Complications
About 50% of people with Down's syndrome (DS) have congenital heart disease (CHD).[17][28][29] Atrioventricular septal defect is the most common form of CHD in DS (31% to 61% in population-based studies of CHD subtypes in DS), with a much higher prevalence than in the general population.[33]
Evaluation by a paediatric cardiologist, including an echocardiogram, is recommended in all newborns with DS (even in the absence of a murmur).[17][28][29]
Children with Down's syndrome (DS) may have shorter arms and legs than age-matched peers without DS. Their growth rate and height may be decreased. Likelihood for obesity may be greater, possibly caused by inactivity and low muscle tone.
Weight, length, weight-for-length, head circumference, and BMI should be measured at each well-child visit throughout childhood and adolescence.[17]
Infants with Down's syndrome (DS) can be born with transient myeloproliferative disorder which is a form of leukaemia. Children with DS have a higher risk of acute myeloid leukaemia (AML) than the general population, with a median onset of 2 years compared with 8 years in the general population. Most cases of AML in children with DS occur between the aged of 1 and 5 years, with an average age of 2 years. After age 3 years, acute lymphocytic leukaemia (ALL) occurs more frequently, with most cases occurring by age 6 years. Children with DS are more responsive to certain forms of chemotherapy, and disease resistance and recurrence are uncommon.
After age 3 years, acute lymphocytic leukaemia (ALL) occurs more frequently than acute myeloid leukaemia (AML), with most cases occurring by age 6 years. Children with Down's syndrome are more responsive to certain forms of chemotherapy, and disease resistance and recurrence are uncommon.
Much more common and earlier age of onset than in the general population. Pathological findings are present in the brain of nearly all people with Down's syndrome (DS) by age 40, although not all will display signs of Alzheimer's disease. The average age of onset is 54.5 years.[75] Adults with DS and suspected or possible Alzheimer's disease may show significant decline in cognitive abilities as well.[76]
A rare but increasingly recognised cause of developmental regression in teens and young adults with Down's syndrome. Can include loss of previously acquired developmental skills, catatonia, agitation, hallucination, depersonalisation.[74]
Develops in about 10% of infants with Down's syndrome. Typically resolves spontaneously within 3 months. Despite most infants with transient leukaemia recovering on their own, 20% to 30% of these cases will later be diagnosed with a more serious disease, acute megakaryocytic leukaemia (AMLK), which is a subtype of acute myeloid leukaemia (AML).[79][80]
Rate is about 8%. Types of seizure disorder vary: 47% focal seizures, 32% infantile spasm, 21% to 69% tonic-clonic seizures.[81]
Enquire about the occurrence of signs and symptoms of neurological dysfunction (such as seizures), and perform a neurological exam at least annually throughout childhood.[17]
Adults with Down's syndrome (DS) have a lower rate of psychiatric disorders than adults with other cognitive disabilities. However, depression in adults with DS is estimated to be about 11% and may be attributed to several factors: challenges in transitioning from childhood to adulthood, increased awareness that they are different and may change, loss of personal relationship with their peers, obesity leading to a sedentary lifestyle, poor diet, limited exercise and/or social activity, and medical complications such as hypothyroidism and obstructive sleep apnoea.[78]
Many children with Down's syndrome have global developmental delay. Cognitive abilities vary greatly, with challenges in the expressive language domain compared with receptive language. IQ can range from mild to moderate intellectual disability, between 40 and 72.
Chronic ear disease and hearing loss can further affect language development.[70]
Ongoing developmental assessment and psycho-educational evaluation is recommended.
An estimated 30% to 60% of children with Down's syndrome (DS) have obstructive sleep apnoea. Predisposing factors include small upper airway, mid-face and mandibular hypoplasia, large adenoids, protruding tongue, hypotonia, and obesity.[70]
Referral for a sleep study or polysomnogram for all children with DS is recommended between 3 and 4 years of age.[17] Appropriate therapies may include tonsillectomy/adenoidectomy or supplemental oxygen during sleep.[71] Physicians are encouraged to discuss symptoms of sleep problems at every well-child care visit.
Adults with DS have more predisposing factors for obstructive sleep apnoea than children with DS, as they will have the craniofacial anomalies and are also more likely to be obese or have hypothyroidism. Adults with DS who have obstructive sleep apnoea may also have signs of hypoxaemia, hypoventilation, and sleep fragmentation, which may increase their risk for cardiovascular and neurological complications.[72]
The higher frequency of (mostly conductive) hearing loss in children with Down's syndrome (DS) is secondary to their anatomical anomalies, including mid-face hypoplasia, easily collapsible eustachian tube, stenotic ear canals, and small external canal.
Hearing screen is required in all newborns in general. Hearing evaluations should be repeated at 6 months, 12 months, and once a year thereafter.[17]
Referral to a paediatric otolaryngologist is recommended if tympanic membrane is not visualised and/or otitis media recurs frequently.[17]
Aggressive interventions, both medical and surgical, have led to decreased incidence of hearing loss, good control of chronic rhinitis, and timely diagnosis of sleep-disordered breathing in individuals with DS.[70]
In general, placement of myringotomy tubes are considered if there are >4 ear infections in 6 months, >6 ear infections in 1 year, or persistent middle ear fluid for 3 consectutive months.[34] Additionally, as children with DS are prone to chronic ear disease, it will be important to assess the need for multiple sets of myringotomy tubes.
Interval ear examinations (i.e., every 3-6 months) may need to be performed by the otolaryngologist until the tympanic membrane can be visualised by the paediatrician and tympanometry can be performed reliably.[17]
The immune system in children with Down's syndrome has clinical and laboratory differences that predisposes children to a higher incidence of upper respiratory tract infections, chronic middle ear effusions, and chronic otitis media.
Hypothyroidism is particularly common in Down's syndrome (16% to 20%) and may be detected by newborn screening or during yearly routine screening.
Hyperthyroidism occurs at a lower frequency than hypothyroidism.[28][35]
All newborns are required to have a newborn screening, including thyroid testing. If the screen is normal, a follow-up for thyroid function with thyroid-stimulating hormone measurements at 6 months, 12 months and then yearly is recommended throughout childhood and adolescence. More frequent thyroid tests (i.e., every 6 months) are indicated if anti-thyroid antibodies are detected at any point.[17]
As a result of low resting metabolic rates, about one half of all girls with Down's syndrome (DS) are overweight by the third year of life and one half of all boys with DS are overweight by early childhood (3-8 years of age).[73]
Refer to a physician with expertise in paediatric sleep for any child with signs or symptoms of obstructive sleep apnoea or abnormal sleep study result. Discuss obesity as a risk factor for sleep apnoea.[17]
Consistent exercise and a balanced diet are recommended. Routinely screening for obesity and sleep apnoea is important.[17]
Congenital cataracts are seen in 4% of children with Down's syndrome (DS).[5] Nasolacrimal duct may be obstructed as a complication of mid-face hypoplasia but it improves with age.
Other abnormalities include strabismus (23% to 44%), accommodative esotropia, myopia, hyperopia, and blepharitis.[35]
Children with DS should have an ophthalmic evaluation with photoscreening at each well-child visit. Abnormal findings or lack of access to photoscreening should prompt referral to a paediatric ophthalmologist. If lacrimal duct obstruction is present, refer for evaluation for surgical repair of the drainage system if not resolved by 9-12 months of age.[17]
Include delayed primary and secondary dentition, missing teeth, small or misshapen teeth, or severe crowding as a result of small oral cavity.[35] Average age of eruption of the first tooth is between 12 and 20 months, as compared with 6 months in typically developing children.
Skin disorders such as xerosis, hair thinning, alopecia areata, vitiligo, folliculitis, and keratosis pilaris are common in children with Down's syndrome, and parents and paediatricians should be attentive to signs and symptoms. Xerosis and hair thinning could be a sign of hypothyroidism and may warrant an interim thyroid function test.[17]
Patients with behavioural problems, including inattention, hyperactivity, or withdrawal, should receive a behavioural assessment and tailored behavioural intervention. In certain cases, psycho-pharmacological intervention may be necessary and should be explored with the child's primary care physician and/or child psychiatrist or developmental-behavioural paediatrician.
Present in <1% of individuals with Down's syndrome.[17]
May be indicated by history of chronic constipation not responding to diet change or stool softeners.
Caused by intolerance to gluten (a protein in wheat, rye, barley, and possibly oats). Damages the small intestine and prevents absorption of nutrients from food.
Occurs in 7% to 16% of individuals with DS and may present with diarrhoea, bloating, or growth failure. About one third of individuals with Down's syndrome who have coeliac disease may not manifest gastrointestinal signs and symptoms.[28][35]
Screening for total immunoglobulin A and anti-tissue transglutaminase antibodies is recommended if symptoms associated with coeliac disease are noted.[17]
Present in 7% to 19% of children with Down's syndrome (DS), although most studies are limited by sample size and ascertainment bias.[77][78]
As for all children, children with DS should be screened for autism spectrum disorder (ASD) between 18 and 24 months of age. If there is suspicion of ASD, early referral to a specialist is imperative.[17]
About 15% of patients have lax atlanto-axial joints (atlantodens interval >4.5 mm on the lateral spine x-ray in flexion, neutral, and extension view). May result in spinal cord compression in 1% to 2% of cases.
In terms of atlanto-axial subluxation, symptoms of myelopathy should be sought, including neck pain/stiffness, changes in head positioning or torticollis, spasticity or change in tone, radiculopathy, changes to gait loss or previously attained bowel/bladder control, or hyper-reflexia. Cervical spine x-ray is indicated if symptoms are present. A careful history and physical is important at all health maintenance examinations.[17]
Musculoskeletal disorders, such as ligamentous laxity and low muscle tone, may contribute to knee and hip problems, and increase susceptibility to subluxation and dislocations.[35]
Children with Down's syndrome are not at increased risk of solid tumors with the exception of testicular cancer.[82]
For this reason, the testes should be palpated in males at each well-child visit to check for lumps or swelling. Testicular self exams should be taught to adolescents and adults with Down's syndrome or to their trusted carers.
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