2026 Proffered Presentations
S077: LOCALIZATION AND PERFORMANCE OF AUDITORY BRAINSTEM IMPLANTS BASED ON MRI MEASURES OF PADDLE PLACEMENT
Justin Cottrell1; Matthew Breen2; Matthew Van Leeuwen2; William Shapiro2; Mahan Azadpour2; David Friedmann2; Daniel Jethanamest2; Sean McMenomey2; Donato Pacione2; John Golfinos2; Mari Hagiwara2; Gul Moonis2; J. Thomas Roland Jr.2; 1Yale University; 2NYU
Introduction: Auditory brainstem implantation (ABI) can assist select patients with hearing loss and contraindication to cochlear implantation. Outcome variability exists, ranging from no auditory perception, to rare but possible open set speech perception. The drivers of these performance differences is multifactorial, with optimal placement of the stimulating paddle over the cochlear nucleus(CN) representing one contributor.
We sought to develop a novel means of imaging ABI paddle placement utilizing post-operative MRI images to determine correlation with ABI performance, and ideal paddle placement properties.
Methods: A single centre retrospective study design was utilized, with patients from 2009 to 2023 over >18yo that received an ABI included. A measurement scheme utilizing post-operative MRI scans was developed to triangulate ABI paddle placement against the brainstem (Figure 1). Measurement data was subsequently gathered for insertion depth into the Foramen of Luschka, in addition to sagittal/axial/coronal paddle angles. The measurement values were ultimately compared to post-operative Categories of Auditory Performance (CAP) scores with the ABI.
Results: Twenty-one patients with neurofibromatosis type 2 (NF2) that underwent ABI placement met inclusion criteria. The average ipsilateral tumor volume was 19.4cm3 (Stdev 20.7), and contralateral tumor volume of 2.7cm3 (stdev 4.4). The most common surgical approach was translabyrinthine (n=16, 76%), followed by transcochlear (n=3, 14%), and retrosigmoid (n=2, 10%). Large variation in CAP score was achieved in patients, with a maximal performance of 5 (n=4), and minimum performance of 0 (n=7). The average performance was 2.1 (Stdev 2.0). One-third (n=7) of patients were deemed excellent performers, 33% (n=7) good performers, and 33% (n=7) poor performers.
The average insertional depth into the Foramen of Luschka was 1.0cm (Stdev 0.4), with average axial paddle angulation of 62.7o(Stdev 29.7o), average sagittal paddle angulation of 108.7o (Stdev 44.4o), and average coronal paddle angulation of -14.5o(Stdev 62.4o). Single variable linear regression showed a statistically significant negative relationship between insertion depth and CAP score (p=0.049). A trend of higher axial angulation being associated with a higher CAP score was also observed, although not statistically significant (p=0.16). Insertion depth and axial angulation showed a negative correlation, in which higher insertion depth was associated with a decrease in axial angulation value, although not statistically significant.
Conclusions: We present a novel means of measuring ABI paddle placement utilizing MRI to improve the objectivity of paddle placements assessments. Multicenter collaboration to increase the number of patients studied with this new measurement scheme will be required before stronger measurement associations can be determined.
Figure 1
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