Plugging of a Dehiscent Superior Semicircular Canal Damages the Spiral Ganglion Regardless of the Material Used

In canal that After visual verification of successful blockage ABSTRACT Objective: The use of bone wax to plug a dehiscent superior semicircular canal has been found to be associated with poorer hearing outcomes in humans when compared with the use of bone. Animal models showed that plugging the superior or lateral semicircular canal with bone wax caused an inflammatory reaction in the middle ear that was significantly more severe than with bone or Teflon. Damage to the cochlea can lead to alterations in the size, number and density of the spiral ganglion neurons. This study aims to examine potential cochlear damage caused by plugging a dehiscent superior semicircular canal with different materials in gerbils by analyzing the spiral ganglion of the basal cochlear turn. Methods: We used hematoxylin and eosin-stained mid-modiolar paraffin sections from 44 operated ears and 19 non-operated control ears to examine spiral ganglion structures in cochlear cross-sections through the lower basal turn and upper basal turn. We calculated the number of spiral ganglion cells and measured their size. We also measured the area of the Rosenthal's canal and assessed the density of neurons within it. Furthermore, the degree of interstitial edema within the spiral ganglion was assessed. Results: For most of the plugging materials, the main pathological finding following surgery was a loss of spiral ganglion cells predominantly in the lower basal turn. No evidence was found for a shrinkage of spiral ganglion cells or a reduction in spiral ganglion cell density as a result of plugging the superior semicircular canal. Conclusion: The spiral ganglion appears to be more severely damaged in the lower basal turn compared to the upper basal turn for the majority of mate rials used for plugging a dehiscent superior semicircular canal.