Surgeon Oriented Preoperative Radiologic Evaluation in Cochlear Implantation - Our experience with a Proposed Checklist

Abstract

Introduction Preoperative temporal bone imaging studies have been routinely performed prior to cochlear implantation. Radiologists need to report these examinations with special focus on the surgeon's expectations. Objectives To provide a basic structured format, in the form of a checklist, for reporting preoperative computed tomography (CT) and to its clinical impact on operative findings. Methods The preoperative temporal bone CT scans of 47 patients were analyzed and reported according to the proposed checklist. Intraoperative assessment of mastoidectomy, posterior tympanotomy and round window access was done by the surgeon in a blinded fashion and were correlated with the radiological findings to assess its significance. Results The proposed radiological checklist was reliable in assessing operative difficulty during cochlear implantation. Contracted mastoid and lower tegmen position were associated with a greater difficulty of the cortical mastoidectomy. Presence of an air cell around the facial nerve (FN) was predictive of easier facial recess access exposure. Facial nerve location and posterior external auditory canal (EAC) wall inclination were predictive of difficult round window (RW) accessibility. Conclusion Certain parameters on the preoperative temporal bone CT scan may be useful in predicting potential difficulties encountered during the key steps involved in cochlear implant surgery.

Low‐Lying Tegmen and Surgical Outcomes Following the Middle Cranial Fossa Repair of Superior Canal Dehiscence

“…During mastoid surgeries and transmastoid approaches, a lowlying or overhanging tegmen can obscure the antrum and SCC and impede the identification of important anatomical landmarks, thereby predisposing patients to higher risks of intraoperative complications such as facial nerve ablation and labyrinth injury. 16,18,20 Sloping of the tegmen has also been shown to obstruct transmastoid access to the attic when managing cholesteatoma endoscopically. 15 As the tegmen is encroached on the tympanic ring, the SSC is expected to be more difficult to visualize during SCD repairs, especially when performed via the transmastoid approach.…”

“…LLT has been regarded as an anatomical obstruction of the surgical field during otologic procedures. During mastoid surgeries and transmastoid approaches, a low‐lying or overhanging tegmen can obscure the antrum and SCC and impede the identification of important anatomical landmarks, thereby predisposing patients to higher risks of intraoperative complications such as facial nerve ablation and labyrinth injury 16,18,20 . Sloping of the tegmen has also been shown to obstruct transmastoid access to the attic when managing cholesteatoma endoscopically 15 .…”

A high-resolution computed tomography based scoring system to predict ease of electrode insertion in cochlear implantation

“…14 and further studied for cochlear implantation by Mandour et al . 1 Whereas Sun et al . did not correlate their radiological findings with intra-operative findings, Mandour et al .…”

“…An anteriorly placed sigmoid sinus represents surgical restraints while performing posterior tympanotomy and accessing the round window. Our method to infer sigmoid sinus position is in conjunction with the method proposed by Sun et al 14 and further studied for cochlear implantation by Mandour et al 1 Whereas Sun et al did not correlate their radiological findings with intra-operative findings, Mandour et al found significant correlation between the two. Both these studies have utilised two additional lines on high resolution CT and have graded the sigmoid sinus position.…”

“…The aims of this study were fourfold: (1) to investigate the accuracy and internal validity of the proposed scoring system; (2) to establish correlation between the proposed scoring system and intra-operative difficulties; (3) to determine a cut-off score above which a surgeon can be certain of a difficult surgery; and (4) to provide surgeons and radiologists with a structured checklist for pre-operative analysis and reporting, with relation to each key surgical step.…”