The secondary spiral lamina and its relevance in cochlear implant surgery

  • Sumit Agrawal Department of Otolaryngology-Head and Neck Surgery, Western University, London, ON, Canada
  • Nadine Schart-Morén Department of Surgical Sciences, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
  • Wei Liu Department of Surgical Sciences, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
  • Hanif M. Ladak Department of Otolaryngology-Head and Neck Surgery, Western University, London, ON, Canada; Department of Medical Biophysics and Department of Electrical and Computer Engineering, Western University, London, ON, Canada
  • Helge Rask-Andersen Department of Surgical Sciences, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
  • Hao Li Department of Surgical Sciences, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
Keywords: Basilar membrane, cochlea, human, secondary spiral lamina, synchrotron-phase contrast imaging

Abstract

Objective: We used synchrotron radiation phase contrast imaging (SR-PCI) to study the 3D microanatomy of the basilar membrane (BM) and its attachment to the spiral ligament (SL) (with a conceivable secondary spiral lamina [SSL] or secondary spiral plate) at the round window membrane (RWM) in the human cochlea. The conception of this complex anatomy may be essential for accomplishing structural preservation at cochlear implant surgery.

Material and methods: Sixteen freshly fixed human temporal bones were used to reproduce the BM, SL, primary and secondary osseous spiral laminae (OSL), and RWM using volume-rendering software. Confocal microscopy immunohistochemistry (IHC) was performed to analyze the molecular constituents.

Results: SR-PCI reproduced the soft tissues including the RWM, Reissner’s membrane (RM), and the BM attachment to the lateral wall (LW) in three dimensions. A variable SR-PCI contrast enhancement was recognized in the caudal part of the SL facing the scala tympani (ST). It seemed to represent a SSL allied to the basilar crest (BC). The SSL extended along the postero-superior margin of the round window (RW) and immunohistochemically expressed type II collagen.

Conclusions: Unlike in several mammalian species, the human SSL is restricted to the most basal portion of the cochlea around the RW. It anchors the BM and may influence its hydro-mechanical properties. It could also help to shield the BM from the RW. The microanatomy should be considered at cochlear implant surgery.

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Published
2018-03-14
How to Cite
Agrawal S., Schart-Morén N., Liu W., Ladak H. M., Rask-Andersen H., & Li H. (2018). The secondary spiral lamina and its relevance in cochlear implant surgery. Upsala Journal of Medical Sciences, 123(1), 9–18. https://doi.org/10.1080/03009734.2018.1443983
Section
Original Articles