Can imaging suggest the aetiology in skull base osteomyelitis? A systematic literature review

Abstract

IntroductionTo assess differentiating features between bacterial, Aspergillus, and Mucor skull base osteomyelitis (SBO) with regard to clinical presentation and imaging appearances.Material and methodsA literature search was performed in April 2020 for studies on SBO with a minimum sample size of 10 patients. Studies that reported presenting symptoms, cross-sectional imaging findings, complications, and mortality were included in the analysis. The quality of included articles was tested using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. A data extraction form was used to retrieve relevant parameters from each of the articles.ResultsThirteen articles were included in the final analysis. Diabetes mellitus was the most common predisposing factor (12.5-91.0%). Presenting complaints in all bacterial SBO studies were otogenic, while fungal SBO patients had nasal/ocular complaints. Rates of mortality and surgical intervention in the fungal group were 50-100% and 50%, respectively, as compared to the bacterial group – 7-87% and 10%, respectively. On imaging, the site of initial infection in bacterial SBO was the external auditory canal, while in fungal SBO it was the paranasal sinus. The incidence of orbital extension was < 5% in bacterial and 44-70% in fungal SBO, among which Mucor had rates of 65-70%. Bone erosion was less extensive in bacterial SBO, and the patterns differed. The highest incidence of vascular involvement and non-enhancing lesions (23-36%) was seen in Mucor. Aspergillus showed highest sino-cranial extension (52-55%) and homogenous bright enhancement.ConclusionsSystematic analysis of the clinico-radiological parameters in each of the studies revealed differences in presentation, clinical course, extension, bone erosion, and enhancement.

Atypical presentations of fungal osteomyelitis during post COVID-19 outbreak – Case series

“…Diagnosis of mucormycosis and aspergillosis is achieved based on the clinical features, DNE (diagnostic nasal endoscopy) radiology (CE-MRI/CECT) [13] , histopathological and microbiological analysis. The bacterial and fungal osteomyelitis don’t differ in their radiology (CE-MRI/CECT) imaging findings; however according to a study by Deeksha Bhalla et al, the bacterial skull base osteomyelitis (SBO) presents with bone erosion in the later stage along with lesser extent of bony erosion compared to fungal SBO [14] . Other advanced aids include Immunohistochemistry, In-situ hybridization, Polymerase chain reaction (PCR) based molecular identification of DNA sequencing based on bar codes 18 S, ITS,28 s, rDNA, MALDI‑TOF [15] .…”

Trends and Outcomes of Fungal Temporal Bone Osteomyelitis: A Scoping Review

“…However, little is known on the differences in CT and MRI characteristics between fungal and bacterial TBO. A small review of fungal skull base osteomyelitis (both otogenic and sinogenic) found that fungal TBO occasionally appears on MRI as T2 hypointensity with blooming on gradient echo sequences due to the concentration of ferromagnetic elements during fungal metabolism (93). Adjunctive imaging with nuclear medicine studies were less commonly used in our review, most likely because of the lack of widespread availability, expense, time commitment, and radiation exposure (15).…”

Skull base osteomyelitis imaging

“…Diffusion restriction can be seen in localized abscesses. Fungal infections however can demonstrate conspicuous T2 hypointensity with blooming on gradient sequences (from the presence of ferromagnetic elements – iron, zinc, manganese) [24 ▪▪ ].…”

“…Polymicrobial infection is also noted. Fungal infections could occur in the absence of immunosuppression [24 ▪▪ ,38,39 ▪▪ ].…”

“…Imaging differences have been noted between bacterial and fungal etiologies [24 ▪▪ ]. Orbital involvement, vascular complications (most common-cavernous sinus thrombosis) and intracranial extension have been reported to be more common in fungal SBO.…”