Childhood hearing loss: avoidable, preventable and treatable

HEARING loss affects over 350 million people worldwide, with over 30 million being children. The World Health Organisation (WHO) has issued a paper in line with the principles of the Convention on the Rights of People with Disabilities focusing on "improving hearing and access to communication to facilitate education and employment and fostering social inclusion and psychological well-being in people with hearing loss".

A three-pronged approach comprising Prevention, Identification and Intervention has been established.

Paediatric hearing loss affects children globally with 60 per cent of cases being preventable.

A greater number of children affected are from low-resource settings (low and middle-income groups).

This article details several cases of children with hearing loss, and aims to highlight the importance of early diagnosis and treatment that is appropriate for the stage of life, degree of hearing loss and economic factors that impact families with these children.

Case 1

History: A four-year-old girl presented with repeated right ear discharge and hearing loss. She is known to snore and mouth breathes, and has a family history of asthma. She has been seen by her primary care practitioner thrice in the last year with similar complaints and treated with oral antibiotics and eardrops. Her teachers have mentioned that she is easily distracted and can be disruptive.

Diagnosis and management: Glue ear (Otitis Media with Effusion with possible perforation of the ear drum). Cases of ear discharge and hearing loss in pre-school children are very common. The vast majority of children in this age group have or will have issues pertaining to their middle ear simply due to the incomplete development of their mid-face and structures associated with it.

The tube that connects the back of the nose to the middle ear (Eustachian or pharyngotympanic tube) is shorter, more horizontal and less sturdy in a young child. Lymphoid tissue similar to the tonsils at the back of the throat known as the adenoids also swell up (contributing to nasal blockage and resulting in snoring) with infections of the upper respiratory tract and increase the infective load and/or physically block the opening.

Most often, this condition if left alone for a few months or treated symptomatically resolves as the child develops. In instances where the condition recurs regularly and is affecting the speech and development of the child, a specialist opinion for surgical treatment of the adenoids (adenoidectomy) and glue ear, or for hearing aids, may be necessary. Insertion of small tubes - some of which are akin to a yo-yo/ dumb bell (called grommets) are inserted using a microscope by an ENT specialist to help equalise pressure across the ear drum and improve hearing and speech and in so doing, concentration and possibly other behavioural issues.

Case 2

History: A 35-year-old mother of two children is pregnant with her third child. She develops a rash and is unwell for a week during her first trimester of pregnancy. Her son is born slightly before term and is found to have hearing loss on the newborn hearing screen. She notices that he doesn't respond at all to sounds.

Diagnosis and management: Congenital rubella infection. One in every 1,000 children is born deaf. Infective causes of deafness are the most common causes of preventable deafness despite immunisation programs worldwide.

Rubella is a highly contagious viral infection which can be transmitted from mother to fetus. Other congenital infections such as measles, mumps, cytomegalovirus (CMV), toxoplasmosis and herpes can cause profound deafness. There have been spikes in measles cases in Singapore and worldwide with deaths from the disease mainly due to lack of vaccination for a variety of reasons.

Congenital rubella syndrome is often picked up when the child has had its newborn hearing screening and later if is about a year old and does not display the normal reactions to sounds. Infected children should be managed in a multi-disciplinary setting with specialist eye, heart and ENT care. Cataracts, congenital heart defects and sensorineural hearing loss are among the more common conditions associated with in utero transmission to the child. Prompt specialist audiological and ENT input with the need to provide hearing aids or other devices (cochlear implants - Figure 1) may be advised.

Case 3

History: After a protracted bout of the 'flu, Millie, who was only eight years old, developed viral meningitis. She was admitted to the intensive care unit and made a slow recovery. Her hearing in both ears was badly affected. She could barely hear loud noises and only felt them as vibrations.

Diagnosis and management: Profound sensorineural hearing loss secondary to viral meningitis. She was referred to the ENT and audiology department for specialist input. A trial of hearing aids failed and she was offered cochlear implantation. Given the urgency in performing the procedure before calcification of the cochlea (similar to hardening) occurred, an operation was performed within a few weeks to help restore her hearing.

Cochlear implants have revolutionised hearing rehabilitation in both the young and old. Indications vary accordingly but age at implantation, at either extreme, is becoming less rigid. Results in children who are born congenitally deaf are very good in most cases when implantation is performed before the child has started to verbalise (becomes lingual). In certain instances (cultural or due to financial constraints), sign language is the preferred modality of communicating. The Deaf community has its own well-established practices for signing and there are schools, libraries and other social institutions for the Deaf to engage in (i.e. Deaf Culture).

Case 4

History: John was born with multiple defects affecting the development of his eyes, ears, facial bones and teeth. His ears were badly misshapen and very small. He could barely hear and testing his hearing was difficult.

Diagnosis and management: Treacher Collins Syndrome. This syndrome is a genetic disorder which affects approximately 1 in 50,000 people. Children born with this condition require hearing rehabilitation and surgery depending on the severity of the condition. In general, the external and middle ear are affected.

This means that the shape and size of the outer ear, ear canal and the three small bones (malleus, incus and stapes aka hammer, anvil and stirrup) of the ear are abnormal.

Reconstruction of the external ear can be done in stages using the patient's own rib cartilage and shaping it into an external ear. Another option is the use of a prosthetic ear which can be designed bespoke and can be inserted using titanium screws attached to the side of the head (Figure 2).

Hearing aids that attach to the side of the head onto the skull are also very helpful (Figure 3, Bone-Anchored Hearing Aids, BAHA). They transmit sound waves by vibrating the skull and thereafter transmitting the energy to the inner ear.

Summary

Paediatric hearing loss manifests in many ways. It can be mild, moderate, severe or profound. The causes vary and treatment options depend on the degree of hearing loss, the age at presentation, what structural defects are present, the resources available to the patient and potential for rehabilitation. Modern surgical techniques such as cochlear implantation have transformed hearing restoration.

Better hearing aids with the capacity to filter sound, and be programmed to suit the needs of the individual and provide other modern conveniences (e.g. Bluetooth) are available too. Early prevention, identification and intervention are essential in making inroads in the treatment and rehabilitation of children with this disability.

This series is produced in collaboration with Singapore Medical Specialists Centre.