Clinical Aspects of Down Syndrome from Infancy to Adulthood

Siegfried M. Pueschel
American Journal of Medical Genetics, Supplement 7: 52-56 Copyright © 1990 Wiley-Liss, Inc.
Reproduced with permission of John Wiley & Sons, Inc.

In past decades, most individuals with Down Syndrome were usually not afforded adequate medical care. Many children with Down Syndrome were institutionalized and they were often deprived of all but the most elementary medical services. Fortunately, there have been major improvements in the health care provision during the past 20 years.

Professionals who are providing services to persons with Down Syndrome need to be aware of those clinical conditions that are more often observed in this population. Certain congenital anomalies (congenital cataracts, anomalies of the gastrointestinal tract, and congenital heart disease) often require immediate attention, as some of them may be life threatening. During the subsequent childhood years a number of clinical conditions and disorders such as infectious diseases, increased nutritional intake, periodontitis, seizure disorders, sleep apnea, visual impairment, audiologic deficits, thyroid dysfunction, and skeletal problems usually occur at a higher prevalence. During adolescense specific aspects of maturation and certain health issues (skin infections, thyroid disorders, increased weight gain, and others) as well as mental health concerns need to be taken into consideration. Similar concerns may also be observed during adulthood which in addition is often marked by accelerated aging and the threat of Alzheimer disease in some persons with Down Syndrome.

Special attention needs to be paid to these disorders and conditions during the lifetime of a person with Down Syndrome. Appropriate medical care should be provided to and no form of treatment should be withheld from a person with Down Syndrome that would be given unhesitatingly to an individual without this chromosome disorder.

KEYWORDS: natural history, childhood, adolescence

Introduction

When John Langdon Haydon Down published his classic paper in 1866 describing the phenotype of persons with the syndrome which today bears his name, he focused on only 2 clinical manifestations indicating that "the coordinating faculty is abnormal" and "the circulation is feeble." However, since then many clinical-pathological findings have been reported. In particular during the past decades, we have become aware of numerous medical concerns in persons with Down Syndrome.

Within the framework of this paper it is not possible to cover all clinical disorders observed in persons with Down Syndrome in an encyclopedic fashion. Only the most important clinical concerns can be discussed. Although some of the medical conditions may occur at any time during the life of an individual with Down Syndrome, certain clinical aspects are described in a life cycle approach, i.e., specific congenital anomalies should be identified neonatally, the detection of visual and hearing impairments need to be pursued primarily in early childhood, sexual maturation is a topic of adolescence, and the accelerated aging process is noted during the adult years.

Clinical Aspects in the Neonatal Period

Certain congenital anomalies of infants with Down Syndrome require immediate attention. Some of them may be life-threatening and need to be corrected at once: others may become apparent during subsequent days and weeks.

Congenital Cataracts
Although it is sometimes difficult to examine an infant's eyes, it is important to identify children with Down Syndrome who have dense congenital cataracts. These cataracts occur in about 3% of children with Down Syndrome and must be extracted soon after birth in order to allow light to reach the retina. Subsequently, appropriate correction with glasses or contact lenses will assure adequate vision.

Congenital Anomalies of the Gastrointestinal Tract
Numerous anomalies of the gastrointestinal tract have been observed in infants with Down Syndrome including tracheoesophageal fistula, pyloric stenosis, duodenal atresia, annular pancreas, aganglionic megacolon, and imperforate anus. Most of these anomalies require immediate operation in order to allow nutrients and fluids to be absorbed. Knox and Bensel (1972) reported the prevalence of gastrointestinal malformations in Down Syndrome to be 12%. These congenital anomalies need to be corrected promptly. No form of treatment should be withheld from any child with Down Syndrome that would be given unhesitatingly to a child without this chromosome disorder.

Congenital Heart Disease
It is of importance to diagnose congenital heart disease in early infancy because some children with severe congenital heart defects may develop heart failure, thrive poorly, and may acquire pulmonary artery hypertension. Therefore, the newborn infant with Down Syndrome should have an electrocardiogram, and a chest roentgenogram, and if indicated, an echocardiogram and a consultation by a pediatric cardiologist. Congenital heart disease is diagnosed in approximately 40% of children with Down Syndrome (Buckley, 1983). The most often observed cardiac lesion is an atrioventricular canal, followed by ventricular septal defect, tetralogy of Fallot, patent ductus arteriosus, atrial septal defect, and others. Appropriate medical management may include administration of digitalis and diuretics. Prompt surgical repair of the cardiac defect should be carried out at an optimal time in the child's life. This then will improve significantly the quality of life of the individual with Down Syndrome.

Clinical Aspects in Childhood

Infections
Previously, infectious diseases were responsible for the observed increased mortality and morbidity in children with Down Syndrome (Deaton, 1973). Some reports indicate that children with Down Syndrome have a high prevalence of respiratory infections. Such infections are more often seen in children who have congenital heart disease and pulmonary artery hypertension. Otitis media also has been noted more often in children with Down Syndrome than in other children who do not have this chromosome abnormality.

Some individuals with Down Syndrome have immunologic deficiencies including T cell and B cell dysfunctions which may render them more susceptible to infections (Levin et al., 1975; Hann et al., 1979). As in other children, infectious diseases should be diagnosed and treated promptly.

Nutrition
During infancy feeding problems and poor weight gain may be observed in some children with Down Syndrome. In particular, children with significant congenital heart disease may present with failure to thrive. However, once the congenital heart defect is repaired, the children usually thrive well subsequently.

On the other hand, increased weight gain often becomes apparent in many individuals with Down Syndrome. Therefore, it is important to inform parents concerning appropriate dietary practices from early childhood on in order to avoid excessive weight gain. Proper intake of a balanced diet, avoidance of high caloric food items, and regular physical exercises are important for all children including those with Down Syndrome.

Periodontal Disease
Children with Down Syndrome frequently have abnormalities in tooth eruption, tooth shape, and sometimes congenital absence or fusion of teeth; however, the most devastating dental concern relates to periodontal disease. According to Cutress (1971) both a factor inherent in trisomy 21 and an environmental component are responsible for the increased susceptibility to periodontal disease noted in persons with Down Syndrome. Whereas a relatively high frequency of periodontal disease has been reported in institutionalized persons with Down Syndrome, this disorder is less common among individuals with this chromosome disorder residing in the community.

Thus, it is important that persons with Down Syndrome are examined regularly by a dentist, that they practice appropriate dental hygiene, receive fluoride treatments, follow good dietary habits, and have restorative care, if needed, which should prevent dental caries and periodontal disease.

Seizure Disorder
Recent estimates indicate that the frequency of seizures in Down Syndrome ranges between 2.6 and 8.8% (Pueschel and Rynders, 1982). MacGillivray (1967) reported the prevalence of grand mal seizures to be 8.1%. Infantile spasms are also seen in young children with Down Syndrome. In a study of 89 children with Down Syndrome (Pueschel, 1984) 5 infants developed infantile spasms when they were less than 1 year old. After ACTH treatment, these children displayed marked improvement and their subsequent developmental progress was similar to that prior to the onset of seizures.

It is important to recognize seizure disorders in youngsters with Down Syndrome and to initiate prompt treatment with anticonvulsant medications.

Sleep Apnea
Several reports have appeared on sleep apnea due to upper airway obstruction in children with Down Syndrome (Southall et al., 1987; Phillips and Rogers, 1988). The upper airway can be obstructed by large tonsils and adenoids, lingual tonsils, choanal stenosis, or glossoptosis. Children usually are noted to have noisy breathing, frequent apnea and snoring during sleep, alveolar hypoventilation and arterial hypoxemia. Children with this symptom complex may not only have poor drainage of fluid from the middle ear via the Eustachian tube causing frequent serous otifis media, but more importantly, may also suffer from cerebral hypoxia and develop pulmonary artery hypertension with resulting cor pulmonale and heart failure. Children who are diagnosed to have upper airway obstruction often can be treated successfully by tonsillectomy and adenoidectomy, a modified pharyngopalatal surgical approach (Strome, 1986) or, at times, by tracheostomy.

Visual Impairment
Children with Down Syndrome frequently have eye disorders including blepharitis, strabismus, keratoconus, nystagmus, hypoplasia of the iris, and refractive errors. It has been reported that up to 70% of children with Down Syndrome have refractive errors, most of them are myopic. Nearly half of the children with Down Syndrome have strabismus, about 35% have congenital nystagmus, and 20% have a blocked tear duct (Mumma, 1984).

Because children with Down Syndrome have such a high frequency of eye disorders, they should be examined regularly by a competent pediatric ophthalmologist. Normal visual acuity is important for any child. However, if the child is mentally retarded, as most youngsters with Down Syndrome are, an additional handicap of sensory impairment may further limit the child's overall functioning and may prevent the child from participating in significant learning processes.

Audiologic Dysfunction
Numerous reports from the literature attest to the fact that 60-80% of children with Down Syndrome have middle ear involvement, often resulting in hearing deficit (Schwartz and Schwartz, 1978; Balkany et al., 1979a). Most persons with Down Syndrome who have middle ear problems have a conductive hearing loss. In addition, some children may have abnormalities of the ossicular chain as reported by Balkany et al. (1979b). Eustachian tube dysfunction, increased lymphoid tissue in the hypopharynx, and abnormal function of the tensor veli palatini muscle may be responsible for the increased prevalence of fluid accumulation in the middle ear with resulting hearing impairment observed in many children with Down Syndrome. Treatment approaches include antibiotic therapy, placement of ventilation tubes into the middle ear, and/or amplification.

A hearing impairment in young children with Down Syndrome may affect their psychological development. Therefore, proper assessment of the child's hearing and prompt treatment if a hearing loss is uncovered are of paramount importance. It has been well documented that even a mild conductive hearing deficit may lead to a reduced rate of language development and secondary interpersonal problems.

Thyroid Disorders
Although there are only a few reports in the medical literature indicating hyperthyroidism in children with Down Syndrome, most investigators have found hypothyroidism in this population. Some authors estimate the prevalence of thyroid disorders to vary from 3 to 50%. Pueschel and Pezzullo (1985) found that up to 20% of children with Down Syndrome had evidence of either compensated or uncompensated hypothyroidism.

It thyroid dysfunction is not recognized early, it may further compromise the children's central nervous system function. Because of the clinical symptoms of hypothyroidism are sometimes interpreted as being part of the "Down Syndrome Gestalt," thyroid function studies including T4, TSH, and others, if indicated, should be carried out at regular intervals. It a person with Down Syndrome is found to be hypothyroid, prompt thyroid hormone treatment should be forth coming. Optimal thyroid function then will allow normal learning processes to take place.

Atlantoaxial and Atlantooccipital Instability
It has been estimated that between I 0 and 30% of individuals with Down Syndrome have either atlantoaxial instability, atlantooccipital instability, or both (Pueschel and Scola, 1987; Powers et al., 1989). In a large scale study (Pueschel and Scola, 1987), atlantoaxial instability was observed in 15% of individuals with Down Syndrome, 13.5% had asymptomatic and 1.5% symptomatic atlantoaxial instability. More recently Powers et al. (1989) observed that up to 30% of youngsters with Down Syndrome have atlantooccipital instability.

It is usually recommended that individuals with atlantoaxial instability not engage in certain sport activities that potentially could injure their neck. If neurologic symptoms become apparent, surgical intervention is indicated.

Both atlantoaxial and atlantooccipital instability in individuals with Down Syndrome should be identified as early as possible because of its relatively high prevalence and its potential for remediation. We recommend that a radiograph of the cervical spine be obtained in all persons with Down Syndrome at age 21/2 or older. Since most individuals with Down Syndrome may have difficulties verbalizing specific complaints relating to neck discomfort and neuromotor difficulties, a neurologic examination and radiographic studies are often indicated. Sometimes, their motor dysfunction and broad-based gait may conceal significant neurologic concerns. Therefore, it is important to diagnose children with atlantoaxial and atlantooccipital instability, since a delay in recognizing these conditions may result in irreversible spinal cord damage.

Clinical Aspects in Adolescence

Adolescent Development
Adolescence is frequently a challenging time for both the young person with Down Syndrome and the family. This may be a very troublesome time period even for those of normal intellectual abilities; however, a mentally retarded adolescent's problems are frequently intensified at this time. Adolescents with Down Syndrome have many of the physical attributes of normal youngsters, however, they often do not possess the intellectual and behavioral capabilities to cope with either the demands of the environment or their own desire for independence. They are faced with preparing for vocational competence as well as developing an array of social skills needed to function in society.

In recent years novel programs that focus on the transition from adolescence to adulthood have been developed with the goal to assist the young person with Down Syndrome to prepare for the world of work.

We have studied adolescent development in boys with Down Syndrome (Pueschel et al., 1985) and found that the patients' secondary sex characteristics are quite similar to those of normal youngsters. There was no significant difference between the size of the genitalia of adolescents with Down Syndrome and that of normal control boys. Concerning hormone measurements, serum follicle stimulating hormone, lutinizing hormone, and testosterone levels increased with advancing age up to 18 years in our study population similar to those hormonal changes observed in normal adolescents.

With regard to the sexual maturation of girls with Down Syndrome, our studies showed that the average onset of menstruation was 12.5 years, whereas the average menarche of their nonhandicapped sisters was 12.1 yours. Most girls and women with Down Syndrome have regular menstrual cycles. The length of the menstrual cycle varies between 22 and 33 days with a mean of 27 days. Their average menstrual flow lasts approximately 4 days. Two-thirds of the adolescent girls with Down Syndrome have concomitant symptoms such as cramps, headaches, lethargy, and abdominal bloating.

Ovulatory patterns of women with Down Syndrome were studied by Tricomi et al. (1964). These investigators found that 39% of the women showed a definite pattern of ovulation, 15% probably ovulated, another 15% possibly ovulated, and 31 % had no evidence of ovulation.

Although both males and females with Down Syndrome displayed fairly normal sequential development of primary and secondary sex characteristics and their pituitary-gonadal axis appears to be intact, there are still many unanswered questions concerning the adolescents' sexual functions, libido, and fertility. Since most individuals with Down Syndrome now live in the community with all its risks, opportunities, and freedoms, it is paramount that further studies concerning adolescent and sexual development be pursued.

Health Issues in Adolescence
Most youngsters with Down Syndrome enjoy good health during adolescence. Although the above described medical concerns in childhood such as sensory impairments, thyroid dysfunction, skeletal abnormalities, and sleep apnea are also observed in some adolescent persons with Down Syndrome, there are several clinical conditions that are more prevalent during this time period which will be discussed briefly. These conditions include increased weight gain, skin infections, and psychiatric disorders.

Increased Weight Gain
As mentioned above, many adolescents with Down Syndrome have a tendency to become overweight. This is usually due to increased food intake, reduced activity level, and a decreased intracellular metabolic rate. Growth charts of adolescents with Down Syndrome show that a certain number of individuals gain more weight than one would ordinarily expect.

Parents of children with Down Syndrome should have nutritional counseling starting shortly after the birth of their child in order to establish appropriate eating habits that will prevent obesity in their child.

Skin Infections
Youngsters with Down Syndrome, in particular those who are overweight, usually develop skin infections in the perigenital area, their buttocks, and thighs. These infectious lesions usually start out as follicular pustules which subsequently may develop into abscesses if not treated promptly. Approximately 50-60% of adolescents with Down Syndrome have these skin infections. With proper skin hygiene, application of antibiotic ointment if follicular skin eruptions are noted, and sometimes systemic antibiotic treatment if there are recurrent multiple abscesses, these infections can usually be controlled.

Psychiatric Disorders
In recent years we have seen many individuals with Down Syndrome with depressive disorders, conduct disorders, and adjustment problems. The family environment may be an important factor in the type of behavioral symptoms expressed in the adolescent. Youngsters coming from more dependent family environments tend to often have emotional and mood disorders, whereas those from homes where there is discord and conflict may be at a greater risk for antisocial behavior. Of course, supportive families have the best outcome in regard to behavior in adolescents with Down Syndrome. We have seen several young persons with Down Syndrome with grief reactions following bereavement. When the adolescent has a nonadaptive response following an identifiable stress, an adjustment disorder may develop. Although affective disorders, particularly major depressions, have rarely been reported in persons with Down Syndrome, recent observations found several of them with depressive episodes. Specific treatment and counseling are indicated when the diagnosis of a behavioral or psychiatric disorder has been made.

Clinical Aspects in Adulthood

Many of the topics that have been discussed before also pertain to the mature person with Down Syndrome. Appropriate nutrition, regular exercise, prevention of infectious diseases, testing for thyroid disorders, identification of skeletal abnormalities, routine dental examinations, and others are equally important in this age group. However, 5 conditions need particular mention:

Cataracts
A high frequency of acquired cataracts (30-60%) has been reported in adults with Down Syndrome. However, most cataracts rarely become dense enough to warrant surgery.

Hypothyroidism
Hypothyroidism is more often observed (up to 50%) in adults with Down Syndrome than in younger children. Therefore, thyroid function tests should be carded out in these individuals at least yearly.

Mitral Valve Prolapse
Mitral valve prolapse and aortic regurgitation have been found to be more prevalent in adults with Down Syndrome necessitating regular cardiac examinations. If mitral prolapse and aortic regurgitation have been identified in a person, antibiotic prophylaxis is recommended prior to dental examinations and surgical procedures.

Hearing Loss
Many persons with Down Syndrome above the age of 20 have a high frequency hearing loss. If the hearing impairment is moderate to severe and is also noted in the lower frequencies, persons with Down Syndrome may need amplification.

Alzheimer Disease
Another condition which deserves special attention in the adult person with Down Syndrome is related to the aging process. There have been many reports of a high prevalence of Alzheimer disease in adults with Down Syndrome. Malamud (1964) noted that almost l00% of the autopsies of 35 persons with Down Syndrome 40 years and older showed evidence of Alzheimer disease in contrast to only 14% of a comparable mentally retarded non-Down Syndrome group. Also, Burger and Vogel (1973) acknowledged full development of Alzheimer morphology in individuals with Down Syndrome. These authors found senile plaques, even beginning in the second and third decades of life. They also noted neurofibrillary changes and granulovacular degenerations as well senile plaques in the hippocampal region in persons with Down Syndrome.

Although neuropathologic specimens from autopsies indicate that persons with Down Syndrome have histologic evidence of Alzheimer disease, one cannot state categorically that Alzheimer disease will be present in all persons with Down Syndrome beyond the age of 30 or 40. Reports from institutions for persons with mental retardation as well as our own observations indicate that many adults with Down Syndrome are as "normal" as other handicapped people and hardly ever exhibit personality changes or psychological problems as observed in Alzheimer disease. Ellis et al. (1974) mentioned that the detection of dementia may be difficult. In spite of these difficulties, observations of early signs of Alzheimer disease have been reported in 15-25% of elderly persons with Down Syndrome.

Conclusion

As detailed above, there are numerous clinical concerns in persons with Down Syndrome which should be taken into consideration in the course of their medical care. If provided with optimal medical services, fostering their well-being in all areas of human functioning, the quality of life of individuals with Down Syndrome will be enhanced and their contribution to society will be substantial.

References

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