Perforations: An audiologist's perspective

An audiologist’s perspective on perforations

On initial identification of a perforation, an audiologist would refer to an ENT specialist. Where there has been a longstanding history of perforation already seen and managed by ENT, or where the patient is being referred for audiological care by an ENT specialist. Then further referral might not be warranted, but interdisciplinary collaboration is required – with ENT and Audiology working together.

Perforations of the eardrum can occur for various reasons and present in different sizes and orientations

Perforations can happen to children, young people or the elderly. Some perforations can be transient (where they heal quickly), some recurrent (heal then rupture) or longstanding (have never healed). Some perforations frequently weep or secrete a discharge, while some stay completely dry. For some patients, their perforation causes great discomfort, and some patients don't feel anything!

What causes perforations?

Infections of the middle ear: In cases of glue ear, buildup of too much fluid in the middle ear, right against the eardrum as a result of eustachian tube dysfunction, can lead to a rupture of the eardrum.

Physical Trauma: A foreign object inserted too far down the ear canal and into the eardrum e.g. cotton buds, keys, hairpins, etc, or head injury resulting in fractured bone puncturing the eardrum or injury directly to the eardrum as a result of an external force directly in the region of the eardrum.

Barotrauma: rapid change in pressure with poor equalisation by the eustachian tube can lead to a perforation. As the pressure behind the eardrum is outside normal ranges, the eardrum can be stretched taut and ruptured as a result.

How an audiologist identifies a perforation.

Identifying a perforation during an audiological assessment can be done in several ways.

Otoscopy:

 During otoscopic examination, examination of the external auditory canal and the tympanic membrane through a magnifying glass with a bright torchlight shone into the ear canal against the eardrum can reveal a perforation.

Middle Ear Pressure /Tympanometry:

A probe inserted into the ear canal alters the pressure within the ear canal up to the eardrum. The result might be a flat tympanogram, as the perforation is significantly large enough to result in no movement of the tympanic membrane. The measured ear canal volume would be larger than expected as the exposed middle ear (as a result of the perforation) and external ear canal volume are all measured.

Audiometry:

Hearing thresholds might be altered.  There is typically a difference between air conduction thresholds and bone conduction thresholds i.e an air bone gap. Hearing would typically be described by the patient as muffled or "woolly."

Otoacoustic emissions:

Would typically be unobtainable as this relies on sound being reflected back to the probe microphone to be measure.

Audiological hearing loss management considerations with a perforation – hearing rehabilitation (hearing aids).

Since hearing thresholds are typically worsened with a perforation, an audiologist can help manage the hearing loss with carefully programmed hearing aids.

The coupling of the hearing aids to the ear needs to be considered. A small dome might not be ideal with a large central perforation; use of moulds with loose wax filters can pose a risk – if the wax filters fall out of the mould and go into the middle ear.

Receiver-in-the-canal hearing aids may work intermittently for those with discharging or wet perforations as liquid would often interrupt the electrical workings of the receiver, so these would not be ideal. 

Behind the ear hearing aids and waterproof hearing aids might work better for those with discharging or wet perforations.

If the perforation is small, pinhole and dry, most hearing aids can be considered as applicable to the type of hearing loss.

If you have a perforation and wish to find out what can be done for your hearing loss as a result of the perforation. Contact us on 01634 479 550.