Mental Retardation

1. Mental Retardation

2. Contents : • Definition • Prevalence • Classification • Causes • Clinical Evaluation • Investigation • Management

3. Definition Mental Retardation is defined statistically as tested cognitive performance that is two standard deviation below the mean of the general population ( roughly below the 3rd percentile )

4. The Classical definition comprises 3 components : 1- subaverage intellectual function . 2- that result from an injury , disease or abnormality before the age of 18 years . 3- resulting in impaired ability to adapt to the environment .

5. Prevalence : Mental retardation is present in about 2 to 3% of the population.

6. AAMR Classification Scheme IQ classification: I.Q.(intelligence quotient) is 100; normal ranges from 90 to 110 1-Border line { IQ 70-80 } 2-mild MR { IQ 55-70 } 3-moderate MR{ IQ 40-55 } 4-sever MR { IQ 25-40 } 5-profound MR { IQ below 25 }

8. Etiology • Unknown “ 30-40 % “ • Genetic “ 5% “ • Early embryonic ( prenatal ) “ 30% “ • Prematurity , IUGR (perinatal) “ 10 % “ • Acquired medical condition (trauma , infection ..) “ 5% “ • Environment “ 5-20% “

9. Etiology classification : • Prenatal • Perinatal • Postnatal

10. Prenatal causes : »Genetic Disorders : Fragile X syndrome FXS :most common cause . Klinefelter syndrome :male with extra x chromosome 47,XXY Down syndrome : Meabolic disorders: PKU, Tay-sachs, Galactosemia Skin disorders : neurofibromatosis and Tubererous sclerosis . Prader-Willi Syndrom : Endocrine : hypothyroidism

11. Fragile X syndrome (FXS) • Is the commonest cause of MR. • The incidence has been estimated at approximately 1 in 1,500 males and 1 in 2,500 females. • Mutation of a gene on the long arm of the X chromosome is responsible for FXS and involves instability of trinucleotide repeat sequence . • DNA-analysis of the FMR-I gene is the best way to diagnose which is usually done on lymphocytes.

12. Fragile X syndrome (FXS)cont.. • C/P: { phenotype } • Large ears , Large testes (testicular volume>30 ml in adults) , Plantar crease , Hyperextensible joints , Simian crease, • Broad forehead, Increased hand width, Increased hand length , Elongated face, High arched palate , • Mitral valve prolapse , Hypotonia , Hernia, Double jointed thumbs , Scoliosis and Flat feet

13. Fragile X syndrome (FXS)cont.. • C/P: {NEUROCOGNITIVE } • Mental retardation , Hyperactivity , Attentional problems , Language delays , Hand flapping , Hand biting , Irritability , Perseveration , Excessive temper tantrums Gaze avoidance , Sensory aversion , Self-stimulatory behavior and Autism

16. »Cranial Malformations : Anencephaly : microcephaly : Hydrocephaly :

17. »Congenital Factors : Maternal : Rubella , congent. Syphilis & Rh incompitability Toxins :drugs , fetal alcohol syndrom ..

18. Perinatal Causes :  Low Bwt : premature , teen pregnancy , poor nutrition .. 21 % with MR Birth Anoxia : breech presentation , knotted umbilical cord.

19. Postnatal Causes : Child abuse and neglect : Traumatic brain injury : Infection : meningitis and encephalitis Nutritional deficiencies : Cultural and familial :

20. Clinical Evaluation • Complete History : • Examination :

21. History »complete and detailed history« complete systemic review surgical history : trauma , accidents medical illnesses : hospitalization , general heath pregnancy history : maternal age , parity , infections.. birth : type , wt . GA ,complications , apgar score Postnatal : incubator , ventilator , disease ..

22. History (cont.) drugs: mother and child developmental Hx : mile stones , loss it , speech .. educational Hx : schooling , IQ tests behavioral Hx : skills , attention , activity family Hx : consanguinity , inherited ds .. social Hx :

23. Examination »complete and detailed examination« • Growth parameters : • Dysmorphic features : • CNS examination : • Other system and skin exam : • IQ tests : • Developmental testing :

24. Investigations »» there is no specific investigation for MR but good hx and physical examination guide us toward the proper one «« • DNA analysis: chromosomes • FISH probes: Prader-willi,wiliams,cri du chat syndrom • Metabolic labs:plasma a.a. , urine organic a. ,TFT , ck • Imaging : brain MRI , CT , skeleton films • Psychological Assesment: • Electrophysiology : EEG , auditory & visual evoked potentials

25. When to do the investigations? • Cytogenetic studies if:MicrocephalyMultiple (even minor) somatic anomaliesFamily history of mental retardationFamily history of fetal lossIQ <50Skin pigment anomalies (mosaicism)Suspected contiguous gene syndromes (e.g., Prader-Willi, Angelman, Smith-Magenis)

26. Metabolic studies if :Episodic vomiting or lethargyPoor growthSeizuresUnusual body odorsSomatic evidence of storage diseaseLoss or plateau of developmental skillsMovement disorder (choreoathetosis, dystonia, ataxia)Sensory loss (especially retinal abnormality)Acquired cutaneous disorders • MRI of the brain if :Cerebral palsy or motor asymmetryAbnormal head size or shapeCraniofacial malformationLoss or plateau of developmental skillsMultiple somatic anomaliesNeurocutaneous findingsSeizuresIQ <50

27. Management of MR »» there is no specific Rx for MR «« »General rules : -Identify the cause then initiate a comprehensive plan -Special educator , Language , behavioral and occupational therapists -Special school programs -Community services