endocochlear inflamation

8/9/2019 endocochlear inflamation

1/9

Review article

Endocochlear

inflammation

in cochlear

implant

users:

Case

report

andliterature

review

Alice Benatti a,*, Alessandro Castiglione b, Patrizia Trevisi b, Roberto Bovo a, Monica Rosignoli c,Renzo Manarad, Alessandro Martini e

aOperative Unit of Otolaryngology and Otosurgery, Padua University, Via Giustiniani, 2, Padua, ItalybDepartment of Neurosciences, Padua University, Via Giustiniani, 2, Padua, ItalycENT Department, Audiology Service, Ferrara University, Cso Giovecca 203, Ferrara, ItalydNeuroradiology, Padua University, Via Giustiniani 2, Padua, ItalyeDepartment of Neurosciences, Operative Unit of Otolaryngology and Otosurgery, Padua University, Via Giustiniani, 2, Padua, Italy

International Journal of Pediatric Otorhinolaryngology 77 (2013) 885–893

A R T I C L E I N F O

Article history:

Received 7 January 2013

Received in revised form 7 March 2013

Accepted 10 March 2013

Available online 8 April 2013

Keywords:

Cochleitis

Endocochlear phlogosis

Implant complications

Granulating

labyrinthitis

A B S T R A C T

Objectives: Cochlear implantation is a relatively safe procedurewith a lowcomplication rate. Theoverall

rate of complications among cochlear implant patients ranges from 6% to 20%. Major complications are

those that are life-threatening or require surgery, whereas minor complications are those that can be

medically treated. Nonetheless, certain complications, even if highly rare, may require specific

investigations and treatments. Among these rare complications are those with endocochlear

involvement, such as cochleitis or labyrinthitis, with fibrosis or ossification that could lead to

explantation. The aims of the present study

were to report a particular case of post-operative cochleitis

and to review the rate of complications after cochlear implantation, emphasising those conditionswith

proven endocochlear involvement.

Methods: We refer to the case of an eight-year-old Ital ian boy affected

by the sudden

onset of

headache,

ipsilateral

otalgia and facial

paresis, who presented to our clin ic for inexplicable

worsening of the performance of his implant and his residual hearing, six years after surgery.

A

complete

investigation including (clinical history,

routine, autoimmune

and serological bloodtests, electrophysiological measurements

from the cochlear

implant and neuroimaging) was

performed and is herein

described.

Additionally, a comprehensive

review

of the literature was

conducted using internet search engines; 274 papers

were selected,

88 of which were best suited to

our purposes.

Results: In our case, the progression of the symptoms and the performance decrement required

explantation,

followed by a complete

recovery. Reviewing the literature revealed only three reports

concerning

cases of proven

endocochlear phlogosis that required revision surgery.

Wound swelling/

infection and vertigo remain

the two most common complications of cochlear implantation. Failure

of the device

is the third most frequent complication (10.06% of all complications and 1.53% of

cochlear implantations).

Other rare conditions (such as granulating labyrinthitis with cochlear

fibrosis, ossification and erosion, silicone

allergy and the formation of a biofilm around the internal

device) are possible and unpredictable. Although

rare (approximately 1%), such

cases may require

explantation.

Conclusions: Despite efforts by both surgeons and manufacturers, device-related and surgical

complications still occur. These and other rare conditions demand specific management, and their

frequency may be underestimated. Further studies are needed to assess more realistic rates of complications and devise more efficient strategies for early diagnosis and treatment.

2013

Elsevier Ireland Ltd. All rights reserved.

* Corresponding author at: Operative Unit of Otolaryngology and Otosurgery, Giustiniani, 2, Padua 35128, Italy. Tel.: +39 339 6657486; fax: +39 049 821 1994.

E-mail addresses: [email protected] (A. Benatti), [email protected] (A. Castiglione), [email protected] (P. Trevisi),

[email protected] (R. Bovo), [email protected] (M. Rosignoli), [email protected] (R. Manara), [email protected] (A. Martini).

Contents

lists

available

at

SciVerse

ScienceDirect

International Journal of Pediatric Otorhinolaryngology

jo urn al hom ep ag e: www.els evier . c om/locat e/ i jp o r l

0165-5876/$ – see front matter 2013 Elsevier Ireland Ltd. All rights reserved.

http://dx.doi.org/10.1016/j.ijporl.2013.03.016

http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]://www.sciencedirect.com/science/journal/01655876http://www.sciencedirect.com/science/journal/01655876http://www.sciencedirect.com/science/journal/01655876http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://dx.doi.org/10.1016/j.ijporl.2013.03.016http://www.sciencedirect.com/science/journal/01655876mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]://dx.doi.org/10.1016/j.ijporl.2013.03.016


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failure, dizziness/vertigo and infections represent the most

common complications (Table 2); however, certain complica-

tions may require specific investigations and treatments [6,41–

44].

Such cases are very

rare

and not usually reported in

casestudies; they include (Table 3) [10,45–60]: cochleitis, granulating

labyrinthitis, pneumocoele, pneumolabyrinth, surgical emphy-

sema, particular malpositioning or migration, biofilm array

infections and allergic reactions to internal device [43,61–74].

Although these are rare complications, they should be considered

as major complications because explantation may be required

[61,62]. As a consequence of pathological and inflammatory

processes, cochlear erosion [75], fibrosis and/or ossification may

occur, leading to device malfunction, extrusion of electrodes or

displacement of the intracochlear array, with unpredictable

consequences for the patient’s health and the performance of the

implant [63,76–80].

The aims of this study were to review the complication rate

after

cochlear

implantation

and

to

investigate

the

causes

of

unexpected clinical manifestations in an eight-year-old Italian boy

six years after cochlear implantation surgery, who was charac-

terised by headache, ipsilateral otalgia and facial paresis and

worsening

of

his

residual

hearing

and

the

performance

of

hiscochlear implant.

2. Materials and methods

2.1.

Clinical,

audiological

and

genetic

data

A detailed family and clinical history was obtained from the

young patient and his parents. Acquired and environmental factors

that might be related to hearing loss were investigated. A complete

audiological evaluation was performed using micro-otoscopy,

pure-tone (250–8000 Hz) audiometry to evaluate air and bone

conduction, speech audiometry to determine the speech recogni-

tion threshold and impedancemetry (tympanometry and acoustic

stapedial

reflexes).

Other

clinical

data

were

collected,

including

Table 2

Complications after/during cochlear implant surgery. The percentages refer to the total number of cases for which data analysis was possible (the studies with unspecified

and/or unavailable data were excluded from the total number of cases); % = percentage of total complications (1083, including unusual complications); %* percentages of total

cochlear implants (7132).

Type of complication No. % (of 1083 complications) %* (of 7132 cochlear implants)

Wound complications 223 20.59 3.13

Infections,

swelling,

haematoma,

suture

rupture

153

14.13

2.15

Subcutaneous haematoma, seroma, emphysema 57 5.26 0.80

Keloid 11 1.02 0.15

Thin

flap

2

0.18

0.03Equilibrium disorders 113 10.43 1.58

Vertigo 111 10.25 1.56

Nystagmus 1 0.09 0.01

Neuritis, labyrinthitis 1 0.09 0.01

Device complications 311 28.72 4.36

Failure 109 10.06 1.53

Gain

reduction,

Absence

of

stimulation

57

5.26

0.80

Infections 4 0.37 0.06

Malpositioning, migration, kinking 102 9.42 1.43

Extrusion

39

3.60

0.55

Leaks 90 8.31 1.26

Gusher 62 5.72 0.87

Csf (cerebrospinal fluid) 14 1.29 0.20

Fistula 9 0.83 0.13

Dural tear 4 0.37 0.06

Rhinoliquorrea 1 0.09 0.01

External, middle ear complications 92 8.49 1.29

External, media otitis, tympanic membrane perforation 58 5.36 0.81

Cholesteatoma 13 1.20 0.18

External

auditory

canal

injury

6

0.55

0.08

Acute otomastoiditis 14 1.29 0.20

Pocket retraction 1 0.09 0.01

Peripheral nerve complications 115 10.62 1.61

Temporary facial nerve palsy 46 4.25 0.64

Permanent facial nerve palsy 12 1.11 0.17

Facial stimulation 20 1.85 0.28

Chorda tympani injury 20 1.85 0.28

Change in taste 3 0.28 0.04

Post-operative pain, transient neuralgia 10 0.92 0.14

Alteration

in

facial

sensibility

4

0.37

0.06

Other 63 5.82 0.88

Worsening/increase/onset of tinnitus 16 1.48 0.22

Haemorrhage

13

1.20

0.18

Unspecified intraoperative complications 13 1.20 0.18

Cerebritis (1 case)/meningitis (7 cases) 8 0.74 0.11Non user 5 0.46 0.07

Respiratory distress, laryngospasm 3 0.28 0.04

Ocular disorders 2 0.18 0.03

Hypertension 1 0.09 0.01

Burn

1

0.09

0.01

Tachycardia, hyperthermia 1 0.09 0.01

Abdominal distension 1 0.09 0.01

Unusual

complications

(Tab

3)

76

7.01

1.07

Total 1083 100 15.19

A. Benatti et al. / International Journal of Pediatric Otorhinolaryngology 77 (2013) 885–893 887


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routine, autoimmune and serological blood tests, evaluation of the

thyroid and renal functions, electrophysiological measurements

from the cochlear implant and neuroimaging of the temporal bone.

Behavioral audiometry and auditory brainstem response (ABR)

testing were useful to define the clinical indications for a cochlear

implant at the age of 2 years, when he underwent the first

implantation surgery (2006). Direct sequencing of the GJB2 gene

was also performed to investigate the genetic cause of his hearing

loss.

2.2. Neuroimaging

Axial and coronal imaging with a high resolution computed

tomography (HRCT) scanner and a 1.5-tesla magnetic resonanceimaging (MRI) system was repeated during this young patient’s

life. In 2006, the patient underwent preoperative HRCT and MRI

scans for diagnostic and surgical purposes. In 2012, due to the

onset and progression of his symptoms, two temporal bone HRCT

scans were conducted, one month apart. He also underwent an MRI

of the temporal bone 24 h after explantation surgery for diagnostic

and prognostic purposes.

2.3. Literature review

A complete review of the literature was conducted using

computer search engines and internet databases; the search terms

‘fibrosis’, ‘ossification’, ‘cochlear implant’, ‘complications’, ‘cochlei-

tis’

and

‘labyrinthitis’

were

combined

as

follows:

‘(fibrosis

orossification) and (cochlear implant)’, ‘(cochleitis or labyrinthitis)

and (cochlear implant and/or complications)’. A second search was

performed using a combination of the search terms ‘cochlear

implant’ and ‘complications’. The English, Italian, Spanish, German

or French language articles were retrieved and included in the

review they reported cases of particular interest or research

published between 1996 and 2012.

3.

Case

report

3.1. Clinical, audiological and genetic data

The patient is an 8-year-old Italian boy affected by profound

congenital

bilateral

sensorineural

hearing

loss

of

unknown

origin.

Born at term after a normal pregnancy from unrelated parents with

no familial hearing loss, he underwent a left cochlear implantation

(Nucleus Freedom Contour, CI24RE) at the age of two years (2006).

Pre-operative click-evoked ABRs for bilateral ear stimuli at a level

of 95 dB nHL (normal Hearing Level) were absent. No GJB2

mutations were found.

The operation was uneventful and all of the electrodes were

properly inserted through the cochleostomy, achieving good

impedance values. The electrically evoked compound action

potential (ECAP) thresholds were measured intraoperatively using

the neural response telemetry (NRT) capabilities of Cochlear

Corporation’s (Cochlear1, Lane Cove, New South Wales, Australia)

CI24RE-CA device. The correct array position was documented by

postoperative skull radiography. He obtained good results and hewas followed-up regularly without problems until December

2011, when the device was tested and all of the electrodes were

found to have low impedance values and normal NRT thresholds.

At that time, the pure-tone and speech audiometry (with cochlear

implant) results were within normal ranges. The pure tone average

(PTA0.5,1,2

kHz), the average of the pure-tone thresholds at 500 Hz,

1 kHz, and 2 kHz, was 25 dB nHL and speech recognition at 30 dB

SPL (sound pressure level) was 80% of the words in an open set

(Fig. 1).

In February 2012, six years after the surgery, he presented to

our tertiary care hospital complaining of ipsilateral otalgia,

headache and cochlear implant ‘‘discomfort’’. No potential causes

were identified in the first examination; no signs of infection,

extrusion,

migration,

neuritis

or

vestibular

concerns

were

found.The results of micro-otoscopy and tympanometry were normal;

the acoustic reflex was absent as expected, due to the pre-existing

conditions. Nevertheless, a temporal bone CT scan was ordered and

steroid treatment (with partial symptom remission) was pre-

scribed. Technical analysis of the device was conducted, revealing

impedance variations of three electrodes and undetectable NRT

thresholds. The pure-tone audiometry results were still acceptable

with the cochlear implant (PTA = 32 dB nHL) but the young boy

presented severe tone-speech dissociation (Fig. 1). When provid-

ing a history, the patient and his parents did not refer to any

particular event, except for a violent head injury on the right side

that occurred three weeks before and a minor head injury on the

left side (the implanted side) that occurred a few days later. After

one

month,

he

returned

to

the

clinic

for

clinical

aggravation

with

Table 3

Unusual post-operative complications of cochlear implantation. The number of cases should be considered an underestimate.? = unavailable or unspecified data.

Unusual post-operative

complications

No. of

cases

Explantation Children

(18 years)

References

Cochlear complications

Pneumolabyrinth 3 None Rother et al. [65]; Ott et al. [69]; Hempel et al. [45]

Oesteolisys/erosion

5

4/5

1

Neilan

et

al.

[46];

Ho

et

al.

[71];

Cervera-Paz

&

Linthicum [75]; Doherty & Linthicum [84];

personal observation (2012, unpublished data)

Chronic

granulating

labyrinthitis

3

3/3

1

Levi

et

al.

[63];

Ho

et

al.

[62];

Bertuleit

et

al.

[61]Fibrosis/oesteogenesis 19 19/19 Côté et al. [47]

Silicone allergy/foreign

body reaction

25 14/25 3 Ciorba et al. [43]; Lim et al. [68]; Pirzadeh et al. [10];

Liu et al. [48]; Kunda et al. [70]; Migirov et al. [25];

Puri et al. [49]; personal observation (2012,

unpublished data)

Bacterial/fungal biofilm

formation

5 4/5 2 Neelam et al. [50]; Ruellan et al. [51]; Pawlowski et al. [52];

Cristobal

et

al.

[53];

Makarem

et

al.

[74]

Pneumocoele 4 None 2 2 Qiu S. et al. [64];

Epidural/subdural haematoma 4 None 1 Gosepath et al. [54]; Sunkaraneni et al. [55]; Dodson et al. [21];

Stamatiou

et

al.

[56]

Misplacement into the

carotid canal

8 8/8 1 1 Nevoux et al. [66]; Son et al. [57]; Tange et al. [58];

Gastman et al., [59]; Jain & Mukherji [60]; personal observation

(2012, unpublished data)

Total (%) 76 52/76 (68.42% of 76) 4 (?) 12 (?)

A. Benatti et al. / International Journal of Pediatric Otorhinolaryngology 77 (2013) 885–893888


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fever (38.5 8C) and hyperemia of the external auditory canal and

cheeks. The patient was treated with the oral nonsteroidal anti-

inflammatory drugs cephalosporin and betamethasone for 7 days,

but they produced only a modest and transient benefit.

Given the fluctuating course of the symptoms, the patient

continued steroid therapy, 30 mg of Deflazacort per day, and

experienced partial improvement, but the hearing threshold of his

implant gradually worsened (Fig. 1).

After approximately one month, the patient had thinning or

disruption of the posterior wall of the external auditory canal with

reacutisation of symptoms, likely due to contact with a part of theinternal device array causing a ‘‘granuloma’’ of approximately

2 mm in diameter in the posterior wall of the external auditory

canal, near the annulus.

A few days later, the patient developed acute left facial nerve

paralysis (grade III on the House-Brackmann scale).

Technical analysis of the device revealed high impedance of 3

apical electrodes (20, 21 and 22) and basal electrode 1. The

external device functioned normally. Subsequently, an integrity

test on the CI24RE cochlear implant was performed by Cochlear

Italia SRL and it was concluded that the receiver–stimulator and all

of the electrodes were functioning within the specifications

(Normal Device Function) according to the ‘‘European consensus

statement on cochlear implant failures and explantations’’ [81].

The

results

of

the

blood

tests

were

all

within

the

normal

rangeswith the exception of the serum biochemistry, which showed an

increase in acute-phase reactants and the presence of IgM and IgG

specific for paramyxovirus type 1 that became negative to

subsequent one month control, exception for (obviously) IgG.

The worsening of his clinical condition, with left facial paralysis

grade IV, fever and persistent tone-speech dissociation, led to

hospitalisation for the removal of the internal device.

The presence of a small granuloma, most likely due to the array

having rotated, was confirmed intraoperatively; the inflammatory

reaction was essentially limited to the external auditory canal,

with no evidence of middle ear involvement.

After surgery and antibiotic therapy, complete regression of the

symptoms was achieved. A temporal bone MRI was performed 24 h

after

the

explantation

to

evaluate

the

inner

ear

and

the

VII/VIII

nerve complex. Histological examination confirmed the presence

of fibrotic tissue around the array. Two months later, the patient

underwent a right cochlear implantation without complications.

3.2. Neuroimaging

Temporal bone MRI and CT scans conducted in 2006, before the

first cochlear implantation, were normal with the exception of

mild plagiocephaly that was clinically insignificant. In 2012, two

months after the onset of symptoms, the patient underwent

another CT scan of the temporal bone, without contrast, whichshowed the following: (1) normal post-surgical anatomy and

correct array positioning; (2) presence of phlogistic material in the

left mastoid air-cells with preservation of the trabecular bone

microarchitecture and (3) presence of a granuloma in the posterior

wall of the external auditory canal, near the tympanic membrane,

with partial bone erosion (Fig. 2). No other significant alterations

were observed. Because his clinical condition worsened and his

facial nerve paralysis was aggravated, with both refractory to the

usual therapy, a HRCT exam was repeated one month later,

confirming the previous findings and showing a slight improve-

ment of the radiologic inflammatory signs. However, the HRCT

scans revealed hyperdensity in the left cochlea, likely attributable

to the initial fibrosis/ossification of the basal and apical turns

(Fig.

3).The post-explantation MRI revealed (Fig. 4) left cochlear

ossification and fibrosis with partial involvement of the internal

auditory canal. The VII/VIII nerve complex was not clearly visible in

the distal portion of the internal auditory canal.

4.

Discussion

A total of 274 reports were including in our metanalysis, 88 of

which best matched our purposes. Most of them referred to the

common or predictable (even if rare) complications of cochlear

implant surgery (Tables 1 and 2) and lacked insight into the

aetiology and management of particular cases because they

focused on the occurrence and classification of major and minor

complications

[6,41–43].

The

collective

data

confirmed

the

Fig. 1. Audiological data before explantation surgery. Tonal and speech audiometry showed the constant decline of implant benefits compared to the good performance

demonstrated at the end of 2011; (a) tonal audiometry results with the left cochlear implant (open set) and residual hearing without the cochlear implant (headphones); (b)

speech audiometry results with the left cochlear implant, using an open set of words, revealed an SRT equal to 25 dB SPL before the onset of symptoms, with worsening

performance in subsequent tests, so that there was a severe discrepancy between the tonal and speech audiometric results (SRT = Speech Recognition Threshold, the lowestlevel at which the speech signal can be correctly identified 50% of the time).



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complications rates reported in single studies. Device failure

remains the third most frequent complication (10.06% of the total

complications and 1.53% of the complications of cochlear

implantation) after wound-related complications and vertigo

(Table 2). However, these last two complications (vertigo and

wound involvement) are usually temporary and medically

treatable, whereas device failure necessitates surgical revision. It

can be deduced that device failure is the principal cause of

explantation/reimplantation (Table 1). Vertigo is most likely due to

surgical trauma to the vestibular labyrinth: its residual function

causes equilibrium disorders, which generally are self-limited and

resolve within a few weeks, as occurs in other vestibular disorders.Permanent facial palsy is a very rare complication (0.17%), most

likely due to intraoperative monitoring of the intratympanic and

mastoid portions of the facial nerve. In addition, the non-users (the

implant recipients who do not use them) are very rare (0.07%),

underlining the benefit and usefulness of cochlear implant, even if

it is possible that they are not always included in case studies on

post-operative complications. Cerebritis (1 case) and meningitis (7

cases) have an occurrence rate of 0.01% and 0.10%, respectively

(Table 2); nevertheless, the risk of meningitis among implanted

patients (100/100,000) is higher than that of the general

population (1.38/100,000) [82].

The particular cases reported in single papers range from simple

wound infection to meningeal involvement without distinction

being made between endocochlear or extracochlear complications[43,64–74]. Pneumolabyrinth, pneumocoele and epidural or

subdural haematoma appear to not require explantation

(Table 3). Only three reports [61–63] discovered in our literature

search involved proven endocochlear phlogosis in cochlear

implant users that resulted in explantation, of which two

[61,62] concerned fibrotic and oesteogenic processes (Tables 2

and 3). It is interesting that endocochlear involvement was usually

preceded or accompanied by bone erosion in the external auditory

canal [61–63].

In summary, our case report describes a late post-operative

complication leading to explantation because of extensive

cochlear involvement with fibrosis and ossification and, conse-

quently, malfunction of the implant. The clinical, neuroimaging

andsurgicalfindings

suggesteda

secondary

inflammationprocessof unknown origin with endocochlearand internal auditory canal

phlogosis. Consequently, granulating formations in the middle

and inner ear gave rise to partial erosion of the cochlea and

massive fibrosis/ossification of the basal and apical turns.

Contralateral cochlear implantation (Nucleus Freedom Contour)

was performed 2 months after the explantation (5 months after

the onset of symptoms). This operation was uneventful and all of

the electrodes were properly inserted through the promontorial

cochleostomy, achieving good impedance values and NRTthresh-

olds. Subsequently control showed a quick recovery to implant

benefits (Fig. 5). The correct array position was documented by

postoperative skull radiography.

Fibrotic and oesteogenic processes subsequent to inflammation

of

the

labyrinth

are

well

known

events

occurring

after

meningitis

Fig. 3. The second temporal bone HRCT scan showed: (A and B) slight improvement

of the radiologic inflammatory signs and (C and D) hyperdensity of the cochlea

likely

attributable

to

the

initial

fibrosis/ossification

of

the

basal

and

apical

turns.

Fig. 4. A temporal bone MRI performed 24 h after explantation revealed: (A–C)

cochlear ossification and fibrosis with partial involvement of the internal auditory

canal (white arrowheads); (C and D) reactive tissue formation in the mastoid with

air-fluid levels in the surgical cavity (white asterisk). The integrity of the explanteddevice was tested by the manufacturer and it was reported to be normal.

Fig. 2. Axial temporal bone HRCT scans showing the array position and the

phlogistic findings in the mastoid and external auditory canal. (A and B) There is no

evidence of electrode extrusion or migration; (C) a granuloma and adjacent eroded

bone (white arrow) are present in the posterior wall of the external auditory canal,

near

the

tympanic

membrane;

(D)

the

mastoid

air-cells

are

full

of

phlogisticmaterial.

A. Benatti et al. / International Journal of Pediatric Otorhinolaryngology 77 (2013) 885–893890


7/9

or during otosclerosis [76–79]. It is well known that fibrotic

phenomena occur near the array, but the cochlear abnormalities

induced by an implant are mainly of little clinical significance and

do not compromise the device’s functions [80,83–86]. While

middle ear infections can lead to meningitis, in this case, the

patient never showed the pathognomonic symptoms of meningitis

or mastoiditis. Therefore, his endocochlear involvement seems

more likely to be due to (unpredictable) reactive processes that are

very similar to a foreign body reaction, which was initiated and

sustained by traumatic events [75]. In our case, a manufacturer’s

report to rule out direct damage of the device causing its failurewas obtained from Cochlear Italia SRL. Furthermore, his para-

myxovirus infection may have provoked phlogistic activity

resembling an autoimmune cross-reaction [87,88], which would

explain all of the early and late symptoms. It is also possible that

those events can be attributed to predisposing conditions.

The impedance of the most apical and basal electrodes was

high, which mimics in implanted patients [85] the evolution of the

oesteodystrophic process in patients affected by otosclerosis [89–

93]. It is important to note that if predisposing conditions are

identified, they should be investigated prior to surgery.

5.

Conclusions

Cochlear

implantation

is

a

relatively

safe

procedure

with

acomplication rate of 6–20%. The frequency of complications has

consistently declined over the last 15 years settling and, to date, is

approximately 15% among cochlear implant patients. Reviewing

the literature (Tables 2 and 3) revealed that the majority of

complications are minor ones that do not affect the final outcome;

however, the classification criteria used to define minor and major

complications may be different. Furthermore, inner ear malforma-

tions or comorbidity may increase the risk of complications (such

as meningitis or gusher) [20], and the length of the follow-up

period may influence the reported occurrence rates. For these

reasons, the reported percentages of complications can vary widely

among the studies.

Unusual complications are rare and unpredictable situations

that

must

be

considered

major

complications

because

they

usually

require revision surgery (Table 3). Although massive fibrosis and

ossification of the cochlear lumen is a rare complication after

cochlear implantation, explantation may be required in such cases,

with specific treatment being administered to counteract the

pathophysiological process and reduce the overall symptoms.

The pathophysiological mechanisms underlying acquired or

congenital factors that constitute, in selected cases, a contraindi-

cation to bilateral cochlear implantation need to be identified.

Further studies are necessary to manage the events similar to those

of the case presented here, which may have resulted from

predisposing conditions, and to refine diagnostic procedures andtreatment options.

Consent

Written informed consent was obtained from the family

according to current national rules and laws for publication of

this case and any accompanying images.

Competing interests

The authors declare that they have no competing interests.

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