Journal Club: Human round window niche and size prediction using Steveners plane.

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Today's journal article

Boubaker F, Puel U, Imbs S, Blum A, Parietti-Winkler C, Gillet R. Round window measurements for cochlear implantation with UHR-CT: Importance of the Stenvers plane and membrane size. 

Why I picked this article

Round window is an opening in the bone surrounding the inner ear. Cochlear implant can be inserted through the round window. Pre‑op imaging can make a hard round‑window exposure easier and help avoid a cochleostomy. This research investigated how to best analyse CT scans during pre-op assessment. It looked at the details of which CT plane and which RW measurements actually predict whether a surgeon will reach through the RW or need a promontory cochleostomy. 

Some of the research findings

Study design & Imaging: 
  • Retrospective single‑centre series; n = 66 patients (40 female, 26 male), mean age 60.4 ± 17.7 years (range 26–84).
  • All patients had pre‑operative ultra‑high‑resolution CT (UHR‑CT) and proceeded to cochlear implantation.
  • CT scan resolution: 0.12 mm, 
  • Image reconstruction: FC80 kernel and hybrid iterative reconstruction.
What was measured and how
  • Two radiologists reviewed RW region anatomy in three planes: axial, parasagittal, and Stenvers (an oblique plane aligned with the basal turn and RW axis).
  • Parameters: 
    • RW niche type: tunnel (type 1), triangle (type 2), semicircle (type 3), or closed (type 4) shape
    • RW minimal width. 
    • RW membrane size and inclination. 
    • RW bony overhang size and inclination.
  • Surgical outcome classified as easy RW access vs need for promontory cochleostomy.
Part of Figure 1. Example of Stenvers plane. Boubaker et al. 2025

Key results
  • RW membrane size measured in the Stenvers plane was the only parameter that differed between the two surgical outcomes and was the most reproducible metric.
  • Optimal cut‑off: RW membrane size < 1.55 mm (Stenvers plane) predicted the need for cochleostomy; ≥ 1.55 mm aligned with easy RW access.
  • RW membrane size in parasagittal and Stenvers planes were highly correlated, but Stenvers performed best for prediction.
  • Minimum width and type of the RW niche and the size/inclination of the bony overhang did not influence surgical approach and showed variable inter‑observer agreement.

Haruna's takeaway

I didn't know this particular plane had a name!! We have, however, thought of this analogous plane in our microCT dataset. While we have the capability to collect 3D data from a number of medical imaging platforms, analysis of 3D images is highly complex, and we often need to select just one particular 2D plane for comparison. Consistency in selecting a 2D plane is hard, and this publication's approach is helpful to know. 

Also appreciate the data publication on the round window niche. This is a very important anatomical structure and more data the better! 

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This is Haruna's 77/100 of the 100-day challenge to post a science blog article every day! I love inner ear biology & cochlear physiology.