de cuerpo carotideo con LigaSure Laringectomía horizontal supraglótica láser CO : nuestra experiencia en seis años Estudio comparativo mediante tomografía computarizada de la morfología de la sutura timpanoescamosa entre colesteatoma atical y oídos sanos Tensores del velo del paladar y del martillo: vínculos anatómicos, funcionales y sintomáticos Los patrones normal y vestibular en la posturografía dinámica de pacientes con enfermedad de Menière Epidemiología de las epistaxis ingresadas en un hospital de tercer nivel Enero-Febrero 2010. Volumen 61. Número 1. Páginas 1-88
www.elsevier.es/otorrino
Mucormicosis rinoorbitocerebral, un estudio retrospectivo de 7 casos Profilaxis antibiótica en cirugía otorrinolaringológica Recomendaciones de la Comisión para la Detección Precoz de la Hipoacusia (CODEPEH) para 2010 Fallo barorreceptor tras la resección bilateral de paragangliomas carotídeos Miositis fulminante del compartimento muscular cervical posterior. A propósito de un caso Síndrome de sonda nasogástrica: a propósito de un caso Tiroides lingual: un hallazgo casual
Full English text available Incluida en: MEDLINE/Index Medicus EMBASE/Excerpta Medica Concerlit, Aidsline Bibliomed, Biosis, Healfnstar, IBECS
www.elsevier.es/otorrino
ORIGINAL ARTICLE
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications César Orús Dotú,a,* María del Prado Venegas Pizarro,a Julia De Juan Beltrán,a and Manolo De Juan Delagob Sección de Otología, Servicio de ORL, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain Servicio de Radiodiagnóstico, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
a
b
Received September 4, 2009; accepted October 16, 2009
KEYWORDS Cochlear implantation; Reimplantation; Surgery; Complications
Abstract Introduction: Cochlear implants are, for many reasons, expirable electronic devices and may occasionally have to be replaced. The surgical cochlear reimplantation technique is not substantially different from the initial implantation but does have some peculiarities. These distinctive features are analysed in this paper not only from the point of view of surgical technique but also with respect to the complications involved and the functional auditory outcome obtained. Objectives: An accurate description of the surgical findings, peculiarities of the surgical technique and complications found during the process of cochlear reimplantation. An evaluation of the audiometric functional outcome of the reimplantation. Materials and method: A descriptive retrospective review of 34 reimplantations in the same ear, carried out at our department during the period between 1993 and 2008, in 27 patients in a tertiary hospital by the same team of senior surgeons. The cochlear implants replaced were 2 Ineraid® (Smith & Nephew Richards, TN), 23 Laura® (Philips Hearing Implants), 8 nucleus 24K® (Cochlear Corp., Englewood, CO) and 1 Clarion® (Advanced Bionics, Sylmar, CA). Results: The rate of reimplantation in the same ear was 18.5% per patient. The most frequent reason in our series was internal failure of the device (14 cases). Other causes were substitution for a technological update (7 cases), misplacement of electrodes (8 cases), necrosis/infection of the skin flap with exposure of the implant (3 cases) and external injuries (2 cases). The most important surgical findings were partial mastoidectomy reossification, absence of ossification in the posterior tympanostomy and the permeability of the basal turn of the cochlea when it housed the electrodes. Complete reintroduction of the electrodes was achieved in 25 patients and partial reintroduction in 2 patients. The rate of complications generated was similar in reimplantation and in virgin ear implantation, except for when the original implant was an Ineraid® device.
*Corresponding author. E-mail address:
[email protected] (C. Orús Dotú).
0001-6519/$ - see front matter © 2009 Elsevier España, S.L. All rights reserved.
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications
107
Conclusions: The surgical technique for reimplantation and multireimplantation has characteristic peculiarities at each step. However, in general terms, its complexity is similar to that of implantation in virgin ears and the rate of complications is also similar. The introduction of the new electrodes is simple and complete in the immense majority of cases, given that the cochlea remains permeable, as long as it houses the electrodes; otherwise it tends to become reossified. The functional auditory outcome of the new implant is in relation with its capacities. If these are equal to those of the initial implant, then the auditory outcome will be similar; if they are better, then so will the outcome be. One exception is ears with long periods of auditory deprivation. © 2009 Elsevier España, S.L. All rights reserved.
PALABRAS CLAVE Implantación coclear; Reimplantación; Cirugía; Complicaciones
Reimplantación coclear en el mismo oído: hallazgos, peculiaridades de la técnica quirúrgica y complicaciones Resumen Introducción: Los implantes cocleares son, por diversos motivos, dispositivos electrónicos perecederos y, en ocasiones, han de reemplazarse. La técnica quirúrgica de reimplantación coclear, si bien no difiere substancialmente de la implantación virgen, sí tiene unas peculiaridades características. En este artículo se analizan estas peculiaridades, no sólo desde el punto de vista técnico, sino también respecto a las complicaciones que genera y el rendimiento funcional auditivo que consigue. Objetivos: Descripción detallada de los hallazgos operatorios, las peculiaridades de la técnica quirúrgica y las complicaciones generadas en el proceso de reimplantación coclear. Evaluación del rendimiento auditivo funcional del paciente reimplantado. Material y método: Revisión descriptiva retrospectiva de 34 reimplantaciones en el mismo oído, realizadas en nuestro servicio durante el periodo entre 1993 y 2008 en 27 pacientes en un hospital terciario por el mismo equipo de cirujanos. Los implantes reemplazados fueron 2 Ineraid® (Smith & Nephew Richards), 23 Laura® (Philips Hearing Implants), 8 Nucleus 24K® (Cochlear Corp.) y un Clarion® (Advanced Bionics). Resultados: La tasa de reimplantación por paciente en el mismo oído fue del 18,5%. La causa más frecuente de reimplantación en nuestra serie fue el fallo interno del implante (14 casos). Otras causas fueron la substitución por actualización tecnológica (7 casos), malposición del haz de electrodos (8 casos), necrosis/infección del colgajo cutáneo con exposición del implante (3 casos) y por último traumatismos externos (2 casos). Los hallazgos operatorios más significativos fueron la reosificación parcial de la mastoidectomía, la ausencia de osificación de la timpanotomía posterior y la permeabilidad de la espira basal de la cóclea cuando esta alojaba el haz de electrodos. En 25 pacientes, se consiguió una reintroducción completa del haz de electrodos y en 2 pacientes una introducción parcial. La tasa de complicaciones generadas fueron, tanto cuantitativamente como cualitativamente, comparables a la tasa de implantación en el oído virgen, salvo cuando el implante original fue del tipo Ineraid®. Conclusiones: La técnica quirúrgica de reimplantación y de multirreimplantación tiene peculiaridades específicas en cada uno de sus pasos, pero, en términos generales, tiene una complejidad parecida a la implantación de oídos vírgenes y se asocia a una tasa de complicaciones similar. La introducción del nuevo haz de electrodos es sencilla y completa en la inmensa mayoría de los casos, dado que la cóclea permanece permeable, siempre y cuando aloje al haz de electrodos; en caso contrario, tiene tendencia a reosificarse. El rendimiento auditivo esperable del nuevo implante está en consonancia con sus prestaciones. Si son iguales a las del implante substituido, el rendimiento auditivo del implantado es similar, y si son mejores, también lo es su rendimiento, excepto en oídos con grandes periodos de deprivación auditiva. © 2009 Elsevier España, S.L. Todos los derechos reservados.
Introduction We must accept that the cochlear implant has undoubtedly represented the biggest and best advance in the field of modern otology and has marked a before and after in the treatment of profound sensorineural hearing loss. The
extensive experience accumulated in cochlear implant units over the past 30 years allows us to affirm that the tonal and functional auditory results obtained are very good and constantly improving, which is better. Although a cochlear implant is a sturdy and reliable electronic device,1 at times, and for various reasons,
108
it needs to be replaced. Our service has accumulated significant experience in reimplantation; not in vain, 18.5% of our implanted patients have undergone reimplantation. This high rate of implantation is mainly due to the policy of choice of implants. The first implant used in our service was the Ineraid® in 1989. This implant was developed at the University of Utah (USA), it had 8 electrodes in a ball and was percutaneous; it was osseointegrated in the temporary shell through a metal pedestal. Although its audiological features were good, the interface between skin and pedestal was a continuous source of problems, which in many cases led to reimplantation. In addition, in 1990, the firm Cochlear® bought the company that manufactured the Ineraid® implants; in July 2000, the company ceased to provide maintenance and repair service, offering in return a reimplantation with their own devices (Nucleus 24k®). In the early 1990s, a new cochlear implant began to be used, called Laura®, of European technology. This implant represented an improvement over its predecessor, as the stimulator-receptor was subcutaneous. However, followup of the results over the years showed that this device offered limited audiological results, with low performance and a high rate of internal failure. Due to these reasons, all the patients with a Laura® implant had to be reimplanted with better-performing devices (Nucleus 24K®, Nucleus freedom®). This article exhaustively describes the surgical findings observed and the specific surgical techniques used for virgin implantation in its four key steps (incision, bone drilling, posterior tympanostomy and cochleostomy). It also offers an analysis of the complications created by this process and the auditory and functional performance achieved by reimplanted patients.
Materials and method This is a retrospective, descriptive study of 34 cochlear reimplantations carried out in 27 patients in the same ear, in the period between 1993 and 2008 (Table 1). The sample is comprised by 15 male patients and 12 female patients suffering from profound, bilateral sensorineural hearing loss, in 14 cases of pre-lingual introduction and in 13, postlingual. Most patients (23) were reimplanted once (85%), 2 patients were reimplanted on two occasions, another patient 3 times and, finally, one patient was reimplanted 4 times. In 2 of the 34 reimplantations the original implant was placed at a hospital different from ours. The implants replaced were 2 Ineraid®, 23 Laura®, 8 Nucleus 24K® and one Clarion®. The Ineraid® cochlear implant consisted of a metal pedestal osseointegrated into the temporal calota through a ring that was fixed with 8 4mm screws. The electrode wires started at the base of the pedestal. They were naked, unprotected by any type of cover and ended in a metal ball. The group of 8 electrodes (6 active, one reference and one ground) were introduced into the basal secretory coil of the cochlea through the round window (no promontory cochleostomy was performed). The Laura® cochlear implant (Figure 1) was subcutaneous and formed by a coil placed in the temporary shell. This
C. Orús Dotú et al
was joined to the processor by a silicone-protected cable. The processor was a flat, thick, metal box that was placed at the retroauricular level in the space created by the mastoidectomy. On occasions, its great size made it necessary to trim and sink the lateral sinus. From the processor, a single active electrode emerged, placed in the basal secretory coil through a standard promontory cochleostomy. Since the surgical technique for reimplantation is substantially different according to the original type of implant to be replaced, the 34 reimplantations have been divided into two groups. Group A, the largest with 25 patients and 31 reimplantations, included the substitutions of subcutaneous models with other subcutaneous models. Group B, with only 2 patients and 3 reimplantations, included patients who went from an original percutaneous model (Ineraid®) to a subcutaneous one. The reimplantation surgeries were performed by the same team of senior surgeons.
Results Reimplantation rate and causes of reimplantations (Table 1) The rate of reimplantation in the same ear in our series was of 18.5% (27 reimplanted patients from a total of 146 implanted patients). The cochlear implant that motivated most reimplantations was the Laura® (23/34). The most common cause of reimplantation was the internal fault, in 11 cases, which occurred within 5 years of the original implantation in most patients. The second cause of reimplantation was update or technological improvement due to poor performance, with the substitution of 7 Laura® implants by other implants offering better audiological performance, mainly Nucleus 24k®. Two reimplantations were due to poor positioning of the electrode bundle in the original implant. In one case (patient No. 21), the electrode bundle was located in the vestibule of the posterior labyrinth. In another case (patient No. 20), the electrode was placed on a bone neocanal created on the promontory, since the original cochlea was partially ossified by an otosclerous focus; this manoeuvre did not produce a good auditory result, thus forcing a reimplantation. Another case was reimplanted due to the partial introduction of the electrode bundle in the first surgery. Finally, in 2 cases, an electrical trauma (electric knife) and a mechanical trauma (broken coil) damaged the implant, leading to its reimplantation. The most frequent causes of reimplantation of the patients who originally received an Ineraid® implant (2/27) were the major cutaneous complications that left much of the temporary bone shell exposed, and which, secondarily, produced problems of osseointegration of the pedestal. The most common cause of reimplantation of the 8 Nucleus 24K® implants was incorrect electrode positioning in 6 cases (3 in the vestibule, one in the soft tissue and one in the hypotympanum). Only one case was due to mechanical trauma and the last case was due to cutaneous necrosis associated with a partial electrode introduction. This was the second reoperation for Patient No. 1.
T 12 2 12
Cause Cutaneous necrosis Cutaneous necrosis partial introduction Prob. osseointegration/cutaneous necrosis
Findings Stuck ball Stuck ball Stuck ball
IE Partial (8) Complete (11+11) Partial (9)
Better Better Better Better Same Better Better Better Better Better Better Same Worse Worse Better Better Better Same Better Better Better Better Better
None None None None Seroma Seroma None None None
AP Same Same Better Same Same Better Better Better
AP Worse Better Same
Complication Ninguna None None None Seroma None None Bleeding lateral sinus None None None None None Transient PF None None None None None None None None
Complication Cutaneous necrosis Seroma Seroma
AB indicates Advanced Bionics implant (Hires 90K®); Age, age at which the first implantation took place; AP, Auditory performance of the implant; F, female; FD, facial nerve dehiscence in the second elbow; IAD, Ineraid® implant; IE, degree of introduction of the electrode in the reimplantation; IR, type of implant placed in the reimplantation; M, male; N24K, Nucleus 24K® implant; NF, Nucleus Freedom® implant with perimodiolar electrode; NFB, Bifurcated Nucleus Freedom® implant (double array); NFS, Nucleus Freedom® implant with straight electrode; No., number of patients; No. R, number of reimplantations; OI, original implant type; PTF, posterior tympanostomy fibrosis; T, years between implantation-reimplantation.
Subcutaneous to subcutaneous group (A) No. No. R Gender/age OI IR T Cause Findings IE M 42 L L 2 Internal failure − Complete 3 1st M 44 L L 1 Internal failure − Complete 2nd M 45 L N24k 1 Low performance PTF Complete 3rd M 12 L N24K 6 Mechanical trauma: broken coil − Complete 4 1st M 13 L N24k 5 Internal failure − Complete 5 1st F 4 L N24k 4 Internal failure − Complete 6 1st M 4 L N24k 7 Internal failure − Complete 7 1st F 6 L N24k 5 Internal failure − Complete 8 1st M 4 L N24k 5 Internal failure FD Complete 9 1st M 46 L N24k 4 Internal failure − Complete 10 1st F 5 L N24k 4 Internal failure − Complete 11 1st F 6 L N24k 3 Internal failure − Complete 12 1st F 14 N24k NFS 0,5 Mechanical trauma: impact PTF/FD/adhesive Complete 2nd M 3 L N24k 5 Low performance PTF Complete 13 1st F 33 L N24k 8 Low performance − Complete 14 1st F 4 L N24k 4 Low performance − Complete 15 1st M 4 L N24k 3 Low performance − Complete 16 1st M 51 L N24k 6 Low performance − Complete 17 1st M 59 L N24k 7 Low performance − Complete 18 1st F 32 L L 1 Trauma: electric knife − Complete 19 1st F 35 L L 3 Internal failure − Parcial 2nd F 38 L N24k 1 Partial introduction Ossification basal spiral Outside cochlea 3rd (vestibule) F 39 N24k NFB 1 Malposition in vestibule Double cochlear ossification Complete (11+11) 4th M 54 L NFS 2 Electrode in canal on promontory PTF/Ossification basal spiral Parcial (12) 20 1st M 10 L N24k 0,2 Malposition in vestibule Ossification basal spiral Complete 21 1st M 14 N24k N24k 3 Partial introduction − Complete 22 1st M 27 N24k NFS 2 Malposition in vestibule Ossification basal spiral Complete 23 1st M 13 N24k NF 1 Malposition in soft tissues PTF Complete 24 1st F 53 N24k NFS 1 Malposition in vestibule Ossification basal spiral Complete 25 1st M 70 N24k N24k 0,1 Malposition in hypotympanum − Complete 26 1st 27 1st F 17 AB AB 13 Internal failure stimulator Ossification Complete
Percutaneous to subcutaneous group (B) No. No. R Gender/age OI IR F 46 IAD N24k 1 1st F 58 N24k NFB 2nd F 51 IAD N24k 2 1st
Table 1 Description of reimplantations. Causes, findings, introduction of electrodes, complications and functional auditory performance
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications 109
110
Figure 1 Laura® cochlear implant. Reimplantation surgery for a Laura® implant. Note the large size of the internal processor embedded in the mastoid.
One Clarion® cochlear implant from Advanced Bionics was replaced due to an internal fault after 13 years of dependable service.
Findings, reimplantation surgical technique and complications First step: incision and subcutaneous time In group A, the implant to be replaced was subcutaneous, so no prior skin defects were observed and the skin was complete in all cases. The only problem encountered was fibrosis of the tissues, which slightly hindered the dissection. The reimplantation technique in this group was correctly systematised. The incision was made on the previous incision. Later, the receptor stimulator was exposed; the stimulator was usually surrounded by a pseudocapsule, which held it like a glove, and once exposed, this was followed by a meticulous dissection of the electrode bundle. In the Cochlear® models, the ground electrode (easily identifiable by its terminal ball) was dissected first, followed by the bundle of active electrodes, which was followed until its entry into the mastoid. Sometimes the ground electrode was found very deep and it was cut and left, but it is better to keep the electrode to analyse the cause of failure and determine whether it is covered by the implant warranty. In the Laura® cochlear implant, the manoeuvre was simpler, since it only has one electrode bundle. This step is relatively simple and not very complex, giving few problems. In the 31 reoperations, there were no major complications, only 3 seromas that responded to comprehensive treatment. In group B, from Ineraid® to subcutaneous implants (3 reoperations), the incision step was much more complex. This was because there were large cutaneous defects produced by the pedestal that, in addition, coexisted with scar areas and free grafts or skin rotations, used previously to solve the problems of bone exposure caused by the pedestal
C. Orús Dotú et al
Figure 2 Skin scarring in a patient with an Ineraid® cochlear implant. Note the presence of multiple scars and areas of alopecia corresponding to local flaps used to solve the problems of the pedestal.
(Figure 2). In these cases, the reimplantation technique was not as systematic, but the trend was to make the incision as far as possible from the conflictive zone. The intention was to position the new implant beneath the thickest area of the retroauricular skin and also to carry out a large milling of the temporary shell up to the meningeal plane to prevent the implant from standing out and producing a decubitus from the deep planes to the superficial planes. The cutaneous defect created by the pedestal was sutured. Despite these measures, we had significant complications. Patient No. 1 developed a progressive necrosis of the skin flap with implant exposure, which caused it to be explanted and reimplanted in a second operation, and two seromas that resolved spontaneously. Second step: bone milling The most frequent finding was the partial reossification of the closed antro-mastoidectomy made in the original surgery, which was found in varying degrees in all reoperations. In some cases, the reossification surrounded the electrodes in their course towards the tympanostomy; in Case 1, the reossification completely covered the entire stimulatorreceptor area (Patient No. 27). The active electrode was in all cases surrounded, totally or partially, by a very fibrous mucous layer that accompanied it up to its entry into the box. In one case of a marked prolapse in the lateral sinus, the electrode was found closely adhered to its vascular fascia. The reimplantation technique was the same in the two groups (A and B). It consisted of a relatively simple re-milling of the reossification of the mastoidectomy margins until it was left accessible, with the usual surgical limits. In those cases where there was bone inclusion of the electrodes, they were released from their bone path with the aid of a small cut drill. Finally, when the implant was buried in bone, the entire bone covering it was released with the
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications
aid of a small shear. Once the newly formed bone had been milled, the entire trajectory of the active electrode to the posterior tympanostomy was liberated. Typically, the electrode was found wrapped in a fibrous mucous layer. Using crocodile tongs and a small sickle, it was possible to release the active electrode without damaging it, except in 4 cases in which it was accidentally cut. If the electrode was adhered to the lateral sinus, its liberation involved the opening of the sinus with the subsequent haemorrhage, which was controlled with bipolar scalpel and strips of Surgicel® at the opening of the tear. In general terms, this surgical step was relatively simple and even easier than in virgin ears, since much of the mastoidectomy had already been carried out. No complications were generated, with the exception of the bleeding of the lateral sinus, which was controlled intraoperatively with standard measures. Third step: the posterior tympanostomy Fortunately, no reossification of the posterior tympanostomy was observed in most cases in the 29 reoperations; it remained permeable and practicable. However, in 5 cases, we found obliteration of the tympanostomy at the expense of soft tissues and fibrosis, formed by the reorganization of the muscle and Tisuecol® that was used to seal the tympanostomy. In 2 cases, we observed dehiscence of the facial nerve in the second elbow, one of them associated with a tympanic adhesion developed by the implanted ear during monitoring. The reimplantation technique in this surgical step was extremely simple, in those cases where it was permeable, given that there was nothing to be done. In the case of fibrous closure, we conducted a thorough repermeabilization with removal of fibrous tissue; however, despite this, there was one case of transient House-Brackmann grade III facial paralysis, which healed completely in a few weeks (Patient 13). From the point of view of complications, only the temporary facial paralysis was notable. The other reoperations did not produce any complications. Fourth step: the cochleostomy and the introduction of new bundle of electrodes The surgical technique in this step varies depending on the type of implant to be replaced. In Group A, with 31 reoperations, the implant to be replaced had a standard electrode introduced by a promontory cochleostomy. In this group, there were 2 different management situations. On the one hand, in 22 reoperations, the bundle of electrodes to be replaced was in situ, correct and fully housed in the cochlear scala tympani. In these cases, it was only necessary to pull gently on the bundle until it was extracted completely, clean the small fibrous remains surrounding the prior cochleostomy and then reintroduce the new bundle of electrodes. In 21 cases, the reintroduction was successful and complete, with no difference with respect to the technique on a virgin ear. It is understood that the bundle of electrodes to be replaced acts as a guide or stent that maintains both the cochleostomy and the scala tympani permeable, making the introduction of the new bundle very easy. Only in the second reoperation of Patient No. 19 was the introduction
111
of the bundle of electrodes partial, for reasons that could not be seen. In the other 9 reoperations, the bundle of electrodes was wrongly positioned, either completely out of the cochlea in 7 cases (4 in the vestibule, 1 in the hypotympanum, 1 in soft tissue and 1 in a neocanal carved on the promontory) or partly introduced in 2 cases, these being the causes of reimplantation. The manoeuvres for the implantation of the new bundle of electrodes were different, depending on where the badly positioned bundle to be replaced was situated. In the 4 cases in which the bundle to be replaced was in the vestibule, reossification phenomena were observed in both the cochleostomy and in much of the basal spiral; in one of the four cases (Patient No. 19), there was a double cochlear ossification, one in the basal spiral and one affecting the beginning of the middle spiral. In these 4 cases, it was necessary to perform a revascularization of the cochleostomy and the basal spiral. Fortunately, newly formed bone has characteristics somewhat different from the cortical bone of the spiral, its texture is more friable (lump of sugar) and it has a more whitish colour. Therefore, with the aid of a sturdy spatula, it was possible to extract fragments of newly formed bone that obliterated the spiral until it was repermeabilized. The flow of perilymphatic fluid evidenced that it had been achieved successfully. Once repermeabilized, the bundle of electrodes was introduced again. In three cases, the reintroduction of the new bundle of straight electrodes was complete; in the case of the double ossification, the introduction was of only 10 electrodes. In the latter case, it was decided to reimplant, in the same surgical step, a branched implant in which one of the 2 bundles of active electrodes was introduced by the repermeabilized basal spiral and the other electrode was introduced by a second supra-promontory cochleostomy, which allowed access to the middle spiral, overcoming the obstacle of the start of the scala media, following the technique described by Dr. Manrique. The basal spiral was permeable both in soft tissues and in the case where the electrode bundle to be replaced was located by mistake in the hypotympanum. Two cochleostomies were conducted in the correct location and it was possible to completely and safely reintroduce the new bundle of electrodes. Finally, in the case where the electrode to be replaced was included in a neocanal on the promontory (the virgin cochlea had a partial otosclerous ossification of the basal spiral), large reossification phenomena were found covering both the bundle of electrodes and the round and oval windows. In this case, the bony outgrowths were lowered with a diamond drill until it was possible to visualise the start of the scala tympani, through which it was possible to partially introduce about 12 mm of the new straight electrode. In two cases (Patient 22 and the third reoperation of Patient 19), the bundle of electrodes was partially introduced and they had different outcomes. In Patient 22, it was possible to reintroduce the new bundle of electrodes completely. However, in Patient 19, the cochlear destructuring, fibrosis and bleeding were so manifest that they prevented the placement of the bundle in the cochlea. In a subsequent
112
4th reoperation, it was possible to successfully implant a branched implant (following the technique described in the previous paragraph). The cochleostomy in Group B (Ineraid®) was much more complex, since the Ineraid® cochlear implant was introduced through the round window and it was therefore necessary to make a new promontory cochleostomy to introduce the new electrode. Moreover, in two cases, one of the 8 ball electrodes of the Ineraid® became stuck in the middle spiral, so the reintroduction of the new straight electrode by the promontory cochleostomy was partial, of only 8 electrodes in the basal spiral. One of these patients (No. 1) was reoperated; a branched CI was implanted through a double cochleostomy, according to the technique described above (Figure 3). In summary, of the 27 patients reimplanted with 34 reoperations, it was possible to achieve a complete placement of the new bundle of electrodes in 25 patients. In only 2 cases (Patients 2 and 20), the electrode was partially introduced, with 9 and 12 active electrodes, respectively.
Auditory performance Audiological performance, both tonal and functional, of the reimplanted patients followed the following process, excluding the cases with problems in the location of the electrode bundle. In those cases where there was a change from an implant with low performance (Laura®) to another with better performance (Cochlear®), the performance was significantly better, in terms of an increase in recognition of disyllables in an open context (15%) and also from the patient’s subjective viewpoint. The only exceptions were Patients 4 and 5, in whom the Laura® implant was replaced with a Nucleus 24K®. These patients did not obtain any improvement with the new implant with better features. They were 2 children suffering from congenital pre-lingual deafness with long periods of auditory deprivation.
Figure 3 Branched implant with double cochleostomy. Note the ball electrode embedded in the middle secretory coil and the two bundles of 11 electrodes of the branched implant, one located in the basal secretory coil and the other in middle and upper secretory coil.
C. Orús Dotú et al
In the cases in which patients were reimplanted using implants with the same features, the auditory performance was the same. We never obtained worse results when the implant replaced was substituted by an implant with improved technology.
Discussion Rate of reimplantation and causes In 1978, Dr. Clark in Melbourne carried out the first multichannel implant, opening the modern era in this field. Since then, the auditory functional outcomes offered by the implant have progressively improved.1 This derives from the synergism of a number of causes of different natures. On the one hand, it is undeniable that much of the success is due to technological innovations resulting from ongoing industry effort. On the other hand, increased medical knowledge about the behaviour of the cochlea and the auditory pathway deprived of sound stimuli has enabled prognostic factors associated with satisfactory auditory performance of the implant to be clearly established. Finally, the surgical technique of implantation has not only been simplified, but it has also achieved, and is constantly achieving, a minimization of the morbidity of the surgical process of implantation. It is important to note, in this sense, the tendency towards making small incisions and especially the concept of softsurgery developed by Lenarz et al.2 However, despite these improvements, it has not been possible to avoid the replacement of the implant by a newer or better device in some circumstances. In most published series3-10 (Table 2), the rate of reimplantation lies in a range between the 4.1% of Sorrentino et al.,3 and the 9.4% of Ray et al.5 Our rate is of 18.5% (27 of 146 patients implanted); that is, 2 times more than the series with the highest percentage. The cause of this high rate of implantation is mainly due to the policy of choice of implants. The implant unit of the Hospital Sant Pau was started in 1989 and was a pioneer in Catalonia. At that time, the Ineraid® was a good implant, despite being percutaneous. The cutaneous and osseointegration problems of the pedestal, along with the disappearance of the manufacturer from the market, forced many of the patients to be reimplanted. Subsequently, we switched to the Laura® CI. This implant of European technology represented an advance, given that the internal part was totally subcutaneous; however, monitoring its performance over the years showed that it offered low functional auditory performance (or at least worse than other models then available). Since there was no standard at that time (the early 1990s), the only way to verify low performance was to experience it. Therefore, the diagnosis of poor performance took place at 4 or 5 years of the implantation. In addition, the implants also presented a rate of internal failures which, in view of the years, could be described as unacceptable. The set of problems described generated a large number of patients who had to be reimplanted. The reimplantations sometimes generated further complications that led to re-reimplantations, resulting in a vicious cycle for some patients. For all these
−
−
−
H indicates hardware; S, Software.
Lassing 45/882 (5.1%) 46% 12% 10% 17% HSCSP 27/146 (18.5%) 14/34 (41.1%) 7/34 (20.5%) 3/34 (8.8%) 8/34 (23.5%)
30/36 (83%)
−
− 13% − − malposition 2/34 (5.8%) − −
−
5% temporal pathology
6/36 (17%)
36/500 (7.2%)
Venail
10/33 (30%)
31 (38%)
2/15 (13%)
7% migration stimulatorreceptor
−
−
2/16 (13%)
Brown 44/803 (5.5%) 78% − − − − 6% 9% 7.3% children 3.8% adults
−
−
−
2.2% CSF fistula 6.7% temporal pathology
−
−
−
3 (15%)
Others
Côté 43 H: 53% 11.1% − 13.3% − 13% only − children 5.4% adults 8% children
8/33 (24%)
−
−
Alexiades
15/33 (45%)
12/80 (15%) 6x more frequent if large incision
Ray 80/844 (9.4%) 17/80 (22%) 20/80 (25%) −
33/618(5.3%)
5/15 (30%) large incisions
Ray 15/272 (5.5%) 6/15 (40%) − −
Electrode migration
2/20 (10%) vestibule
Cutaneous problem Malposition Trauma (necrosis, infection)
11/20 (55%) − − 4/20 (20%) H: 7/20 (35%) S: 4/20 (20%)
Technological improvement
Sorrentino 20/487 (4.1%) (3.8% adults, 4.5% children)
Low performance
Hard/soft error
Author Cases
Table 2 Causes of reimplantation
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications 113
114
reasons, it follows that the inadequate policy for implant selection and their need to be replaced were the main causes of the high rate of reimplantation (20 of the 34 reimplantations were due to implant failure or technological improvement). In most published series, the causes of reimplantation are qualitatively comparable to ours. The internal failure of the implant and the replacement by technology improvement are the most common causes of reimplantation in most published series (Venail, 83%9; Brown, 78%8; Sorrentino, 55%,3 and Cote, 53%7). The internal fault rates are three times higher in children than in adults (Parisier11). Finally, it is worth noting that in the older series, poor implant performance was a not inconsiderable cause of reimplantation, e.g., 25% for Ray et al.5 Fortunately, the rate of internal failure of the last generations of implants is significantly lower: between 0.2% and 0.4%.7 The second most frequent cause of reimplantation was the appearance of problems arising from cutaneous necrosis/infection of the implant. It has been reported that these problems are associated with the use of large incisions. Ray et al.5 described a probability that was 6 times higher when the incision was large. These data justify the current use of retroauricular mini-incisions of just 4 or 5 cm. Our rate of cutaneous complications is perhaps slightly higher than those reported in most series, and may be explained by the use of percutaneous implants such as Ineraid®, which were the ones that primarily showed this kind of problem. Other causes of reimplantation were implant breakage or malfunction due to trauma of various kinds: mechanical in children, electrical in adults and malpositioning of the implant. Finally, a very rare cause of reimplantation was the migration of the bundle of electrodes in the cochlea. A total of 151 spontaneous extrusions of the bundle of electrodes have been documented in the world literature.12 The final cause of the extrusion is unknown, although it is most commonly associated with implantation in an obliterated cochlea. It has been postulated that perhaps the reossification of the permeabilized cochlea manages to slowly eject the active bundle of electrodes. The extrusion as a result of the vertical growth of the tip of the mastoid, which manages to drag the bundle of electrodes and extrude it, has also been described in very young children. Therefore, in paediatric implantations, it is advisable to fix the bundle of electrodes to the top of the mastoid and not to the point. Finally, large haematomas in the immediate postoperative period can surround the bundle of electrodes and displace it. This is the mechanism that could explain the presence of the bundle of electrodes in the soft tissues of our Patient No. 24. This was a child who was implanted at another hospital and suffered a large haematoma in the immediate postoperative period, requiring emergency surgical revision. He attended our hospital due to lack of performance, and the CT showed the presence of the bundle in the retroauricular soft tissues.
Surgical technique of reimplantation The surgical technique of reimplantation was carried out following the same surgical steps as the implantation
C. Orús Dotú et al
in virgin ears, peculiarities.
although
each
step
had
different
Incision and subcutaneous step It is significantly easier to replace a subcutaneous implant than a percutaneous one (Ineraid®). In the subcutaneous, there are usually no previous skin defects so the reimplantation technique can be systematised following the process outlined in the Results section. This is a conceptually simple but very laborious surgical step, since the electrodes are usually closely surrounded by tough, fibrous mucosa. The incision and subcutaneous surgical step in the substitution of percutaneous devices is much more complex, because there is a break in the skin upon removing the pedestal. The process also tends to leave large scars or local rotation flaps used before the reimplantation to solve common problems of the skin-pedestal interface. In these cases, the technique must be individualised for each case, but following the recommendations described in the Results section. Although we followed this pattern, in a very complex case (Patient No. 1), the skin covering the implant became necrotic again at 3 months after reimplantation, forcing a new re-reimplantation. We carried this out in two different surgical steps; we explanted in a first operation and, 3 months later, after the skin and subcutaneous tissue became normal, we placed the new implant, which remained stable at 2 years of follow up. It follows that, in cases of large cutaneous necrosis, it is advisable to carry out the reimplantation in two stages. The bone milling step This surgical stage was usually simpler and quicker in reimplantations than in implantations in virgin ears. In all cases, the mastoidectomy had already been carried out and the only process left to do was the milling of the newly bone at the external shell level and, more rarely, in the posterior wall of the EAC. The cavity was always covered with mucosa that was often removed to facilitate the recognition of structures. The entire stimulator-receptor was completely buried in bone in only one case out of the 34 reimplantations, and this operation was more laborious than usual. The posterior tympanostomy surgical step The posterior tympanostomy was usually the most delicate surgical stage in implantations in virgin ears, as it offered the greater chance of injuring the second elbow of the facial nerve. The great fortune of reimplantation surgery is that tympanostomy almost never suffers ossification phenomena; in other words, this surgical step has already been done in most reoperations, thereby simplifying the process even more. The only notable peculiarity of this surgical step was when the tympanostomy was obliterated by soft tissue, resulting from the reorganisation of the fascia or cartilage and biological glue, which was interposed between the second elbow and the active electrode preventing electrical stimulation of the facial nerve. Its permeabilization is delicate but not complex; the remnants of tissue need to be withdrawn with patience, avoiding any injury to the facial nerve. It is especially important to be careful when the facial nerve is dehiscent.
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications
Only in one case in the 34 reimplantations was there facial palsy, which was moderate and with complete recovery within weeks. This case was a narrow tympanostomy in which the surgeon of the first operation had to expose the second elbow of the facial nerve to gain access to the promontory. Our current trend is to try not to interpose any material on the posterior tympanostomy. Another difficulty that can be found in this surgical step is the adhesion of the tympanic membrane to the inner surface of the tympanic cavity, making it easy to perforate. In this procedure, it is advisable to detach the membrane from the promontory carefully, through the tympanostomy, and place a fragment of cartilage between the electrode and the tympanum. Patients reoperated with this manoeuvre progress successfully. All in all, this surgical step, like the previous one, is simple in the hands of surgeons used to cochlear implantation. The step of cochleostomy and introduction of the new electrode The performance of this surgical step is the most variable in the reimplantation technique. It may be a very simple or extremely complex procedure. In the subcutaneous to subcutaneous group, it was a simple or complex procedure depending on where the bundle of active electrodes was located in the original implant. In cases where it was in situ, the implant itself acted as a lead or stent, which maintained the entire scala tympani permeable. In these cases, the introduction of the new bundle of electrodes was as simple as in the virgin technique; it was only necessary to pull on the old bundle of electrodes, clean the small fibrous slough around the edge of the cochleostomy and introduce the new bundle. Fast and simple. Quite the opposite happened in the 9 reoperations in which the bundle of electrodes was found either outside the cochlea,7 or partially introduced2. Of these 9 reoperations, in 6 cases the basal spiral of the cochlea was reossified and it remained permeable in only 3 cases, furthering the idea that it is the bundle of electrodes itself that acts as a guide and prevents cochlear obliteration. The corollary to be drawn from this experience is that in those cases where, for whatever reason (infection by pseudomonas, etc.), it is necessary to reimplant the patient in 2 different operations (first explant and, within a few months, reimplant), it is reasonable to leave the bundle of electrodes at the level of the cochleostomy, leaving it in situ in the first stage and only withdrawing it in the second operation, just before reintroducing the new one. Despite the ossification of the basal turn in all cases, we obtained a complete reintroduction either with a straight electrode or a branched electrode. Patient number 20, with an otosclerous ossification, was the only instance in which could we not fully insert it, and the programming was done with 12 functioning electrodes. In the percutaneous to subcutaneous group, this surgical step was even more complex because a ball electrode became stuck in the first spiral in the two patients. There is no manoeuvre that allows the ball to be extracted without damaging the auditory neural tissue in the area, so the only solution was the insertion of a branched CI, as has been described in the Results section. One patient (No. 2) refused the reimplantation.
115
The literature also describes the problems of relocation of the new bundle of electrodes. Lassing et al.,10 in 5 cases out of 58 reoperations, had to carry out perimodiolar millings to improve the location of the bundle. In 53 of the 58 cases, the insertion depth was equal to or greater than the original. In 17 reimplantations, Miyamoto et al.13 achieved complete reinsertions in most of them, but in a small, statistically-significant proportion, the degree of insertion was less. To summarize this surgical step, it is worth noting the paradox that it is either easier than the virgin technique or much more complex and that, in any case, it is possible to place the new bundle of electrodes completely in the vast majority of reoperations.
Complications Surgical complications in the reimplantation surgery in our series were very low in the subcutaneous to subcutaneous group; we did not observe any major complications and only 5 minor complications. The minor complications were 3 seromas that were resolved with conservative treatment, one case of intraoperative lateral sinus bleeding and one transient House-Brackman grade III facial palsy. The complications observed in the percutaneous group were very common. There were complications in the 3 reoperations, one major complication from cutaneous necrosis with implant exposure and 2 seromas. Fortunately, this type of reimplantation has been phased out, and it has only a descriptive, historical value. These results are in line with those reported in the medical literature (Table 3). Balkany et al.,14 Ray et al.,4 Côte et al.,7 and Haens et al.15 did not find any major complications either in 16, 15, 45, and 15 reoperations, respectively. Only the series of Parisier16 and Fayad17 describe two intraoperative episodes of cerebrospinal fluid (CSF) fistula that were resolved in the same surgical step and 2 cases of cutaneous necrosis that forced a rereimplantation. Reimplantation percentages and types of complications were very similar to those obtained in virgin implantations. Ramos et al.18 describe a complication rate of 9.8% in virgin ears in 346 patients, the most frequent being technical failure and CSF fistula. Cervera et al.19 report a complication rate of 6.1% in 135 patients, with 3 cases of complete failure of the implant and 3 skin flap complications. Manrique et al.20 report a low complication rate in implants on mastoidectomy cavities. In summary, our experience was fairly similar to the experience of most authors. It can therefore be accepted that reimplantation between subcutaneous models is associated with a complication rate similar to implantation in virgin ears, thus making it a safe procedure.
Auditory performance One might think that cochlear reimplantation represents a new aggression for the underlying cochlea neural tissue and may lead to a decrease in the performance of the new implant. In turn, the fibrosis generated by the first electrode may decrease the effectiveness of the stimulation of the new implant, decreasing its performance. Our
116
C. Orús Dotú et al
Table 3 Complications of reimplantation Author
Number of eimplantations
Minor surgeries
Major surgeries
Fayad 43 2 perilymphatic fistulas 3 cutaneous necrosis Balkany 16 None None Parisier 27 2 CSF fistulas 2 cutaneous necrosis Ray 15 − − Côté 45 − − Haensel 15 − − HSCSP 34 5 seromas 1 cutaneous necrosis One bleeding of lateral sinus One transitory PF
experience and the experience published in the medical literature show that these conjectures are not true. This fact was already apparent in the transition from the single channel implant to the multichannel implant. Hamzami et al.21 show that the results in verbal recognition tests are better. As can be seen in Table 1, patients who were implanted with better-performing devices matched, and in most cases improved, their auditory performance, provided that the bundle of electrodes was placed entirely in the cochlea. Patients improved their speech discrimination and reported an improvement in the quality and quantity of sounds perceived. The only exceptions were Patients 4 and 5, in whom a Laura® implant was replaced by a Nucleus 24K®. These patients did not obtain any improvement with the new implant. They were among the earliest patients implanted at our unit, and were patients with pre-lingual profound hearing loss, belatedly implanted at 12 and 13 years of age. The lack of improvement in the results could be attributed more to the great auditory deprivation that to the implant itself. This experience has been described by other authors: Sorrentino et al.3 report that 90% of their reimplanted patients equalled or improved their performance. Ray et al.4 reported that the performance of the new implant does not depend on the cause of reimplantation or the aetiology of deafness, nor on the time of use prior to implant failure. Henson et al.22 came to similar conclusions in a multicentre study. Hamzavy et al.23 demonstrated that, although the vast majority of their patients matched the performance of the original implant after three months of reimplantation, they did not succeed in two cases and that it is therefore important to be careful with the expectations offered to the patient. Fayad et al.17 reported that in some cases the reimplanted patient referred changes in sound quality but with no impact on functional auditory performance. Reimplantation should therefore be considered as a generally safe procedure that does not diminish the performance of the new implant, and even improves it.
Performance of electrodes
Introduction
Same or better Same or better Same or better Perceptive change Same or better Same or better Same or better Same or better
Same or better in 40/43 Same Same Same Same Same Same or better in 33/34
Conclusions As a corollary to our experience, we may say that reimplantation is generally a relatively common, although infrequent, procedure in a unit of cochlear implants. The most common cause of reimplantation was and still is internal implant failure. However, the improvement in the reliability of existing implants will lead to, in a not too distant future, the most common cause not being implant fault, but implant update or improvement. Maybe in a few years, many users of cochlear implants will request reimplantation in the light of improvements in the field of electronics, of acoustic signal coding systems and of the stimulation strategies emerging in the market. In expert hands, the reimplantation process is not usually complex, nor does it generate more complications than implantation in virgin ears, with the historical exception of percutaneous implants or in cases where the implant to be replaced was previously malpositioned. Cochlear reimplantation, as well as multiple reimplantation (more than one reimplantation), is a safe procedure, and the performance offered by the new implant is usually equal to or better than that of the replaced device.
Conflict of interests The authors declare no conflict of interests.
References 1. Manrique M, Morera C, Lavilla MJ, Cervera-Paz FJ. Analysis of the cochlear implant as a treatment technique for profound hearing loss in pre- and postlocutive patients. Acta Otorrinolaringol Esp. 2006;57:2-23. 2. James C, Albegger K, Battmer R, Burdo S, Deggouj N, Deguine O, et al. Preservation of residual hearing with cochlear implanta tion: how and why. Acta Otolaryngol. 2005;125:481-91.
Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications 3. Sorrentino T, Côté M, Eter E, Laborde ML, Cochard N, Deguine O, et al. Cochlear reimplantations: technical and surgical failures. Acta Otolaryngol. 2008 Nov 23:1-5. 4. Ray J, Proops D, Donaldson I, Fielden C, Cooper H. Explantation and reimplantation of cochlear implants. Cochlear Implants Int. 2004;5:160-7. 5. Ray J, Gibson W, Sanli H. Surgical complications of 844 consecutive cochlear implantations and observations on large versus small incisions. Cochlear Implants Int. 2004;5:87-95. 6. Alexiades G, Roland Jr JT, Fishman AJ, Shapiro W, Waltzman SB, Cohen NL. Cochlear reimplantation: surgical techniques and functional results. Laryngoscope. 2001;111:1608-13. 7. Côté M, Ferron P, Bergeron F, Bussieres R. Cochlear reimplantation: causes of failure, outcomes, and audiologic performance. Laryngoscope. 2007;117:1225-35. 8. Brown KD, Connell SS, Balkany TJ, Eshraghi AE, Telischi FF, Angeli SA. Incidence and indications for revision cochlear implant surgery in adults and children. Laryngoscope. 2008;119: 152-7. 9. Venail F, Sicard M, Piron JP, Levi A, Artieres F, Uziel A, et al. Reliability and complications of 500 consecutive cochlear implantations. Arch Otolaryngol Head Neck Surg. 2008;134: 1276-81. 10. Lassig AA, Zwolan TA, Telian SA. Cochlear implant failures and revision. Otol Neurotol. 2005;26:624-34. 11. Parisier SC, Chute PM, Popp AL, Suh GD. Outcome analysis of cochlear reimplantation in children. Laryngoscope. 2001;111: 26-32. 12. Connell SS, Balkany TJ, Hodges AV, Telischi FF, Angeli SI, Eshraghi AA. Electrode migration after cochlear implantation. Otol Neurotol. 2008;29:156-9.
117
13. Miyamoto RT, Svirsky MA, Myres WA, Kirk KI, Schulte J. Cochlear implant reimplantation. Am J Otol. 1997;18(6 Suppl):S60-1. 14. Balkany TJ, Hodges AV, Gomez-Marin O, Bird PA, Dolan-Ash S, Butts S, et al. Cochlear reimplantation. Laryngoscope. 1999; 109:351-5. 15. Haenzel J, Engelke JC, Dujardin H, Westhofen M. Cochlear reimplantation - experiences and results. Laryngorhinootologie. 2004;83:83-7. 16. Parisier SC, Chute PM, Popp AL. Cochlear implant mechanical failures. Am J Otol. 1996;17:730-4. 17. Fayad JN, Baino T, Parisier SC. Revision cochlear implant surgery: causes and outcome. Otolaryngol Head Neck Surg. 2004;131:429-32. 18. Ramos A, Charlone R, de Miguel I, Valdivielso A, Cuyas JM, Perez D, et al. Complications in cochlear implantation. Acta Otorrinolaringol Esp. 2006;57:122-5. 19. Cervera-Paz FJ, Manrique M, Huarte A, Garcia FJ, Garcia-Tapia R. Study of surgical complications and technical failures (correction of technical defects) of cochlear implants. Acta Otorrinolaringol Esp. 2000;51:96. 20. Manrique M, Cervera-Paz FJ, Espinosa JM, Perez N, Garcia-Tapia R. Cochlear implantation in radical cavities of mastoidectomy. Laryngoscope. 1996;106(12 Pt 1):1562-5. 21. Hamzavi JS, Baumgartner WD, Adunka O, Franz P, Gstoettner W. Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices. Audiology. 2000;39:305-10. 22. Henson AM, Slattery 3rd WH, Luxford WM, Mills DM. Cochlear implant performance after reimplantation: a multicenter study. Am J Otol. 1999;20:56-64. 23. Hamzavi J, Baumgartner WD, Pok SM. Does cochlear reimplantation affect speech recognition? Int J Audiol. 2002;41:151-6.
