10.14639/0392-100X-N0931
Objective. The objective of this study is to analyse surgical outcomes in a series of patients who underwent subtotal petrosectomy in combination with cochlear implantation. Methods. Retrospective chart review. Thirty patients (32 ears) underwent subtotal petrosectomy and cochlear implantation in one stage. Indications for subtotal petrosectomy included the following: cholesteatoma, chronic otitis media, previous canal wall-down, osteoradionecrosis, revision surgery for clinical reasons, inner ear malformations, middle ear anatomical variations and severe cochlear ossification. Results. Follow-up ranged from 2 to 54 months. Only 2 complications related to the subtotal petrosectomy (1 subcutaneous abdominal haematoma and 1 subcutaneous abdominal seroma) occurred in this series. Complete electrode insertion was achieved in all but 4 cases. Conclusions. Subtotal petrosectomy is a safe procedure and can offer technical advantages in some cases of complex cochlear implantation.
cochlear implantation
application/xml
1827-675X
931
6
en
Maurizio Falcioni
https://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
inner ear malformation
Subtotal petrosectomy and cochlear implantation
Text.Serial.Journal
https://www.actaitalica.it/
40
Otology
2021-01-21
2020-06-16
2021-01-21
2021-01-21
1
Maurizio Falcioni
2020
10.14639/0392-100X-N0931
Otorhinolaryngology and Otoneurosurgery Department, University Hospital of Parma, Italy
1827-675X
6
inner ear malformation
Subtotal petrosectomy and cochlear implantation
https://www.actaitalica.it/article/download/931/498
40
ACTA OTORHINOLARYNGOLOGICA ITALICA 2020;40:450-456; doi: 10.14639/0392-100X-N0931




Otology


Subtotal petrosectomy and cochlear implantation
Petrosectomia subtotale e impianto cocleare
Giulia D’Angelo, Giulia Donati, Andrea Bacciu, Maurizio Guida, Maurizio Falcioni
Otorhinolaryngology and Otoneurosurgery Department, University Hospital of Parma, Italy


SUMMARY
Objective. The objective of this study is to analyse surgical outcomes in a series of patients
who underwent subtotal petrosectomy in combination with cochlear implantation.
Methods. Retrospective chart review. Thirty patients (32 ears) underwent subtotal petrosec-
tomy and cochlear implantation in one stage. Indications for subtotal petrosectomy included
the following: cholesteatoma, chronic otitis media, previous canal wall-down, osteoradione-
crosis, revision surgery for clinical reasons, inner ear malformations, middle ear anatomical
variations and severe cochlear ossification.
Results. Follow-up ranged from 2 to 54 months. Only 2 complications related to the subtotal
petrosectomy (1 subcutaneous abdominal haematoma and 1 subcutaneous abdominal se-
roma) occurred in this series. Complete electrode insertion was achieved in all but 4 cases.
Conclusions. Subtotal petrosectomy is a safe procedure and can offer technical advantages
in some cases of complex cochlear implantation.
KEY WORDS: cochlear implantation, subtotal petrosectomy, cholesteatoma, cochlear
ossification, inner ear malformation

RIASSUNTO                                                                                          Received: June 16, 2020
                                                                                                   Accepted: August 25, 2020
Obiettivo. L’obiettivo dello studio è analizzare i risultati chirurgici in una serie di pazienti
sottoposti a petrosectomia subtotale e impianto cocleare.
                                                                                                   Correspondence
Metodi. Studio retrospettivo. Trenta pazienti (32 orecchie) sono stati sottoposti a petrosecto-
                                                                                                   Giulia Donati
mia subtotale e impianto cocleare, in unico tempo. Le indicazioni alla petrosectomia subto-
                                                                                                   Azienda Ospedaliero-Universitaria di Parma, UOC
tale sono state le seguenti: colesteatoma, otite media cronica, precedente tecnica aperta,         Otorinolaringoiatria e Otoneurochirurgia, via
osteoradionecrosi, chirurgia di revisione per motivazioni cliniche, malformazioni dell’orec-       Gramsci 14, 43126 Parma, Italy
chio interno, varianti anatomiche dell’orecchio medio, e severa ossificazione cocleare.            Tel. +39 0521 703542. Fax +39 0521 703788
Risultati. Il follow-up è compreso fra 2 e 54 mesi. Nella serie si sono verificate solo 2          E-mail: ju.donati@hotmail.it
complicanze correlate alla petrosectomia subtotale (1 ematoma addominale sottocutaneo e
1 sieroma addominale sottocutaneo). È stata ottenuta l’inserzione completa degli elettrodi         Funding
in tutti i casi a parte 4.                                                                         None.
Conclusioni. La petrosectomia subtotale è una procedura sicura che in alcuni casi com-
plessi di impianto cocleare può offrire dei vantaggi tecnici.                                      Conflict of interest
                                                                                                   The Authors declare no conflict of interest.
PAROLE CHIAVE: impianto cocleare, petrosectomia subtotale, colesteatoma, ossificazione
cocleare, malformazione dell’orecchio interno
                                                                                                     How to cite this article: D’Angelo G, Do-
                                                                                                     nati G, Bacciu A, et al. Subtotal petrosec-
                                                                                                     tomy and cochlear implantation. Acta Otorhi-
                                                                                                     nolaryngol Ital 2020;40:450-456. https://doi.
Introduction                                                                                         org/10.14639/0392-100X-N0931
Cochlear implant (CI) has long been proven to provide hearing rehabilitation
                                                                                                   © Società Italiana di Otorinolaringoiatria
to patients with bilateral severe-to-profound sensorineural hearing loss (SN-                      e Chirurgia Cervico-Facciale
HL) who do not benefit from traditional hearing aids.
In the majority of cases, the standardised transmastoid facial recess approach                                    OPEN ACCESS

perfectly suits the surgical requirements, and surgical risks are fairly low 1,2.                  This is an open access article distributed in accordance with
                                                                                                   the CC-BY-NC-ND (Creative Commons Attribution-Non-
However, cochlear implantation in complex situations (concomitant chronic                          Commercial-NoDerivatives 4.0 International) license. The
otitis media with or without cholesteatoma, previous canal wall-down tech-                         article can be used by giving appropriate credit and mentio-
                                                                                                   ning the license, but only for non-commercial purposes and
niques, inner ear malformations with severe risk of cerebrospinal fluid leak,                      only in the original version. For further information: https://
etc.) may be challenging 1-5.                                                                      creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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                                                                                              Subtotal petrosectomy and cochlear implantation




Subtotal petrosectomy (SP) was first described by Rambo           3 children were scheduled for a baseline control CT scan
in 1958 6 and then modified and popularised by Fisch in           within 3 months from surgery. In patients with previous
1965 7. The main steps of the procedure are: 1) blind sac         cholesteatoma or radical cavity (all adults), in which the
closure of the external auditory canal (EAC); 2) exentera-        risk of a cholesteatoma entrapment is higher, a new scan
tion of middle ear and mastoid, including perisigmoid,            was planned at 3 years.
perilabyrinthine, perifacial and hypotympanic cells; 3) re-
moval of middle ear epithelium and mucosa; 4) closure of          Details of surgical technique
tympanic orifice of the Eustachian tube; 5) and obliteration      The main concepts of the surgical technique have been
of the cavity with abdominal fat 8. In 1998, Issing et al. and    described in previous publications 1,18. A few significant
Bendet et al. 9,10 proposed SP as the technique of choice         refinements have been introduced and should be stressed
for cochlear implantation in ears affected by chronic otitis      because of their importance when combining SP with the
media (COM). Over the past few years, SP has been pro-            positioning of a CI.
gressively applied to a variety of difficult situations in CI     The standard retroauricolar skin incision should be ex-
surgery 1-14, slowly overcoming the initial resilience of the     tended supero-posteriorly for 2-3 cm, in order to create the
majority of the CI surgeons.                                      implant hosting pocket more posteriorly than in a standard
In fact, through the closure of the tubal orifice and the EAC,    case. This is very important because, after a SP, the devel-
SP permits complete isolation of the surgical cavity from         opment of a retroauricolar skin depression is very common
the external environment, decreasing the risk of postopera-       even if without clinical significance in most of the cases.
tive infection, cerebrospinal fluid (CSF) leakage and men-        However, in presence of a CI, if the anterior margin of the
ingitis 14,15. In addition, the unobstructed view and illumi-     receiver-stimulator is placed in correspondence of this de-
nation of the surgical cavity provide an excellent control        pression, it can lead to extrusion (Fig. 1).
and visualisation of all available landmarks 1,16. Finally, the   When performing the blind sac closure of the EAC, a second
wide angle of approach to the round window area, obtained         layer created by the posterior reflection of the tragal carti-
by removing the postero-superior wall of the EAC, makes           lage is strongly recommended. This helps to reinforce the
each manoeuvre during array insertion much easier. These          closure and reduce the risk of connecting cable extrusion at
advantages are particularly important in presence of sur-         this level. At the same time, it may limit the medial growth
gical difficulties such as cochlear obliteration or distorted     of the skin in case of a break-down of the first layer closure.
anatomy 13,17.                                                    An aggressive drilling of the anterior and inferior walls of
The purpose of this study is to report our experience in a        the EAC is performed, especially at the level of the bony
group of 30 patients who underwent SP combined with CI.           anulus, to minimise the possibility of leaving some skin de-
                                                                  bris at this level.
Materials and methods                                             The facial ridge is lowered as much as possible to offer the
A retrospective analysis of patients who underwent SP in          best exposure of the round window niche. For this purpose,
combination with CI at the Department of Otorhinolaryn-
gology and Otoneurosurgery of the University of Parma
between January 2015 and March 2019 was performed.
Subjects gave informed consent to the study and the study
received the approval from the local Ethical Committee
(Ref N. 36071). Patients requiring primary CI underwent
complete otologic, audiologic, logopaedic and radiological
examination (CT and MRI). Revision cases were only in-
vestigated by CT scan. Cochlear implantation was advised
for standard indications, with no patients implanted for in-
validating tinnitus and/or single side deafness. Data collect-
ed from patients’ medical records included: demographic
information, indication for SP, surgical time, intraopera-
tive findings, electrophysiological data and postoperative
complications, as well as clinical and radiologic follow-up
findings. Follow-up was defined as the period of time from        Figure 1. Extrusion of the receiver/stimulator in the area of the retroaurico-
surgery to the most recent office visit. All patients but the     lar retraction.



                                                                                                                                          451
G. D’Angelo et al.




the removal of the bone anterior to the facial nerve is even                      must be accommodated on the medial wall of the cavity
more important. Unobstructed access to the round window                           and kept in place by the fat, in order to be maintained away
niche represents one of the advantages of the SP and, espe-                       from the subcutaneous layer. This reduces the risk of extru-
cially in difficult cases, it must be maximised.                                  sion in the area where the aforementioned skin retraction
Drilling of the perilabyrinthine, hypotympanic, retrofacial                       will develop.
and mastoid tip cells is accomplished. Residual mucosa is                         Whenever possible, the electrode array is inserted into the
dissected or coagulated from these areas, as well as from                         scala tympani (ST) through the round window membrane.
the promontory and the tubal orifice, in order to avoid leav-                     In cases where the round window niche is not accessible
ing any potentially infected tissue and/or the formation of                       (Fig. 3), a promontorial cochleostomy is performed. In
mucous cysts/granulomas. At the end of the preparation,                           presence of cochlear ossification, a first attempt to reach
the cavity must be denuded by mucosa for the maximum                              the ST is performed, drilling progressively the promontory
extent (Fig. 2). In case of previous radical cavity or chole-                     in an antero-inferior direction, starting from the round win-
steatoma, the same technique is applied to carefully remove                       dow niche. If no cochlear lumen is visible, drilling is moved
all squamous epithelium, to avoid leaving skin debris with                        superiorly in order to locate the scala vestibuli (SV). When
subsequent risk of inclusion cholesteatoma.                                       this latter is patent, a further attempt to open the ST is per-
When the implant is finally in place, the connecting cable                        formed (2-3 mm) before taking the final decision (Fig. 4).




Figure 2. Final view of the bony cavity after cleaning of the pneumatisation and the mucosa (A, B, C, D - 4 different cases).



452
                                                                                                                 Subtotal petrosectomy and cochlear implantation




                                                                                       (both of them had a normal cochlea on the contralateral
                                                                                       side). In 3 cases the surgery was started as a standard trans-
                                                                                       mastoid approach and an intraoperative switch to SP was
                                                                                       required due to unpredicted difficulties.
                                                                                       The group included 19 female (63%) and 11 male (37%) pa-
                                                                                       tients. The right ear was involved in 14 cases (44%), and the
                                                                                       left ear in 18 (56%). The mean age at the time of surgery was
                                                                                       49 years (range 4-78 years). Of the 32 ears, 23 had already
                                                                                       been operated at least once. Eleven ears already had a CI and
                                                                                       were revision cases (9 previously treated in other centres).
                                                                                       Among these, 9 were revision surgeries of a standard CI tech-
                                                                                       nique, 1 was a revision of a CI in a previous canal wall down
                                                                                       and 1 was a revision of already a SP with CI. Table I shows
                                                                                       the demographic characteristics, indications for SP and previ-
                                                                                       ous ear surgeries of the series. The indications for SP (some-
Figure 3. Coronal CT scan showing a superior protrusion of the jugular bulb
covering completely the round window area; a promontorial cochleostomy had             times multiple in the same patient) listed: cholesteatoma (10)
to be performed in order to reach the cochlear lumen.                                  (Fig. 5), chronic otitis media (3), previous radical cavity/ca-
                                                                                       nal wall-down mastoidectomies (4), severe cochlear oblitera-
                                                                                       tion (10), previous CI extrusion (2), previous extra-cochlear
                                                                                       array positioning (1), anatomical variations (3), inner ear mal-
                                                                                       formations (3), osteoradionecrosis (1).
                                                                                       All ears presented a preoperative pure tone average (PTA)
                                                                                       > 90 dB with discrimination less than 10%. In 26 cases, the
                                                                                       hearing aid could not be used in the ear-to-be-implanted
                                                                                       for audiological or clinical reasons (i.e. infection, previous
                                                                                       blind sac closure of the EAC, large meatoplasty, etc.).
                                                                                       The Neurelec Digisonic SP device was used in 3 cases, the
                                                                                       Oticon ZTI CLA in 10, the Oticon ZTI EVO in 1, the Nu-
                                                                                       cleus CI 24 RE (ST) in 2 and the Nucleus CI 512 CA in the
                                                                                       remaining 16.
                                                                                       Three ears were implanted into the scala vestibuli and the
                                                                                       remaining 27 into the scala tympani. In 2 cases, due to se-
                                                                                       vere ossification, it was not possible to clearly identify the
                                                                                       scala in which the array was positioned.

Figure 4. Intraoperative view of a severe cochlear ossification secondary to
otosclerosis; after a promontorial drill-out, a cochlear lumen has been identi-
fied only at the level of the scala vestibuli (short arrow), while the scala tympani
was completely ossified (long arrow).


Results
The study group was composed of 30 patients who under-
went SP in combination with cochlear implantation as a
single-stage procedure. Two patients were implanted bilat-
erally, resulting in a total of 32 surgically treated ears. Two
additional cases (1 revision for complete array extrusion in
an infected SP and 1 inner ear schwannoma) were excluded
from the series because, intraoperatively, the cochlear drill-
out was considered too destructive to achieve sufficient                               Figure 5. Extensive iatrogenic cholesteatoma secondary to a standard coch-
hearing restoration, even if a probe was partially inserted                            lear implantation.



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G. D’Angelo et al.




Table I. Demographic characteristics, previous ear surgeries and indications for SP of the series.
 Case        Sex          Age            Side                      Previous ipsilateral                                                       Reason for SP
                                                                        ear surgery
 1            M            20             R                                 NO                                                                Malformation
 2            M            73              L                          Stapedotomy, CI                                                        Cholesteatoma
 3             F           67              L                     Radical mastoidectomy                                                   Previous radical cavity
 4             F           46              L                                NO                                                    Anatomical abnormalities (high JB)
 5            M            57              L                     CWD tympanoplasty, CI                                        Previous CWD, array extrusion, ossification
 6            M            62              L                                NO                                                                 Ossification
 7            M            10             R                                 NO                                                    Anatomical abnormalities (high JB)
 8            M            55             R                            Stapedotomy                                                             Ossification
 9             F            5              L                             SP with CI                                       Incomplete array insertion, malformation, CSF leak
 10            F           62              L                       CWU tympanoplasty                                                               COM
 11            F           63             R                                  CI                                                              Cholesteatoma,
 12            F           71              L                          Stapedotomy, CI                                             Ossification, previous CI malposition
 13            F           78              L                          Stapedotomy, CI                                                        Cholesteatoma
 14            F           48             R                     CI with multiple revisions                                Array and CI extrusion, blindsac closure breakdown,
                                                                 (SP during last revision)                                                     ossification
 15            F           59             R                     Stapedotomy and revision                                                       Ossification
 16           M            48              L                CWD tympanoplasty and revisions                                            Previous CWD, ossification
 17            F           47              L                 CWU tympanoplasty and revision                                           Cholesteatoma, ossification
 18            F           37              L                                 SP                                                      Cholesteatoma, previous SP
 19            F           74             R                                 NO                                                               Cholesteatoma
 20            F            8              L                                 CI                                                     Cholesteatoma, array extrusion
 21            F           69             R                                  SP                                                       Previous SP, cholesteatoma
 22            F           66             R                       CI and revision with SP                                               Previous SP, ossification
 23            F           31             R                                 NO                                                                 Ossification
 24           M            42             R                        CWU tympanoplasty                                                         Cholesteatoma
 25           M            17             R                          CI, myringoplasty                                                             COM
 26            F           72             R                                 NO                                                              Ossification, COM
 27            F           76              L                       CWD tympanoplasty                                                Previous CWD, cholesteatoma
 28            F           56              L                           Stapedotomy                                                             Ossification
 29            F           31              L                                 CI                                                    Posterior wall erosion, ossification
 30           M            63              L                                NO                                                             Osteoradionecrosis
 31           M             4              L                                NO                                                                Malformation
 32            F           63             R                     Stapedotomy and revision                                                       Ossification
M: male; F: female; R: right; L: left; CI: cochlear implant; SP: subtotal petrosectomy; JB: jugular bulb; CWU: canal wall up; CWD: canal wall down; COM: chronic otitis media; CSF:
cerebro-spinal fluid.



Full insertion of all the active electrodes was accomplished in                               revision of the abdominal wound. Another patient devel-
28 ears. In 3 patients the inserted electrodes were 18/20, 18/20                              oped a delayed seroma in the same area, treated with a sim-
and 21/22, respectively. In the last case, in spite of an aggres-                             ple aspiration in the office at the time of implant activation
sive drilling of the basal turn, only 10/22 electrodes were in-                               The follow-up of the series ranged from 2 to 54 months
serted because of severe post-labyrinthitis obliteration.                                     (mean, 22 months with a SD of 14 months). One patient
The median value of the surgical time for the non-revision                                    died because of cardiological problems 1 year after the sur-
cases was 172.5 minutes, with an IQR of 60 minutes. When                                      gery, 3 patients are not daily implant users (2 of them are
compared with a homogeneous control group of standard                                         lost at follow up), while 3 additional patients are followed-
CI interventions, performed by the same surgeon during the                                    up in other centres near their hometown.
same period (median value 117.5 min, IQR 48.75), the dif-                                     All patients but the children and the 2 lost to follow-up un-
ference was statistically significant (p 0.0079).                                             derwent the proposed radiological schedule. Presently, on-
After surgery, 1 patient experienced a subcutaneous hae-                                      ly 18 patients underwent a CT scan at 2 or more years after
matoma in the area of the fat harvesting, requiring surgical                                  surgery. No residual cholesteatoma has been found to date.



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The CI was activated between 20 and 30 days after surgery.              insertion (only 4 cases of incomplete insertion). Even in
All patients but 3 had all the inserted electrodes active, con-         all the otosclerosis cases, in spite of an aggressive drill-out
firming the intraoperative impression. There was a patient              of the basal turn, a complete electrode array insertion was
with no active electrodes; this was a revision case where a             possible in 100% of the patients.
middle ear infection was complicated with a labyrinthitis               The price to pay for these advantages is represented by the
leading to complete modiolus destruction; the patient did               necessity of an additional abdominal incision with the con-
not experience any auditory sensation, despite a complete               sequent risk of complications (1 subcutaneous haematoma
electrode insertion. Due to the extreme heterogeneity of                and 1 seroma in our series). These were the only compli-
the patients’ group (children, comorbidities, periverbal pa-            cations directly connected to the surgical technique (the
tients, revision surgery, different length of follow-up, etc.)          other was atrial fibrillation in a cardiopathic patient). How-
the audiological performances ranged from sound detec-                  ever, these results may be achieved only if the technique
tion to 100% of discrimination.                                         is meticulously performed in every step, as confirmed by
                                                                        3 patients in the series that had already undergone a SP (1
Discussion                                                              with and 2 without a simultaneous CI) and required revi-
                                                                        sion surgery.
The indications for performing SP in combination with CI                Another criticism of the technique is the prolonged surgi-
have been described by many authors in the literature 1,2,9,18-22.      cal time, which was significant longer (p 0.0079) compared
Nowadays, most authors agree that CI combined with SP is                to standard CI interventions; however, the difference can be
the best surgical choice in deafened patients with chronic              justified, at least partially, by the complexity of the SP cases.
otitis media, cholesteatoma or/and previous cavity 1,4,5,16,23.         There is general consensus that SP and CI can be safely per-
In these situations, SP avoids disease recurrence and al-               formed simultaneously in the majority of the cases 1,12,16. It
lows the creation of a closed and protected environment,                is still debated whether, in active purulent COM, cholestea-
significantly reducing the risk of infection and electrode              toma and previous cavity, SP should precede CI of several
array extrusion 3,15. However, during the last years the sci-           months (6 to 12), as recommended by most authors 3,9,21,22.
entific literature has documented a progressive increase                This staging strategy can reduce the risk of meningitis re-
in papers documenting the effectiveness of SP combined                  sulting from the insertion of an electrode in a potentially
with cochlear implantation, even in patients with severe                contaminated field 1,22 and reduce the risk of residual cho-
cochlear ossification/obliteration, inner ear malformations             lesteatoma. In agreement with other authors 2, we usually
with high risk of CSF leak, fracture of the temporal bone               prefer to perform SP and CI in a single stage. We believe
with inner ear involvement and unfavourable anatomic                    that SP usually permits a macroscopic total squamous epi-
conditions 1,2,9,10,13,16,17,19,21,24,25. Some cases of revision sur-   thelium and infected tissue removal, facilitated by the wide
gery may also benefit from a larger and more comfortable                exposure. In addition, the staged strategy introduces a sig-
approach. However, these indications are still not shared               nificant delay in the hearing rehabilitation process. We rec-
by all surgeons, probably because SP is not routinely per-              ommend a two-stage procedure only for special cases with
formed in all otologic centres.                                         surgical impression of incomplete disease removal (never
Most of the cases in our series presented more than one                 encountered till now). In the osteoradionecrosis case in-
indication for adopting the technique. Under these cir-                 cluded in the series, being the patient affected by bilateral
cumstances, SP provides an excellent control of all the                 occlusion of 2 carotid stents (100% and 50%), the infective
middle ear structures and, if required, offers the possibil-            risk was judged inferior of that of an additional surgery.
ity to manage the carotid artery, the jugular bulb and, also,           In most cases (without cholesteatoma or previous cavity)
an anomalous course of the facial nerve. Unpredicted in-                where the technique is correctly performed, the risk of skin
traoperative difficulties may also suggest a switch from                entrapment is so low that, in our opinion, does not require
the classic approach to the SP, even if this increases surgi-           a radiological follow-up. A CT scan is usually acquired
cal time.                                                               within 3 months after surgery (not in children), and can be
The complete control of all the landmarks gives the pos-                used as baseline in case a further investigation is required
sibility to perform safer surgical manoeuvres 1,6. In particu-          in the future.
lar, a better control of the round window area may increase             In presence of radical cavity or COM with cholesteatoma,
the possibility of a correct and complete insertion even in             despite all efforts to meticulously remove all squamous
presence of complex cases 8,12,16.                                      epithelium, residual cholesteatoma can occur even many
This was confirmed in our series by the absence of extra-               years after surgery 1,3,10,15. Hence, prolonged follow-up in
cochlear array positioning and the high rate of electrodes              these patients is necessary. The most adopted protocol is



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complications, the technique must be mastered perfectly in                   16
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