This study is of importance to neurotologists and neurosurgeons. It is unclear why patients with NF2 have poorer outcomes with an auditory brainstem implant compared to non-tumour patients. This effect is postulated to be due to damage to certain cells in the cochlear nucleus that are needed for sound modulation either by the tumour or the surgery to remove it. This study looked at the effect transecting the cochlear nerve has on the cochlear nucleus with and without electrocautery in anaesthetised adult gerbils. They effectively showed that electrocautery close to the root entry zone caused significant cochlear nucleus cell body injury. Transection of the cochlear nerve away from the root entry zone along with distal electrocautery did not show any histopathological damage to the cochlear nucleus when sectioned and looked at under a microscope. This encourages surgeons to debulk tumours and peel them medially before applying electrocautery. It is however not very clear how this accurately translates to humans and the exact distance one would need to keep from the brainstem before electrocautery can be safely applied.

Effect of cochlear nerve electrocautery on the adult cochlear nucleus.
Iseli CE, Merwin WH 3rd, Klatt-Cromwell C, et al.
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Anand Kasbekar

BMedSci, DOHNS, FRCS (ORL-HNS), DM, Nottingham University Hospitals NHS Trust; Associate, The University of Nottingham; Otology and Hearing Group, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, UK.

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