Vol. 117 No.
2 February 2014
Brain abscess potentially secondary to odontogenic infection: case
report
Joseph Yang, DMD, MBE,a Stanley Y. Liu, DDS, MD,b Mehran Hossaini-Zadeh, DMD,c and
M. Anthony Pogrel, DDS, MD, FRCS, FACSd
University of California, San Francisco, CA, USA
Odontogenic infections are rarely implicated in the causes of brain abscess formation. As such, there are very few
reports of brain abscesses secondary to odontogenic infections in the literature. This is due partly to the relative rarity of brain
abscesses but also to the difficulty in matching the causative organisms of a brain abscess to an odontogenic source. The
authors report a case of a 50-year-old woman whose brain abscess may potentially have been secondary to an odontogenic
infection. The patient’s early diagnosis, supported by imaging and microbiologic assessment, along with early minicraniotomy
and extraction of infected dentition followed by a course of cephalosporins and metronidazole, contributed to a successful
outcome. (Oral Surg Oral Med Oral Pathol Oral Radiol 2014;117:e108-e111)
Brain abscesses are rare, but they represent a serious tomography (CT) contributed to a mortality rate of 36%
infection of the brain parenchyma in which a localized to 66%.3 Despite advancements in imaging modalities
area of suppuration develops. The incidence of brain and diagnostic techniques, failure to recognize an
abscesses is approximately 1 in 100,000 in the United odontogenic origin as the source of a brain abscess may
States, and brain abscesses account for 1 per 10,000 still remain a diagnostic challenge, particularly among
hospital admissions.1 They may be the result of direct clinicians who are not dentally oriented. This case
head injury, a complication of neurosurgical proce- report presents the signs and symptoms, management,
dures, or the result of secondary infections from distant and hospital course for a patient whose brain abscess
sites.2 A review of 400 cases from China found that the was possibly of odontogenic origin.
most common etiology was ear infections, accounting
for 65.75% of brain abscesses, followed by blood-borne
infections at only 13%.3 Rarely, odontogenic infections REPORT OF CASE
are implicated in the etiology of brain abscesses.4 A A 50-year-old woman with a history of migraine headaches,
review of the literature found fewer than 20 reports of hypertension, fibromyalgia, bipolar disorder, and end-stage
brain abscess of odontogenic origin, with only 6 cases renal disease on hemodialysis presented to her local emergency
reported in this century so far.5 Owing to the relatively department (ED) complaining of right leg weakness. The patient
reported feeling right leg weakness 5 days previously, which
low incidence of brain abscesses, the clinician’s chal-
she had originally thought to be secondary to her fibromyalgia,
lenge is to recognize the possibility of such a diagnosis which had presented similarly in the past. On the morning of her
and to prevent a delay in treatment. When brain presentation to the ED, she woke up and was unable to move
abscesses are diagnosed early and managed with her right leg at all. Before the onset of her right leg weakness,
surgical debridement and appropriate antibiotics, re- the patient reported a 2-week history of headaches and blurry
ported mortality rates range from 0% to 24%.6 This is vision, which were similar in nature to previous migraines. She
a significant improvement from the mortality rates up denied having any measurable fevers but did report chills and
until the 1960s, when despite diagnosis of a brain dizziness. She also denied any recent history of nausea, vom-
abscess, antimicrobial resistance and lack of computed iting, diarrhea, seizures, sensory deficits, or language difficul-
ties. The patient also reported receiving multiple root canals in
A portion of this manuscript was presented as a poster at the 2013
the past 2 years, with accompanying episodes of pain and
California Association of Oral and Maxillofacial Surgeons Annual drainage in her upper right quadrant. At the time of her
Meeting. presentation to the ED, the patient denied taking any medica-
a tions. The patient reported a 20-pack-year history of tobacco use
Resident, Department of Oral and Maxillofacial Surgery, University
of California, San Francisco. but denied any alcohol or illicit drug use.
b
Chief Resident, Department of Oral and Maxillofacial Surgery, A CT scan ordered by the ED physician found a 2-cm
University of California, San Francisco. lesion in the left frontoparietal region near the paracentral
c
Health Sciences Associate Clinical Professor, Department of Oral primary motor cortex. A magnetic resonance imaging (MRI)
and Maxillofacial Surgery, University of California, San Francisco. scan confirmed the same lesion. Neither study was performed
d
Chairman and Professor, Department of Oral and Maxillofacial
with contrast, given the patient’s end-stage renal disease. With
Surgery, University of California, San Francisco.
Received for publication Jun 6, 2013; returned for revision Jul 28,
these findings, the patient was transferred to our medical
2013; accepted for publication Aug 13, 2013. center and admitted under the care of the neurosurgery
Ó 2014 Elsevier Inc. All rights reserved. service. Of note, the nephrology service was consulted to
2212-4403/$ - see front matter determine the appropriate management of the patient’s dial-
http://dx.doi.org/10.1016/j.oooo.2013.08.011 ysis needs during her hospitalization, given her history of
e108
OOOO CASE REPORT
Volume 117, Number 2 Yang et al. e109
end-stage renal disease thought to be secondary to either
immunoglobulin A nephropathy or hypertension.
Upon admission to our medical center, the patient began to
have progressive right arm weakness, measuring 2 out of 5 on
right-hand grip. Imaging with contrast studies was ordered,
after assessing the benefits versus risks with the nephrology
service. Both the CT and MRI (Figure 1) showed a 2.0 1.2-
cm lesion centered in the left paracentral lobe with features
suggestive of an intracerebral abscess. Given these findings,
the infectious disease service was consulted to determine the
most appropriate antibiotic regimen to begin. With that
service’s recommendation, the patient was started on vanco-
mycin 500 mg intravenously (IV) after hemodialysis sessions,
ceftriaxone 2 g IV every 12 hours (q12h), and metronidazole
500 mg IV q8h. The patient was then taken to the operating
room for a left frontal minicraniotomy for abscess drainage.
Brain abscess specimens were submitted to microbiology for Fig. 1. Diffusion tensor imaging with magnetic resonance
aerobic, anaerobic, fungal, and acid-fast bacilli cultures. The imaging (sagittal view): The circle encloses the lesion of the
bacterial cultures returned positive exclusively for numerous left frontoparietal region.
viridans streptococcal growths, presumptively Streptococcus
anginosus. All other brain abscess cultures were negative.
Additionally, blood and urine samples were cultured, which
were negative. Upon receiving these results, and given the
patient’s history of chronic odontogenic pain with recurrent
episodes of intraoral drainage, the infectious disease service
requested a consultation from the oral and maxillofacial
surgery service to evaluate a possible odontogenic source for
the streptococcus-proven intracranial abscess. Besides
a possible odontogenic source, the infectious disease service
did not believe there was any evidence of streptococcal
contribution from the patient’s gastrointestinal tract, genito-
urinary tract, or nasopharynx. The infectious disease service Fig. 2. Panoramic radiograph: extensive root canal therapy of
also recommended the continuation of ceftriaxone to cover the the right maxillary first molar and canine, as well as periapical
viridans streptococci, metronidazole to cover any pending radiolucencies of the right maxillary first molar and canine.
anaerobic species, and discontinuation of the vancomycin,
given the speciation of the streptococcal growths.
During consultation, the patient again reported a 2-year tissue specimens associated with the 3 symptomatic teeth were
history of recurrent pain and drainage in her right maxillary sent to microbiology for aerobic and anaerobic cultures, as
arch, where she had received multiple root canal therapies and well as to surgical pathology. Additionally, a right maxillary
fixed prostheses. In her current state, the patient reported sinus swab was sent for bacterial culture. After extraction of
significant pain in her right maxillary arch. On extraoral the right maxillary posterior dentition, there remained
examination, there was no cervical or submandibular lymph- a maxillary sinus wall defect, which was immediately repaired
adenopathy. There was no evidence of trismus or facial by a buccal fat graft.
swelling. On intraoral examination, the right maxillary first Bacterial cultures from the oral specimens yielded entero-
molar and first premolar were found to be sensitive to cocci, Candida albicans, anaerobic gram-negative rods, lac-
percussion and palpation, with suboptimally fitting restorations tobacilli, and viridans streptococci. The right maxillary sinus
and mild mobility. There was no gross swelling intraorally. A swab cultured numerous polymicrobial growths, including
panoramic radiograph (Figure 2) showed root canal therapy of nafcillin-resistant Staphylococcus aureus, enterococci,
the right maxillary first molar and canine, as well as periapical Candida albicans, anaerobic gram-negative rods, lactobacilli,
radiolucencies of the alveolar bone associated with the right and viridans streptococci. The histopathologic diagnosis for
maxillary first molar and canine. Given the patient’s 2-year the tissue specimens was sclerosing osteitis. Upon receiving
history of chronic odontogenic pain and drainage, the intraoral these results, the infectious disease service recommended
examination findings, and the absence of evidence indicating coverage of streptococcal growths with cefepime 2 g IV after
pathology of the patient’s gastrointestinal and genitourinary hemodialysis sessions for 4 weeks, and metronidazole 500 mg
tracts, the patient was taken to the operating room for orally (PO) q8h for 4 weeks for anaerobic coverage. Although
extraction of her right posterior maxillary dentition, local the patient’s prior ceftriaxone regimen was being used to cover
debridement, and microbiologic assessment. Intraoperatively, the streptococcal growths during her hospitalization, it was for
we found fistula tracts apical to the right maxillary first molar the sake of convenience for the patient’s hemodialysis sessions
and canine (Figure 3). Both alveolar bone and granulation that ceftriaxone was switched to cefepime.
ORAL AND MAXILLOFACIAL SURGERY OOOO
e110 Yang et al. February 2014
abscess and chronic right maxillary odontogenic infec-
tions.2 Although useful as a research tool, molecular
fingerprinting is not performed routinely in the clinical
setting, particularly when there is strong evidence to
suggest a specific bacterial source, as was true in the case
presented here. Nevertheless, the future integration of this
technique into the clinical realm would be a much
welcomed diagnostic tool in cases in which a specific
bacterial source is difficult to ascertain.
Infections may spread to the brain either by hema-
togenous spread or by contiguity with the brain.2 Given
that ear infections account for most brain abscesses,
whereas blood infections contribute to a smaller am-
ount, it is likely that contiguity is the most common
route of infectious spread to the brain. The blood-brain
barrier makes hematogenous spread less frequent. In the
case presented here, because blood cultures were
negative, it is presumed that the odontogenic infection
Fig. 3. Intraoperative intraoral photograph after full-thickness
traveled to the brain by way of contiguity. A negative
mucoperiosteal flap elevation of right posterior maxilla.
Fistulas with sclerosing osteitis, as confirmed by surgical blood culture also rules out the likelihood of a bac-
pathology, were prominently associated with the right teremia secondary to periodontitis. In addition, it is
maxillary first molar (arrow) and first premolar. thought that in most immunocompetent hosts, the
reticuloendothelial system quickly quells any bacter-
The patient was discharged from the hospital on the tenth emias of an oral source. Unsurprisingly, immunocom-
postoperative day, and by that time she had experienced a full promised populations experience an increased incidence
return of her right arm strength, with some residual weakness of brain abscess.7 Besides immunocompromise, under-
in her right leg. lying brain pathologies such as stroke or neoplasm may
increase one’s risk for brain abscess formation.10-11
DISCUSSION Unusual in our case report is the frontoparietal location
Brain abscesses are frequently polymicrobial, with the of the abscess, because it is most frequently the
most common reported organisms to be microaerophilic temporal lobe and cerebellum that are most susceptible
streptococci (such as viridans streptococci), anaerobic to brain abscesses.3
bacteria (Bacteroides species, Actinobacillus actino- In addition to the rarity of the diagnosis, patients with
mycetemcomitans), Staphylococcus aureus, and faculta- cerebral abscesses may show no distinctive symptoms
tive anaerobic gram-negative bacteria (enterobacteria).7-9 early in their course.3 Most patients present with
The case presented here is unusual in that there was only headache, nausea, and vomiting, but fever and neuro-
viridans streptococcal growth cultured from the brain logic signs are notably absent in the early stages.3 Even
abscess. Because viridans streptococci are normally by the time patients are referred to the neurosurgery
found only in the oropharynx, gastrointestinal tract, service, up to a third of patients lack any localizing
genitourinary tract, or nasopharynx, their presence else- signs.3 Such is the challenge that is presented as the
where in the body, particularly the brain, indicates either clinician tries to work quickly toward a diagnosis of
active infection or contamination. As reported elsewhere, brain abscess. Once the diagnosis has been made,
brain abscesses of odontogenic infection are normally treatment consists of 3 arms: administration of antibi-
treated with penicillin-based antibiotics for streptococcal otics, drainage of pus, and the treatment of the primary
coverage, along with metronidazole for any remaining focus of infection.3 It is particularly this last component
anaerobic coverage.5 In the case presented here, however, of treatment that calls upon dentally oriented clinicians
the infectious disease service decided to continue the to remain vigilant in the identification of oral or
patient on the original ceftriaxone and metronidazole odontogenic sources for brain abscesses.
regimen, rather than switch to a penicillin-based antibi-
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