Otites externes nécrosantes: Apport de l’imagerie isotopique

Abstract

Objective : the Necrotizing (malignant) External Otitis is a very serious, potentially lethal affection. It touches exclusively a debilitated population, where from the necessity of a premature and reliable diagnosis for a beam of cliniquo-biological, radiological and isotopic arguments. Its care as well as its treatment are heavy and require a better definition of the
moment of cure. The purpose of our work is to specify the place of the isotopic explorations in the care of the NEO.

Materials and methods : we report a retrospective study bringing together 29 patients hospitalized for suspicion of necrotizing external otitis of period going from 2003 till 2009.

Résultats : the Middle Age of our population is 64.2 years, with a clear male prevalence. The majority of our patients are diabetics (90% of the cases) with a cardiac and hypertensive Co-morbidity among 19 patients. All our patients consulted, within 47 average days. An assessment of imagery was carried out, comprising a scanner for 16 of our patients. It was

normal in 4 cases and had shown lesions of osteitis in 12 cases. The osseous scintigraphy marked in MDP-Tc99 was carried out among 24 patients, within 9.69 average day. It was positive for all our patients, objectifying an osseous hyperfixation. All our patients received an adapted treatment. After amendment of the clinico-biological signs, a scintigraphy in Ga67 was practiced for 16 patients within 74 average days. It confirmed the cure among 12 patients, at which one decided to stop the antibiotic therapy. In the other cases, it objectified an osseous hyperfixation translating the persistence of the active infectious process, from where prolongation of the treatment.

Conclusion : it comes out from our work that the imagery is essential to confirm the diagnosis and to specify the extent of the osteitis. Indeed, the scanner and the MRI offer an excellent resolution and evaluate the extension of the infection perfectly. However, because of their poor sensitivity, they have little interest to the early phase of the diagnosis and for the therapeutic follow-up. The osseous scintigraphy has the advantage of an excellent sensitivity, approximately 100% in particular at the early stage, but is not specific. The tomographic techniques (SPECT) and the quantification improve however its specificity. The scintigraphy with gallium 67 seems quite as sensitive as and more specific than the osseous
scintigraphy, especially if it is quantified, and appears essential with the therapeutic follow-up. Its standardization would have an excellent predictive value of cure, allowing the stop of the antibiotic therapy

Keywords : Necrotizing External Otitis, scintigraphy with gallium, the osseous scintigraphy.