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

Role of Pre-Operative High-Resolution Computed Tomography for Surgical Planning in Patients Undergoing Cochlear Implantation - An Observational Study

Background

Currently preoperative magnetic resonance imaging (MRI) brain and High-Resolution Computed Tomography (HRCT) scanning of temporal bones form part of routine Cochlear implantation (CI) assessment. Pre- operative imaging demonstrates anatomic details or anomalies if any, that prove essential in pre-surgical evaluation of patients. These form a road map for the surgeon to anticipate any difficulty during surgery, to aid in decision making to implant the most appropriate ear, plan surgical technique, or select electrode arrays.

Methods

A descriptive observational pilot study was conducted at tertiary care hospital involving 51 paediatric patients worked-up for CI. Patients after detailed clinical evaluation and MRI Brain, a tentative surgical plan was formulated by a candidacy CI screening committee. Patients selected for surgery underwent HRCT temporal bones and surgical plan was modified after analysing the same. Percentage of cases in which surgical plan changed (in terms of laterality of surgery) after correlating with HRCT findings were determined and data analysed.

Results

A total of 51 patients worked up for CI were included in the study. In 37.3% cases, there were unfavourable MRI findings. HRCT scan was used to aid the surgical road map in these patients, which based on MRI findings would have had suboptimal outcome.

Conclusion

With this understanding, we recommend that, MRI with precise interpretation would be sufficient to furnish all necessary information in preoperative assessment of CI patients, and a HRCT temporal bones maybe indicated only in difficult cases or those with unfavourable MRI findings, may aid predict surgical events.

Radioclinical Assessment of Posterior Tympanotomy Difficulties during Ordinary Cochlear Implantation: A Prospective Case-Series Study

OBJECTIVES

This study proposes a preoperative radiologic scoring system for predicting posterior tympanotomy (PT) and mastoidectomy-associated difficulties during cochlear implantation (CI).

STUDY DESIGN

It was a prospective case-series study.

SETTINGS

The included CI surgeries were performed at tertiary referral institutions from October 2022 to April 2023.

SUBJECTS

We included 73 CI candidates performed via the PT approach.

INTERVENTION

The proposed radiologic score, composed of 13 items, was fulfilled and evaluated before each CI surgery.

MAIN OUTCOME MEASURE

We correlated this score with the intraoperative difficulty and surgical duration.

RESULTS

The operation was straightforward in 42 patients with a score of 3.87 ± 1.72 and challenging in 31 patients with a score of 10.66 ± 1.73. The radiologic score was strongly correlated with the surgical difficulty and duration (p < 0.0001).

CONCLUSIONS

Our proposed radiologic score was a valid, reliable, and precise tool to predict intraoperative difficulty during cochlear implantation. Chorda-facial angle was the strongest predictor, significantly affecting the difficulty, surgical duration, and preoperative radiologic score. A score equal to or more than 7.5 was expected to be associated with surgical difficulty.

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

OBJECTIVE

To compare treatment response from the middle cranial fossa repair of superior canal dehiscence (SCD) between cases with and cases without low-lying tegmen (LLT).

STUDY DESIGN

Cohort study.

SETTING

Single tertiary care institution.

METHODS

Two investigators independently reviewed preoperative high-resolution temporal bone computed tomography images and classified the ipsilateral tegmen as either "low-lying" or "control." Patients completed a symptom questionnaire and underwent audiometric testing pre- and post-operatively. Multivariable regression models assessed for symptomatic resolution and audiometric improvement following surgery with tegmen status as the primary predictor. Models controlled for patient age, sex, bilateral SCD disease, dehiscence location, prior ear surgery status, surgery duration, and follow-up duration.

RESULTS

Among a total of 410 cases included, we identified 121 (29.5%) LLT cases. Accounting for all control measures, patients with LLT were significantly less likely to experience overall symptom improvement (adjusted odds ratio: 0.32, 95% confidence interval [CI]: 0.18-0.57, p < .001) and reported a significantly lower proportion of preoperative symptoms that resolved following surgery (adjusted β: -25.6%, 95% CI: -37.0% to -14.3%, p < .001). However, audiometric outcomes following surgery did not differ significantly between patients with and patients without LLT.

CONCLUSION

This is the first investigation on the relationship between LLT and surgical outcomes following the middle fossa repair of SCD. Patients with LLT reported less favorable symptomatic response but exhibited a similar degree of audiometric improvement.

Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Bilateral Anterior Displaced Sigmoid Sinus in Cochlear Implantation: A Proposed Solution

To assess the safety, time consumption and presumed postoperative complications of posterior repositioning in cases with bilateral anterior displaced sigmoid sinus (ADSS) having cochlear implant surgery. Cases with bilateral ADSS were included. A cortical bone chip was harvested. Sinus plate was drilled thin and removed, ADSS was repositioned posteriorly and secured by the bone chips. The procedure was completed using the standard posterior tympanotomy (PT) technique. Follow up was done both clinically and by computed tomography (CT). Out of 632 cases operated upon in more than 7 years, only 7 cases had Bilateral ADSS (1.1%) of which 5 were females (71.45%). The average age was 8.2 ± 12 (6 children and an adult). No intraoperative bleeding was encountered in any of the 7 cases. The average operative time was 103.6 ± 9.7 min. No minor nor major complications were detected in all 7 cases. To keep the advantages of PT, repositioning of ADSS in bilateral cases can be done safely with a reasonable increase in the average operative time.

Temporal bone computed tomography checklist-TeSLANO: introduction of a standardized preoperative imaging evaluation for middle ear surgery

PURPOSE

Aim of the study was to evaluate if the introduction of the imaging checklist TeSLANO would improve the identification of crucial anatomical findings from temporal bone computed tomography (TBCT) scans among a cohort of Otolaryngology residents.

STUDY DESIGN

Single-blinded prospective cohort study.

SETTING

Tertiary care university hospital and referral center for otology and skull base surgery.

METHODS

The cohort was composed by eight Otorhinolaryngology residents (four junior and four senior) that were individually asked to identify all relevant anatomic findings from preoperative TBCT scans. Supervising surgeon showed to each resident four TBCT scans before and four after the introduction of a systematic checklist evaluation system based on the TeSLANO acronym. Statistical analysis was performed using McNemar's test and results were considered significant with a P value < 0.05.

RESULTS

Introduction of the checklist improved global identification of critical anatomical structures from 48.75 to 89.17% (P < 0.05). The postimplementation identification percentage improved for both the senior and junior groups (P < 0.05).

CONCLUSIONS

The imaging checklist TeSLANO allows a systematic approach to review TBCT scans and significantly improves identification of critical anatomical structures in Otorhinolaryngology residents.

Combined preoperative HRCT parameters for prediction of round window visibility in pediatric cochlear implant patient

OBJECTIVE

To evaluate the add value of combined analysis of high resolution computed tomography (HRCT) temporal bone parameters in accurate prediction of round window (RW) visibility through posterior tympanotomy.

PATIENTS AND METHODS

a retrospective observational study was held in a tertiary center, conducted on 45 cochlear implant pediatric candidates between January 2017 and September 2019. Candidates were referred for CT temporal bone. They were classified into fully visible RW cases and partially or non-visible RW cases. Radiological measurements were compared between the two groups for prediction of RW visibility separate and in combination.

RESULTS

45 patients were included in the study (26 males (57.8%) and 19 females (42.2%)). Their median age was 4 years (2-12 years). There were 38 (84.4%) fully visible and 7 (15.6%) partially or non-visible RW cases. Kashio posterior line (n:32/3), fascial recess width (FRW) (mean: 4.9 (3.5-7.5)/4.2 (4-4.7) mm) and round window location (RWL) (3 (1-4)/2.8 (1-3)mm) measurements significantly differentiated between the two groups; (P value 0.034, 0.012 & 0.025 respectively). Posterior kashio line and cut off values of ≥4.75 mm of FRW & 2.95 mm of RWL were showed sensitivity 84.2%, 63.2% & 65.8%, and accuracy 80%, 68.9% &68.9% in prediction of RW visibility respectively. Combination of Kashio prediction line with cut off value ≥ 7.45 mm (sum of FRW & RWL) showed P value 0.003 with further improve in the sensitivity and overall accuracy in prediction of RW visibility from 84.2% to 80% up to 91.4% and 88.6% respectively.

CONCLUSION

combined parameters using Kashio line with FRW and RWL increases sensitivity and overall accuracy in prediction of RW visibility rather than single parameter.