Hearing loss in children may be due to a broad range of pathology. Early detection and management are essential for proper language and psychosocial development of children. Clinicians need to be able to to identify potential reversible causes and rule out more sinister conditions.
There are three main types of hearing loss: sensorineural, conductive and mixed. The former, sensorineural, although generally uncommon in children, is the main cause of permanent hearing loss in the paediatric setting. It results from a disturbance of the auditory pathway involving the cochlea of the inner ear, through to the brainstem. Conductive hearing loss typically occurs due to a disruption in the transmission of sound at the level of the external or middle ear. The most common cause of conductive hearing loss in children is otitis media with effusion, otherwise known as glue ear.
This article provides a clinical approach to assessing a child with hearing difficulty using Weber’s and Rinne’s tests and a guide to interpreting the examination findings.
But first, Sarah’s Story….
Sarah is a 9-year-old girl who has just begun Grade 4. She is very excited to be back at school after many months of limited contact with friends amid the pandemic. Over the summer, her mum, Michelle, notices that Sarah has become more ‘absent’ and doesn’t seem to be hearing anything she tells her. This is concerning and out of the norm for Sarah who is usually very witty and quick to respond. Mum has noticed that the volume of the TV is higher and many times she has ignored the doorbell ringing (according to mum it’s impossible to miss the doorbell!). The situation prompts mum to act following her attendance of the Parent-Teacher’s meeting where complaints are made about Sarah’s inattentiveness in class, consequently leading to her grades dropping.
Sarah has undergone numerous treatments for ear infections in the past with oral antibiotics and topical treatments as well. Michelle is worried and brings Sarah to the GP the following day. Otoscopy shows a very narrow external auditory canal, dermatitis and a milky discolouration of the external ear. The GP is concerned and feels that he has exhausted every treatment option and decides to refer for review in the Emergency Department. Sarah is generally well and has no other past medical or drug history. There is no known family history of deafness and Sarah does not swim.
The history and physical exam
The presentation of hearing loss differs depending on the age of the child. Auditory anomalies, in newborns, are exclusively picked up via universal screening programmes. In older children, the presentation is usually similar to Sarah’s story. They may have behavioural changes, delayed language skills or listen to the TV at a louder volume than everyone else. These are often picked up by their teachers. It is important to ascertain whether there are other associated otological symptoms including otalgia, otorrhoea, vertigo or tinnitus. A thorough history should be obtained. This includes asking about other neurological symptoms, background medical history (including a thorough medication history), and possible precipitating events such as recent viral infection, trauma, or commencement of a new medication.
The tuning fork tests
Weber and Rinne tests are reliable and useful tools for assessing hearing loss in older, verbal children. They help distinguish between conductive and sensorineural hearing loss and so are more useful in patients with unilateral hearing difficulty. Children with mixed, or bilateral hearing loss, should be referred to an ENT specialist for a more formal pure tone audiometry assessment. It doesn’t matter which test you perform first. These tests should, however, be performed with a full cranial nerve and neurological exam.
How do I do Rinne’s test?
Before you begin the exam, it is important to explain to the child what you are about to do to in way they can understand. Try to put them at ease and make sure they are sitting comfortably, ideally in a silent room. Ask about pain especially over the mastoid.
Rinne’s test aims to compare air conduction with bone conduction. In a normal situation, air conduction is greater than bone conduction.
- Begin by striking a 512 Hz tuning fork against your knee or elbow.
- Place the base against the patient’s mastoid process (for those who like to watch it on a video, check one out here)
- Allow it to stay there for 2-3 seconds to allow them to appreciate the intensity of the sound then promptly raise the fork off the mastoid process and place the vibrating tips about 1cm from their external auditory meatus
- Leave it there for a few seconds before taking the tuning fork away from their ear
- Ask the child whether the sound was louder at the beginning (when it was held against their mastoid) or whether it became louder (when it was held in front of their ear).
How do I interpret Rinne’s test?
In a normal ear, air conduction is greater than bone conduction, that is to say sound is more efficiently transmitted to the cochlea via air than via bone. So, a patient who hears the tuning fork loudest when it is placed 1cm from the external auditory meatus has a positive Rinne’s test and a person who hears loudest when placed over the mastoid process has a negative Rinne’s test. The challenge in making these interpretations is in the case of a false positive Rinne’s test where there is unilateral sensorineural hearing loss. This is where Weber’s test is most useful in providing further clues.
How do I do Weber’s test?
- As in Rinne’s test, begin by striking the 512 Hz tuning fork against your knee or elbow
- Then, place the base of the fork in the midline, high on the patient’s forehead
- Ask whether they hear the sound in the midline or if the sound lateralises to either the affected or good ear.
- If the child is unclear, then ask if they hear the sound everywhere – be careful not to ask in a leading manner.
How do I interpret Weber’s?
If a patient has a unilateral sensorineural hearing loss, the sound will lateralise – move to the good ear. If a patient has unilateral conductive hearing loss, the tuning fork sound would be heard loudest in the affected ear. Where hearing loss is bilateral and symmetrical of either type, Weber’s test would be normal.
The table below summarises the outcomes of Rinne’s and Weber tests
- Acute otitis media
- Foreign body
- Congenital stenosis
- Impacted cerumen
- Keratosis obturans
- Middle ear tumour
- Otitis externa
Sarah presents to the Emergency Department and mum narrates the story to the attending doctor. Her right ear appears to be the troubling ear and she is experiencing mild pain on that side. The doctor proceeds to perform a focused ENT exam. He begins with otoscopy and notes that there is unilateral, right sided narrowing of the external auditory canal secondary to oedema and notices that the overlying skin is milk coloured, resembling candida infection. Her left ear is impacted with cerumen but otherwise looks normal. Using a 512 Hz tuning fork, he performs Weber and Rinne’s tests.
Rinne’s test demonstrated unilateral right sided negative result i.e. bone conduction is greater than air conduction in the right ear. There is lateralisation of the tuning fork sound to the left ear on Weber’s: Sarah has reduced hearing in her right ear due to conductive hearing loss likely secondary to fungal otitis externa.
The rest of her ENT exam is normal, and she is neurologically intact. The doctor explains to mum that Sarah most likely has a fungal infection of her outer ear and will require a trial of anti-fungal ear drop for 2 weeks. He also prescribes a short course of topical steroid ear drops to reduce the swelling and recommends oil drops for the impacted left ear, telling Michelle to return to her GP if Sarah has further issues with her hearing in the future. He reassures mum that a formal auditory test is not required at this time until the treatment is completed.
Dimitrov L, Gossman WG. Pediatric Hearing Loss. [Updated 2020 Nov 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538285/