Post-tympanostomy tube otorrhea in children: A clinical overview.

The first ventilation tubes, or grommets, were introduced by Politzer in the 19th century. However, he soon discovered that the insertion of these tubes caused otorrhea, which blocked the tubes and kept them from aerating the middle ear. As a result, the use of grommets was abandoned for more than a century.

Grommets were "reinvented" by Armstrong in 1954, and since then, tube insertion has become one of the most widely performed otolaryngologic procedures. These tubes are usually placed for the treatment of otitis media with effusion and recurrent otitis media. Even so, post-tympanostomy tube otorrhea (PTTO) remains the most common complication of tube placement, and studies show that its incidence ranges from 5 to 38%. Yet the difference between Politzer's time and the current era is that we now have a better understanding of PTTO, and we also have the means to prevent and treat it.

PTTO can be classified according to the time of its onset. Early PTTO occurs within 2 weeks of grommet insertion. Delayed PTTO occurs beyond 2 weeks postoperatively, and its incidence peaks at 3 months. Approximately 10 to 20% of children will experience PTTO during the immediate postoperative period. (1,2) The incidence of delayed PTTO is approximately 30% while the tube is still in place; the incidence is even higher among infants and among young children who have recurrent infections. (2,3)

Causes and risk factors

There are four primary causes of PTTO (4):

* entry of water through a grommet and into the middle ear

* a concomitant upper respiratory tract infection 

* reflux from the nasopharynx 

* an immunologic deficiency

In my practice, approximately 15% of children will have some otorrhea during the lifetime of their grommets, usually as a result of water contamination.

The rate of PTTO is not associated with either the type of surgical technique or the type of preoperative preparation. (5,6) Early PTTO can be accompanied by a middle ear infection (which you will notice if you see a mucoid discharge during surgery), purulent middle ear fluid, or external ear canal contamination.

Preventing PTTO

Does the type of tube make a difference in the incidence of PTTO? A number of studies have looked at the use of silicone-coated and silver-oxide-impregnated tubes as a possible means of reducing the rate of PTTO. Chole and Hubbell reported that there was a lower incidence with silver-oxide-impregnated tubes. (7) Conversely, our study in Perth of 100 children who received either a surface-treated silver oxide tube or a silver-oxide-impregnated tube in one ear (we used the other untreated ear as a control) found that these special tubes had no effect on the incidence of PTTO. (8)

Perhaps the most effective means of preventing PTTO, at least during the immediate postoperative period, is to instill antibiotic/steroid drops. In one of the first studies of topical antibiotic drops in children with ventilation tubes, Baker and Chole found that there was a significantly lower rate of PTTO among treated patients (0% during the first 2 wk) than among the control group (almost 20%). (9) We conducted another study in Perth of 100 ears in children who had been treated with topical antibiotic drops. We found 13 cases of PTTO among the untreated ears and only one case among the treated ears. (10) We then conducted another trial of two different postoperative dosages: 2 drops three times a day compared with only one dose. (11) We found that the single-dose treatment was just as effective as the multidose regimen except in children who had mucopurulent discharge at the time of surgery, those who had very thick glue, and those who had an upper respiratory tract infection or incipient otitis media.

In 2001, Morpeth et al compared topical ciprofloxacin/hydrocortisone drops with neomycin/polymyxin B/hydrocortisone drops. (2) With both agents, there was less otorrhea in the treated ears than in the untreated ears. However, because of ciprofloxacin's lack of ototoxicity, Morpeth et al recommended it as the treatment of choice. The two primary advantages of ciprofloxacin drops, and ofloxacin drops as well, are their lack of ototoxicity and their broad antibacterial spectrum.

Managing established PTTO

If, after the usual management with ear toilets and topical eardrop therapy, the ventilation tubes persist in draining and if immune deficiency, sinusitis, and reflux have been excluded as possible causes, further management is suggested. In Australia, we are somewhat more intensive in our management of the draining grommet than are physicians in other countries. In some nations, grommets that continue to drain are simply removed. We, on the other hand, occasionally hospitalize these children and administer intensive ear toilets with half-strength povidone iodine. Then we prescribe topical eardrops and occasionally intravenous antibiotics. We believe that it is better to leave the grommets in place because removing them can cause problems, such as a recurrence of middle ear effusion and otitis media. However, I must emphasize that this is end-stage treatment of the draining ventilation tube.

Our emerging understanding of biofilms

I have become particularly interested in the concept of biofilms. (13) A biofilm develops when a quorum of bacteria aggregates in the middle ear fluid; it has been detected on grommets and on the surface of the middle ear mucosa. Pseudomonas aeruginosa is particularly effective in producing biofilms. A biofilm is relatively impervious to systemic and topical antibiotics.

As it forms, a biofilm produces structures that have a mushroom-like appearance. A matrix of these structures produces mucopolysaccharide and lactamase. Topical and systemic antibiotics do kill the faster-growing cells in the matrix, but they have no effect on some very dormant cells that also reside there. As a result, the biofilm can survive antibiotic therapy and eventually become active at a later time. I am certain that this is an important reason that persistent otorrhea recurs after treatment has been stopped. Even though the middle ear fluid is bacteriologically sterile, it still contains dormant pathogens. Owing to our new understanding of biofilms, I now remove all grommets that are continually infected and have them analyzed by scanning electron microscopy to see if they have any of these dormant cells on them.

At the moment, we have two potential options for attacking biofilms: Tris-edetic acid (EDTA) and substituted furanones:

EDTA. EDTA increases the permeability of bacterial cells and allows antibiotics to penetrate them. It is a potentially useful therapy not only for patients with PTTO, but for those with chronic otitis media and chronic sinusitis, as well; aerosolized EDTA can even help treat lung infections in children with cystic fibrosis. After a few days of EDTA dosing has broken down the dormant cells, the biofilm is set up for a follow-up attack with either topical, systemic, or even aerosolized antibiotics. Veterinary studies have been performed on various animals with chronic sinusitis that did not resolve with systemic antibiotics or topical nasal sprays. But after EDTA was administered, the sinusitis resolved in a number of cases for 6 months or more.

I believe that a strategy of prepping the ear with EDTA before administering systemic antibiotics is a very good idea for the treatment of children with chronic otorrhea. We will be conducting a study of EDTA in the near future. EDTA is given intravenously for heavy-metal poisoning, so it should be safe for the inner ear and other local structures in the middle ear.

Substituted furanones. Substituted furanones were discovered in sea water by an engineer in Sydney, Australia. They prevent the formation of bacterial biofilms in sea water, and over eons of time, no resistance to them has occurred. Substituted furanones are nontoxic and relatively stable in the body. They prevent the formation of biofilms by interrupting the signals that are transmitted between bacterial molecules. Without this communication, a biofilm cannot form. Substituted furanones represent an ideal means of attacking bacteria where a biofilm is suspected of having formed--specifically in cases of chronic otorrhea caused by bacteria on a ventilation tube surface or in the middle ear mucosa. They might also prove to be beneficial in treating the chronic rhinitis that these children have and perhaps in treating children with cystic fibrosis. Further research into the safety of substituted furanones and their applicability to the management of children's ear and nasal disease will be conducted.

Comments

Dr. Rutka: When there is a discharge from a tube, I presume it is emanating from the middle ear space. But is it only the middle ear itself? Are mastoid air cells involved as well? Where can you localize this discharge, if that is even possible?

Dr. Coates: I think the discharge probably originates in the middle ear mucosa, but the mastoid might be involved, as well. I don't know whether any studies have addressed this issue.

Dr. Dohar: An imaging study performed previously found that both compartments are involved. Mastoiditis is a factor in children with a discharging grommet, otitis media with effusion, or acute otitis media.

Dr. Rutka: If we believe that topical therapy is effective in treating PTTO, it might take a leap of faith to believe that the drops will actually get into the mucosal lining of the mastoid and stop the discharge from occurring there. The drops might not even get through the tube. In fact, do we know what the natural history of PTTO would be in most patients if we just followed them? Do we know what would happen if we just left them alone?

Dr. Roland: The incidence of mastoiditis probably relates in some way to chronicity. I think a tube that has been draining for 2 days is much less likely to have mastoid involvement than a tube that has been draining for 2 months. Not only do drops get into the middle ear, a measurable level of almost 30 [micro]g/ml can get into the mucosa of the middle ear. So there is some level of penetration.

Dr. Croxson: What do those of you who treat discharging grommets currently use?

Dr. Vesterhauge: My treatment is ciprofloxacin eardrops.

Prof. Van de Heyning: First we perform vacuum aspiration to remove the debris in the outer ear canal, then we administer topical ciprofloxacin.

Dr. Haynes: I don't insert many tubes, but I do see a fair number of patients who are referred to me with PTTO. I prescribe acetic acid irrigations as the first drop, followed immediately by ciprofloxacin drops. We don't use neomycin/polymyxin B/hydrocortisone much anymore. I find that the one-two drop combination really works. By the time patients come to me, they have already been treated with oral antibiotics, so we don't usually prescribe them because they've already failed. But in the rare case of an adult who hasn't already had a trial of a fluoroquinolone, we will try that. We also treat the eustachian tube as well. I use both a steroid-containing nasal spray and an antihistamine spray.

Dr. Schapowal: The main point is to make a proper diagnosis. It seems to me that primary care physicians do not always exclude contact allergies, inhalation allergies, or immune deficiencies before they refer. You must also make sure that fungi are not involved, because they are involved in 4% of cases. Finally, we also clean and irrigate, and we use topical ciprofloxacin drops, which are very effective. We also swab all patients who have chronic or recurrent discharge.

Prof. Deitmer: We take a swab and then administer a topical quinolone. If we are not successful, then we administer culture-directed systemic therapy, either orally or intravenously.

Dr. Roland: I also start with a quinolone drop. I'm an advocate of aural irrigations that the patient's parents can administer at home so that the child does not have to come in and see me twice a day. I usually prescribe a solution of half 3% hydrogen peroxide and half sterile water; I have the patient irrigate with 20 or 30 ml, wait 10 minutes, and then instill the quinolone drops. This has solved most of the problems I see with refractory otorrhea. If a patient does need systemic therapy, it would be culture-directed and it would be started after the patient had failed 10 to 14 days of topical therapy. I have no hesitation about giving an oral quinolone to children if the culture shows that is what they need.

References

(1.) Balkany TJ, Barkin RM, Suzuki BH, Watson WJ. A prospective study of infection following tympanoplasty and tube insertion. Am J Otol 1983;4:288-91.

(2.) Epstein JS, Beane J, Hubbell R. Prevention of early otorrhea in ventilation tubes. Otolaryngol Head Neck Surg 1992;107:758-62.

(3.) Debruyne F, Jorrisen M, Poelmans J. Otorrhea during transtympanal ventilation. Am J Otol 1988;9:316-7.

(4.) Rosenfeld RM, Isaacson MD. Tympanostomy tube care and consequences. In: Rosenfeld RM, Bluestone CD, eds. Evidence-Based Otitis Media. Hamilton, Ont.: B.C. Decker, 1999:124-9.

(5.) Scott BA, Strunk CL, Jr. Posttympanoplasty otorrhea: The efficacy of canal preparation. Laryngoscope 1992;102:1103-7.

(6.) Giebink GS, Daly K, Buran DJ, et al, Predictors of postoperative otorrhca following tympanostomy tube insertion. Arch Otolaryngol Head Neck Surg 1992;118:491-4.

(7.) Chole RA, Hubbell RN. Antimicrobial activity of silastic tympanostomy tubes impregnated with silver oxide. A double-blind randomizcd multicenter trial. Arch Otolaryngol Head Neck Surg 1995;121:562-5.

(8.) Coates H, Chai F, Oates J. Use of surface treated and silver oxide impregnated tympanostomy tubes in reducing post operative otorrhoea. Aust J Otolaryngol 1998;3:16-9.

(9.) Baker RS, Chole RA. A randomized clinical trial of topical gentamicin after tympanostomy tube placement. Arch Otolaryngol Head Neck Surg 1988;l14:755-7.

(10.) Coates H, Sashikumar A. A prospective clinical trial of antibiotic/ steroid eardrops and incidence of infection following ventilation tube insertion. Journal of the Otolaryngologic Society of Australia 1990;6:272-4.

(11.) Harlock J, Coates HL. Single dose antibiotic/steroid eardrop prophylaxis and ventilatin tube insertion. Aust J Otolaryngol 1992;1:30-2.

(12.) Morpeth JF, Bent JP, Watson T. A comparison of cortisporin and ciprofloxacin otic drops as prophylaxis against post-tympanostomy otorrhca. Int J Pediatr Otorhinolaryngol 2001;61:99-104.

(13.) Post C. Direct evidence of bacterial biofilms in otitis media. Laryngoscope 2001;l11:2083-94.

Harvey Coates, MS, FRACS 

Dr. Coates is a senior ENT surgeon at the Princess Margaret Hospital for Children in Perth, Western Australia. He specializes in pediatric otology and obstructive sleep disorders and has a particular interest in treating his country's Aborigine population.