Acute Mastoiditis: The Role of Imaging for Identifying Intracranial Complications

The Laryngoscope
C 2012 The American Laryngological,
V
Rhinological and Otological Society, Inc.
Acute Mastoiditis: The Role of Imaging for Identifying Intracranial
Complications
Michal Luntz, MD; Keren Bartal, MD; Alexander Brodsky, MD; Rabia Shihada, MD
Objectives/Hypothesis: Brain CT is performed in patients presenting with acute mastoiditis (AM) to identify intracranial complications (ICC). Recently, however, the need for CT scans in such patients has been questioned owing to concerns
regarding long-term effects of brain irradiation, with some clinicians claiming that the decision to scan should be based on a
patient’s clinical presentation. This study was aimed at characterizing the typical clinical presentation of patients who already
have ICCs when diagnosed with AM, and to compare it to that of AM patients presenting without ICCs.
Study Design: Prospective case series.
Methods: All patients hospitalized with AM between July 1997 and December 2009 in an otologic tertiary referral center were divided into those with and those without ICCs on presentation. Prereferral clinical characteristics and the signs,
symptoms, and inflammatory indexes at presentation were compared between the two groups.
Results: Of 71 patients presenting with AM, 10 had at least one ICC (sigmoid sinus thrombosis [nine patients], perisinus
empyema [five patients], subdural abscess [one patient], and epidural abscess [one patient]). Patients with and without ICCs
did not differ regarding most clinical characteristics or presenting signs and symptoms. None presented with neurological
signs or cranial nerve deficits.
Conclusions: It is not possible to define an evidence-based index of suspicion for ICCs in patients with AM. Diagnostic
imaging at presentation accordingly remains mandatory.
Key Words: Acute mastoiditis, imaging, intracranial complications.
Level of Evidence: 2c.
Laryngoscope, 122:2813–2817, 2012
INTRODUCTION
Acute mastoiditis (AM) is the most common of the
otogenic complications.1,2 In the preantibiotic era,
between 2% and 6% of patients with AM developed suppurative intracranial complications (ICCs), with fatal
outcomes in 75% of them.3 Since the introduction of
antibiotics, the incidence of AM has declined.4,5 In 1959,
Palva et al. reported that 0.4% of their patients with
acute otitis media (AOM) developed AM,6 whereas the
reported incidence during the 1980s was 0.004%.7 Over
the last two decades, however, the incidence of AM has
gradually increased.8–13 The reported incidence of AMrelated ICCs today is also surprisingly high, ranging
between 5% and 29%.14–20
AM-related ICCs may be present at the time of AM
diagnosis or may appear later in the course of the disease despite what would be considered adequate
treatment.8,11,14,15 Because of the life-threatening nature
of otogenic ICCs, AM-related ICCs should be diagnosed
From the Department of Otolaryngology–Head and Neck Surgery,
Bnai Zion Medical Center, Technion–Israel Institute of Technology, Haifa,
Israel.
Editor’s Note: This Manuscript was accepted for publication June
15, 2011.
The authors have no funding, financial relationships, or conflicts
of interest to disclose.
Send correspondence to Michal Luntz, MD, Department of Otolaryngology–Head and Neck Surgery, Bnai-Zion Medical Center, Technion–Israel Institute of Technology, P.O. Box 4940, 31048 Haifa, Israel.
E-mail: michal.luntz@b-zion.org.il
DOI: 10.1002/lary.22193
Laryngoscope 122: December 2012
as early as possible. Given that delays in diagnosis of
otogenic ICCs are associated with increased morbidity
and mortality, and because physician delay is recognized
as a highly significant delaying factor,21 diagnostic imaging has become a mandatory part of the very early
workup of patients with AM.22–24 Recently, however, the
need to perform computed tomography (CT) scans in
patients presenting with AM has been questioned
because of concerns about the long-term effects of brain
irradiation,25,26 causing some clinicians to claim that the
need for CT should be based on the clinical presentation
of the individual patient.20
Accordingly, the aim of the present study was to
characterize the typical clinical presentation of patients
with AM who also had ICCs at the time of AM diagnosis,
in an attempt to differentiate it from the clinical presentation of patients with AM without ICCs.
MATERIALS AND METHODS
All patients referred to our otologic tertiary referral center
between July 1997 and December 2009 were enrolled in this
prospective study. Diagnosis of AM was based on clinical signs
of AOM on otoscopy, inflammatory findings over the mastoid
area (tenderness, erythema, edema, and/or abscess), and protrusion of the auricle. Patients with a history of chronic otitis
media and cholesteatoma were excluded from the study.
The management protocol was aimed at obtaining a sample for bacterial culture at the earliest opportunity (so that
antibiotic treatment could be initiated as early as possible, but
without compromising the potential need for culture-based
Luntz et al.: Brain Scan for Acute Mastoiditis Complications
2813
Fig. 1. Management protocol for
acute mastoiditis. HRCT ¼ high-resolution computed tomography; CT
¼ computed tomography; ICC ¼ intracranial complication; ME ¼ middle ear; VT ¼ ventilating tube.
change in antibiotic treatment if required in the future) and
prompt evaluation for the presence of ICCs. Because the duration that might be required for middle ear drainage is usually
more prolonged in patients with AM than in patients with noncomplicated AOM, a ventilating tube was inserted in all cases.
To have the patient sedated/anaesthetized only once for both
middle ear drainage and the imaging required to exclude ICCs
on presentation, as well as to enable draining of a possible localized intracranial suppuration when suggested by the imaging
findings, patients diagnosed clinically with AM immediately
underwent high-resolution CT (HRCT) of the temporal bones and
contrast-enhanced brain CT. According to the imaging findings,
patients underwent the required surgical drainage (Fig. 1). As
soon as an adequate sample for bacterial culture was available,
broad-spectrum antibiotic treatment with intravenous ceftriaxone
was initiated. When presented with spontaneous perforation,
and the patient’s condition thus did not allow for any delay in
initiation of antibiotic treatment, a sample for bacterial culture
was immediately taken from the draining ear (after proper
cleansing), treatment with antibiotics with broad-spectrum antibiotics was started, and HRCT of the temporal bones and
contrast-enhanced brain CT were performed only afterward.
Thus, imaging of all patients was performed within the first 24
hours of admission.
If no clinical improvement was observed within 24 to 48
hours, the antibiotic treatment was changed to a culture-based
choice. When clinical deterioration was noticed or development
of a complication was suspected or both, repeated imaging and
redrainage were considered.
Patients were divided into those who had ICCs on presentation and those who did not. The two groups were compared
with regard to prereferral clinical characteristics (age, history
of AOM, history of AM, predisposing factors, duration of symp-
Laryngoscope 122: December 2012
2814
toms, prior antibiotic treatment and its duration), signs and
symptoms at presentation (protrusion of the auricle, postauricular swelling, postauricular erythema, postauricular fluctuation
[i.e., subperiosteal abscess], tympanic membrane erythema,
tympanic membrane bulging, otorrhea, fever, neurological
signs), and inflammatory indexes at presentation.
The data were evaluated by SPSS software, version 17
(SPSS, Inc., Chicago, IL). The Fisher exact test was used to
detect differences in the prevalence of categorical variables
(gender, history of AOM, history of AM, and prior antibiotic
treatment) between the two groups of patients. The Mann-Whitney U test was used to compare differences in age, duration of
symptoms, duration of prior antibiotic treatment, and inflammatory indexes. A value of P < .05 was considered significant.
RESULTS
During the 12-year study period, a total of 71
patients were hospitalized with AM in our institution.
Ten of them had at least one ICC. The types of complications and their incidence are listed in Table I.
Table II summarizes the prereferral clinical characteristics of the two groups of patients, those with ICCs
and those without them. There were no significant differences between the patients in the two groups with
regard to any of the listed prereferral characteristics.
Table III summarizes the signs and symptoms of
the two groups of patients at the time of presentation
with AM. Although the groups did not differ with regard
to most of the presenting signs and symptoms, significantly more patients in the ICC group than in the nonLuntz et al.: Brain Scan for Acute Mastoiditis Complications
TABLE I.
Intracranial Complications in 10 Patients With Acute Mastoiditis.
Type of Complication
Sigmoid sinus thrombosis
TABLE III.
Signs and Symptoms at Presentation.
No. of Patients*
Patients
Without ICCs
(N ¼ 61)
9
Patients
With ICCs
(N ¼ 10)
P Value*
Perisinus empyema
5
Protrusion of auricle, no. (%)
59 (97)
9 (90)
.37
Epidural abscess
Subdural abscess
1
1
Postauricular swelling, no. (%)
59 (97)
10 (100)
1.00
Postauricular erythema
Postauricular fluctuation
58 (95)
2 (3)
10 (100)
5 (50)
1.00
.0004
46 (75)
6 (60)
.44
45 (74)
6 (60)
.45
*In some patients more than one intracranial complication was
diagnosed.
(subperiosteal abscess),
no. (%)
Tympanic membrane
ICC group had postauricular fluctuation (subperiosteal abscess) (P ¼ .0004) and otorrhea (P ¼ .048). However, 60%
of the group with ICCs did not present with otorrhea, and
50% did not present with a subperiosteal abscess.
Indexes of inflammation at presentation (white
blood cell count and C-reactive protein) did not differ
between the two groups (Table IV).
None of the patients in either group had neurological
signs or cranial nerve deficits at presentation. Later in the
course of disease, three patients in the ICC group developed
weakness of the 6th cranial nerve, and one patient (who suffered from common variable immunodeficiency) developed
unilateral deafness. All four of those patients were treated
with steroids, and the three with cranial nerve palsy were
also treated with acetazolamide (Diamox).
The duration of hospitalization was significantly
longer for patients in the ICC group (mean 6 standard
deviation [SD], 17.8 6 9.28 days; range, 6–30 days) than
for those in the non-ICC group (mean 6 SD, 7.26 6 1.77
days; range, 4–12 days; P ¼ .001).
All patients recovered. The cranial nerve palsy in
the three affected patients resolved within 3 months.
The patient who developed profound unilateral sensorineural hearing loss did not recover his hearing.
erythema, no. (%)
Tympanic membrane
bulging, no. (%)
Otorrhea, no. (%)
8 (13)
4 (40)
.048
Fever, no. (%)
Neurological signs
35 (57)
0
4 (40)
0
.33
*Fisher exact test.
ICC ¼ intracranial complication.
more AM-related ICC. By far the most common complication was sigmoid sinus thrombosis, seen in nine of these
10 patients, and this was followed by perisinus empyema,
seen in five patients (Table I). Similar findings have been
reported in other studies over the last decade.17,18
The prereferral clinical characteristics of the
patients included in the present series (Table II) are in
accordance with previous reports.15,20,24,27,28 Both in our
study and in several earlier ones,9,15,18,29 most patients
were children under the age of 8 years old. Likewise, as
in our study, the duration of symptoms prior to diagnosis
of AM ranged in most cases between 1 and 30
days,8,13,15,18,21,25 and a significant number of patients
had been treated with antibiotics adequate for AOM
prior to the presentation of AM. Thus, our findings
reemphasize earlier findings8,11,15,18,24,28 that the use of
antibiotics for AOM is not an absolute safeguard against
AM and its complications
Notably, comparison between the two groups of
patients, those with ICCs and those without, showed
that they did not differ with regard to their prereferral
DISCUSSION
Despite the use of more potent types of antibiotics,
AM-related ICCs still occur and are potentially fatal.15,24
Their incidence is high, ranging in different studies
between 5% and 29% of patients.14–20
In the present prospective study, out of 71 patients
consecutively admitted with AM, 10 (14%) had one or
TABLE II.
Prereferral Clinical Characteristics.
Age, yr, mean6SD (range)
Patients Without ICCs (N¼61)
Patients With ICCs (N¼10)
P Value
2.1061.55 (0–7)
3.9264.83 (1–16.5)
.23*
Gender, male, no. (%)
31 (51)
2 (20)
.093†
Prior history of AOM, no. (%)
Prior history of AM, no. (%)
23 (38)
2 (3%)
2 (20)
0 (0)
.47†
1.00†
Predisposing factors, no.
0
1 (CVID)
Symptom duration, d, mean6SD (range)
Prior antibiotic treatment, no. (%)
5.4366.27 (1–30)
19 (32)
5.662.41 (2–10)
6 (60%)
.12*
.15†
Antibiotic treatment, d, mean6SD (range)
4.7363.76 (1–14)
2.7161.49 (1–5)
.38*
*Mann-Whitney U test.
†
Fisher exact test.
ICC ¼ intracranial complication; SD ¼ standard deviation; AOM ¼ acute otitis media; AM ¼ acute mastoiditis; CVID ¼ common variable
immunodeficiency.
Laryngoscope 122: December 2012
Luntz et al.: Brain Scan for Acute Mastoiditis Complications
2815
TABLE IV.
Indexes of Inflammation.
Patients Without ICCs (N¼61)
WBCs, K/uL, mean6SD (range)
CRPs, mg/L, mean6SD (range)
20.0867.39 (6–41)
Patients With ICCs (N¼10)
20.7665.87 (11–32)
99.3674.22 (0.2–235)
148.736146.8 (0.5–390)
P Value*
.57
.61
*Mann-Whitney U test.
ICC ¼ intracranial complication; WBCs ¼ white blood cells; SD ¼ standard deviation; CRPs ¼ C-reactive proteins.
characteristics or to most of the presenting signs and
symptoms observed (Tables III and IV). Significant differences were found between them for two presenting
signs, otorrhea and postauricular fluctuation (subperiosteal abscess) (Table IV). Our finding that AM patients
who present with otorrhea are more likely to develop
ICCs than those who do not confirms an earlier report
by our group in this connection.15
On the other hand, although our results showed
that in patients with AM the presence of otorrhea or subperiosteal abscess at presentation increases the risk of
developing an ICC, the fact that 60% of our patients who
presented with ICC did not have otorrhea, and that 50%
of those who presented with ICC did not have a subperiosteal abscess, indicates that the absence of otorrhea and
subperiosteal abscess at presentation in an AM patient
does not necessarily imply that the patient does not have
an ICC. This means that it is not possible, merely on the
basis of signs, symptoms, or laboratory inflammatory
indexes at presentation, to differentiate those AM
patients who present with ICCs from those who do not,
and that diagnostic imaging is required for that purpose.
Bilavsky et al.19 reported that children with complicated mastoiditis, defined as AM with either extracranial
(CT finding of a subperiosteal abscess or clinical finding of
CN [cranial nerve] palsy) or intracranial complications
(CT finding of sinus vein thrombosis or osteomyelitis, or
clinical finding of CN palsy) had significantly higher
fever, absolute neutrophil counts, and C-reactive protein
levels than children without such complications of AM. In
our study, fever was more common (although not significantly) in the non-ICC group, and the two groups did not
differ in fever grade or in inflammatory indexes (Tables
III and IV). Bilavskys’ study,19 however, was aimed at differentiating between complicated (extra- or intracranial)
and noncomplicated AM, and not—as in our study—
between AM patients with and without intracranial complications. Mallur et al.24 also emphasized the absence of
specific clinical symptoms indicative of ICCs in patients
with AM. Other authors20 have suggested that it is possible to decide on the need for CT in patients with AM on
the basis of the clinical picture in each patient. To the best
of our knowledge, however, no previous studies have
aimed at characterizing the typical clinical presentation
of AM patients who already have ICCs at the time of AM
diagnosis, and at differentiating such a clinical presentation from that of AM patients without ICCs.
CONCLUSION
AM patients with and without ICCs share largely
similar clinical presentations. It is thus not possible to
Laryngoscope 122: December 2012
2816
define an evidence-based index of suspicion for ICCs in
patients with AM, which could be used to identify those
AM patients in whom cranial imaging should be performed at presentation and those in whom it should be
withheld. Because of the life-threatening nature of otogenic ICCs and the potential for rapid clinical
deterioration in such cases (further morbidity and longterm sequelae as well as mortality3,11,22,28), their prompt
diagnosis is mandatory. Owing to the high incidence of
ICCs in patients with AM, the presentation of AM itself
can be considered to represent a risk for developing otogenic ICCs. Therefore, because cranial imaging is
considered the gold standard for the diagnosis of otogenic ICC complications, we consider it mandatory in
patients presenting with AM.
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