異なる内耳解剖学における最適な電極配置のための人工内耳電極挿入トレーニングシステムの試験

Overview

This study demonstrates an advanced electrode insertion training system using interchangeable transparent inner ear models to simulate both normal and malformed cochlear anatomy. The system enables resident surgeons to practice cochlear implant electrode placement across various anatomical variants, including incomplete partition types I-III, cochlear hypoplasia, common cavity, and enlarged vestibular aqueduct, under expert supervision. The goal is to improve surgical precision and reduce complications by providing experiential training that reflects the anatomical diversity encountered in clinical cochlear implant populations.

Key Study Components

Area of Science

• Otolaryngology
• Neurotology
• Surgical Simulation

Background

• Successful cochlear implant electrode insertion is critical for postoperative rehabilitation and device function.
• Anatomical variations in the inner ear are more prevalent in cochlear implant recipients than in the general population.
• Standard cadaveric temporal bone training often lacks exposure to congenital inner ear malformations.
• Inadequate training in malformed anatomies contributes to intraoperative complications during electrode insertion.

Purpose of Study

• To demonstrate the use of a transparent, interchangeable inner ear model training system for cochlear implant electrode insertion.
• To provide experiential recommendations for optimal electrode placement across different inner ear anatomies.
• To evaluate training effectiveness through supervised practice by resident surgeons.

Methods Used

• Use of manufacturers-provided angled soft-grip forceps to handle and stabilize the electrode array.
• Alignment of forceps with superior-inferior trajectory to guide electrode along the lateral cochlear wall.
• Advancement of electrode with resistance monitoring and slow re-advancement to prevent buckling or extracochlear deviation.
• Anatomy-specific techniques: for IP type I, limit insertion to 360 degrees; for IP type II, stop before cystic apex; for IP type III, maintain lateral wall trajectory to avoid internal auditory canal entry.
• For common cavity: prebend electrode and introduce curved segment first to form a stabilizing loop.
• For cochlear hypoplasia and enlarged vestibular aqueduct: measure cochlear dimensions and select appropriate electrode length to avoid overinsertion.
• Post-procedure analysis of insertion accuracy, trajectory, angular depth, and technique comparison across anatomies.

Main Results

• Superior-inferior electrode alignment promoted lateral wall trajectory and reduced medial wall deviation.
• In IP type I, electrode lengths matching cystic cochlea enabled appropriate angular coverage; insertion beyond 360 degrees caused apical contact overlap.
• In IP type II, stable positioning was maintained when insertion was confined to the formed basal turn.
• In IP type III, lateral wall-directed insertion prevented unintended entry into the internal auditory canal.
• In common cavity, introducing the curved electrode segment first facilitated a stable looped configuration.
• In cochlear hypoplasia, reduced dimensions limited insertion depth, requiring precise electrode length matching.
• In enlarged vestibular aqueduct, limiting insertion depth prevented overlap and interchannel interference.
• Smaller cochleae allowed greater angular coverage for electrodes of identical length compared to larger cochleae.

Conclusions

• Anatomical identification and proper electrode selection are essential for reproducible and safe electrode insertion.
• The training system allows repeatable, anatomy-specific practice that bridges the gap between standard simulation and clinical variability.
• Resident surgeons benefit from supervised exposure to both normal and malformed inner ear models, improving technical readiness.
• Future work should evaluate different electrode designs and correlate training performance with actual surgical outcomes.

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