Anatomy / Physiology
The middle ear is a cavity in the skull that houses the small conductive bones of the ear. Sound passes from the external ear canal through the middle ear and then into the inner ear from which neurological stimuli are transmitted to the brain which is where we sense hearing. The middle ear is the area deep to the ear drum as we look at it. It is in connection with a group of air cells called the mastoid air cells that are housed in the mastoid bone behind the ear and is also in connection with the Eustachian tube that connects the middle ear to the back of the nose (nasopharynx).
Typically in childhood in association with upper respiratory tract infections, ear infections and immature Eustachian tubes a phenomenon called glue ear forms behind the eardrum. This is simply fluid that accumulates here but clearly can have a significant impact on the child’s hearing.
Glue ear is visible on otoscopy and typically is seen as a dull or amber coloured ear drum because of the fluid behind it. It can be tested for using an audiogram (hearing test) and tympanometry (pressure traces of the middle ear).
Glue ear (amber fluid behind the eardrum)
Glue Ear and Grommets
Glue ear when first seen should undergo a period of ‘watchful waiting’ for 3 months as a large percentage of them will spontaneously resolve. If however, after this period there is still the presence of glue ear and that the child is still troubled with their hearing affecting schooling, speech development or behaviour then consideration for grommets should be undertaken.
Although in adults local anaesthetic grommet insertion may be considered, for children a general anaesthetic is required. Grommets are usually placed in the safe part of the drum in the anterior inferior segment. A small incision (myringotomy) is undertaken, fluid is sucked out and then the grommet which often is a plastic ventilation tube is snuggly placed in the tympanic membrane. Not infrequently an adenoidectomy undertaken to treat the glue ear problem too
The ears should be kept dry for as long as the ENT surgeon has suggested and the child is often followed up to see that the hearing has improved.
Grommets are occasionally placed for other indications. The following list summarises why grommets are used
- Glue ear
- Recurrent acute otitis media (middle ear infections)
- As part of treatment for large retraction pockets
- Eustachian tube problems