Otogenic brain abscesses: A systematic review

Abstract

Objective: Otogenic brain abscesses are one of the most significant life-threatening complications of otologic infections. Given their low prevalence, otogenic brain abscesses require a high index of suspicion for diagnosis. In this systematic review, we aim to provide an analysis of otogenic brain abscesses and describe common clinical signs and symptoms, bacteriology, location, treatment options, morbidity, and mortality.

Data sources: PubMed, Cochrane CENTRAL database, Google Scholar, and Scopus.

Methods: A systematic review of literature was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses recommendations. Variables assessed included clinical signs and symptoms, bacteriology, location, treatment, morbidity, and mortality.

Results: Twenty-nine studies met inclusion and exclusion criteria, corresponding to a total of 1307 otogenic abscess cases for review. Fifty-five percent of abscesses were found in the temporal lobe and 28% in the cerebellum. Most patients (88.3%) had a history of suppurative chronic otitis media. The most common symptoms were headache, altered mental status, papilledema, and meningeal irritation. Fever, nausea, and vomiting affected about 40% of patients. The most commonly cultured bacterial species was Proteus mirabilis. In addition to antibiotics, most otogenic brain abscesses were treated by burr hole aspiration. Average mortality following advent of computed tomography was 8.11%.

Conclusion: Although rare, otogenic brain abscesses may occur as a complication of suppurative otitis media and require a high index of suspicion. Appropriate imaging studies and multidisciplinary expertise are crucial in the diagnosis and management.

Level of evidence: 4.

Keywords: Brain abscess; computed tomography; magnetic resonance imaging; otologic infection.

Figure 1

Coronal T1 fat‐suppressed post gadolinium (A) and axial T2 (B) MR images demonstrate an intra‐axial left temporal lobe peripherally enhancing lesion (white asterisk), adjacent dural enhancement (white arrowhead) and a peripheral rim of T2 hypointense signal (short white arrow). There is surrounding edema resulting in uncal herniation (long white arrow). On coronal (C) and axial (D) CT, there is a soft tissue mass in the left middle ear and mastoid with erosion of the middle ear ossicles (black arrowhead), expansion of the aditus ad antrum (black asterisk) and erosion of the tegmen (black arrow).

Figure 2

Flowchart demonstrating the study selection process, following the established Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) recommended guidelines.

Figure 3

Location of otogenic intracranial abscesses across all studies. The location of 905 out of 1302 total otogenic abscesses was specified. Most were located in the temporal lobe (n = 722, 55% of total) or cerebellum (n = 369, 28% of total). “Other” includes frontal lobe, parietal lobe and subdural locations (n = 66, 5% of total). The location of 145 otogenic abscesses was not specified (11%).

Figure 4

Complications: 12 of 18 studies specified complications in patients with otogenic abscesses. Out of the 681 otogenic abscesses covered in those studies, 238 (35%) were cases with complications. The figure demonstrates the most common complications patients suffered.

Figure 5

Microbiology. Microbiology data was available from 14 studies that specified a total of 16 common isolates from otogenic intracranial abscesses. Eleven of 14 (78.5%) of studies had P. mirabilis as the most common isolate while 1 of 14 (7.1%) specified Streptococcus species as the most common isolate. Two studies had more than one common isolate: one with P. mirabilis + Streptococcus species and one with Streptococcus and Staphylococcus species.

Figure 6

Treatment algorithm of otogenic brain abscesses at our institution.