Case • 6

Down ’ s syndrome

SUMMARY A 40-year-old male patient presents to you in your dental surgery with a loose tooth. What is the cause and what will you do?

Dental history He has been seen in your practice for several years and attends with his mother on most occasions ( Figure 6.1 ).

You have been monitoring his periodontitis for many years. The patient achieves a moderate degree of oral hygiene but cleaning posteriorly is always suboptimal. He has had a series of episodes of acute symptoms from this tooth but has always refused to let you extract it.

Medical history The patient has Down ’ s syndrome. He has a patent ventriculoseptal defect that is unrepaired and a mild to moderate learning disability. He reports recurrent upper respiratory tract infections.

Social history The patient lives at home with his parents and works part-time in a supermarket. He does not smoke or drink any alcohol.

� What are the causes of Down ’ s syndrome?

Down ’ s syndrome is caused by complete or partial trisomy of chromosome 21. The majority of patients have a complete third copy of the chromosome, but there are several diff erent ways in which cells can acquire additional chromosome 21 DNA. This is important because not all individuals with Down ’ s syndrome have a similar phenotype. The types of trisomy 21 are explained in Table 6.1 .

� How does this cause the condition?

The long arm of chromosome 21 includes a region called the Down syndrome critical region. Genes at this site encode transcription factors that control development, including that of the brain. An increase in copy number of genes in this region is thought to account for most of the neurological and facial, and possibly other, features of Down ’ s syndrome. Other genes have been identifi ed for leukaemia and other complications.

� What is the risk of having a child with Down ’ s syndrome?

Because most cases are caused by chromosomal non-disjunction during egg formation, the risk is linked to maternal age. The risk rises markedly after 40 years. The risk in a mother aged 30 is approximately 1 in 1000 but this rises to almost 1 in 100 at age 40 years and higher after that.

Prenatal screening relies on a variety of tests, including ultrasound screening. The most accurate tests require amniocentesis and are reserved for those at the highest risk. The newest tests promise accurate diagnosis on the basis of a blood test. The combination of prenatal testing and termination of pregnancy has resulted in falling incidence in many parts of the world. This is somewhat compensated for by a generalized increase in maternal age and greater life expectancy for those aff ected.

Two-thirds of aff ected fetuses die during normal development and the frequency of trisomy 21 in the population is 1 in 650 – 1000 live births.

Fig. 6.1 The patient on presentation.

History

Complaint The patient has been complaining of a sore, loose lower back tooth for 1 week. It is particularly sore when eating and the patient often fl inches whilst chewing.

History of complaint There were no recent symptoms from this tooth until 1 week ago. When the pain started, the patient ’ s mother noticed that he stopped bruxing.

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Table 6.1 Types and causes of Down ’ s syndrome

Type of trisomy % of patients Cause Signifi cance

Free trisomy Down ’ s syndrome 95% A ‘ free ’ third copy of chromosome 21 in every cell. Meiotic non-disjunction (failure of chromosomes or chromatids to separate during cell division) in development of the egg (95%) or sperm (5%) results in gametes with an extra copy of chromosome 21. After fertilization and embryogenesis, every cell carries a copy of the third chromosome

Commonest type. Not inherited

Translocation Down ’ s syndrome

2% One copy is translocated to another chromosome, most often chromosome 14 or 21, in a cell division during development of the egg, or occasionally sperm. Sometimes the translocation aff ects only the child. Occasionally the translocation is stable and can be passed from generation to generation

About half of cases have a familial pattern of inheritance

Mosaic Down ’ s syndrome 2% Patients are a mosaic of normal cells and cells with trisomy 21. The gametes are normal but non-disjunction during a somatic division in embryogenesis gives some cells trisomy. If the trisomy arises early a large proportion of the patient ’ s cells are aff ected; if late, fewer are aff ected

The features vary depending on which cells are aff ected. Some patients may be of Down ’ s appearance but normal intelligence or vice versa, and the features are often mild.

Not inherited

Other types 1% Caused by a variety of diff erent chromosomal rearrangements involving chromosome 21

Table 6.2 Categories of learning diffi culty

Learning diffi culty/disability

Indicative IQ Eff ects

Mild 50 – 70 Most can lead normal lives but may need assistance in handling diffi cult situations

Moderate 35 – 49 Need to use simple language when talking. Can generally attend to the basic tasks of life after training but more complex activities such as using money usually require support within a special residential environment

Severe 20 – 34 Many able to look after themselves but with careful and close supervision

� The patient has ‘ mild to moderate learning diffi culty ’ . What does this mean?

A wide range of terms may be used to describe intellectual ability. Terms such as mental retardation, intellectual impairment and mental subnormality are no longer used in the UK, though they are considered acceptable in other cultures. Learning diffi culty and learning disability are considered synonymous in the UK. Mental incapacity is a legal term used to describe ability to make informed decisions. It relates to intellectual ability but is not the same as learning diffi culty.

Learning diffi culty is defi ned as a signifi cant impairment of intelligence and social functioning acquired before adulthood. The defi nitions are from the Education Act 1996 and the Special Educational Needs and Disability Act 2001 that defi ne the educational needs and aid the individual in gaining access to legal protections and rights.

Learning diffi culty is usually divided into mild, moderate and severe, but these defi nitions are not always helpful in health care because they are based on analysis of social functioning as well as psychometric testing. The categories do not correlate directly with intelligence, though they are often equated, as shown in Table 6.2 .

The majority of individuals with Down ’ s syndrome have mild to moderate learning diffi culty. Regardless of learning diffi culty, all those with Down ’ s syndrome will require lifelong help with accommodation and supportive working. Some can lead largely independent lives with support whereas, for others, daily supervision will be necessary.

� Before you examine the patient, are there signifi cant medical features of Down ’ s syndrome that you need to consider immediately?

Yes, there are several, but the one of immediate importance is general joint laxity that involves the atlantoaxial joint. Care must be taken positioning the head and neck to avoid dislocation, which would have severe consequences. In practice this is most likely to aff ect patients under general anaesthesia or sedation. However, individuals with Down ’ s syndrome also have poor muscle tone so that the joint is not fully stable even when conscious. Simply ensuring head support, including lateral support, is suffi cient. About 15% of patients are aff ected in this way, though only 1 – 2% are at

high risk of spinal cord compression. Examination of a conscious patient poses minimal risk.

� Is the patient able to give consent for the examination?

Capacity to give consent must be assessed in line with the Mental Capacity Act 2005. You need to assess capacity to consent at each visit in relation to the treatment to be carried out. As this individual works part-time in a supermarket and has presented for treatment independently, it is very likely that his consent would be valid for examination but not necessarily for any treatment.

In the meantime, you can proceed with examination and diagnosis.

Examination

Extraoral examination � How can you recognize Down ’ s syndrome?

Down ’ s syndrome has a readily recognized physical appearance, characteristic facies and signs aff ecting the hands that are readily recognized in the dental setting. These include:

• Short stature

• Short neck

• Obesity

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• Short limbs

• Broad head and sloping forehead

• Round face

• Large lips

• Flat nasal bridge

• Oblique slanting eye fi ssures

• Epicanthic skin folds on the inner corner of the eyes

• White spots on the iris (Brushfi eld spots)

• Short stubby hands and fi ngers

• Inward-curving fi fth fi nger

• However the individual features and their prominence vary considerably between individuals. The patient ’ s appearance is shown in Figure 6.1 .

There are multiple slightly tender mobile cervical lymph nodes.

Intraoral examination The tongue appears large and makes examination of the lower teeth a little diffi cult. The oral hygiene is generally good anteriorly but there is fairly thick plaque around the gingival margins of the molar teeth. There are a few small restorations and no dental caries. The lower right second molar is grade II mobile and tender on pressure.

� Interpret these fi ndings in the light of Down ’ s syndrome.

Recurrent upper respiratory tract infections are common in individuals with Down ’ s syndrome and noted by the patient. This is likely to account for the lymphadenopathy but you need to consider alternative explanations.

The tongue is not enlarged, but appears so. It has a forward posture, associated with mouth breathing, and poor muscle tone. This is more prominent in children with Down ’ s syndrome and becomes less prominent in late childhood. Poor tongue control can lead to problems with speech and swallowing.

Individuals with Down ’ s syndrome have a lower prevalence of dental caries than the normal population, though this can be overcome by high levels of dietary sugar. Caries resistance has been claimed to be due to high titres of secretory IgA against Streptococcus mutans in saliva and a high salivary pH. However, late eruption, spacing of the teeth and shallow fi ssures also contribute and may be as important.

There is predisposition to plaque-induced gingivitis and periodontitis that might account for the mobile lower molar. Immune function, particularly neutrophil function, is impaired and thought to be the cause, though the exact causes are not defi ned. There are also changes in complement and antibody levels, required for optimum neutrophil function. Mouth-breathing contributes to gingivitis. Once periodontitis develops, the teeth have short conical roots and are more quickly compromised.

Bruxism is a feature of Down ’ s syndrome. The patient stopped bruxing when symptoms started, suggesting pain of periodontal ligament origin, and this is consistent with the tooth mobility and pain on eating.

These and other oral features of Down ’ s syndrome are listed in Table 6.3 .

Investigations � What investigations should be carried out and why?

As periodontitis is the most likely cause for the tooth mobility, the patient ’ s periodontal assessment should be updated with pocket depths around as many teeth as possible and a radiographic survey, unless recent fi lms are available. Periapical radiographs are the view of choice but may not be possible because of the combination of the tongue and lack of cooperation. A panoramic radiograph is a suitable second choice provided the patient can sit still for the required period. Alternatively, an oblique lateral is a good choice; the exposure is very short and the fi lm is held against the patient ’ s face, so that the eff ects of movement during exposure are minimized.

In this case, you already have a panoramic radiograph that was taken a year ago and shows the cause of the problems.

� The panoramic radiograph is shown in Figure 6.2 . What do you see?

Consistent with Down ’ s syndrome, there are missing third molars and small teeth with short conical roots and spacing

Table 6.3 Oral features of Down ’ s syndrome

Fissured lips Open-mouth posture and mouth-breathing Tongue protrusion Lack of muscle tone Fissuring of the dorsal surface of the tongue Drooling Bruxism Developmental absence of some teeth Teeth with short conical roots Interdental spacing Delayed eruption Small teeth, including conical crown forms Shallow fi ssures Hypoplastic/hypocalcifi ed enamel Class 3 skeletal pattern and malocclusion Taurodontism (0.54 – 5.6%) Prone to periodontal disease Prone to intraoral candidal infection and angular cheilitis Resistant to dental caries

Fig. 6.2 Panoramic radiograph.

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or psychosis. These have more profound eff ects on dental treatment. The most severely aff ected will not be amenable to dentistry without general anaesthetic.

It is important to evaluate how treatment has been provided in the past. This patient has been treated in the practice for several years and has had some restorative work carried out, which indicates good cooperation for treatment under local anaesthetic. On the basis of what is known about this patient, he may require only standard types of support such as behaviour management or inhalation sedation, possibly with oral sedation. Intravenous sedation or general anaesthesia might be considered for more demanding treatments.

� Can the patient refuse to accept the extraction? He has before.

All patients over the age of 16 take responsibility for their own treatment. The degree of capacity required for consent to be valid increases with the complexity of the procedure. If the patient understands the risks of endocarditis and the advantages and disadvantages of extracting the tooth, his opinion is fi nal.

If you believe that the patient does not understand the issues, then he does not have capacity to consent because he cannot make an informed decision. It is still possible to provide treatment within the framework set by the Mental Capacity Act 2005, which governs consent. This states that:

i. A patient is assumed to have capacity to consent unless proven otherwise. Such a loss of capacity may be permanent or temporary.

ii. Capacity has to be assessed at each visit, in relation to the treatment and recorded.

iii. A person must be able to understand, retain, and weigh the information given and communicate their decision to have capacity.

iv. When a person lacks capacity to consent, treatment must be provided within ‘ best interest ’ of the patient and consideration given to all the relevant circumstances. The person should be encouraged to participate in the decision-making process. Consideration must be given to past and present wishes, feelings, values and beliefs that would infl uence the decision. Consult with family, next of kin, carer, lasting power of attorney, or deputy of court as appropriate.

v. Individuals can nominate a lasting power of attorney who can give or withhold consent on their behalf for health care decisions in the event that they lack capacity.

vi. ‘ Advance directives ’ can be made to advise of treatment that the person does not wish to undergo in the event that that person lacks capacity. These can only rule out specifi c items and cannot require specifi c treatment to be carried out. In order to be binding the directive must show capacity and validity applicable to the specifi c situation.

If the patient cannot make an informed decision, it will be necessary to ensure that any proposed treatment is reason-able and in the patient ’ s best interests, and the least restric-

anteriorly. There are only a few shallow restorations but there is marked periodontitis.

There is generalized horizontal bone loss posteriorly with almost complete bone loss around the lower right third molar. Calculus is present in all posterior interdental spaces.

Diagnosis � What is your diagnosis?

Extensive bone loss due to advanced periodontal disease with apical involvement and, almost certainly, a perioendodontic lesion.

Treatment � Will the patient need antibiotic cover for whatever

treatment you prescribe?

No. The unrepaired ventriculoseptal defect is not currently considered to require antibiotic cover for dental treatment. However, the patient remains at risk of bacterial endocarditis and infections such as this need to be treated vigorously and without delay. As the patient must understand the risk, signs and symptoms of endocarditis, most of the responsibility will rest with carers, whose involvement will be essential.

More detailed information on endocarditis is given in Case 44 .

� What treatment would you recommend?

In principle, individuals with Down ’ s syndrome must be off ered the same standard of care as other patients. In this case the prognosis for this tooth in any individual would be poor. When the predisposition to periodontitis, endocarditis and infection is taken into account, the only treatment that can be recommended is extraction. This had been recommended before but was refused.

In the longer term, there is a need for continuing periodontal treatment and monitoring. Removal of subgingival calculus is a priority.

If sedation or general anaesthesia is required, then extraction of the lower left second molar and scaling and root planing could all be carried out in one episode.

� Does the level of learning diffi culty help in planning treatment?

Only slightly. Knowing that the cause of the learning disability is Down ’ s syndrome is probably more useful than the level of disability itself. Individuals with Down ’ s syndrome are generally considered to be friendly, tolerant, cheerful, gentle and patient but somewhat stubborn. This stereotype often holds true, but all are individuals and vary considerably. They all have their own range of abilities that you will need to assess. Some will be anxious about dentistry.

A third of patients will suff er additional psychiatric disorders that may include Alzheimer ’ s disease, attention defi cit hyperactivity disorder, autism, depression, bipolar disorder

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tive option in terms of the individual ’ s basic rights, based upon section 5 of the Mental Capacity Act 2005. This states:

For those who lack capacity the following conditions must be met:

• The treatment is undertaken in connection with another person ’ s care or treatment;

• The person doing it takes reasonable steps to estab-lish whether the recipient has capacity;

• There is reasonable belief that the recipient lacks capacity;

• There is reasonable belief that the treatment is in the best interests of the patient;

• If restraint is to be used to carry out the treatment, there is reasonable belief both that it is necessary to undertake treatment in order to prevent harm to the person and that the treatment is a proportionate response to the likelihood of the person suffering harm and the seriousness of that harm.

In the event that the patient does not have capacity, the proposed treatment must be discussed with parents, legal guardians or carers and may also be agreed by two dentists or doctors. The NHS consent form for those who lack capac-ity (consent form 4) should be used.

Delay is not an appropriate response. There is a need for urgent treatment and failure to follow through and deliver it would be negligent.

Long-term management � Are there any long-term issues to consider in planning

dental treatment?

Yes, the reduced life expectancy must be taken into account when planning treatment. The mean lifespan for people with Down ’ s syndrome has increased signifi cantly in the last decades and currently stands at about 50 years, with some individuals reaching 60 years or more.

Congenital heart disease carries signifi cant mortality in the long term. It is also possible for patients to acquire cardiac defects in later life, either de novo or as developmental defects reveal themselves in later life.

There is also a predisposition to atherosclerosis as part of generalized premature ageing. Mitral valve prolapse aff ects about half of adults without congenital heart defects. It is now recommended to have a second cardiac assessment in early adulthood as most deaths result from cardiac causes.

Eyesight is often impaired and may worsen with age as a result of opacifi cation of the lens, making oral care more diffi cult.

In later life, three-quarters will develop Alzheimer ’ s disease. The pathogenesis of the neurological degeneration is the same as that in normal individuals, but accelerated because of an extra copy of the amyloid precursor protein carried on the extra chromosome 21. Microscopic evidence of senile plaques and amyloid deposition in the brain is present in all those reaching 40 years of age. Dementia is an increasing problem as the lifespan increases.

� With all this patient ’ s problems, perhaps he should be referred for specialist care?

There is no reason why the majority of individuals with Down ’ s syndrome should not be treated in general dental practice. Despite this, they and their carers often report diffi culty gaining access to dental care. Dentists may be reluctant to take on care for a variety of reasons, often of spurious validity. It is important that all such patients are able to obtain care in an appropriate local setting, ideally with other family members. Specialized services are available, but often stretched. They may be able to provide advice and backup when medical support or treatment under sedation or anaesthetic is required. This would be prudent because the airway may be compromised by the tongue, poor nasal patency and short neck. However, most individuals with Down ’ s syndrome need only routine dental care from a caring, patient and well-informed dentist.

Table 6.4 General features of Down ’ s syndrome.

Cardiovascular Cardiovascular defect 40 – 50% Ventriculoseptal defect 33% Atrioseptal defect 10% Tetralogy of Fallot 6% Isolated patent ductus arteriosus 4%

Musculoskeletal Short broad hands Short stature Obesity from adolescence Inwardly curved fi fth fi nger Single palmar fl exion crease Hypoplasia of maxillary sinuses Absence of frontal/sphenoidal sinuses Joint, including atlantoaxial, instability Large fontanelles with late closure Persistent frontal suture (metopic suture) Muscular hypotonia

Skin Early skin ageing Early greying of hair

Endocrine Hypothyroidism Diabetes Reduced fertility

Haematological Acute leukaemia (in childhood)

Immunological Impaired cellular immunity Impaired neutrophil function Susceptibility to infection, especially fungal and including angular cheilitis

Neurological Learning disability Epilepsy Autism Attention defi cit hyperactivity disorder Obsessive compulsive disorder Tourette ’ s syndrome Hearing loss, usually conductive in type Depression Alzheimer ’ s disease Dementia Poor eyesight

Gastrointestinal tract

Duodenal atresia Imperforate anus Tracheo-oesophageal fi stula Hirschsprung ’ s disease Coeliac disease Reduced peristalsis/constipation

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� What other features of Down ’ s syndrome may be present?

There are many features associated with Down ’ s syndrome that will only be seen in a minority of patients, as shown in Table 6.4 . Many have implications for dental diagnosis or treatment.,

Acknowledgements Figure 6.1 by kind permission of the Down ’ s Syndrome Association ( www.downs-syndrome.org.uk ).