High Resolution Computed Tomography in Stapedial Otosclerosis

Abstract

The value of high-resolution CT scanning in diagnosing stapedial otosclerosis and in influencing surgical planning was studied. 40 cases, consisting of patients of both genders, above the age of 14 years, with a clinical diagnosis of otosclerosis underwent HRCT of the temporal bones. Images were acquired in axial plane, with a bone algorithm, keeping slice thickness at 0.5 mm and intervals of 0.5 mm. Reconstruction of the volume data set was done to obtain overlapping slices in various planes, so as to obtain the best possible images of the footplate of stapes. The thickness of the footplate was measured and the site of lesion was noted in these images. On exploratory tympanotomy, the footplate was assessed and graded according to a visual scale. HRCT was able to diagnose stapedial otosclerosis in 85% ears. It was able to identify the presence of a thickened footplate correctly with a sensitivity of 85.3% (P value 0.16). It was able to correctly localize the site of otosclerotic focus in 85% cases (P value \0.01). Thus, an estimate of the thickness of the footplate likely to be encountered and thus the amount of drilling likely to be required to create a fenestra; and the likely site of maximum thickness could be made preoperatively. This study also established the value of multislice CT on the acquisition of such data. This method obviates the requirement of difficult patient positioning, reduces scanning time; while greatly improving the sensitivity of the scanning.

Imaging Studies in Otosclerosis: An Up-to-date Comprehensive Review

“…The authors argued that the presence of false negatives was justified by an annular fixation of the footplate. 11 This type of fixation found intraoperatively was also consistent with the histological findings of a study by Cherukapally et al 12 In 2001, Shin et al found a sensitivity of CT scans in the diagnosis of otosclerosis of 91.3%. The false negatives were also attributed to early, "infraradiological" disease.…”

“…38 Finally, Priya et al did not find the radiological correlation between thickness of the footplate and audiometric parameters. 11 In general, location and size of otosclerotic foci seem to be poorer predictors of sensorineural HL than endosteal involvement and injuries to the cochlear integrity. 8,32…”

“…5) was estimated in between 27.5 and 33.9% in CT studies performed in India, with a male preponderance. 11,41 Preferably, the presence of obliterative foci ought to be always ruled out, as it implies an increasing risk of intraoperative complications. Besides, whenever diagnosed, it changes surgical planning, as the surgeon often requires local drilling to place the prosthesis.…”

High Resolution CT Imaging in Pathologies of Temporal Bone

“…HRCT accurately predicted thickened foot plate in 50% of cases with a sensitivity of 100% and specificity of 98% using imaging criteria of otosclerosis, which include increased thickness of foot plate >0.6 mm, grey foot plate(otospongiotic), hypodensity anterior to oval window, widened oval window and partial or complete obliteration of oval window by thickened footplate. S. R. Priya et al 9 , detected the sensitivity foot plate thickening is 85.3%. The sensitivity of detecting otosclerosis by evaluating footplate thickness may increase with thickness.…”

“…1,4 Hidden areas of the middle ear such as sinus tympani and facial recess are well appreciated in HRCT 5 , allowing better understanding of the aetiology, pathology, disease course with early detection of complications which alters treatment modality and has considerably reduced the morbidity and mortality pertaining to lesions of the temporal bone. 6 In addition to cholesteatoma, a very serious condition of the middle ear, HRCT plays a major role in the presurgical evaluation of other pathologies such as chronic suppurative otitis media (TT type), malignant otitis externa 7 , otosclerosis 8,9 and anatomical variations like high riding jugular bulb etc. The prospective study aimed to study pathologies of the temporal bone along with their complications on HRCT and to correlate with their surgical findings.…”