Mental Retardation (learning Difficulties )
prof elham aljammas April 2017In ICD -10 and DSM-1V the term mental retardation denotes intellecual impairment starting early in life ( as distinct from dementia which is intellecual impairment developing later in life ). Other term of this condition include Mental deficiency . Mental subnormality . Mental handicap . learning difficulties .
Educationalists use a different classification based on a person ability to benefit from education and training .The group of mental retardation are recognized :-According to the degree of impairment –Mild IQ 70-50Moderate IQ 49-35Severe IQ 34-20Profound IQ below 20.
AETIOLOGY OF MENTAL RETARDATION (LEARNING DIFFICUTIES)
Mild mental retardation is usually due to a combination of genetic and environmental factors.Sever mental retardation is usually due to pathological conditions of which most can be diagnosed in life and about two — thirds before birth.Both mild and sever retardation are more common in the lower social classes possibility because of loss effective preventive measures.GENERAL CAUSES
I - Conditions with Known aetiology A- Prenatal Factors 1 Genetic causes a- Chromosomes Autosomes Down’s syndrome Sex chromosomes Klinefelter’s syndrome (XXY),Turner’s syndrome (XO) b- Genes Dominant genes Neurofibromatosis, and Tuberose sclerosis (Epiloia) Recessive gene phenyketonuria,Homocystinuria Galactosaemia.Sex -Linked genes Lesch — Nyhan syndrome2- Environmental FactorsMaternala- Infections (Rubella, Syphilis , Others) b- Intoxications -any drug in pregnancy is a potential teratogenic (Toxic) c- Irradiation — XR radiation d – Malnutrition 3- Interaction of genetic and environmental factors a- Abnormality in the Neural tube system. b- Incompatibility c- specific biochemical abnormalities
B- Perinatal factors Injury during delivery Hypoxia of the brain-cerebral palsy. C- Postnatal factors a- Infections -Meningitis , Encephalitis b- Intoxications- Leed, Murcory other heavy metals c- Injury like head injury causes brain lesion. d- Psychological factors - child reacts to the traumatic experience by many, protective mechanisms II- Conditions with Unknown aetiology a- Syndromes -occurring sporadically in the family (de- Lange , Sturge weber syndromes). b- Some cases of mild mental retardation with no physical abnormality some time occurring familially.
Some Examples Of Mental Retardation (Learning Difficulties)
1. Fragile X syondromeIn this condition a break is seen in an X chromosome in proportion of cells cultured in a medium deficient folate. About 80 per cent of males and about 30 per cent of females with a fragile X chromosome have mental retardation. The syndrome is the second most frequent cause of mental retardation ( only Down’s syndrome is more common).2- Mongolism (Down Syndrome, Trisomy21 )It is due to chromosomal abnormality type, it is due to an extra chromosome at 21 group of Denver Scale.It is now Known that most mongols born to older mothers have extra chromosome, No. 21 chromosome.Other types of. Mongol have chromosornal translocation, this chromosomal disturbance result from natural aging of the mother that is above 40 years of age.Mongol constitute 5 — 10% of all mental defect.
Clinical features
3- Cri – du- chat syndromedue to chromosal abnormality , it is due to loss of part of chromosome No. 5Clinical featureskitten like crySmall Jaw hypertelorsmsever mental retardation
Sex chromosome abnormalities1- Klinefelter syndrome ( Karyotype xxy) ј of cases are mentally retarded occur in male only.Clinical features very tall gynaecomastia small under developed testes limited sexual drive mental retardation2- Turner’s Syndrome (Karyotype xo ) clinical features Occur only in female short stature primary aminorrhea webbed neek, cubitus valgus, malformation of aorta.Diseases due to genetic abnormalities 1- Epiloia (Tuberous sclerosis ) Clinical features Butterfly shaped rash on nose, checks, chin and forehead epileptic fit mental Retardation 2- Others like Neurofibromatosis sturg-weber syndrome Others: Epilepsy with Mental Retardation
Physical disorder among the mentally retarded
Among the severely and profoundly retarded , most have physical problem such as : Sensory or motor disabilities. Epilepsy Disorder of hearing or vision Motor disabilities are frequent and include spasticity , ataxia and athetosis .Psychiatric disorder among the mentally retarded
All kinds of psychiatric disorder can occur in the mentally retarded and diagnosis may be difficult because of low intelligence .Schizophernia – pt. have limited thinking , delusions and hallucination are simple . - Affective disorder –mentally retarded people with depressive disorder are less lickly than those of normal intelligence to complain of low mood.- Mania is diagnosed mainly on overactivity and behaviour disorder like excitument and irritability .- Adjustment disorder and neurosis :are common among the less severely retarded , conversion and dissociative symptom less common in mentally retarded subject. Personality disorder : these common among the mentally retarded and lead to greater problem in the management. Organic psychiatric disorder : these disorder are common among mentally retarded people . Delirium , is more common among children and elderly. Dementia cause a progressive decline in intelecual and social functioning from previous level .
- Over activity and autistic behaviour : hyperkinetic syndrome occur more commonly among mentally retarded children than among those of normal intelligence , and some of severely retarded children are overactive , distractible and impulsive . - Sexual problems :masturbation in public is the most frequent sexual problem , most of the inherited type associated with infertility , difficult problem may arise when pregnancy occur , termination of pregnancy or sterilization is considered .
The effect of mental retardation on the family
The parent are distressed when they found that the child is mentally retarded , some parent reject the child at first . More often mental retardation is not diagnosed until after the first year of life . The parent may experience prolong depression , with guilt , shame or anger . Most parent achieve a satisfactory adjustment , most parent faced with prolonged hard work and social problem .Assessment of a case mentally retarded
severe mental retardation can usually be diagnosed in infancy as it is often associated with physical abnormalities or delayed motor development . The diagnosis of less sever mental retardation is more difficult because it is based on delayed psychological development , a full assessment include the followings :History taking – any history in the family suggested an inherited disorder and abnormality in pregnancy or delivery. physical examination : the physical ex. Include recording head cirumfernce , height and weight , attention to the vision and hearing .Behaviouaral assessment –based on observations of child’s ability to communicate , sensory , motor skills and any usual behaviour , it is often to ask parent , teacher and others involved .
4. Developmental testing : this include measurements of intelligence , languages motor performance and social skills. 5.Biochemical screening : for any enzymetic deficiency and in born error of metabolism .
Prevention of mental retardation
1.SegregationThat is as mentally defective must not marry and have children .2. Sterilization : either by casteration or tubal ligation .3. Birth control .4. Public education –Dr. should give advice an genetic and general health of community .5. Treating the infection .6.Treating the epidetic fit.7. Dealing with intoxications .Management of mental retardation
Medical - critinism , phenylkitonura early by special diet . - epilepsy by antiepleptic drugs. - abnormal behaviour by minor T. and hypnotic . - minimal brain lesion by T. and behaviour modification techniques .2. Surgical – for hydrocephaluscranial deformity Temporal lobectomy for temporal lobe epilepsy. 3. Service for mentally retarded Services for prevention – - genetic screening and counselling . - anti-natal care by immunization of woman before the pregnancy . - post –natal care for phenylketonuria, hypothyroidism and galactosaemia.
2. Special services - care of the mildly retarded by the parent and family Dr. - care of severely retarded children in hospital and school . - care of adolescent and adults particular problem arises in adolescent services required for employment . - care for family parent need help as soon as the diagnosis of retardation is made .
3. Education , training and occupation services - education and training should begin early . - extra education and training before school age can help retarded children after having the school most mildly retarded people are able to work .