Current Medical Imaging     Send Orders for Reprints to reprints@benthamscience.net Current Medical Imaging, 2022, 18, 249-255 249 RESEARCH ARTICLE Changes in the Area Adjacent to the Internal Receiver-Stimulator of Coch- lear Implant: A Retrospective Study Isra Aljazeeri 1,2,* , Tawfiq Khurayzi 3 , Yassin Abdelsamad 4 , Fida Almuhawas 1 and Abdulrahman Hagr 1 1 King Abdullah Ear Specialist Center, College of Medicine, King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia; 2 Aljabr Ophthalmology and Otolaryngology Hospital, Ministry of Health, Ahsa, Saudi Arabia; 3 King Fahad Central Hospital, Ministry of Health, Jizan, Saudi Arabia; 4 Research Department, MED-EL GmbH, Riyadh, Saudi Arabia ARTICLE HISTORY Received: July 13, 2021 Revised: September 01, 2021 Accepted: September 19, 2021 DOI: 10.2174/1573405617666211104095421 Abstract: Background: In some patients with cochlear implants, bony resorption at the internal re- ceiver-stimulator site can be observed on postoperative computed tomography. Therefore, it is es- sential to elucidate the effects of the internal receiver-stimulator on the scalp and bony bed over time. Objective: We aimed to evaluate how the internal receiver-stimulator of a cochlear implant device changed the thickness of the surrounding scalp and skull over time using computed tomography. Methods: This retrospective study evaluated patients who underwent cochlear implantation and re- ceived two computed tomography scans postoperatively for different indications at a tertiary refer- ral centre. The main outcomes were scalp thickness and bony bed depth. Results: Fourteen ears were included in this study. There was very good inter-rater reliability among the two readers who evaluated the computed tomography of the included patients, with a Cronbach’s alpha of 0.94. The mean scalp thickness over the internal receiver-stimulator was 6.02 (+/-2.4) mm in the first scan and decreased with no significant change to 5.62 mm (+/-1.64) in the second scan (p = 0.59, paired t-test). The mean depth of the bony bed increased significantly from 1.39 mm (+/-0.93) to 2.62 mm (+/-1.24) (p = 0.03). Conclusion: There was no change in the thickness of the scalp overlying the internal receiver-stim- ulator indicating that the scalp was more resistant than the bony skull to the tensile pressure exerted by the internal receiver-stimulator. In contrast, the bony bed depth of the internal receiver-stimula- tor increased over time. This can result in decreased internal receiver-stimulator protrusion and de- creased risk of device displacement and migration. Keywords: Cochlear implants, auditory brain stem implants, radiology, tomography, X-Ray computed, otolaryngology, audiol- ogy. 1. INTRODUCTION Cochlear implantation has become one of the most effec- tive treatments for severe to profound sensorineural hearing loss. The Internal Receiver-Stimulator (IRS) is the thickest segment of the internal part of the Cochlear Implant (CI) de- vice. Since receiving approval from the Food and Drug Ad- ministration in 1984, the design of the CI device has evolved dramatically. The IRS is classically placed in a bony pocket drilled within the calvarial bone of the skull [1, 2]. The scalp overlying the IRS has inelastic, tense skin and is tightly ad- herent to the calvarial bone of the skull [3]. *Address correspondence to this author at the King Abdullah Ear Specialist Center, College of Medicine, King Saud University Medical City, King Saud University, PO Box 245, Riyadh 11411, Saudi Arabia; Tel: 011472643; Fax: 0114775690; E-mail: dr.isra.aljazeeri@gmail.com Since a CI is designed to be a life-long implanted device, we hypothesised that the tensile stretch arising from the pres- ence of the IRS in its tight pocket may cause some changes in the area where it is placed. These changes are more impor- tant to study in paediatric populations since they are expect- ed to live longer. Some studies suggest that the drilled bony bed can regrow with time, causing IRS protrusion, which can lead to increased pressure over the adjacent tissues [4]. This can increase the force applied to the scalp. In extreme situations, exposure or extrusion of the device can occur, which requires surgical reconstruction and is likely to neces- sitate the removal of the device [5, 6]. On the contrary, there have been reports of findings that suggest that pressure over the skull bone can cause resorption of the bony bed [7, 8]. Understanding the effect of the IRS over time on the scalp and bony bed is a fundamental step in finding a solution to prevent such a devastating complication. 1875-6603/22 $65.00+.00 © 2022 Bentham Science Publishers