Endocrine Abstracts

Purpose

To describe the role of imaging in diagnosis and detection of complications of necrotising external otitis in diabetic patients.

Material and methods

Our retrospective study included 43 diabetic patients who suffered from necrotising external otitis, from 1992 to 2020. All our patients had CT scan of the temporal bones and the brain. MRI was performed in 4 cases.

Results

The mean age was 69.4 years with female predominance. The average duration of diabetes follow up was over 10 years. In 33 cases, the causative agent was bacteria; fungal pathogens were found in 11 cases. In all cases, CT scan showed thickening soft tissue and cortical bone erosion of the external auditory canal. In 31 cases, it revealed opacification of the mastoid air cells and middle ear (erosion of the ossicular chain in 8 cases). Periauricular soft tissues inflammatory changes was noted in 10 cases. In the complicated cases, CT scan revealed: an anterior extension of the infection to the temporomandibular joint (5 cases), a bone destruction of the intratympanic facial canal (2 cases), an erosion of the tegmen tympani (2 cases ), a parapharyngeal (2 cases) and parotid (1 case) involvement, a retropharyngeal abscess (1 case), an extension to the nasopharynx (2 case), a skull base extension (4 cases), an extension to the cervical vertebra (1 case) and an extension to the petrous apex (1 case). The CT angiography revealed venous obstruction of the sigmoid sinus (1 case), cavernous sinus (1 case) and internal jugular vein (3 cases), an osteolysis of the carotid canal (2 cases) and the jugular bulb with thrombosis of this latter and the petrous part of the internal carotid artery (1 case). MRI, performed in 4 cases, showed: a retropharyngeal abscess with skull base extension (1 case), cervical vertebra extension with epidural abscess (1 case) and thrombosis of the sigmoid sinus and the internal jugular vein (1 case).

Conclusion

Necrotizing external otitis remains a serious invasive infection which must be highly suspected mainly in diabetic patients. Imaging is necessary to establish the diagnosis and to detect complications.