CLINICAL PAEDIATRICS:

PRINCIPLES

&

PRACTICE

Volume Two

DR. E.L. LEE, DR. Y.S.CHOY

Copyright © 2023 Dr. E.L. Lee, Dr. Y.S.Choy. All rights reserved.

All rights reserved. No part of this book may be used or reproduced by any means, graphic, electronic, or mechanical, including photocopying, recording, taping or by any information storage retrieval system without the written permission of the publisher except in the case of brief quotations embodied in critical articles and reviews.

www.partridgepublishing.com/singapore

Because of the dynamic nature of the Internet, any web addresses or links contained in this book may have changed since publication and may no longer be valid. The views expressed in this work are solely those of the author and do not necessarily reflect the views of the publisher, and the publisher hereby disclaims any responsibility for them.

ISBN

ISBN: 978-1-5437-7228-9 (sc)

ISBN: 978-1-5437-7230-2 (hc)

ISBN: 978-1-5437-7229-6 (e)

08/14/2024

PREFACE

It has been 25 years since the second edition of ‘Paediatric Problems in Tropical Countries’ was last published. During this time, we have witnessed the sad demise of Professor Maxwell Robinson, the chief editor of the first and second edition. Max, as he preferred to be called, spent three short years as head of the Department of Paediatrics at the University Hospital in Kuala Lumpur. This was then the first medical faculty of the newly independent nation. During his tenure, he was involved in the training of a core of paediatricians in Malaysia. He was much loved and stimulated research activities in tropical diseases in children. After his departure, he made many return trips to Malaysia for lecture assignments, conducting examinations for post-graduates as well as renewing links with old friends. We shall miss his warm hearted presence. His invaluable contributions to previous editions of this book are included in the present text. We would like to dedicate this edition to his fond memory. Since my recent retirement, after much prompting from young medical students, colleagues and parents of children under my care, I decided to pick up the challenge once more to revise a third edition of the book. I have invited Dr. Y.S. Choy, a talented doctor with special training in human genetics and metabolic diseases, to co-edit and rewrite this third edition.

Paediatric knowledge and practice, in tandem with living standards in Asian countries have advanced tremendously during this interval. We have decided to adopt a new title for this edition: CLINICAL PAEDIATRICS: PRINCIPLES AND PRACTICE. This text is designed to provide medical students and trainee paediatricians with information that will enable them to understand the scope of medical problems that children face, and how to deal effectively when confronted with these problems. The needs of children still demand a core of doctors, paediatricians, nurses and ancillary personnel to keep children healthy. Mass migration and travel between countries have resulted in importation of diseases once considered rare in Asia, such as chikungunya, cystic fibrosis, and sickle cell anaemia. Advances in neonatal care, cardiovascular surgery, cancer therapy, bone marrow and organ transplants are now widely available in the developing world. This has placed new demands on practitioners of child care.

The authors/editors have carefully reviewed the previous edition with the goal of providing a fresh perspective to the text. Progress in the understanding of, and new insights into the pathophysiology of many disorders, demand a change in concept and reclassification of many diseases. The objective of the authors/editors is to provide the young trainee with a comprehensive text. This will enable the student to understand the pathogenesis of various disorders, recognize the clinical features and make use of appropriate diagnostic tests to confirm the clinical suspicion. The sources for current paediatric knowledge and practice are from published medical journals as well as from personal paediatric practice. The principles of treatment are provided in the text; the details and variations in treatment are learnt from senior doctors during the residency years. The goal is to provide knowledge of the extent of treatment that is currently available. The practicing doctor will have to decide if he/she is competent to provide care and treatment, or to refer the patient to an experienced doctor to provide specialized care for the child with a particular illness. Resources vary in both developed and developing countries. The child’s interest is always the priority.

With almost fifty years fulfilling medical practice (Dr. Lee) behind me, l would like to quote from the much-admired Dr. William Osler, a father of modern medicine who reminded us that the practice of medicine is a calling, not a trade. His obsession with knowledge was equally matched by his humane and compassionate bedside manner. He acknowledged that, like every doctor, he was not immune to making mistakes. These can be very painful experiences for both the doctor and patient. Learning from mistakes, improving and not duplicating them is what counts. To quote his famous dictum He who studies medicine without books, sails an uncharted sea; but he who studies medicine without patients, does not go to sea at all. Know your medicine and close the professional gap between the patient and yourself. Your life in medicine will be amply rewarded.

Finally, we would like to acknowledge our sincere appreciation to our spouses and family members, who have endured our intrusion into family time to complete this project. In particular, my daughter Li-Wei and Chern-Hsiang Choy, helped with preparation and typing of manuscripts. With perpetual patience Li-Wei endured my illiteracy with the computer and on many occasions had to rescue manuscripts that were lost in the ‘cloud’.

The author’s proceeds from sale of this edition will be donated to established voluntary societies for children with special needs.

E.L.Lee / Y.S.Choy

ACKNOWLEDGEMENT

The authors are very grateful to the contributors of the second edition of Pediatric Problems in Tropical Countries which form the nucleus from which the present textbook Clinical Paediatrics- Principles and Practice is built upon:

CONTENTS

Chapter 27 Disorders of Eye, Ear, Nose and Throat

Chapter 28 The Child Who Wheezes

Chapter 29 Bronchopneumonia in Children

Chapter 30 Fluid and Electrolyte Homeostasis: Theoretical and Practical Consideration

Chapter 31 Major Gastrointestinal Symptoms in Infancy and Childhood

Chapter 32 Infective Enteritis, Malabsorption Disorders

Chapter 33 The Acute Abdomen in Childhood

Chapter 34 Major Hepatic Disorders in Children

Chapter 35 Inborn Errors of Metabolism

Chapter 36 Renal Disorders in children

Chapter 37 The Pale Child

Chapter 38 Thalassaemia/Haemoglobinopathy

Chapter 39 Abnormal Bleeding in Childhood

Chapter 40 Major Malignancies in Childhood

Chapter 41 Heart Disease in Infancy and Childhood

Chapter 42 Common Congenital Heart Disease (CHD)

Chapter 43 Miscellaneous Disorders of the Cardiovascular System

Chapter 44 Developmental and Neurodegenerative Disorders of the Central Nervous System

Chapter 45 Cerebral Palsy, Hydrocephalus, Macrocephaly

Chapter 46 Seizure Disorders in children

Chapter 47 Infections, Inflammatory, Toxic & Vascular Disorders of the Central Nervous System

Chapter 48 The Weak and Hypotonic Child

Chapter 49 Common Behavioural and Psychiatric Disorders in Children

Chapter 50 Common Skin Disorders in Children

Chapter 51 Disorders of Bone, Joint and Connective Tissue

Chapter 52 Paediatric Emergencies

Chapter 53 Drug Usage in Special Situations

CHAPTER 27

Disorders of Eye, Ear, Nose and Throat

Common Eye Disorders

Development of Vision

A baby’s vision is an important source of information about his external environment and contributes significantly to his overall development. A full term baby has fairly well developed eyes. Even at birth, he can see and will demonstrate visual interest at the parent’s face. Visual fixation is present by 2 months of age, when the infant starts to visually follow moving objects. Accommodation is well developed by 4 months. This enables the infants to consciously locate and reach out for a familiar toy. By 6 months, he can study a toy held in his hands and later enjoys transferring it from hand to hand. This phenomenon signals the mature development of fusional convergence. At this age the baby begins to appreciate shapes and depth but only reaches the adult level of stereo-acuity by age 7 years. At one year the diameter of the eye ball measures about 75% of adult level, so that his distant visual acuity is about 6/36. By 2 to 3 years his acuity has improved to about 6/18 to 6/12. The Snellen letter acuity reaches the adult level, i.e. 6/6 or 20/20 by about 6–7 years.

There are various methods of assessment of visual acuity. For children below 3 years of age, careful and patient observation of the baby often is useful. The Catford drum which has alternating black and white stripes can be used to estimate visual acuity. By 3 to 5 years of age, various card tests with symbols, E chart and matching alphabet tests are available. The Standard Snellen visual acuity chart can be used from about 6 years of age onwards.

Amblyopia

This denotes a lazy eye and results from any major disturbance preventing normal visual development in the early years. Commonly, amblyopia is unilateral and may be due to squint, anisometropia (unequal refractive error), congenital ptosis, congenital unilateral cataract, or even prolonged patching of one eye. Bilateral amblyopia may be due to bilateral congenital cataracts or bilateral high refractive errors. It is important to detect amblyopia early because in most cases it is reversible with treatment. Most studies suggest that beyond 5 to 6 years of age, it is difficult to reverse amblyopia. Poor vision and amblyopia are suspected if one or both eyes are unable to fixate and follow a moving object. A flash light shone on one eye with the other occluded, and then on both eyes, is one simple method to screen for amblyopia. The corneal light reflex should remain centrally placed, as the eye follows the moving light source. Wandering fixation attempts or lack of visual interest usually indicates poor visual acuity. A child who objects to occlusion of the fixating eye but not of the other eye may have poor vision in the latter eye. The child needs further evaluation to determine visual acuity, refraction and precise examination of the fundi.

Squint or Strabismus

This implies a misalignment of the eyes. It occurs when binocular visual fusion fails. Squinting eyes do not focus in the same direction. The non-squinting eye remains fixated on an item of visual interest, whereas the squinting eye deviates from it. One eye may squint persistently and is referred to as constant unilateral squint. If the visual acuity and ocular movements of both eyes are of equal range, the fixating eye may switch from one eye to the other. This is known as alternating squint.

Anomalous alignment of the eye that is persistent at all times is known as manifest squint. Minor degrees of ocular misalignment can be masked. The brain attempts to fuse the visual images by altering the tension of the eye muscles so that the eyes look straight, when the child is focusing at an object. However, squinting occurs when the eye is tired or when visual interest is relaxed. This is known as intermittent squint or latent squint. It is uncovered when binocular single vision is interrupted such as when one eye is occluded.

Concomitant and inconcomitant squints. Most childhood squints are concomitant, i.e. the squint is present in all positions of gaze. Concomitant squint is mostly a result of innate anomalies in binocular vision or of refractive errors. Occasionally it may arise from visual impairment in one eye such as cataract, vitreous opacity, or retinal disorders. Inconcomitant squints or paralytic squint is only present in certain positions of gaze. There is restriction in ocular movements in one or both eyes, caused by nerve palsy or other disorders of the central nervous system.

Diagnosis

Detection of squint is important in paediatric examination:

Inspection. A careful look will suggest any misalignment. A convergent squint or esotropia means that one eye is turned in (Figure 27.1). A divergent squint or exotropia means that one eye is turned out. A vertical squint occurs when one eye turns up or down; this is uncommon. A pseudosquint gives an impression of a squint, usually convergent, due to epicanthic folds and or a wide bridge of the nose, a condition not uncommon in Oriental races.

Figure 27.1 Convergent squint of the right eye

Corneal reflection. A torch light held at a near distance to view the light reflections is a simple method of squint detection. If the reflection emerges from the centre of both pupils, the eyes are straight. A reflection in one eye which is inner or outer, relative to the central reflection in the fixating eye, suggests a convergent or divergent squint respectively.

Cover test. This is a simple and better method of detecting all forms of squint. The child is encouraged to look at an object (at reading distance), and while fixing the gaze on the object, the doctor’s hand is quickly placed in front of the fixating eye. If the other eye moves to take up fixation, then this confirms a squint. If the uncovered eye moves out to take fixation, a convergent squint is present; if the uncovered eye moves in, then a divergent squint is diagnosed. If the other eye remains fixed at the object and does not move, then there is no squint. This test is repeated with an object at a far distance.

Management

A suspicion or diagnosis of squint requires prompt referral to an ophthalmologist for full evaluation. The objectives of management are to ensure good vision in both eyes, proper alignment of the eyes, and attainment of binocular single vision. Refractive errors are corrected, with glasses, if necessary. To impose visual training in an amblyopic eye, the better eye is occluded for varying periods. Once visual acuity has improved, surgery is performed to correct the residual misalignment. In early onset squints, surgical correction before 2 years of age is advisable, in the hope of attaining functional binocular vision after the surgical procedure.

Refractive Errors

This is an important cause of blurred vision in children especially of pre-school and school-going ages. These children may be screened for poor vision with simple test types such as E charts, letter matching, and picture charts. Children with visual acuities less than 6/12 or 20/40 should be referred for further eye evaluation including refraction. It is important to detect and correct significant refractive errors early in children before irreversible amblyopia develops.

Hypermetropia or long sightedness is relatively common in children. Unless severe, visual acuity is usually not affected in hypermetropia. This is because the child compensates by accommodating strongly to focus images clearly on the retina. High degrees of hypermetropia predisposes to accommodative convergent squint.

Myopia or short-sightedness is common in school-going children, particularly in East Asian countries and is caused by a combination of genetic and environmental factors, such as prolonged periods of near work, associated with reading, studying and computer usage. It is frequently recognised by 6-7 years of age, through screening programmes. Common features are squinting while viewing television or reading, accompanied by frequent blinking, tearing and rubbing of eyes. If uncorrected, the affected child may be unable to see the blackboard clearly. It is commonly progressive initially, and tends to stabilise in the teenage years. The child should initially be evaluated by an ophthalmologist to exclude any serious causes of visual impairment. Appropriate corrective glasses are prescribed. Good eye care habits include:

•Read sitting up, with reading material at 30 cm from the eyes. Lighting should be sufficiently bright.

•Computer screen should be further than 50cm from the viewer, adjust for minimum glare.

•Rest your eyes every 30-40 minutes by viewing distant objects.

•Participate in more outdoor activities.

•Ensure yearly eye checks.

Astigmatism denotes unequal refraction or power between the vertical and horizontal meridian of the cornea resulting in blurred or distorted images. Minor degrees of astigmatism are common, does not affect vision, and are commonly associated refractory defects. Only moderate to high astigmatism needs to be corrected; by use of cylindrical lens that compensates for the abnormal curvature of the cornea.

Keratoconus is a rare progressive, bilateral corneal ectasia, characterised by paraxial stromal thinning and weakening, progressing to breaks in Bowman membrane. This eventually results in visual defects from irregular distortion of the cornea. The disorder usually affects males, with signs of visual impairment often starting at puberty.

Keratoconus has diverse causes such as protracted atopic dermatitis, vernal keratoconjunctivitis, retinitis pigmentosa and Leber congenital amaurosis. The corneal stromal disorder may also be part of a generalised congenital connective tissue disorder such as Ehlers-Danlos syndrome, Marfan syndrome or of Down syndrome.

Treatment is initially with glasses to improve visual acuity, followed by soft or rigid contact lenses, surgical removal of scar tissues, keratoplasty and ultimately corneal transplantation.

Ocular Manifestations of Intrauterine Infections

Certain maternal infections during pregnancy affect the eyes and other organs in the growing foetus. These include rubella, toxoplasmosis, syphilis, cytomegalovirus and human immunodeficiency virus. The ocular manifestations of these congenital infections are as follows:

Rubella

The most frequent effect on the eye is cataract, often unilateral, with slight microphthalmia in the affected eye. The fundus has a salt and pepper appearance, mixed fine dark and light pigmentation of the retinal epithelium. Vision usually remains satisfactory. This may later deteriorate when sub-retinal neovascularisation occurs.

Toxoplasmosis

The most frequent lesion associated with congenital toxoplasmosis is chorioretinitis (Fig. 27.2). It is usually bilateral and often affects the macular region, severely compromising vision. The characteristic lesion is a rounded, atrophic chorioretinal patch with greyish-black pigmentation at the edges.

Figure 27.2 Fundus showing typical toxoplasma chorioretinitis over macular area.

Syphilis

Congenital syphilis is typically associated with a diffuse chorioretinitis with fine dark and light spots. Chorioretinitis is usually accompanied by papillary atrophy with narrowing of retinal vessels. Interstitial keratitis is now rarely seen and presents in later childhood, often precipitated by mild trauma. It presents with intense pain, photophobia and circumcorneal infection, followed by superficial and deep vascularisation and opacification.

Human immunodeficiency virus

Congenital AIDS is rapidly becoming important as the number of AIDS infected mother increases. The most common ocular sign is soft exudates (cotton wool spots) in the retina. Ocular manifestations of toxoplasmosis and CMV may be present due to opportunistic infections in the inadequately treated child.

Cytomegalovirus

The lesions of CMV consists of multiple large areas of chorioretinitis with pigmentation at the edges, similar to those described in toxoplasmosis.

Common Neonatal Eye Infections

Ophthalmia Neonatorum

Infections of the conjunctival sac occurring within one month of birth are included under this term. The baby presents with a purulent or mucopurulent discharge, lid swelling and conjunctival congestion. The important organisms include Neisseria gonorrhoeae, Chlamydia trachomatis, Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae and Enterococcus. It is difficult clinically to differentiate between the various aetiological types of neonatal conjunctivitis. Laboratory tests such as culture, conjunctival swabs for Gram stain, Giemsa stain, and antigen detection are important to identify the actual organism; antibiotic sensitivity pattern is used to guide treatment.

These infections are mostly acquired from the mother. Thus, once the infective agent is identified, the mother and her sexual partner should also be treated.

Gonococcal conjunctivitis

This appears between two and four days after birth with rapidly progressive swelling of the eyelids, chemosis and abundant purulent secretions making examination of the eyeball difficult. It may cause severe corneal inflammation, ulceration or even perforation. Therefore, it is important to promptly diagnose this condition in any neonatal eye infection. Gram-negative intracellular diplococci in the conjunctival swab is highly suggestive. Bacterial culture will identify the organism.

Treatment should be commenced promptly with a third generation cephalosporin (e.g. ceftriaxone) administered parenterally, without waiting for culture report. Topical erythromycin ointment and frequent eye toilet are important adjuncts in therapy. The infant should also be screened for other sexually transmitted diseases such as syphilis and HIV, as should the parents. These infants are also at risk for pneumonia and septicaemia, and thus require frequent observations.

Chlamydial conjunctivitis

Infection with Chlamydia trachomatis is acquired during the passage down the birth canal. It usually presents between five and fourteen days after birth. It is associated with a red eye, scant mucoid discharge, swelling of eyelid and pseudo-membrane formation. If left untreated, visual loss may result from scarring of the eyelids and corneal pannus which may progress to corneal opacities.

Diagnosis is difficult but a Giemsa stain is useful in detecting the intracytoplasmic inclusion bodies in conjunctival scrapings. An in vitro antigen detection test (Chlamydial IgM), as well as PCR assay have been developed.

Treatment with oral erythromycin (50 mg/kg/day for 14 days) is necessary to prevent risk for pneumonia and sepsis. Local treatment consists of sulphacetamide 10% eye drops, tetracycline or erythromycin ointment applied 4 hourly or azithromycin eye drops twice a day. Parents should also be screened for sexually transmitted disease.

Viral conjunctivitis

This is most commonly caused by adenovirus and herpes simplex virus (HSV).

Neonatal HSV eye infection usually presents 6-14 days after birth, with swollen red watery eyes. Frequently, small vesicular eruptions may be seen on the borders of the eye lids and/or on the face. Keratitis is commonly associated and typically manifests as epithelial linear branching dendritic ulcers. Ocular herpes may be a component of a systemic herpetic infection.

Treatment is with systemic acyclovir for 14 days and topical acyclovir, iododeoxyuridine or vidarabine.

Prophylaxis

Prevention of ophthalmia neonatorum can effectively be carried out by instillation of tetracycline ointment, erythromycin ointment, or 1% silver nitrate eye drops at birth. Silver nitrate drops may cause a mild chemical irritation in the conjunctivae, as its concentration may gradually increase with evaporation after prolonged repeated exposure.

Routine antenatal screening of mother for venereal disease with treatment and follow up of those infected, as well as the sexual partner, is another important aspect of prophylaxis.

Eye Infections in older children

Acute conjunctivitis

Infection of the conjunctival sac is usually bilateral and manifests as redness, a watery or sticky eye discharge, and swelling of the lids. The causative organisms may be bacterial or viral. Exposure to chemical irritants or allergens may also present with similar features.

Allergic eye disorders are dealt with in chapter 20.

Bacterial conjunctivitis

This is commonly caused by Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae and Chlamydia. The infection is highly infectious and a history of recent exposure to other cases is common.

The presentation is initially with itch, eye discomfort and burning pain on exposure to light. The conjunctiva is red, with purulent greenish yellow discharge. The eyelids may be oedematous and may stick together, particularly on awakening. Pupils react normally and cornea is clear in uncomplicated infection. Severe eye pain, blurring of vision and photophobia are signs of serious complications. The infection may spread from one eye to the other, and is contagious to other persons, even 24-48 hours after starting antibiotic treatment.

Topical antibiotic drops such as erythromycin, gentamycin or neomycin during waking hours and ointment at night will eliminate most infections. For severe infections, culture is indicated.

Quinolones or vancomycin may be required. These children should be under the care of an ophthalmologist.

Trachoma

This is an eye infection, usually affecting both eyes, and is still a major cause of blindness in many developing countries. The disease is mainly found in arid subtropical regions of the world where poor hygiene and poverty coexists. WHO estimates it is responsible for blindness or visual impairment in 1.9 million people. The aetiological agent is a bacterium, Chlamydia trachomatis. Flies are frequent carriers.

The initial symptoms are itching, irritation of the eye and eye lids, and watery discharge. Protracted or recurrent cycles of infection generate a chronic inflammatory reaction characterised by a generalised follicular keratoconjunctivitis: germinal centres with dense collections of B-cells and T- cells. This eventually leads to cicatricial conjunctival scarring: manifest as ectropion, trichiasis and upturned eyelashes. Eye rubbing in response to itch and irritation, may in turn trigger recurrent episodes of corneal ulcerations, neovascularisation and further scarring; ultimately leading to blindness.

Treatment consists of topical sulphacetamide, tetracycline or erythromycin and improved hygiene, through facial cleanliness, to prevent reinfection. Single dose of azithromycin is being used for national trachoma control programme. Surgical reconstruction may be required for advanced cases.

WHO has launched a global alliance for elimination of trachoma.

Keratitis

This is a more serious infection of the eye than conjunctivitis. Bacterial corneal ulcer (Figure 27.3) is usually a result of trauma and neglected primary infection. Besides bacterial infections, the cornea may also be damaged by viruses (HSV, varicella-zoster), parasites (amoeba, Onchocerca), trauma and chemical injury.

Figure 27.3: Left corneal ulcer and hypopyon

Keratitis may affect the superficial or deep stroma of the lens. The eye is red, swollen and painful with severe tearing, blurred vision and photophobia. The cornea is hazy from oedema and scarring. Inflammatory white blood cells may collect in the anterior chamber (hyopopyon). Fluorescein staining and slit-lamp examination by an ophthalmologist to indicate the extent of damage is essential. In bacterial keratitis, topical, sub-conjunctival, and parenteral antibiotics are necessary to rapidly control the infection and minimise corneal scarring which can result in permanent visual defect. Steroid drops are sometimes prescribed to reduce inflammation and limit the scarring.

Viral conjunctivitis

This is commonly caused by adenovirus in children. It is highly contagious and infection spreads from contaminated tears or infected upper respiratory droplets. Other viruses implicated are: herpes simplex virus, chickenpox virus, enterovirus 70, coxsackie A24 and HIV virus.

Adenovirus conjunctivitis

The usual presentation is with diffusely pink conjunctiva, which may involve one or both eyes. Ocular itching, tearing, gritting sensation on rubbing and eyelids sticking together, particularly in the morning. The eyelids maybe swollen with punctate or large subconjunctival haemorrhages. Pain and photophobia are unusual features, and may indicate extension to involve the cornea, which may then be hazy due to subepithelial infiltrates. Occasionally, fever, sore throat, cough and preauricular adenopathy are associated findings.

The diagnosis may be confirmed by rapid bedside immunoassay. Typically the conjunctivitis takes 1 to 2 weeks to resolve.

Treatment. Cold compresses and topical lubricants are useful to relief discomfort. Antibiotic drops or ointment are sometimes prescribed to prevent bacterial superinfection.

Herpes simplex kerato-conjunctivitis

HSV is an uncommon but an important cause of unilateral red eye and can lead to visual loss. It begins as blepharoconjunctivitis that heals without scarring. Reactivation of the virus in subsequent cycles lead to superficial punctate keratitis with complaints of pain, photophobia, tearing and blurring of vision. This may evolve to deep branching dendritic corneal ulcerations, best visualised with fluorescence stain. The superficial corneal epithelium may slough off and inflammation may spread to the underlying stroma of the iris. Loss of corneal sensation follows with repeated recurrences. Eventually, an enhanced upregulation of immune response may lead to the destruction of the corneal stroma, leading to loss of vision. HSV keratoconjunctivitis is best managed by an ophthalmologist at an early stage as delayed or wrong treatment (viz. with steroid drops) may lead to severe complications and to visual loss.

Treatment is with topical antiviral drugs: acyclovir or ganciclovir ophthalmic ointment or trifluridine eye drops. In addition, oral acyclovir, ganciclovir and brivudine

have also been widely used and are preferred choices among many ophthalmologists.

Eyelid infections

A stye (hordeolum) is an infected eyelid gland usually with Staphylococcus aureus. This results in an inflamed, tender and eventually pus filled gland of Zeis, near the external edge of the eyelid or Meibomian gland near the internal edge. It does not cause visual impairment, but may cause some pain and discomfort. It is contagious and recurrent episodes are not uncommon. Spread to adjacent tissue may lead to secondary cellulitis.

Treatment consist of eyelid hygiene with frequent washes, warm compress and topical antibiotic ointment. A systemic antibiotic (e.g. Cephalexin, Augmentin) is prescribed in the presence of cellulitis. Removal of an eyelash from an external follicle or surgical drainage of an internal pus collection may expedite the healing. Parents are advised to continue face and eye hygiene and to abstain from touching the eyes with dirty hands and to avoid nose-picking to prevent recurrence.

A chalazion or Meibomian cyst is a cyst from a blocked Meibomian gland on the inner lid margin. Treatment initially is with antibiotic drops or ointment. If this does not resolve, incision and curettage of the cyst may be necessary. Cellulitis of the lids usually occurs as a result of lid trauma or an infected Meibomian cyst. Systemic antibiotics are indicated.

Periorbital and Orbital Cellulitis

This usually occurs as a complication of lid infections or sinusitis. S. aureus, H. influenzae and S. pyogenes are the usual causative organisms.

The child presents with fever and a red swollen eye. There is often a history of recent upper respiratory tract infection with extension into the nasal sinuses. Thereafter, the child becomes increasingly ill with headache, high fever and chills. If infection has not extended into the orbit, the vision is usually normal and there is no proptosis or limitation of ocular mobility. In orbital cellulitis, the eye is painful and becomes severely injected. This is followed by conjunctival swelling (chemosis), and proptosis with limitation of ocular movements. The potential complications are intracranial infection, cavernous sinus thrombosis and loss of vision.

Such a child should be hospitalised for urgent evaluation: Full blood counts and blood cultures, imaging studies, parenteral antibiotics (e.g. parenteral Ceftriaxone plus Flucloxacillin). An urgent ENT and eye assessment is important.

Periorbital cellulitis is an ocular emergency and imaging study provides useful objective assessment of the extent of the disease and assist in plan of management. Preseptal cellulitis involves periorbital tissue swelling anterior to the orbital septum and poses little risk to complications. It is usually due to spread of infection from adjacent tissue such as face, tooth and eyelids. Infection on the face is usually from an insect bite or injuries in the child. In contrast, orbital cellulitis or postseptal cellulitis, represents infection that began in the adjacent paranasal sinuses that has extended into the orbit. This results in proptosis, painful ophthalmoparesis which may lead to visual loss from abscess formation, endophthalmitis or or an orbital compartment syndrome. These patients should be closely monitored for visual impairment. Orbital subperiosteal abscess is often the result of adjacent ethmoid sinusitis (Figure 27.4). Follow-up checks for residual ocular damage and sinus disease is essential.

Figure 27.4: Orbital cellulitis with early orbital subperiosteal abscess (arrow) due to adjacent ethmoidal sinusitis.

Uveitis

This denotes inflammation of the middle layer of the eye, the uvea which is made up of the iris, ciliary body and choroid. Depending on the part of the uvea that is involved, it is termed iritis or anterior uveitis (iris and ciliary body), choroiditis or posterior uveitis, and pan-uveitis. The disease may be unilateral or bilateral. Children account for approximately 5-10% of newly diagnosed disease, and is a major cause of childhood blindness.

Anterior Uveitis

Iritis in children may be due to:

•Juvenile idiopathic arthritis and other HLA-B27 positive related arthropathies, sarcoidosis

•Systemic lupus erythematosus, Behchet disease, multiple sclerosis, Inflammatory bowel disease, nephritis and other autoimmune disorders

•Infectious diseases such as toxoplasmosis, toxocara, herpes simplex, infectious mononucleosis, Lyme disease, leprosy, tuberculosis and syphilis

•Kawasaki disease

•Trauma and intraocular foreign body

•Leukaemia and eye tumours

Clinical findings. Symptoms include pain, redness, photophobia, increased lacrimation and blurring of vision. Examination reveals circumciliary congestion (redness around the limbus) which can be seen with a torch. Cells, keratic precipitates, fibrinous exudates in the anterior chamber and adhesions of the pupil to the lens (synechiae). These findings can clearly be seen with the slit lamp or a magnifier. These children should all be managed under the joint care of an ophthalmologist and paediatrician.

Diagnosis should be made promptly as delay may cause serious complications such as glaucoma, cataract and band shaped keratopathy, all of which will result in permanent visual impairment.

Treatment of uveitis involves pupil dilatation with atropine drops, systemic as well as topical steroid drops, and long-term anti-inflammatory medication, such as methotrexate or cyclosporine to adequately suppress the inflammation.

Posterior Uveitis or Choroiditis

This may also involve the retina and vitreous in the inflammatory process. Infections with Toxoplasma and Toxocara are the most common causes. The disease is marginally more common than anterior uveitis, and can be a more devastating disorder.

Blurred vision and floating opacities in the visual field are often the only symptoms. Pain in the eye is unusual and suggests involvement of the anterior chamber or bacterial co-infection. Vision impairment depends on the sites of residual scarring.

Topical steroids are not effective. Systemic steroids, intravitreal steroid implant and immunomodulator therapy are indicated. Early control of inflammation has been associated with better visual outcome.

Vitamin A Deficiency

This is the commonest cause of blindness in children in some developing countries. Each year about half a million children become blind as a result of this disease. The highest incidence is recorded in Sudan, Ethiopia, Bangladesh and India. The commonest cause is malnutrition. Malabsorption disorders and liver disease are secondary causes.

Clinical Findings. Night blindness is a common symptom. Early eye signs are dryness of the conjunctiva, and presence of Bitot spots. These are localised, irregular, raised whitish or frothy patches on the conjunctiva, usually at the 3 and 9 o’clock position, due to accumulation of squamous keratinised cells adjacent to the cornea. Night blindness has been attributed to loss of globet cells in the conjunctiva resulting in poor production of mucus (xerophthalmia) and low production of rhodopsin, important for low-light vision. Advanced signs include dryness (loss of lustre or shine) of the cornea culminating in ulceration, softening and melting of the cornea (keratomalacia). There is surprisingly little inflammatory reaction in the eye.

Treatment includes prompt intramuscular injection of water-based vitamin, 100,000 IU, followed by 200,000 IU, orally. The ulcerated cornea should be lubricated and protected by antibiotic eye ointment and the eye is padded.

Prevention involves administration of vitamin A drops. The dose for infants is 100,000 IU of retinol palmitate orally, with repeat dose every 6 months. Double this dose for older children. Long term prevention is aimed at education, and eradication of poverty and malnutrition.

Common Congenital Disorders

Dacryostenosis

About 5% of newborns have a blocked tear duct in the eye due to incomplete or delayed canalisation of the terminal end of the nasolacrimal duct. Approximately 15% have punctal agenesis. The disorder is usually unilateral and presents with persistent tearing and occasionally, white mucoid discharge. Most times there is no associated infection. Topical antibiotics are useful for mucopurulent discharge. Frequently, the dacryostenosis improves spontaneously by 18 months of age; after which, probing and syringing to dilate the opening is attempted. Meanwhile, the parents need to be reassured and advised to massage the nasolacrimal sac area several times a day to empty the sac, and keep the eye clean. If the duct still remains obstructed, the duct opening can be enlarged with a small probe. Irrigation with saline is done to ensure patency. Repeated probing may be necessary; the success rate being approximately 90%. Surgical repair is the final option, and is usually delayed till a later age.

Congenital Glaucoma

This is a genetic developmental abnormality that affects the trabecular meshwork preventing aqueous outflow. It is an uncommon but important condition to recognise because its progression results in optic nerve damage, severe visual loss and amblyopia, if treatment is delayed. The presenting symptoms are tearing, photophobia, blepharospasm and a large cloudy cornea in one or both eyes, in a child between 1-24 months of age. The eye ball tension in the affected eye is elevated. As a result, corneal enlargement (horizontal corneal diameter >12mm) and opacification develops, and the eyes appear large (Buphthalmos-Bull’s eye). The diagnosis is usually confirmed by tonometry performed by an ophthalmologist. In infants or uncooperative toddlers, EUA (examination under anaesthesia) may be necessary.

Treatment is with surgical correction. This is conducted through anterior chamber angle surgery, either goniotomy or trabeculectomy, to lower intraocular pressure by diverting the aqueous outflow. Alternatively, the procedure may be conducted by laser surgery. However most children left with some visual handicap. Adjunctive therapy in the post-surgical phase consists of topical carbonic anhydrase inhibitor (metazolamide), beta-blocker (timolol) or prostaglandin analog (latanoprost).

Congenital Cataract

Cataracts are opacities in the lens detected at birth or soon thereafter. Not all congenital cataracts cause visual impairment. Some cataracts are static, whereas others may be progressive. Lenticular opacities larger than 3mm in diameter and located in the visual axis are considered significant, as they may result in blindness. Cataract may involve one or both eyes (Figure 27.5).

Figure 27.5: Congenital cataract in a neonate

Important causes are intrauterine infections (rubella, toxoplasmosis, cytomegalovirus and herpes simplex), chromosomal disorders such as Down, Edward or Patau syndromes, metabolic disorders such as galactosemia, hypoglycaemia, and hypocalcaemia. Some cases are familial, such as myotonic dystrophy but in others (about 30%), a cause cannot be identified.

For the general medical practitioner, screening for any abnormality of the red reflex in a darkened room with an ophthalmoscope is a quick and practical way to detect early cataract changes. An uncertainty or irregular red reflex is an indication for referral to an ophthalmologist, who will confirm the diagnosis with a slit lamp examination. The mature white cataract will be obvious from a torch examination. Treatment is by surgery, followed by visual rehabilitation with optical aids (contact lens or glasses). In spite of treatment, 20-30% of young children do not gain useful vision. Cataracts which occur at a later age have a better prognosis because the visual pathways have already been established prior to the onset of the cataract.

Paediatric Retinopathies

Retinopathy of Prematurity

This occurs in premature babies with birth weight of less than 1500 g. Various factors appear responsible apart from the prematurity and low birth weight, viz. oxygen therapy, vitamin E deficiency, and perfusion failure. The end result is proliferation of new vessels and fibrous tissue in the retinal periphery, leading to total retinal detachment and blindness. It is important to refer susceptible babies with known risk factors to the ophthalmologist for a full eye examination. Cryotherapy and other procedures have been found to be effective in arresting the disease. For details, see chapter 11.

Hereditary Retinal Disorders

This is a genetically heterogeneous group of retinal dystrophic disorders, presenting in children with symptoms of gradual progressive night blindness, visual field loss and eventually loss of central vision. Affected individuals may be misconstrued as clumsy until a constriction of visual field (tunnel vision) is detected.

The disorder is confirmed by a reduced or absent ERG (electroretinogram) response. The fundus examination reveals chorioretinal atrophy, bone corpuscle-like pigment deposits, optic disk pallor, and narrowing of the retinal arterioles. The disease can occur in isolation (non-syndromic) or may be associated with other abnormalities (syndromic). The inheritance pattern may be autosomal dominant, autosomal recessive, or X-linked or mitochondrial (Figure 27.6). Multi-gene panel testing is currently available to identify the specific gene involved. The prognosis for visual loss is variable, depending on the type of inheritance.

Figure 27.6: Pigmentary retinopathy in a child with mitochondrial disease (Kearns Sayre syndrome). Note the pale optic disc and thin retinal vessels with increased pigmentation of the retina.

Leber congenital amaurosis is a rare autosomal recessive disorder but is the most common form of inherited visual loss in children. Over 25 genetic subtypes have been described, accounting for 70-80% of the cases. Typically, symptoms such as progressively declining peripheral vision (tunnel vision), begins in early childhood. Additional ocular features are nystagmus, sluggish pupillary response, enophthalmos, gross refractive errors, optic disk pallor and progressive retinal degeneration. Midfacial hypoplasia and mental handicap are other dysmorphic features.

Previously, only 3 disorders of retinitis pigmentosa were treatable:

•Abetalipoproteinemia (Bassen-Kornzweig disease) presents with acanthocytosis (star-shaped RBCs), anaemia, loss of vision, steatorrhea from fat malabsorption, and peripheral neuropathy. Patients can be treated with fat-soluble vitamins A, E and K.

•Ataxia with vitamin E deficiency (AVED) presents with ataxia and neuropathy which is caused by pathogenic variations in the TTPA gene, which encodes alpha-tocopherol transfer protein. Treatment is with vitamin E.

•Refsum disease (phytanic acid oxidase deficiency) presents with loss of night vision, peripheral neuropathy, anosmia, ataxia, deafness, ichthyosis and cardiac arrhythmia. The disease can be treated with dietary reduction of phytanic acid.

Recent advances in gene therapy offer hope and cure for some congenital retinal diseases which were previously untreatable. FDA has recently approved Luxturna gene therapy for patients affected by RPE65 mutations, as in some patients with Leber congenital amaurosis. Luxturna is delivered to the eye tissue by subretinal injection of a solution containing genetically engineered viruses carrying a healthy copy of the RPE65 gene into the retinal cells.

Ocular Trauma

Accidental trauma

In children, injuries need to be carefully examined as serious damage may result from such injuries. A good history and visual acuity tests (in older children) are useful preliminary steps. The injury may be mild, such as periorbital bruising and sub-conjunctival haemorrhage (Figure 27.7). Superficial foreign bodies on the conjunctivae (Figure 27.8), cornea, and under the eye lids should be suspected in relevant cases. These are carefully searched for, and then removed after instilling local anaesthetic eye drops. Staining with fluorescein dye is helpful in diagnosing corneal abrasions, which are treated with antibiotic ointment and padding.

Figure 27.7: Subconjuctiva haemorrhage and periorbital bruise due to accidental injury.

Figure 27.8: Foreign body of the left conjunctiva in a child after a fall

Hyphaema (blood in the anterior chamber) is a potentially serious injury. With a torch, it is easy to see the blood in the anterior chamber, where it may collect and appear as a level, within several hours of injury. A child with hyphaema should preferably be hospitalised for bed rest and daily observation. Usually the blood is reabsorbed within a few days to a week. In severe cases, where there is a total hyphaema or if bleeding has recurred (secondary hyphaema), opaque staining of the cornea by blood pigments may result in partial or even total visual loss (amblyopia).

Blunt injury may cause choroidal tears, retinal haemorrhage or tears, and optic nerve injury. Trauma to the orbit may cause fractures which may entrap ocular muscles and other orbital contents causing double vision (blow out fracture). Sharp trauma may cause laceration and/or perforations of the lids, conjunctiva, cornea and sclera. These injuries need to be carefully assessed, preferably under sedation or even a general anaesthetic. Such injuries would need careful toilet and repair.

Non-accidental Injury

Eye injuries may be the result of physical assault and are seen in about 40% of non-accidentally injured children. These injuries may cause serious loss of vision; hence it is important to conduct a careful examination of the child’s eye including fundus examination. Common ocular injuries include retinal and vitreous haemorrhages, periorbital swelling and bruising and subconjunctival haemorrhage. Examination should include careful documentation of injuries to other parts of the body. Medico-legal issues are involved.

Tumours in the Eye and Orbit

Retinoblastoma

This is by far the commonest malignant eye tumour in children, with 90% of cases occurring before 5 years of age. Retinoblastoma arises from primitive embryonal retinal cells. More rarely, the tumour may also arise from mature inter-neuronal cells. With the growth of the tumour, small fragments of the mass separate and appear as floaters in the vitreous or may seed and grow in other parts of the retina. Extraocular extension occurs either directly through the sclera or invasion along the optic nerve. When the tumour is localised within the eye ball, cure is possible; but when extension beyond the globe has occurred, it becomes life threatening. Hence it is important to diagnose this condition as early as possible.

In about 1 out of 3 children with retinoblastoma, there is a germline mutation in the RB1 gene i.e., the mutant gene is present in all cells in the body, including the cells in both retinas. The normal RB1 gene helps prevents cells from growing out of control. Children with the RB1 mutant gene usually have bilateral retinoblastomas, as well as multifocal tumours within each eye. They are also more prone to develop neoplasms in the brain and elsewhere in the body in later life.

The commonest presentation is a white pupil or an odd coloured reflex in the pupil (Figure 27.9). Other presentations include difference in colour in each iris, squint, glaucoma (red painful eye), poor vision and proptosis. A child presenting with a white pupil or uniocular visual defect should be promptly referred to an ophthalmologist for a full examination. Differential diagnosis of retinoblastoma includes congenital cataract, persistent hyperplastic primary vitreous and ocular toxocariasis.

Figure 27.9: white eye reflex in a child with retinoblastoma of the left eye.

Treatment usually includes a combination surgery, chemotherapy and radiation. A multi-discipline team familiar with the disease management is necessary.

Other Orbital Tumours

The most common benign orbital tumours encountered in children are:

Dermoid cysts are mobile, small discreet subcutaneous masses that usually occur near the lateral eyebrow. They are benign and contain hair follicles, oil and sweat glands, rarely bone and teeth. The cyst is usually present at birth and gradually increases in size. Treatment is by surgical removal.

Capillary haemangiomas on the eyelids are benign hamartomatous collection of small blood vessels that blanch on compression. They appear sometime after birth, grow rapidly in infancy with gradual spontaneous involution later in life. Often, it may completely disappear and thus are best left alone unless it obstructs the visual field. Intra-lesional steroid injections are sometimes used to expedite the involution. Propranolol has also been used. The dose is 0.6 mg/kg two times daily orally, with gradual increase every 2 weeks to a maximum of 1.5 mg/kg two times daily. Monitoring side effects and dose adjustments are important during therapy. Medication is maintained for 4-6 months. If the haemangioma recurs, medication may be reinitiated.

Primary malignant tumours and secondaries in the orbit commonly present with progressive proptosis. Rhabdomyosarcoma is the commonest malignant tumour of the orbit, and arises from the striated muscles. It presents as a rapidly progressive proptosis. Neuroblastoma and Wilms tumour are the commonest metastatic tumours in the orbit and present as proptosis in one or both eyes with bruising of the eye lids.

Investigations are important to establish the diagnosis and include X-ray, computerised tomography (CT) and magnetic resonance imaging (MRI). It is also important to locate the sites of the primary tumours.

Common Disorders of the Ear, Nose and Throat

Disorders of the ear, nose and throat are common in children for a number of reasons. These structures are directly exposed to pathogens, allergens and noxious elements in the environment. Moreover, the naive immune system improves its efficiency through recurrent encounters with foreign pathogens. In children, the Eustachian tube is shorter and straighter and less efficient in preventing reflux of infected mucus from the nasopharynx to the middle ear. Similarly, acute inflammation or chronic hypertrophy of the adenoids, tonsils and laryngeal structures may readily provoke airway obstruction

Congenital abnormalities

Choanal atresia.

This is a serious abnormality if it occurs bilaterally. Neonates are obligate nose breathers; the disorder may cause death from asphyxia despite vigorous respiratory effort. If the infant cries and breathes through the mouth, airway obstruction is momentarily relieved. Nasal obstruction is suggested by failure to pass a feeding tube beyond the posterior nares and confirmed by endoscopic visualisation of the defect. Insertion of an oral airway allows temporary relief. As the disorder may not occur in isolation, it is important to search for other dysmorphic features involving the eye (coloboma iris, Figure 27.10), the heart and genitourinary tract. Choanal atresia requires surgical repair.

Figure 27.10: Coloboma of right iris in a child with trisomy 8.

Cleft Lip and Palate

This may involve the upper lip, the hard and/or soft palate. The mean incidence is 2.1 per 1000 among Asians. The severity of the cleft varies widely. Submucous cleft palate may be indicated by recurrent nasal regurgitation, hypernasality of voice, bifid uvula (Figure 27.11) or by palpation of a notched hard palate.

Figure 27.11: Bifid uvula

Some cases are associated with dysmorphic syndromes such as:

Patau syndrome (trisomy 13): cleft lip/palate, clenched hands, close-set eyes, polydactyly, low set ears, hypotonia, microcephaly, seizures and mental retardation.

Pierre Robin sequence: cleft palate, micrognathia, and glossoptosis (Figure 27.12). Abnormalities of the DNA near the SOX gene are the most common defects encountered. Malfunction of the SOX gene results in maldevelopment of the mandible. The infant encounters difficulty in breathing and has problems with swallowing. Mandible growth however may catch up by adulthood.

Figure 27.12: A child with Pierre Robin Sequence after glossopexy

Van der Woude syndrome: cleft lip and palate with pits near the centre of the lower lip. This disorder is inherited in an autosomal dominant pattern.

Wolf-Hirschhorn syndrome: microcephaly with high forehead, flat nasal bridge, short philtrum, cleft lip and palate, intellectual disability. A chromosomal disorder, due to terminal deletion of short arm of chromosome 4 (4p-).

Maternal cigarette smoking and valproate during pregnancy have been implicated as possible triggers. Combined cleft lip and palate are more common in boys. Isolated cleft palate is about equal in both sexes.

Many babies with wide cleft palate have difficulty with breast feeding and experienced nurses can advise on alternative feeding methods.

Middle ear infections and serous otitis media are associated with cleft palate. Significant hearing loss may require placement of grommet tubes.

Treatment is surgical. Best results are achieved in centres with a specialised team. Besides cosmetic reconstruction, the aims of treatment are to achieve normal speech, hearing and acceptable dental appearance.

The cleft lip repair is usually performed after 3 months of age and cleft palate closure at age 12-18 months. Velopharyngeal insufficiency may occur due to inability to adequately close the velopharyngeal sphincter, and is characterised by nasal escape, and hypernasality in the speech. Speech, hearing assessment and therapy commence from age 18 months; dental and orthodontic treatment are on-going till adolescence.

Laryngomalacia

This is the commonest congenital abnormality of the larynx and is characterised by stridor which begins soon after birth and is exacerbated with crying. There is no stridor with quiet breathing and no hoarseness of voice. Swallow dysfunction may accompany the disorder.

Laryngomalacia is due to soft and compliant laryngeal cartilages (epiglottis, arytenoid) and is a self-limiting condition which improves with age.

Laryngeal webs, cysts or growths cause both stridor, and hoarseness.

Tracheomalacia involves the cartilage and may extend down the tracheobronchial tree.

Subglottic haemangiomas, tracheal rings and vascular slings are rare causes of respiratory obstruction.

Diagnosis. Stridor is a high-pitched audible respiratory noise that indicates respiratory obstruction. Determining the phase in the respiratory cycle during which the stridor is heard will help elucidate the cause.

Inspiratory stridor usually indicates airway obstruction at or above the level of the vocal cords and results from collapse of the soft tissue with the negative pressure generated by inspiration.

Expiratory stridor is usually associated with obstruction of the tracheobronchial tree within the thorax.

Biphasic stridor usually signifies a fixed obstruction.

Laryngoscopy or tracheo-bronchoscopy will usually identify the cause for the obstruction.

Treatment. The condition improves with time without any intervention in the vast majority, usually by 2 years of age. In the rare infant with severe protracted stridor, failure to thrive and obstructive sleep apnoea, there is a risk of pulmonary hypertension and sudden death. In these infants, tracheostomy or supraglottic plastic procedure may be indicated.

Hearing loss in children

Prompt identification and management of hearing loss in childhood is essential to ensure optimal speech and language development and school performance in subsequent years. Hearing loss is classified by both type and severity. It can be congenital or acquired, conductive or sensorineural or mixed hearing loss.

Types of hearing loss

Conductive: Examples are otitis media, tympanic membrane perforation and congenital ossicular anomalies. Developmental abnormalities e.g. microtia, ear atresia, severe cleft palate, occur less commonly.

Sensorineural: Malfunction of inner ear structures (e.g. cochlear and auditory nerves)

Causes

Genetic abnormalities: These disorders may be due to gene mutation or chromosomal disorders. About 80% of the congenital hearing loss is genetic in origin. About 80% of the genetic causes are non-syndromic and about 80% of the non-syndromic genetic hearing loss and are autosomal recessively transmitted. About 50% of cases are due to GJB2 (Gap Junction Beta 2) gene mutation. Other modes of inheritance of hearing loss are autosomal recessive, autosomal dominant, X-linked and mitochondrial.

There are more than 400 genetic syndromes that include hearing loss. Examples are Alport syndrome, Neurofibromatosis type 2. Waardenburg syndrome, Pendred syndrome, Craniosynostoses syndromes, Di George Syndrome, Noonan syndrome, CHARGE syndrome (Coloboma iris, Heart defect, Atresia choanae, Retardation of Growth, Ear deafness), etc.

Acquired Disorders: These include severe neonatal jaundice, traumatic injury, ototoxic drugs, meningoencephalitis (viral or bacterial). Central auditory dysfunction due to damage or dysfunction at the level of eight nerve, auditory brain stem or cerebral cortex.

Mixed forms are also encountered.

About 50% of newborn, born with bilateral severe hearing loss, do not have any known risk factors. Onset can be prelingual which is present before speech develops or post lingual which occurs after development of speech. All congenital hearing loss have prelingual onset but not all prelingual hearing loss is congenital.

Clinical Evaluation

This should include a detailed family and personal history to elucidate the known causes of hearing loss as well as impact of hearing loss on the child’s speech, language, social development and school performance. A full clinical examination is required with particular attention to associated dysmorphic features, craniofacial and ocular abnormalities.

Otoscopic examination: This is performed to determine the appearance of the tympanic membrane (inflamed, bulging, dull, retracted, perforated), underlying contents of the middle ear (fluid, pus, air-fluid meniscus, handle of malleus, cholesteatoma) and for foreign body and impacted wax in the external ear canal.

Tympanometry: This is to assess the compliance of the tympanic membrane.

Type A: A normal peak suggests normal middle ear function.

Type B: A flattened peak suggests otitis media or perforation.

Type C: A negative peak suggests Eustachian tube dysfunction.

Otoacoustic emission (OAE) such as in neonatal hearing test whereby broadband clicks are delivered to the ear by a probe which also contains a microphone to detect the emission from the hairs of a normal functional cochlea.

Auditory brainstem response (ABSR): This test records the activity of the auditory nerve pathway by surface scalp electrodes, in response to an acoustic stimulus. It is a highly reliable objective test of hearing.

Auditory Steady-State Response testing (ASSR): is similar to ABSR but it is obtained using broadband or frequency-specific stimuli. It is frequently used to give frequency-specific information that ABSR does not give. Test frequencies of 500, 1000, 2000, and 4000 Hz are commonly used. ABSR does not assess low frequency sensitivity but ASSR does.

Audiometric assessment: This determines how the child processes auditory information:

Play audiometry. The child is instructed to perform a task each time they hear a sound presented by headphones or sound field. This test is dependent on co-operation of the child. It is used to assess children aged from 2.5years to 5 years.

Pure tone audiometry is a similar test which requires the subject to press a button each time a sound is heard. It determines the lowest intensity at which an individual hears a pure tone. Octave frequencies from 250 to 8000 Hz are tested using earphones. It is used to test children older than 5 years.

Severity of hearing loss: Loss of decibels are assessed at various sound frequencies. The extent of hearing loss is classified as:

•mild (25–50 decibel loss)

•moderate (51–70 decibel loss)

•severe (71-90 decibel loss)

•profound (91–110 decibel loss)

The frequency spectrum of hearing loss:

Low (<500Hz)

Middle (500-2000Hz)

High (> 2000Hz)

Imaging studies: An MRI imaging can demonstrate an anatomical lesion in the cochlear as well as along the auditory nerve.

Haematology: Blood test for antibodies against herpes simplex, cytomegalovirus, syphilis, toxoplasmosis, rubella or HIV viruses are indicated if intrauterine infection with these agents is suspected.

Renal function test and urinalysis form part of screening tests for Alport syndrome and branchio-oto-renal syndromes.

Electrocardiogram to asses QT interval is done in patients in whom Jervell and Lange-Nielsen syndrome is suspected. The features are long QT associated with severe bilateral sensorineural deafness.

Other ancillary tests such as ophthalmic evaluation and cardiac evaluation are indicated if there is a concern of other organ involvement.

Genetic study. A hearing loss multi-gene panel can be performed to identify the exact cause of the non-syndromic hearing loss for genetic counselling and prevention.

Management

This requires a multidisciplinary approach. Audiologists will provide diagnostic and rehabilitative services. They will supervise the proper use of hearing aids and monitor progress. Speech and language therapists are essential components of management.

Most children with mild to moderate hearing loss can be managed conservatively with supportive management.

The majority of children with hearing loss from otitis media resolve spontaneously. In some children, otitis media may be persistent with viscous fluid in the middle ear (glue ear). The hearing impairment may be prolonged and interfere with the learning process. If this has gone on for more than 3 months, insertion of grommets may be considered. Grommets are small ventilation tubes that are inserted onto the tympanic membrane to aerate the middle ear. This usually expedites the hearing recovery. Thereafter, the tubes usually dislodge spontaneously after several months, or are removed surgically, if required.

Children with mild to moderate permanent hearing loss can be managed conservatively with supportive hearing aid device. If conventional device is unhelpful in children with profound hearing deficit, a bone-anchored hearing aid may be considered.

Cochlear implant is recommended in children with profound hearing loss that do not benefit from conventional hearing aid. The implanted electrodes bypass damaged cochlear hair cells and directly stimulate the cochlear nerve. Most patients benefit significantly from the implant with improvement in sound localization and speech improvement. Many achieve age-appropriate academic performance. Surgical risks include altered taste and infection,

Detection of hearing loss

Universal Screening for hearing loss: Many countries have introduced universal neonatal hearing screening programme. The estimated incidence of hearing impairment is between 1:1000 and 1:2000 babies screened. Babies are screened after birth preferably before release from hospital. Premature babies are screened after 34 weeks gestational age. The initial test in the screening protocol comprises otoacoustic emission (OAE). OAE are sounds originating within the cochlea that are measured