Pre-operative Screening and Manual Drilling Strategies to Reduce the Risk of Thermal Injury During Minimally Invasive Cochlear Implantation Surgery

A worthy technique for transcanal drilling during endoscopic ear surgery

Objective

To evaluate the necessity and effectiveness of a preplanned technique for drilling during transcanal endoscopic ear surgery.

Methods

Study design: Retrospective case series study from June 2011 to June 2015. Setting: Private tertiary care hospital. Patients: Eighty-five ears of 78 patients, age ranging from 9 to 57 years underwent transcanal endoscopic drilling for various types of pathology in their middle and external ear. Interventions: Application of a preplanned technique for transcanal drilling in endoscopic ear surgery that involved short timed drilling with use of intermittent irrigation and suction. Every events of the procedure were done one after another with the single hand of the surgeon. An attachment providing protecting sheath around rotating burr was used during each time of drilling. Main outcomes measure: Efficacy of such drilling technique in single handed endoscopic ear surgery. Presence of any postoperative thermal injury of facial nerve and any lacerated injury of skin of external ear.

Results

This preplanned technique was found suitable for transcanal endoscopic drilling with the single hand of the surgeon. Postoperative facial nerve palsy or laceration of skin of external ear was not noted in any patient.

Conclusion

After using the present technique, transcanal endoscopic drilling could be done easily and safely with single hand of the surgeon.

Clinical Implementation of Second-generation Minimally Invasive Image-guided Cochlear Implantation Surgery

OBJECTIVE

Minimally invasive, image-guided cochlear implantation (CI) surgery consists of drilling a precise tunnel from the surface of the mastoid cortex through the facial recess to target the scala tympani. In the first set of clinical trials of this technique, heat-induced facial nerve paresis (House-Brackmann II/VI) occurred on a patient on the last day of the initial trial which was scheduled to be halted secondary to a change in the regulatory requirements dictated by the 2012 the Food and Drug Administration Safety and Innovation Act requiring Investigational Device Exemption approval for previously exempted customized medical device testing. To address this adverse event, extensive changes were made to the drilling protocol; additionally, a custom insertion tool was developed. To address the Food and Drug Administration Safety and Innovation Act, an Investigational Device Exemption was submitted and, subsequently approved. Herein is described our first clinical implementation of the modified technique.

PATIENT

Seventy-year-old with profound, postlingual sensorineural hearing loss who had previously undergone right CI via traditional approach in 2015.

INTERVENTION

Minimally invasive image-guided left CI.

MAIN OUTCOME MEASURE

Time of intervention, final location of CI electrode array within cochlea.

RESULTS

Surgery took 155 minutes of which the largest components (in descending order) were soft tissue work, closure, and drilling. Full scala tympani insertion with angular insertion depth of 557 degrees of the electrode array was achieved. There were no complications, and the patient had an uneventful recovery and activation.

CONCLUSIONS

Minimally invasive, image-guided CI surgery is achievable and reduces the mastoid depression associated with traditional CI surgery.

CLINICALTRIALSGOV INFORMATION

Study NCT03101917, Microtable Microstereotactic Frame and Drill Press and Associated Method for Cochlear Implantation.

LEVEL OF EVIDENCE

Case Report.

Electrophysiological and histomorphological changes of cochlea in miniature pigs after abrasion of round window niches

Background: In operations of cochlea implantation (CI), many surgeons choose to drill a window on the bone wall of cochlea basic rotation, when more and more patients receive CI with residual hearing, what damage this step would result in is unclear.Objective: To study the effect to inner ear hair cells which is caused by drilling during CI.Methods: 6 miniature pigs are equally divided into two groups, Round window niche of each pig in the experimental group was milled, while the pigs in control group wasn't. After implanting depth of 6.5, 11.5 and 20 mm, round window electrocochleography was recorded to analyze the change of cochlea microphonic (CM) potentials respectively, histomorphological changes was observed.Results: Thresholds of CM in experimental group were higher than that of control group at different depth, amplitudes were smaller. In further group, cilia of inner hair cells (IHC) at bottom rotation were significantly damaged. After operation, ABR hearing threshold of experimental group was higher, differences at low frequency region were more obvious.Conclusions: Damage caused by mulling round window niche may seriously affect the function of the hair cells. Damage of the IHC is greater than OHC. CI through round window may protect residual hearing.