Intratympanic application of triamcinolone in sudden hearing loss—radiologic anatomy in cone beam CT and its’ correlation to clinical outcome

Abstract

Purpose To evaluate temporal bone cone-beam CT in patients with idiopathic sudden sensorineural hearing loss (ISSNHL) being treated with primary and secondary intratympanic (IT) triamcinolone and to possibly correlate these results to the clinical outcome. Methods Retrospective analysis of patients treated with IT triamcinolone for ISSNHL at our department in 2018. Pre-and post-therapeutic audiologic examinations included four-tone average (FTA) at 0.5, 1, 2 and 3 kHz. Using a clinical questionnaire, pre-therapeutic CBCT scans were re-evaluated looking at items, which might interfere with adequate drug diffusion into the inner ear (e.g. bony overhangs or secondary membranes at the round or oval window). Results Thirty-one patients were included. Twenty-four (77%; group A) had experienced ineffective systemic steroid therapy before and seven (23%; group B) received primary IT injections. Four group A-patients (21%) and two group B-patients (33%) showed a post-therapeutic FTA improvement of more than 15 dB HL. Bony overhangs at the round window niche (RWN) were present in seven cases (26%), a secondary membrane at the RWN in four (15%) and soft tissue in eight (30%) cases, respectively. Conclusion Most patients present radiological findings in CBCT imaging, which might interfere with drug diffusion through the RW membrane. Interestingly, soft or bony tissue obstructing the RWN or the OWN was found in 50% of patients, who showed improvement of hearing. We conclude that radiologic 'tiny' findings are either clinically irrelevant or improvement in hearing is independent from intratympanic drug delivery.

Enhancement in the Round Window Niche: A Potential Pitfall in High-Resolution MR Imaging of the Internal Auditory Canal

“…Other studies in the literature have described the anatomic landmarks of the RW to guide cochlear implantation procedures. 9 Roßberg et al, 10 in their retrospective study of conebeam CT examinations in 27 patients before treatment with intratympanic steroids, found granulation tissue obscuring the RWN in 15% (4/27) of patients, similar to our results with a larger cohort. Schachern et al 11 found histologic evidence of granulation tissue in the RWN following experimentally induced otitis media in a cat model.…”

Determination of the Round Window Niche Anatomy Using Cone Beam Computed Tomography Imaging as Preparatory Work for Individualized Drug-Releasing Implants

“…Silverstein found out in an examination of 41 RWNs via tympanostomy and middle ear endoscopy that five were completely obstructed and seven were partially obstructed [ 21 ]. However, even after overcoming anatomic obstructions in the middle ear, problems with round window permeability for compounds, the loss of medications into the nasopharynx via the Eustachian tube, and drug pharmacokinetics within inner ear fluids can still vary significantly [ 12 , 22 ].…”

Round Window Niche Veil is Visible on High‐Resolution Computed Tomography and a Predictor of Local Drug Efficacy to Inner Ear

“…How can we evaluate RWNV by noninvasive measurement? Previous inner ear imaging studies mostly focused on the measurement of the round window niche (RWN) and its position relationship with adjacent structures (such as the cochlear basal turn and facial nerve) to assess its impact on cochlear implantation, [18][19][20][21][22][23][24][25] but little attention had been paid to the existence of RWNV and its possible clinical effects.…”