Learning disability. Flashcards
Define learning disability
Learning disability (mental retardation) = state of arrested or incomplete development of the mind. Characterised by impaired skills manifested in the developmental period (e.g. cognitive, language, motor and social abilities)
Triad of LD
- Low intellectual performance (IQ <70)
- Onset during birth or early childhood
- Wide range of functional impairment (e.g. social handicap…)
Define impairement
any loss or abnormality of psychological, physiological or anatomical structure or function
Define disability
any restriction or lack of ability to perform an activity in the manner or w/in the range considered normal for a human being
Define handicap
a disadvantage for a given individual, resulting from impairment or disability that limits or prevents the fulfilment of a role that is normal for that individual
ICD-10 criteria mental retardation
F70-79
4 categories depending on the severity
Mild mental retardation
- IQ 50-69 (Mental age: 9-12)
- Some learning difficulty at school (identified here); adults able to work + maintain good social relationships + contribute to society
- Adequate language + social + self-care skills
- Difficulties in academic work
- Most live indep. → some need support in housing + employment
Moderate mental retardation
- IQ 35-49 (Mental age: 6-9)
- Language limited (but still can communicate)
- Supervision for self-care but able to do simple work
Severe mental retardation
- IQ 20-34 (Mental age: 3-6)
- Marked degree of motor impairment
- Little or no speech (early childhood) → may eventually have simple comm.
- Associated physical disorders
Profound mental retardation
- IQ <20 (Mental age: <3)
- Severe motor impairment
- Severe difficulties in communication
- Little or no self-care
- Usually require residential care
Aetiology LD
Genetic eg Downs Antenatal eg congen infection such as rubella Perinatal eg IVH Neonatal eg meningitis Postnatal eg CP
Genetic causes LD
• Autosomal chromosome disorders → Down’s
• X linked syndromes →
o X linked dominant syndromes: Fragile X syndrome, rett’s syndrome, Aicardi syndrome
o X linked recessive syndromes: Hunter syndrome, Lesch-Nyhan syndrome, oculocerebrorenal syndrome of Lowe,
• Deletions + duplications → Prader-Willi syndrome (partial deletion Chromosome 15), Cri du chat (partial deletion chromosome 5), Angelman syndrome, beta thalassaemia mental retardation, DiGeorge syndrome, Rubenstein-taybi syndrome, Smith-Magenis syndrome, Williams syndrome, Wolf-Hirchhorn syndrome
• Autosomal dominant conditions → Noonan’s syndrome, tuberous sclerosis, neurofibromatosis T1 (chromosome 17), neurofibromatosis T2 (chromosome 22), sturge-weber syndrome, Von Hippel-Lindau syndrome [renal carcinoma!!!]
• Autosomal recessive conditions → Phenylketouria (chromosome 12; diagnosed at Guthrie test), sanfilippo disease, Hurler syndrome, Laurence-Moon syndrome, Joubert syndrome, gaucher’s disease
• Presumed polygenic conditions → neural tube defects, pervasive developmental disorders
• Mitochondrial disorders [maternally inherited] → myoclonic epilepsy w/ ragged red fibres
• Sex chromosome disorders → turner’s syndrome (one X chromosome, female phenotype), trisomy X, klinefelter’s syndrome, XYY male
Antenatal causes LD
Congenital infection (rubella, CMV, toxoplasmosis)
nutritional def
intoxication (alcohol, cocaine, lead)
endocrine disorders (hypothyroidism, hypoparathyroidism)
physical damage (injury, radiation, hypoxia)
antepartum haemorrhage
pre-eclampsia
Perinatal causes LD
Birth asphyxia
intraventricular haemorrhage
neonatal sepsis
Neonatal causes LD
Hypoglycaemia
meningitis
neonatal infections
kernictus (due to hyperbilirubinaemia)
Postnatal causes LD
Cerebral palsy infection (meningitis, encephalitis) anoxia metabolic (congenital hypothyroidism, hyponatraemia) iodine def.
Environmental causes LD
Neglect
NAI (non-accidental injury)
malnutrition
socioeconomically deprived
Psychiatric causes LD
Autism
Rett’s syndrome (genetic disorder affecting brain development [seizures!!])
CFs LD
- Common physical problems: motor (e.g. ataxia, spasticity), epilepsy, impaired hearing/vision, incontinence
- See each severity (in criteria section)
Dx + Ix LD
Establishing cause:
• Hx → FH, Gestational Hx, birth Hx, neonatal hx, childhood Hx (inc. developmental milestones)
• Physical examination: dysmorphic features, developmental exam…etc
• Ix
o Standard: FBC, U+Es, LFTs, TFTs, glucose, infection screening (blood + urine), serology (CMV, toxoplasmosis…)
o If dysmorphic features → XR skull…etc
o Metabolic disorder suspected → screening (blood + urine)
o If genetic disorder suspected: karytoping
o Other: neurophysiological test (EEG), neuroimaging…etc
IQ test!!!!
Treatment LD
- MDT approach → GP (physical health problems), psychiatrist, SALT, specialist nurses, psychologist, OT, social worker, teachers
- Antipsychotics → challenging behaviour
- Behavioural techniques → applied behavioural analysis, +ve behaviour support, CBT
- Family education
Prevention
Genetic counselling + antenatal diagnosis
Down’s syndrome - pathophysiology / aetiology + RFs
- Trisomy 21
- Maternal age >40
- Previous child w/ T21
- T21 in mother
CFs Down’s - physical features
Physical features (PROBLEMS)
• Palpebral fissure
• Round face
• Occipital + nasal flattening
• Brushfield spots (on iris) + brachycephaly
• Low-set small ears
• Epicanthic folds
• Mouth open + protruding tongue (small mouth)
• Strabismus (squint), sandal gap deformity, single palmar crease
• Also: short stature, overweight
CFs Down’s - medical problems
- Congenital heart defects (VSD, ASD, mitral valve disease, PDA, ToF)
- Congenital GI abnormalities (oesophageal atresia, duodenal atresia, Hirschsprung’s, coeliac)
- Hypothyroid
- Haematological malignancies (AML, ALL)
- Alzheimer’s disease
- Others: sensorineural deafness…etc
CFs Down’s - psychiatric problems
- Depression
- Learning disability
- Less common: BPAD, OCD, tourette’s, schizophrenia, ^ risk of autism
Investigations Down’s
During pregnancy:
o EITHER → serum screening (beta-hCG + pregnancy-associated plasma protein A) and nuchal translucency on USS
o OR → Quadruple testing: beta-hCG, alpha-fetoprotein, inhibin A, estriol
What is Fragile X syndrome?
- 2nd commonest cause of LD
- M>F (due to protective effects of second normal X chromosome in females)
- Variable LD (mild → profound)
Pathophysiology fragile X syndrome
X-linked dominant transmission
CFs fragile X syndrome - behaviour
Behaviour (similar to autism): hand flapping/waving, repetitive mannerisms, shyness, gaze avoidance, poor peer relationships, perseveration, echolalia (meaningless repetition of another person’s spoken words), palilalia (involuntary repetition of words, phrases or sentences), over detailed speech
CFs fragile X syndrome - physical & medical
- Large testicles + ears
- Smooth skin
- Hyperextensible fingers
- Flat feet
- Mitral valve prolapse
- Inguinal + hiatus hernia
- Facial: long, narrow face w/ underdevelopment of mid-face, macrocephaly
- Epilepsy
- Psychiatric problems: depression + anxiety
Ix fragile X syndrome
Brain imaging → reduced posterior cerebellar vermis, enlarged hippocampus + causate nuclei, enlarge ventricles
