Impact of Routine Plain X-ray on Postoperative Management in Cochlear Implantation

The Modified Stenver’s View for Cochlear Implants – What do the Surgeons Want to Know?

“…It is exceptionally challenging to differentiate scala vestibuli and scala tympani on a Stenver's radiograph, although computed tomography (CT) can be used for this purpose (particularly cone beam CT, or fusion with preoperative MRI). Radiographic confirmation of intracochlear position and insertion depth is the primary aim of imaging and the gold standard for doing so [2]. Insertion depth can be estimated from the position of the ampullary limb of the semicircular canal, which is approximately in line with the conventional position for the cochleostomy/round window.…”

“…Intraoperative electrophysiological testing can provide indirect assessment of electrode placement by measuring electrode impedance and electrically evoked compound action potentials, giving information on the integrity of the electrode and the neural responsiveness of the auditory nerve [4]; however, it cannot confirm correct positioning of the electrode array [5] and may be absent even with a correctly positioned electrode. Electrode array misplacements are rare but serious complications, often necessitating revision surgery with an incidence rate between 0.2-5.8% [2]. Reported sites for misplaced electrodes include the internal acoustic meatus, Eustachian tube, internal carotid artery, and superior semicircular canal [5,6] (Figure 2).…”

“…The modified Stenver's view has excellent interrater variability in assessment of depth as well as position of electrode [4,10]. These radiographs also serve as a reference for future electrode migration should extrusion occur at a later date [2]. In under-insertion the electrode has not been advanced sufficiently so that all active electrodes are medial to the cochleostomy.…”

“…The routine use of plain radiographs to assess cochlear implants post-operatively has decreased due to concern regarding exposure to radiation, especially in the paediatric population [3], and the low incidence of electrode misplacement [2]. Some authors advocate the use of radiological confirmation only in cases of surgical suspicion of misplacement due to difficult insertion or abnormal patient anatomy [2,11,12]. However, while the specificity of surgical suspicion for misplacement is high at 88-99.5%, the sensitivity is only 55-60%.…”

“…The modified Stenver's view, first described by Marsh [1], has become the most commonly used radiological method to assess cochlear implant placement [2]. In the absence of international guidance regarding a preferred imaging modality, and indeed the need at all for radiological assessment of placement in patients with normal anatomy [3], what is required of the radiologist in reporting these radiographs can be unclear.…”