If you have ever wondered why despite your deliberate sectioning of an obstructing chorda tympani nerve during tympanoplasty, your patient post op did not experience any loss of taste, then you need to read this new study from USA (Dotty RL et al, Acta Oto-Laryngologica, 2009; 129: 52-56) that was designed to challenge the anatomical description of the glossopharyngeal nerve as it was handed down since 19th century, with startling revelations

This thought provoking review of the NICE clinical guideline 60 Surgical management of otitis media with effusion in children (GG Browning, Clinical Otolaryngology, Volume 33, Issue 6 (p 606-606) ) opined that it may be time to consider ventilation tubes in otitis media with effusion as a once only surgical procedure

december 27  2008

Vol 9 No 2

Otorhinolaryngology news

In this issue

· IX Nerve & New Anatomical Map…?

· OME—Beyond NICE Guidelines…?

· Manubrium Vs RW Anatomy..?

· Case of The week

Coming Events of Importance to Otorhinolaryngologists in Africa

Journal Watch: Effects of hypergravity on histamine H1 receptor mRNA expression in hypothalamus and brainstem of rats: implications for development of motion sickness– Sato GO et al, 2009

 1. Home page of otolaryngologyinafrica.net re-designed for accessibility

2.    A new forum for ENT patients and clinicians launched, For Details, click HERE

3. Receive the latest newsletter info. On your cell phone. Simply point your phone browser http://mobile.otolaryngologyinafrica.net

 Till 2009,

 Biodun

Abstract: 

Background: Although a transtympanic electrode is commonly used for electrocochleography and electrically evoked auditory brainstem response, the variability of responses among healthy subjects is wide. The manubrium is the typical guidepost for electrode placement. This study addresses the hypothesis that

electrode position relative to the round window niche is widely variable.

Study Design: Postmortem anatomic dissection of 41 bequeathed adult crania (82 temporal bones).

Methods: Drill marks were made on the medial wall of the mesotympanum from 2 manubrium-based positions: 1.5 to 2mm posterior to the umbo, and halfway between the umbo and the annulus posteroinferior.

Results: Distances to the lip of the round window niche ranged from 0.8 to 3.5 mm and from 1.8 to 4.5 mm for the 2 electrode sites, respectively. The posteriorly determined site was uniform on the promontory, but the posteroinferior site was into hypotympanic trabeculations in 81% of ears and into the jugular plate in 6%. Distances from the electrode sites to round window niche were not obviously associated with either the orientation of the manubrium in the head or the mastoid size.

Conclusion: The location of a transtympanic positioned electrode using the manubrium as guidepost is not accurately predictable relative to the round window niche.

© Copyright Dr 'Biodun Olusesi,  2005 - 2008

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Extract:

The Guidelines Development Group for these guidelines could not be expected to cover everything and they reasonably limited themselves to the ‘surgical management of otitis media with effusion’, but made reference to medication and hearing aids. What they have perhaps underplayed are the otological complications of ventilation tubes suggesting that by not mentioning them in the summary they are not important. However, the General Medical Council guidelines for gaining informed consent stipulate that not only the benefits but also any potential harms must be discussed with the patients. If one looks at the full report (http://www.nice.org.uk/nicemedia/pdf CGO60FullGuideline.pdf) rather than the summary in this issue, the Guideline Development Group did indeed consider the literature on the complications of ventilation tubes in section 3.3.3 under the subheading ‘Complications of ventilation tube insertion’…...

So, even though they looked at the complications and found the risk of these to be material, this fact seems to get forgotten subsequently and the implication is that ventilation tubes are essentially harmless. This is not the case and in particular when repeatedly inserted because the risk is compound. So much so the NICE report itself actually recommends hearing aids for children with cleft palate to avoid the risk of otological sequellae with multiple reinsertions of ventilation tubes. So should the avoidance of multiple tube insertions not also be the case for all children with OME? Reinsertions are not infrequent in children that do not have any identifiable predisposing abnormalities, such as a cleft palate or Down’s syndrome. The problem in ‘normal’ children is identifying those that are likely to be persistent after the ventilation tubes are extruded and still have a bilateral mild hearing impairment >25 dB HL.

So perhaps there is an even stronger case to be made for performing an adjuvant adenoidectomy in all children at the first time they have surgery for OME. Increasingly it is being recognised, especially with newer methods of removal under vision and the cessation of bleeding at the time that the dangers of postadenoidectomy haemorrhage have been overstated. So until we have identifiers of persistence in normal children, perhaps adenoidectomy should be performed alone without repeat tube insertion at any second operation, if it has not been done previously. If an adenoidectomy had been done initially, along with insertion of ventilation tubes, then a hearing aid should be considered. Ventilation tubes cause too much damage to be repeatedly inserted