Download Postoperative Infection in Cochlear Implant Patients

Postoperative infection in cochlear implant patients
CALHOUN D. CUNNINGHAM III,
MD,
WILLIAM H. SLATTERY III,
OBJECTIVE: Recently, the association of meningitis
with cochlear implants has raised concern over the
safety of these devices. We examined the incidence of all postoperative infections in patients undergoing cochlear implant surgery.
STUDY DESIGN AND SETTINGS: A retrospective chart
review of all patients undergoing cochlear implants
at a private tertiary referral center from 1993 to 2002
was performed. Cochlear implant surgeries in 462
adults and 271 children were reviewed. Patients
with evidence of a postoperative infection or infectious complication related to cochlear implantation
were identified, and data on patient characteristics, surgery, and treatment outcome were obtained.
RESULTS: The overall incidence of postoperative infection in our cochlear implant series was 4.1%.
Major infectious complications occurred in 3.0% of
cases, and the majority of infections required surgical intervention. A history of chronic ear disease
may increase the risk of infectious complications.
There were no cases of meningitis.
CONCLUSIONS: Cochlear implants remain a safe
procedure with a low complication rate. The majority of infections can be managed without removing
the implant device. Advances in surgical technique
and flap design have decreased the occurrence of
wound-related complications. However, identification of risk factors for infection and optimization of
treatment regimens will further reduce the complications associated with postoperative infection.
(Otolaryngol Head Neck Surg 2004;131:109-14.)
I
nfectious complications following cochlear implantation are relatively rare and have been reported to occur
with an incidence ranging from 1.7% to 3.3%.1-3 These
complications frequently involve surgical wound problems such as skin flap necrosis and wound dehiscence,
which may result in persistent infection and potential
device extrusion. Advances in surgical techniques and
From the House Ear Clinic and House Ear Institute.
Presented at the Annual Meeting of the American Academy of OtolaryngologyHead and Neck Surgery, Orlando, FL, September 21-24th, 2003.
Reprint requests: William H. Slattery III, MD, House Ear Institute, 2100 W. 3rd
Street, Los Angeles, CA 90057; e-mail, [email protected].
0194-5998/$30.00
Copyright © 2004 by the American Academy of Otolaryngology–Head and
Neck Surgery Foundation, Inc.
doi:10.1016/j.otohns.2004.02.011
MD,
and WILLIAM M. LUXFORD,
MD,
Los Angeles, California
flap design have fortunately decreased the occurrence
of such complications. Other infectious complications
are the direct result of wound infection with abscess
formation, potentially resulting from ongoing chronic
ear disease or acute otitis media.4,5 Despite aggressive
medical and/or revision surgical therapy, eradication of
infection may ultimately require removal of the implant. Such an outcome will not only be devastating to
the patient who has achieved good speech reception,
but may also place the patient at increased risk for
possible intracranial complications.
Recent reports of meningitis associated with cochlear implants have raised concern over the safety of
these devices.6-8 Specifically, devices using an electrode positioner appear to be associated with an increased risk of postoperative meningitis, and have,
therefore, been withdrawn from the market by the manufacturer. Removal of the device with the electrode
positioner is alone expected to reduce the incidence of
postoperative meningitis. However, cases of meningitis
have been reported with the use of all current FDAapproved implants. When meningitis occurs in the setting of a cochlear implant, the source can be assumed to
be otogenic. Postoperative infections, including acute
otitis media, chronic otitis media, and wound infections
theoretically carry a risk of meningitis, given the potential for intracranial spread along the electrode
through the inner ear. Current recommendations include active immunization against Streptococcus pneumoniae and Haemophilus influenzae type B in all prospective implant candidates as well as patients with an
implant already in place. In addition, consideration
should be given to prophylactic antibiotic treatment
perioperatively.
Identification of risk factors for infectious complications is important to prevent the significant consequences of possible device extrusion or meningitis. We
reviewed all cochlear implants performed over a 10year period at the House Ear Clinic to assess the incidence of postoperative infectious complications and
identify factors that might increase the risk of infection.
METHODS
A 10-year retrospective chart review of all patients
undergoing cochlear implant surgery (N ⫽ 733) at the
House Ear Clinic between January 1993 and October
2002 was performed. In October 2002, we instituted the
routine use of perioperative antibiotics in all cochlear
implant patients because of the risk of meningitis. Prior
109
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Head and Neck Surgery
July 2004
110 CUNNINGHAM et al
Table 1. Characteristics of patients with postoperative infections (n ⫽ 29)
n
Adult
Peds
Total
No. of patients
Gender
Male
Female
Age [mean (range)]
Follow-up [mean (range)]
14
15
29
9
5
57 y (29–76 y)
43 mo (9–105 mo)
8
7
3.5 y (15 mo–10 y)
42 mo (15–83 mo)
17
12
30 y (15 mo–76 y)
43 mo (9–105 mo)
to this time, it had been our custom not to use perioperative antibiotics. There were 271 pediatric implant
patients (age ⬍18 yrs) and 462 adult patients. A total of
734 implant procedures were performed on 733 patients. One patient underwent two separate implant
surgeries in the same ear. Devices from all 3 major
cochlear implant manufacturers (Advanced Bionics,
Sylmar, CA; Cochlear Corporation, Sydney, Australia;
and Med-El Corporation, Innsbruck, Austria) were reviewed. There were 389 males and 345 females (mean
age at implantation, 35 years; age range, 12 months to
90 years). The mean follow-up time was 24 months
(range, 9-116 months). Clinic charts were reviewed to
identify patients with evidence of a postoperative infection or infectious complication involving the implant ear. Selected data from these patients was obtained from clinic charts and hospital records and
entered onto a data collection sheet designed for this
study. Variables including patient demographics, device type, surgical time, perioperative antibiotics, flap
technique, round window seal, cochlear malformations,
surgical complications, time course to infection, infecting organism, history of previous ear disease, and other
medical comorbidities were analyzed. Infection type,
treatment course, and final outcome were also reviewed.
Postoperative infections were classified as early if
they occurred less than 30 days from the time of surgery, or delayed if occurring after 30 days. Infections
were categorized as being a wound infection, complicated otitis media, or meningitis. Cases of complicated
otitis media were infections resulting in adverse sequelae such as tympanic membrane perforation or subperiosteal abcesses. Complications from infection were
classified as major if they resulted in device explantation, surgical wound revision, hospitalization and intravenous (IV) antibiotics, or meningitis. Minor complications were identified as those requiring local wound
care and/or oral antibiotics.
RESULTS
Of the 733 patients, 29 were identified with postoperative infections. The demographics of these patients
and causes of hearing loss are shown in Tables 1 and 2,
respectively. There were 14 adult and 15 pediatric
patients. The mean patient age at implantation was 30
years. The mean length of follow-up was 43 months,
and similar between adult and pediatric groups. Thirty
postoperative infections were identified in the 29 study
patients, for an overall incidence of 4.1%. One patient
underwent two separate cochlear implant surgeries on
the same ear and both were complicated by post-implant infection. Fourteen adult and 16 pediatric infections occurred.
The overall incidence of infection in the pediatric
patients (5.9%) was higher than the adult patients
(3.0%), although the pediatric group had a higher number of minor infections (Table 3). The majority of
infections (n ⫽ 22) were delayed (occurring ⬎30 days
postoperatively), with 8 occurring in the early postoperative period (⬍30 days). The mean time to infection
was 338 days (11.3 mo) with a range of 7 days to 6
years, and a median of 202.5 days (6.75 mo).
Postoperative infections were classified as wound
infections in 26 cases and complicated acute otitis
media in 4 cases (Table 4). There were no cases of
meningitis identified in the entire series. Wound infections were further categorized according to
whether or not device exposure was present. There
were 9 cases of infection with device exposure. Eight
of these 9 cases ultimately required removal of the
implant for resolution of the infection. One case was
successfully treated with revision of the surgical
wound.
Seventeen cases of wound infection without device
exposure were identified. Successful treatment of the
infection required device removal in 3 patients, surgical
wound revision in 5 patients, IV antibiotics in 3 patients, and oral antibiotics/local wound care in 6 patients.
In 8 of the 11 infections requiring device explantation, a prolonged course of treatment consisting of oral
and/or IV antibiotics preceded device removal. Six of
these patients additionally underwent unsuccessful irrigation and debridement of the wound in an attempt to
preserve the implant. In 3 cases, device extrusion was
already present at the time of presentation. In all but
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CUNNINGHAM et al 111
Table 2. Etiology of hearing loss in patients with
infection (n ⫽ 29)
Cause
No.
Congenital
Hereditary
Meningitis
Chronic otitis media
Congenital rubella
Congenital syphilis
Measles
Autoimmune
Vicodin abuse
Menière’s disease
Cochlear otosclerosis
Unknown
13
3
3
2
1
1
1
1
1
1
1
1
one case of device removal, the intracochlear electrode
was left in place to serve as a stent for revision implant
surgery. The electrode was removed in 1 case because
of extensive involvement with cholesteatoma.
In the complicated otitis media group (n ⫽ 4), surgical therapy was required in 1 case. This patient developed acute otitis media 6 years after cochlear implant placement and presented to another institution
with a pneumocephalus which required a middle fossa
craniotomy for repair of a tegmen defect. In the remaining cases, hospitalization and IV antibiotics were required in 1 patient who developed a subperiosteal
ABCs, and oral antibiotics and local wound care were
used to treat the other 2 patients. One of these patients
developed a draining ear following an episode of acute
otitis media and the other developed an early subperiosteal ABCs.
Cultures from infected wounds were obtained from
15 patients. The most common organism isolated was
Staphylococcus aureus (Table 5).
The overall rate of major infectious complications in
this study was 3.0% (Table 6). Device explantation to
control infection was required in 11 patients, for an
overall incidence of 1.5%. An additional seven patients
underwent surgical wound revision combined with IV
(n ⫽ 2) and oral (n ⫽ 5) antibiotics to eradicate
infection. The implant was saved in these 7 cases.
Of the 30 postoperative infections identified, 26.7%
were successfully managed with oral antibiotic therapy
or local wound care alone. The remaining 73.3% required more aggressive treatment consisting of device
explantation (36.7%), surgical wound revision (23.3%),
or IV antibiotics (13.3%).
Preoperative and intraoperative variables were reviewed to determine whether there was an association with postoperative infections (Table 7). Although adult patients had a greater number of
medical comorbidities than pediatric patients, no
specific condition was found to predispose to infection. Two of the 30 patients with postoperative infections received perioperative antibiotics for endocarditis prophylaxis. A history of ear disease was
identified in 15 out of 29 patients. Nine patients had
a history of chronic ear disease with 3 patients undergoing a previous tympanoplasty with intact canal
wall mastoidectomy in the ipsilateral ear and 1 patient with a history of a canal wall down mastoidectomy in the contralateral ear. The other 5 patients
with a history of chronic otitis media had previously
undergone myringotomy and tube placement in the
ipsilateral ear. Only one of these patients had a tube
in place at the time of cochlear implantation. This
patient developed otitis media postoperatively and
was treated with ear drops and oral antibiotics. A
history of acute otitis media treated medically was
identified in 6 additional patients. Of the 4 patients
who developed otitis media postoperatively, 2 patients had a prior history of acute otitis media and 2
had a history of chronic otitis media.
Review of the remaining variables revealed no additional risk factors for postoperative infection.
DISCUSSION
Complications associated with cochlear implants are
relatively rare and usually involve flap problems such
as skin necrosis and wound dehiscence. Wound complications have a reported incidence of 4.5% to
11.2%.1-3 The incidence of infection following cochlear
implant surgery ranges from 1.7% to 3.3%.1,2 Significant overlap exists between these two groups, however,
because of the fact that flap problems often become
secondarily infected and vice versa. Our review of 734
cochlear implant procedures revealed an overall incidence of infection of 4.1%. Excluding minor complications treated with local wound care and/or oral antibiotics, the incidence of major infectious complications
was 3.0%. These results are consistent with the previously published literature. Only 27% of infections in
this series occurred in the early postoperative period,
with the majority (73%) occurring at a mean time of
11.2 months after implantation.
Early postoperative complications are usually a result of flap technique or contamination at the time of
implantation. In our review, 2 of 8 early infections were
due to mild wound dehiscence successfully treated with
oral antibiotics and local wound care. Since the early
1990s we have used a “lazy-S” incision whereby a
standard post-auricular incision is gently curved superiorly and posteriorly over the temporal squamosa. We
believe a smaller incision using this technique has
decreased the occurrence of flap related problems as is
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July 2004
112 CUNNINGHAM et al
Table 3. Classification of postoperative infection (n ⫽ 30)
n (no. of cochlear implant
procedures)
No. of infections
Early (⬍30 d)
Delayed (⬎30 d)
Time to infection [mean (range)] (median)
Adults (n ⴝ 462)
Peds (n ⴝ 272)
Total (n ⴝ 734)
14 (3.0%)
4 (.86%)
10 (2.2%)
11.2 mo (15 d–6 y) (4.25
mo)
16 (5.9%)
4 (1.5%)
12 (4.4%)
11.3 mo (7–820 d)
(12.5 mo)
30 (4.1%)
8 (1.1%)
22 (3.0%)
11.3 mo (7 d–6 y)
(6.75 mo)
Table 4. Categories of postoperative infection (n ⫽ 30)
n (no. of cochlear implant procedures)
Infection type
Wound infection
Device exposed
Device explantation
Surgical wound revision
Device not exposed
Device explantation
Surgical wound revision
IV antibiotic therapy
PO antibiotics/local wound care
Otitis media
Surgical wound revision
IV antibiotic therapy
PO antibiotics/local wound care
Meningitis
Table 5. Pathogens isolated from wound culture
(n ⫽ 30)
Pathogen
Staphylococcus aureus
Escherichia coli
Group A beta-hemolytic Streptococcus
Klebsiella pneumoniae
Pseudomonas aeruginosa
No.
11
1
1
1
1
reflected in the low occurrence of early postoperative
infection. The remaining 6 patients with early infections presented with overt wound fluctuance possibly
related to contamination at the time of implantation.
Bacterial colonization of a surgical implant is a
prelude to clinical infection. Most cases of implantrelated infection that clinically manifest within 1 year
of surgical placement are thought to result from perioperative inoculation of pathogens.9 Systemic and local
antibiotics are therefore used to prevent colonization of
the implant or contamination of adjacent tissues. The
clinical efficacy of antimicrobial prophylaxis, however,
remains largely unconfirmed. A previous review of
antibiotic prophylaxis in cochlear implant surgery by
Adults
(n ⴝ 462)
Peds
(n ⴝ 272)
Total
(n ⴝ 734)
12
5
5
0
7
1
2
2
2
2
1
1
0
0
14
4
3
1
10
2
3
1
4
2
0
0
2
0
26
9
8
1
17
3
5
3
6
4
1
1
2
0
Robinson and Chopra revealed no significant difference
in the incidence of infection with or without the use of
perioperative antibiotics.10 Since the early history of
cochlear implants, we have not used perioperative antibiotics during cochlear implant surgery; the exception
being endocarditis prophylaxis. Our rate of postoperative infection (4.1%) is comparable to the 4.5% infection rate reported with the use of antibiotic prophylaxis.10 Although 73% of our infectious complications
were delayed, colonization of the implant at the time of
surgery must be considered as an etiologic factor. The
majority of wound cultures obtained in our series revealed Staphylococcus aureus, which is the most common pathogen found in surgical implant infections and
may represent a skin contaminant at the time of surgery.9 Despite uncertainty regarding the clinical efficacy of antibiotic prophylaxis, the serious medical consequences and economic sequelae of surgical implant
infections lend support to its use. Although we had no
cases of meningitis in this series, recent reports of
meningitis associated with cochlear implants have further increased awareness of the potential complications
of implant infections. This has led to more formal
recommendations regarding the use of perioperative
antibiotics.6 Since October 2002, we have started using
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CUNNINGHAM et al 113
Table 6. Complications of postoperative infection (n ⫽ 30)
n (No. of cochlear implant procedures)
Major complications (total)
Device explantation
Surgical wound revision
IV antibiotic therapy
Meningitis
Minor complications
Oral antibiotics/local wound care
Adults
(n ⴝ 462)
Peds
(n ⴝ 272)
Total
(n ⴝ 734)
12 (2.5%)
6 (1.3%)
3 (.65%)
3 (.65%)
0
10 (3.7%)
5 (1.8%)
4 (1.5%)
1 (.37%)
0
22 (3.0%)
11 (1.5%)
7 (.95%)
4 (.54%)
0
2 (.43%)
6 (2.2%)
8 (1.1%)
Table 7. Variables related to postoperative infection (n ⫽ 30)
n
No. of infections
Ear (R:L)
Device type
Nucleus 22
Clarion Hi F/positioner
Surgery time (mean hr:min)
Perioperative antibiotics
Flap technique
Post-auricular lazy-S
Electrode insertion
Full
Ossification present
Round window soft tissue seal
Surgical complications
Inner ear malformation
Medical comorbidities
History of ear disease (total)
Chronic otitis media
n
30
13:17
7
8
1:53
2
Nucleus 24
Clarion
10
5
29
Inferiorly based
1
30
4
30
0
2
16
15
9
Partial
0
Acute otitis media
6
perioperative antibiotics in all cases. We plan to monitor our infection rate in this new series to determine
whether there is a difference in the incidence of infections.
We searched for additional factors that may have
contributed to an increased risk of postoperative infection. Of all the factors reviewed, only a history of
previous ear disease appeared significant. Fifteen of 29
patients with postoperative infections had a prior history of chronic (n ⫽ 9) or acute otitis media (n ⫽ 6).
One patient with a prior history of tympanomastoid
surgery for cholesteatoma was found to have recurrent
cholesteatoma at the time of implantation. A canal wall
down mastoidectomy was performed and the ear canal
was closed. A wound infection developed 2 years later
secondary to recurrent cholesteatoma and required explantation of the device. In 4 patients with a history of
chronic (n ⫽ 2) and acute (n ⫽ 2) otitis media, postoperative wound infections developed following recurrent episodes of acute otitis media. Two of these patients were successfully treated with oral antibiotics and
wound care, 1 patient required IV antibiotics to treat a
subperiosteal abscess, and 1 patient underwent a middle
fossa craniotomy to repair a tegmen dehiscence.
We now recommend that all patients with a significant history of previous ear disease be counseled regarding the possible risk of problems postoperatively.
Patients should seek care immediately if signs or symptoms of an ear infection develop. Aggressive antibiotic
treatment is required for these individuals.
Few reports exist in the literature regarding management of postoperative infections following cochlear
implantation. Although previous studies have recommended removal of the infected implant to allow healing of the wound,11,12 current recommendations call for
conservative measures. Postoperative infections must
be assessed for the severity of infection to determine
how aggressive treatment should be. Treatment may
involve oral antibiotics and local wound care, IV antibiotics, and/or surgery. Oral antibiotics and local
wound care were sufficient in one fourth of our cases.
This treatment is appropriate for minor infections.
However, the majority of our cases (60%) required
surgical intervention, and the rate of device explanta-
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Head and Neck Surgery
July 2004
114 CUNNINGHAM et al
tion was high (37%). Wound infections with device
exposure carried a poor prognosis, requiring removal in
the majority of cases (8 of 9). Only one case of device
exposure with infection was salvaged through surgical
wound revision and medical therapy. When device removal is necessary, we recommend leaving the electrode in the cochlea. The electrode is cut at the facial
recess and the intracochlear portion is left in place to
act as a stent. Failure to leave the electrode stent will
most likely result in cochlear ossification in the setting
of an infection and may compromise future attempts at
re-implanting the same ear. When device exposure was
not present, successful treatment was achieved in 14
out of 17 cases without explantation.
Although infectious complications are rare, they assume greater importance in the setting of a cochlear implant given the increased potential for wound breakdown
and contamination of the device. Removal of an infected
implant can have significant emotional and economic consequences for the patient who has achieved good speech
reception. Furthermore, placement of an intracochlear
electrode provides a potential pathway for intracranial
extension of pathogens and an increased risk of meningitis
in the setting of an infection. Advances in surgical technique and flap design have decreased the occurrence of
wound-related complications. However, identification of
risk factors for infection and optimization of treatment
regimens will further reduce the complications associated
with postoperative infection.
CONCLUSION
This series demonstrates that the postoperative infection rate in patients undergoing cochlear implant
surgery without the use of perioperative antibiotics is
similar to previously published reports, with major infectious complications occurring in 3.0%. Although
antibiotic therapy was required in all cases of postoperative infection, surgical intervention was also required in the majority of cases. The rate of device
explantation was high (37%). A prior history of signif-
icant ear disease is a possible risk factor for postoperative infection. With recent awareness of meningitis,
we now recommend prophylactic antibiotics in all cochlear implant patients.11,12,13
We wish to thank Karen I. Berliner, Ph.D. for her critical
review of this manuscript and Stephanie Moody, M.D. for her
invaluable assistance in collecting data on these patients.
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