Level 1 - Development/Behaviour Flashcards
What is Down’s syndrome?
- Trisomy of chromosome 21
Epidemiology of Down’s syndrome?
- Commonest cause of learning disability
- Most common chromosomal abnormality
- Life expectancy 55 years
Risk factors for Down’s syndrome?
- Increased maternal age
- Family history
- Aetiology
- Non-dysjunction of c21 at meiosis
- Rarer – Robertsonian translocation or mosaicism
Features of Down’s syndrome birth?
- Increased rate of spontaneous miscarriage - Presents at birth
Hyperflexibility, hypotonia
Bradycephalc, oblique palpebral fissures, epicanthic folds, ring of iris speckles
Low set ears, flat nasal bridge, protruding tongue, high arched palate
Single palmar crease
Short broad hands
Wide sandal gap between first and second toes
Other features in Down’s syndrome?
- Low IQ (25-70)
- Hearing loss
- Cataracts
- Duodenal or anal atresia
- ASD, VSD, Fallot’s Tetralogy
- Hypothyroidism
- DDH
- Leukaemia
- Almost all develop Alzheimer’s disease by 40 years
Screening available in Down’s syndrome?
o Offered to all women at booking
o Combined test has detection rate of 85%
o A risk of 1:150 or less is classed as high risk and offered invasive diagnostic testing
o Blood sample (10-14 weeks)
Measures beta-hCG, PAPP-A, AFP, uE3
o USS – Nuchal translucency (11-14 weeks)
Measure the size of the nuchal pad at the nape of the fetal neck
Straightforward but has 20% false-positive rate
What is the next step after high risk combined test? What is the NIFT? Invasive diagnostic testing in Down’s syndrome?
If high risk combined test, NIPT screening test offered If NIPT positive (<1:100) then invasive diagnostic testing is offered
o Non-invasive prenatal test
- Detection rate of 99% which screens for Down’s, Edwards and Patau
- Taking blood sample from mother and looking at foetal DNA
o Either chorionic villus sampling (if less than 13 weeks of gestation) or amniocentesis (if beyond 15 weeks of gestation)
o These procedures carry a risk of miscarriage (0.5-1% excess miscarriage risk for amniocentesis)
Management of Down’s syndrome?
- Genetic counselling offered prenatally
- Refer for cardiac assessment, hip USS and audiology
6 weeks - NIPE+ developmental + CV exam + check cataracts
3 & 6 months - follow up
8-10 months - hearing test
- Put parents in contact with a support organisation such as the Down’s Association
- Long-term follow up by a MDT.
What annual testing is needed in Down’s syndrome? What is it like living with Down’s syndrome?
- Annually test TFT- hypothyroid
- Audiology from 18 months - then annually
- Ophthalmic assessment 1-2yearly
Spectrum of disability - on one end, some can lead rich and varied lives (independent, jobs, relationships and marriage) but on the other end they can have severe disability and associated problems
Advances in medical care means people with Down’s can live longer, into 50’s or 60’s depending on level of impairment
Define squint?
- A squint (strabismus) is a misalignment of the visual axes. That is, both eyes are not directed at an object at the same time
What is a pseudo squint?
- A pseudo squint is the impression of misaligned eyes when no squint is present. For example, prominent epicanthic fold
Epidemiology of squint?
- 2% of children have squints
- 60% esotropia
Aetiology of a squint?
o Idiopathic
o Refractive error
o Visual loss
Retinoblastoma, cataract, ocular movements, optic neuropathy
o Cerebral palsy
o Abnormal extra-ocular muscles of innervation
o Cranial III, IV, VI palsies
Risk factors for squint?
o Low birth weight
o Prematurity
o Smoking
o Anisometropia, hypermetropia
o FHx
What are the two types of squint?
o A manifest squint (a ‘tropia’)
A squint present when eyes are open and being used so that when one eye views the object of interest, the other eye is deviated
This may be constant, or intermittent when the squint is present only some of the time
o A latent squint (a ‘phoria’)
A squint that is present only when the use of the two eyes together is interrupted (‘dissociated’)
Describe the directions of a squint?
o Horizontal deviation
Esotropia or esophoria (convergent squint), or exotropia or exophoria (divergent squint).
o Vertical deviation
Hypertropia (upward squint) or hypotropia (downward squint)
o Combined
Describe the squint in relation to eye position?
o Comitant (concomitant) squint
Degree of deviation does not vary with the direction of gaze
This is typical of most childhood squints
This equates to no paralysis or limitation of eye movements but the balance between the muscles in the two eyes has been lost.
o Incomitant (non-comitant) squint
The degree of deviation varies with the direction of gaze
This may indicate an acquired neurological or muscular disease-causing paresis or paralysis of one or more of the extra-ocular muscles resulting in limitation of eye movements.
