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Subannular tube insertion: anatomical considerations
Published online by Cambridge University Press: 16 November 2015
Abstract
To assess the distance between the bony groove created during subannular tubes placement and the chorda tympani, and examine the depth of the hypotympanum and retrotympanum.
Grooves drilled in cadaver temporal bones at two levels were imaged to measure: the distance between the chorda tympani nerve and the tympanic sulcus, and the depth of the hypotympanum and the retrotympanum relative to the annulus.
The chorda tympani was between 0 and 5 mm from the groove cut across the annulus. The hypotympanum average depth was 2 mm (0.44–6.40 mm) and the retrotympanum average depth was 1 mm (0–2.53 mm).
Grooves drilled across the tympanic sulcus should be placed at a point 20 per cent of the height of the tympanic membrane or lower; this will ensure least risk of injury to the chorda tympani nerve. The depth of the hypotympanum and retrotympanum dictates that the posteroinferior part of a subannular tube flange should be approximately 2 × 1 mm.
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- Copyright © JLO (1984) Limited 2015
Footnotes
Presented at the 65th Annual and General Scientific Meeting of the New Zealand Society of Otolaryngology – Head and Neck Surgery, 31 October 2012–2 November 2012, Wellington, New Zealand, and at the Australian Society of Otolaryngology Head and Neck Surgery 2013 Annual Scientific Meeting, 16–20 March 2013, Perth, Australia.
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