Pattern of cochlear obliteration after vestibular Schwannoma resection according to surgical approach

Objectives/Hypothesis To investigate the prevalence and course of cochlear obliteration according to microsurgical approach to inform clinical decision making regarding optimal timing of cochlear implantation. Study Design Retrospective radiologic review and chart review. Methods Patients who underwent microsurgical resection of vestibular schwannoma (VS) with a minimum of two available postoperative magnetic resonance imaging (MRI) scans were analyzed. The prevalence and timing of cochlear and labyrinthine obliteration was classified using relevant MRI sequences. Results MRI studies in 60 patients were analyzed: 20 translabyrinthine (TL), 20 retrosigmoid, and 20 middle fossa (MF) cases. The first and last postoperative MRI was obtained a median of 3.4 months (interquartile range (IQR), 3.0-3.7 months) and 35 months (IQR, 27-83 months) after surgery, respectively. At the time of the first postoperative MRI, 21 (35%) patients had partial basal turn obliteration, and none of the patients had complete basal turn obliteration. At the time of the last postoperative MRI, six (10%) patients had partial basal turn obliteration and 17 (28%) patients had complete basal turn obliteration. The pattern of partial or complete basal turn obliteration differed significantly among all three surgical approaches (P < .001). Specifically, the risk of partial or complete obliteration of the basal turn was highest in the TL cohort and lowest in the MF cohort. Conclusions The prevalence and timing of cochlear obliteration after VS microsurgery varies significantly according to surgical approach. The risk of early and complete obliteration is highest in the TL group and lowest in the MF cohort. These data may inform clinical decision making regarding optimal timing of cochlear implantation in patients with advanced hearing loss after microsurgical resection. Level of Evidence 4 Laryngoscope, 130:474-481, 2020