12Seeing the Problem: Imaging the Implanted Ear
When telemetry or symptoms say something is wrong inside the cochlea, imaging shows you where. From a quick transorbital plain film to flat-panel cone-beam CT, the implanted ear can be imaged to confirm position, catch tip fold-over before the wound is closed, and distinguish a scalar translocation from a migrated array.
TPlain films and the cochlear view
A modified Stenvers (cochlear-view) or transorbital plain radiograph projects the array as a spiral and is the workhorse for confirming insertion depth, counting visible contacts, and detecting gross malposition. Plain film reliably shows the coiled array, partial insertions, kinking, and tip fold-over where the apical contacts loop back on themselves, and it remains adequate in the majority of routine confirmations. Strengths are speed, low cost, low dose, and portability; the weakness is that it cannot resolve which scala the array lies in. A standardized projection and beam-source protocol is what makes plain-film position assessment reproducible, especially intraoperatively with a portable unit.[2004][2019]
TWhen you need cross-sectional CT
Flat-panel / cone-beam CT resolves the scalar compartment and intra-scalar position with less metal artifact and lower radiation than conventional multi-detector CT, making it the modality of choice for detailed position questions. Mid-modiolar CT reconstruction distinguishes scala tympani from scala vestibuli, which is how scalar translocation (the array crossing the basilar membrane) is diagnosed. CT confirms findings that plain film only hints at: the exact level of a fold-over, focal migration, intracochlear new bone or fibrosis, and a misplaced array in the vestibule or a semicircular canal. The trade-off is dose, cost, and metal blooming on multi-detector CT; flat-panel/cone-beam mitigates these but is not universally available.[2016][2007]
CIntraoperative imaging: catch it before you close
An intraoperative radiograph (typically a portable modified-Stenvers view) confirms full, correctly coiled insertion while the surgeon can still act, and prospective series show it reliably catches malposition before wound closure. Tip fold-over and incomplete insertion are the highest-yield intraoperative findings, because both are correctable in the same sitting by re-insertion. Some arrays (notably slim modiolar designs) carry a higher fold-over risk and have made routine intraoperative imaging or field telemetry standard practice in many centres. Electrophysiology (spread-of-excitation, transimpedance matrix) is an increasingly used radiation-free intraoperative alternative or adjunct that can flag fold-over even before imaging.[2004][2019][2020]
CChoosing the right tool, and the dose it costs
Decision logic: use spread-of-excitation/field telemetry first as a no-dose screen, plain film to confirm coil and depth, and CT (flat-panel preferred) when the scalar position or a subtle malposition must be known. Reserve CT for questions plain film cannot answer; do not default to it, given dose and artifact considerations, especially in children. Match the question to the modality: 'is it fully and correctly inserted?' is a plain-film question; 'which scala, and is there a translocation?' is a CT question. Imaging is interpreted alongside telemetry and behaviour: concordant findings (e.g., apical open circuits plus a radiographic fold-over) build the strongest case for or against revision.[2016][2022][2005]
What is the finding and the appropriate action?
Which imaging modality is best for determining whether the array lies in scala tympani or scala vestibuli?
The main advantage of a plain cochlear-view radiograph over CT for routine position confirmation is:
Why is intraoperative imaging particularly valued with precurved slim modiolar arrays?