Response to: Morphometric measurements of the incomplete partition type II (IP-II) cochlea and implications on cochlear implantation

Dear Prof. Lawrence Lustig, I’m a regular reader of O&N journal articles, and today, I came across this article from Prof. Akira Ishiyama and colleagues titled “Morphometric measurements of the incomplete partition type II (IP-II) cochlea and implications on cochlear implantation.” I have the following concerns on the inner ear anatomical type diagnosed in this study. Literature reports that IP type II is characterized with 1.5 turns of cochlea with the presence of central modiolus trunk in the basal turn leaving the middle and apical portion of the cochlea cystic.1Figure 1A shows the schematic form of IP type II, and Figure 1B shows the MRI scan of IP type II. On the other hand, the current paper under question reports IP type II having 2.5 turns and that the spiral ganglion cell bodies are present up to 540 degrees of angular depth. Also, the cochlear portion appears normal with the presence of central modiolus trunk up to the apex, as shown in Figure 2, which is raising doubts about the inner ear anatomy diagnosed in this study.2 Figure 1: Incomplete partition type II. Schematic form (A) and mid-modiolar section from MRI (B).Figure 2: Representative images of the IP-II cochlea and its 3D reconstruction. A, H&E section depicting the interscalar defect superimposed with the manual demarcations of the ST and CD. B, 3D reconstruction of a 2.5-turn IP-II cochlea. C, 3D reconstruction illustrating an IP-II cochlea with three turns.If authors could provide CT scans of temporal bones of samples reported in the paper under question, that would help readers to visualize the inner ear anatomy as we are used to detect from clinical scans. I doubt that the samples taken for analysis in this study may probably not be IP type II.