Mental Mental RetardationRetardation

ContentsContents: :

DefinitionDefinition Prevalence Prevalence ClassificationClassification CausesCauses Clinical EvaluationClinical Evaluation InvestigationInvestigation ManagementManagement

DefinitionDefinition

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

The Classical definition The Classical definition comprises 3 componentscomprises 3 components: :

1- subaverage intellectual function .1- subaverage intellectual function .

2- that result from an injury , disease 2- that result from an injury , disease or abnormality before the age of 18 or abnormality before the age of 18 years .years .

3- resulting in impaired ability to adapt 3- resulting in impaired ability to adapt to the environment .to the environment .

PrevalencePrevalence: :

Mental retardation is present in about Mental retardation is present in about 2 to 3% of the population2 to 3% of the population..

AAMR Classification SchemeAAMR Classification Scheme

IQ classification:IQ classification:I.Q.I.Q.((intelligence quotientintelligence quotient) ) is 100; normal ranges from 90 to 110 is 100; normal ranges from 90 to 110

1-Border line { IQ 70-80 }1-Border line { IQ 70-80 }

2-mild MR { IQ 55-70 }2-mild MR { IQ 55-70 }

3-moderate MR{ IQ 40-55 }3-moderate MR{ IQ 40-55 }

4-sever MR { IQ 25-40 }4-sever MR { IQ 25-40 }

5-profound MR { IQ below 25 }5-profound MR { IQ below 25 }

EtiologyEtiology

Unknown “ 30-40 % “Unknown “ 30-40 % “ Genetic “ 5% “Genetic “ 5% “ Early embryonic ( prenatal ) “ 30% “Early embryonic ( prenatal ) “ 30% “ Prematurity , IUGR (perinatal) “ 10 % “Prematurity , IUGR (perinatal) “ 10 % “ Acquired medical condition (trauma , Acquired medical condition (trauma ,

infection ..) “ 5% “infection ..) “ 5% “ Environment “ 5-20% “Environment “ 5-20% “

Etiology classificationEtiology classification: :

PrenatalPrenatal PerinatalPerinatal PostnatalPostnatal

Prenatal causesPrenatal causes: :

»»Genetic Disorders :Genetic Disorders :Fragile X syndrome FXS :Fragile X syndrome FXS :most common cause .most common cause .

Klinefelter syndrome :Klinefelter syndrome :male with extra x chromosome male with extra x chromosome

47,XXY47,XXY

Down syndrome :Down syndrome :Meabolic disorders: Meabolic disorders: PKU, Tay-sachs, GalactosemiaPKU, Tay-sachs, Galactosemia

Skin disorders : Skin disorders : neurofibromatosis and Tubererous sclerosis .neurofibromatosis and Tubererous sclerosis .

Prader-Willi Syndrom :Prader-Willi Syndrom :

Endocrine : Endocrine : hypothyroidismhypothyroidism

Fragile X syndrome (FXS)Fragile X syndrome (FXS) Is the commonest cause of MR.Is the commonest cause of MR. The incidence has been estimated at The incidence has been estimated at

approximately 1 in 1,500 males and approximately 1 in 1,500 males and 1 in 2,500 females1 in 2,500 females. .

Mutation of a gene on the long arm Mutation of a gene on the long arm of the X chromosome is responsible of the X chromosome is responsible for FXS and involves instability of for FXS and involves instability of trinucleotide repeat sequence .trinucleotide repeat sequence .

DNADNA--analysis of the FMR-I gene is the analysis of the FMR-I gene is the best way to diagnose which is usually best way to diagnose which is usually done on lymphocytes. done on lymphocytes.

Fragile X syndrome Fragile X syndrome (FXS)(FXS)contcont....

C/P: { phenotype }C/P: { phenotype }Large ears , Large testes (testicular Large ears , Large testes (testicular

volume>30 ml in adults) , Plantar volume>30 ml in adults) , Plantar crease , Hyperextensible joints , crease , Hyperextensible joints , Simian creaseSimian crease , ,

Broad forehead, Increased hand width, Broad forehead, Increased hand width, Increased hand length , Elongated Increased hand length , Elongated

face, High arched palateface, High arched palate , , Mitral valve prolapse , Hypotonia , Mitral valve prolapse , Hypotonia ,

Hernia, Double jointed thumbs , Hernia, Double jointed thumbs , Scoliosis and Flat feetScoliosis and Flat feet

Fragile X syndrome Fragile X syndrome (FXS)(FXS)contcont....

C/P: {C/P: {NEUROCOGNITIVENEUROCOGNITIVE } }Mental retardation , Hyperactivity , Mental retardation , Hyperactivity ,

Attentional problems , Language Attentional problems , Language delays , Hand flapping , Hand biting , delays , Hand flapping , Hand biting , Irritability , Perseveration , Excessive Irritability , Perseveration , Excessive temper tantrums Gaze avoidance , temper tantrums Gaze avoidance , Sensory aversion , SelfSensory aversion , Self--stimulatory stimulatory behavior and Autismbehavior and Autism

»Cranial»Cranial Malformations : Malformations :

Anencephaly :Anencephaly :

microcephaly :microcephaly :

Hydrocephaly :Hydrocephaly :

»Congenital Factors :»Congenital Factors :Maternal : Maternal : Rubella , congent. Syphilis & Rh incompitability Rubella , congent. Syphilis & Rh incompitability

Toxins :Toxins : drugs , fetal alcohol syndrom ..drugs , fetal alcohol syndrom ..

Perinatal CausesPerinatal Causes: :

Low Bwt : Low Bwt : premature , teen pregnancy , poor nutrition ..premature , teen pregnancy , poor nutrition ..

21 % with MR21 % with MR

Birth AnoxiaBirth Anoxia : : breech presentation , knotted umbilical breech presentation , knotted umbilical cord.cord.

Postnatal CausesPostnatal Causes: :

Child abuse and neglect :Child abuse and neglect :

Traumatic brain injury :Traumatic brain injury :Infection : Infection : meningitis and encephalitis meningitis and encephalitis

Nutritional deficiencies :Nutritional deficiencies :

Cultural and familial : Cultural and familial :

Clinical EvaluationClinical Evaluation

Complete History :Complete History : Examination :Examination :

HistoryHistory

»complete and detailed history«»complete and detailed history«

complete systemic review complete systemic review surgical history : surgical history : trauma , accidents trauma , accidents

medical illnesses : medical illnesses : hospitalization , general heath hospitalization , general heath

pregnancy history : pregnancy history : maternal age , parity , maternal age , parity , infections..infections..

birth : birth : type , wt . GA ,complications , apgar scoretype , wt . GA ,complications , apgar score

Postnatal : Postnatal : incubator , ventilator , disease ..incubator , ventilator , disease ..

History (cont.)History (cont.)

drugs: drugs: mother and childmother and child

developmental Hx : developmental Hx : mile stones , loss it , speech ..mile stones , loss it , speech ..

educational Hx : educational Hx : schooling , IQ testsschooling , IQ tests

behavioral Hx : behavioral Hx : skills , attention , activityskills , attention , activity

family Hx : family Hx : consanguinity , inherited ds ..consanguinity , inherited ds ..

social Hx :social Hx :

ExaminationExamination

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

InvestigationsInvestigations

»» there is no specific investigation for »» there is no specific investigation for MR but good hx and physical MR but good hx and physical

examination guide us toward the examination guide us toward the proper one ««proper one ««

DNA analysis:DNA analysis: chromosomes chromosomes

FISH probes: FISH probes: Prader-willi,wiliams,cri du chat syndromPrader-willi,wiliams,cri du chat syndrom

Metabolic labs:Metabolic labs:plasma a.a. , urine organic a. ,TFT , ck plasma a.a. , urine organic a. ,TFT , ck

Imaging : Imaging : brain MRI , CT , skeleton filmsbrain MRI , CT , skeleton films

Psychological Assesment:Psychological Assesment: Electrophysiology : Electrophysiology : EEG , auditory & visual evoked EEG , auditory & visual evoked

potentialspotentials

When to do the When to do the investigationsinvestigations??

Cytogenetic studies if:Cytogenetic studies if:MicrocephalyMicrocephalyMultiple Multiple ((even minoreven minor) ) somatic anomaliessomatic anomaliesFamily history of mental retardationFamily history of mental retardationFamily history of fetal lossFamily history of fetal lossIQ <50IQ <50Skin pigment anomalies Skin pigment anomalies ((mosaicismmosaicism))Suspected contiguous gene syndromes Suspected contiguous gene syndromes ((ee..gg.., Prader, Prader--Willi, Angelman, SmithWilli, Angelman, Smith--MagenisMagenis))

Metabolic studies if :Metabolic studies if :Episodic vomiting or lethargyEpisodic vomiting or lethargyPoor growthPoor growthSeizuresSeizuresUnusual body odorsUnusual body odorsSomatic evidence of storage diseaseSomatic evidence of storage diseaseLoss or plateau of developmental skillsLoss or plateau of developmental skillsMovement disorder Movement disorder ((choreoathetosis, dystonia, choreoathetosis, dystonia, ataxiaataxia))Sensory loss Sensory loss ((especially retinal abnormalityespecially retinal abnormality))Acquired cutaneous disordersAcquired cutaneous disorders

MRI of the brain if :MRI of the brain if :Cerebral palsy or motor asymmetryCerebral palsy or motor asymmetryAbnormal head size or shapeAbnormal head size or shapeCraniofacial malformationCraniofacial malformationLoss or plateau of developmental skillsLoss or plateau of developmental skillsMultiple somatic anomaliesMultiple somatic anomaliesNeurocutaneous findingsNeurocutaneous findingsSeizuresSeizuresIQ <50IQ <50

Management of MRManagement of MR

«« ««there is no specific Rx for MRthere is no specific Rx for MR»» »» ««General rulesGeneral rules: :

--Identify the cause then initiate a Identify the cause then initiate a comprehensive plancomprehensive plan

--Special educator , Language , Special educator , Language , behavioral and occupational behavioral and occupational therapiststherapists

--Special school programsSpecial school programs--Community servicesCommunity services