In 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
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Mental deficiency.
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Mental sub normality.
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Mental handicap.
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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 –
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Mild IQ 70-50
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Moderate IQ 49-35
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Severe IQ 34-20
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Profound IQ below 20
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Psychiatry
Zakho hospital
Mental Retardation Dr. Elham
(Learning Difficulties)
Sunday, April 23, 2017
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AETIOLOGY OF MENTAL RETARDATION (LEARNING DIFFICUTIES)
Mild mental retardation is usually due to a combination of genetic and
environmental factors.
Severe 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, andTuberose sclerosis (Epiloia)
Recessive gene :
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phenyketonuria,
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Homocystinuria
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Galactosaemia.
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Sex -Linked genes Lesch — Nyhan syndrome
2- Environmental Factors
Maternal
a- Infections (Rubella, Syphilis , Others)
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b- Intoxications -any drug in pregnancy is a potential
teratogenic (Toxic)
c- Irradiation — XR radiation
d- d – Malnutrition
3- Interaction of genetic and environmental factors
a- Abnormality in the Neural tube system.
b- Incompatibility
c- specific biochemical abnormalities
Perinatal factors
Injury during delivery
Hypoxia of the brain-cerebral palsy.
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.
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Some Examples Of Mental Retardation
(Learning Difficulties)
1. Fragile X syondrome
In 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
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mentally Retarded
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Small rounded head
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Close-set eyes
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Oblique palpebral fissures
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Eepicanthi c folds
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both male and female Mogols are poorly developed sexually and
Hypofuntion of other endocrine glands about ½ Mongol have
congenital heart defect.
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small mouth and teeth , furrowed tongte , and high-arched palate.
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Hands-short and broad with curred fifth finger and a single transverse
palmar crease.
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Hyperextensible, hyperflexible, hypotonic joints.
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3- Cri – du- chat syndrome
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due to chromosal abnormality , it is due to loss of part of chromosome
No. 5
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Clinical features
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kitten like cry
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Small Jaw
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hypertelorsm
Severe mental retardation
Sex chromosome abnormalities
1- Klinefelter syndrome ( Karyotype xxy) ¼ of cases are mentally retarded
occur in male only.
Clinical features
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very tall
o
gynaecomastia
o
small under developed testes
o
limited sexual drive mental retardation
2- Turner’s Syndrome (Karyotype xo )
clinical features
o
Occur only in female short stature primary aminorrhea
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o
webbed neek,
o
cubitus valgus,
o
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 :
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Sensory or motor disabilities.
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Epilepsy
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Disorder of hearing or vision
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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
.
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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 :
1. History taking – any history in the family suggested an inherited
disorder and abnormality in pregnancy or delivery.
2. physical examination : the physical ex. Include recording head
cirumfernce , height and weight , attention to the vision and hearing .
3. 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.
5.Biochemical screening : for any enzymetic deficiency and in bo
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error of metabolism .
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Prevention of mental retardation
1.Segregation
That 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.
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. Dealing with intoxications
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Management of mental retardation
1. 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 hydrocephalus
cranial deformity
Temporal lobectomy for temporal lobe epilepsy.
3. Service for mentally retarded
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1. 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 .
A.L.Y