Ventilation tubes (grommets & T-tubes)
What are ventilation tubes?
Ventilation tubes (commonly known as grommets) are tubes that are surgically placed across the tympanic membrane (ear drum). They allow ventilation of the middle ear by bypassing and taking over the function of the dysfunctional Eustachian tube, and prevent the build up of fluid behind the ear drum.
When are they put in?
Ventilation tubes are inserted in the following conditions:
Otitis media with effusion (glue ear) that is present in both ears, is causing hearing difficulty or other symptoms and has not resolved despite three months of watchful waiting.
Recurrent attacks of acute otitis media (middle ear infections)
Some children have both of these conditions as one can lead to the other.
How are grommets put in?
They are usually inserted under a general anaesthetic, but in adults they can occasionally be inserted using a local anaesthetic. It is performed as a day case procedure, with patients being able to go home on the same day.
The ear is first cleaned of any wax and carefully examined. A cut is then made in the ear drum and the abnormal fluid suctioned from the middle ear. The grommet is then inserted into a position so that it lies across the ear drum. The procedure takes approximately 10 to 15 minutes per ear.
What is the post-operative care?
Mr Trinidade usually asks patients to keep the ears dry for 2 weeks, which means no swimming and using cotton wool smeared in Vaseline into the bowl of each ear during showering. After two weeks, swimming and normal showering or bathing can resume without the need for ear protection.
The first clinic follow-up is at about 6 weeks following the surgery at which point a hearing test is obtained to confirm an improvement in hearing. Once there are no concerns, the next follow up is in 9 to 12 months.
Do grommets have to be removed later on?
In most cases, the ear drum pushes the grommet out after a period of about 9 to 12 months and the the hole that was created in the ear drum to insert it heals closed. Sometimes, the ear drum does not push the tubes out and they need to be manually removed to allow the ear drum to heal. This is done if the grommets stay in for 2 or more years. This is why patients are followed up in 9 to 12 months following insertion – to ensure that the grommets have come out and the ear drum has healed.
How will I know when it comes out?
Most people are not aware when the grommet has come out as it is very small and often becomes covered in the ear's normal wax. You will usually be told whether it has come out or not at your follow up in the ENT clinic.
Once the grommets come out, will further grommets be required?
In 75% of cases, no further grommets will be required as there will be no further collection of glue once the ear drum has healed as the Eustachian tube would have had a year to mature while the first set of grommets were in and may have started to function normally. Some patients do recollect glue, however, and become symptomatic again after the grommets are pushed out. In these cases, a second pair of grommets may be needed.
What are the risks?
Grommet insertion is a commonly performed and safe procedure with minimal risks. In 2% of cases, the ear drum does not heal after the grommets have been pushed out, resulting in a permanent hole (perforation) in the ear drum. This may require a tympanoplasty (which is a repair of the ear drum) later on.
Grommets can sometimes get infected and cause ear drainage. Such an infection is readily treated with antibiotic ear drops such as Sofradex or Ciproxin (oral antibiotics generally do not work for grommet infections). In some cases, even antibiotic drops do not clear up a grommet infection. In these cases, the grommet may need to be removed and a new one inserted (if still indicated) once the infection has fully settled.
Grommet insertion can sometimes result in scarring of the ear drum (called tympanosclerosis) in about 5% of cases. This usually does not cause problems but can sometimes affect hearing long term by causing stiffening of the ear drum or ossicles (hearing bones).
Are there other types of ventilation tubes besides grommets?
Yes, T-tubes are a differently shaped type of ventilation tube that are designed to stay in long term (several years). T-tubes are inserted in a similar way to grommets. They are used when a long term ventilation tube is desirable, such as in people who have chronic Eustachian tube dysfunction causing stubborn glue ear or a collapsed ear drum (retraction pocket) and have required several grommets in the past. A T-tube prevents the need to have new grommets inserted every year. Because T-tubes stay in for a much longer time, they have a higher risk of a permanent ear drum perforation (about 16%).
Rosenfeld RM. A APrent's Guide to Ear Tubes. Hamilton: BC Decker Inc 2005
Two grommets are shown on the left. On the right, a grommet has been placed across the ear drum allowing ventilation into the middle ear (green arrows). The grommet has taken over the function of the dysfunctional Eustachian tube than connects the middle ear to the nose (red X)
Ear drum after grommet insertion
Ear drum before grommet insertion
An ear drum with a grommet inserted. Chalky plaques of tympanosclerosis (scarring) can be seen, a result of previous grommets.
A perforation (hole) resulting from previous grommet insertion. Most will heal but 2% do not and may require surgical repair (tympamnoplasty)
A T-tube has been inserted into this ear drum
Are antibiotic ear drops safe to use in an ear with a grommet or T-tube?
Yes. Many non-ENT doctors do not feel comfortable about prescribing ear drops into an ear with a ventilation tube inserted into it because of a theoretical risk of certain types of drops leaching through it into the middle ear and causing irreversible deafness. Such drops (such as Sofradex and Gentamicin) contain antibiotics that belong to the aminoglycoside family, which do have a risk of hearing loss when administered intravenously, but the risk is very small in drop form. The ENT-UK group, which provides guidance for ENT surgeons, has published guidelines that state that drops containing aminoglycosides can be safely used in ears with perforations for up to two weeks without issue. For this reason most ENT surgeons will routinely prescribe these drops for an infection of a ventilation tube. A baseline hearing test is recommended before drops are started where possible.
There are other drops that do not contain aminoglycosides, such as Ciproxin and Ofloxacin, which contain antibiotics that belong to the quinolone family. These can be used as a safer alternative to the aminoglycoside-containing drops.