Download - 9-Microcephaly- MR
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Microcephaly
Dr Yog Raj Khinchi
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Normal Infant Skull• Flexible enough to get through vagina
– Molding
• Expansile enough to accommodate rapid brain growth
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HEAD GROWTH GUIDELINES• 2 cm every month during 0-3 mo• 1 cm every month during 3-6 mo• 0.5 cm every month during 6-12 mo• OFC (HC) : In term normal baby At birth:35cm 3mo: 41 cm 6mo: 44 cm 1yr: 47 cm 2 yr: 48 cm Adult: 52-55 cm
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HC: Post natal percentiles
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Microcephaly: Definition• Microcephaly denotes an occipitofrontal circumference (OFC) 3 or
more standard deviations below the mean for the individual’s age and gender.
• Craniosynostosis - results from premature fusion of 1 or more sutures results in a small head size with abnormal head shape which should be distinguished from microcephaly.
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HEAD GROWTH DEFINITIONS• Term infant
– <32 cm microcephaly– > 38 cm macrocephaly
• Macrocephaly - excessive head size 2 SD
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Microcephaly• OFC < 32 cm at birth• If OFC < 10 percentile- high risk of Learning Disabilities• If OFC < 3 percentile- near 100% risk of decreased IQ• Primary Microcephaly• Secondary Microcephaly
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Microcephaly: Types• Primary (genetic)
– Familial: • AD –mild forehead slant, prominent ears and borderline MR• AR –typical appearance with slanted forehead, prominent
nose and ears, severe MR– Genetic syndromes: Down and other trisomies Cri-du chat syndrome Cornelia de Lange syndrome Rubinstein-Taybi syndrome
- Anatomical defects in developing brain
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Microcephaly: Types...• Secondary (non-genetic): If noxious agent affects brain growth in utero and upto 1st 2 years of life.
– Hypoxic-ischaemic encephalopathy – Intrauterine infections (TORCH)– HIV– CNS infections – ICH– Fetal hydantoin syndrome (phenytoin in pregnancy)– Fetal alcohol syndrome– Malnutrition– Metabolic (maternal PKU)– Craniosynostosis
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Depending on the severity of the accompanying syndrome, children with microcephaly may have
• Mental retardation, • Delayed motor functions and speech,• Facial distortions, • Short stature, • Hyperactivity, • Seizures, • Difficulties in coordination & balance, • Other neurological abnormalities. Microcephaly
Microcephaly
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Microcephaly
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Child with secondary microcephaly following HIE
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Evaluation - History
• Antenatal history-maternal hyperthermia, exposure to
radiation, exanthematous febrile illness
• Family history of small head/MR/seizures.
• OFC at birth
• Post natal CNS infections particularly in first 2 years of life.
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Measuring OFC• A fibroelastic / metal measuring tape is placed around the
head at the following points:
– Occipital protuberance posteriorly– Nasion anteriorly– Measurement is made by cross tap technique over the
temporal bone.
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Examination
• OFC-plotted in a chart and compared for the norms (age and sex).
• Serial OFC records desirable-rate of growth
• Abnormal head shape, fontanelle & sutures
• Stigmata of intrauterine infections
• Dysmorphism
• Detailed neurological examination
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Investigations• Neuroimaging - CT/MRI of the brain help identify structural
defects.• TORCH titers for intrauterine infections• Karyotype if chromosomal syndrome/ associated congenital
malformation• Maternal phenylalanine levels (for PKU)• Fetal USG-for fetal head size particularly if family history present
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Treatment• Per se head size cannot be changed by treatment
• Associated delay needs to be addressed– Stimulation programme– Special schools
• Treatment of hearing/vision impairment if present
• Treatment of seizures if present
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Mental Retardation (MR)
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Definition• MR is characterized by significant below average intellectual
functioning (IQ<70) concurrently with limitation in two or more adaptive skills viz.,– Communication– Self-care– Home living– Social skills– Community use– Self-direction – Health and safety– Functional academics– Leisure and work
• It manifests before 18 years.• Formal psychometric test is required to make the diagnosis
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Developmental delay• Global developmental delay -child < 5 years age with DQ<70
in 2 or more developmental domains.
• The various domains of development include: gross motor, fine motor, language and social
• DQ = developmental age x 100 chronological age
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How common is it?
• Occurs in about 2.5 % of individuals.
• Mild (8-9 times more common)
• Moderate – Severe
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Etiology
• Specific diagnosis that will provide information about
– Prognosis
– Recurrence risks
– Preferred modes of available therapy
• Prenatal, perinatal or post natal
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• Prenatal– Genetic syndromes-Downs, fragile-X– Congenital hypothyroidism – IEM– TORCH infections/chorioamnionitis– Endogenous/exogenous toxins in mother during
pregnancy– Congenital malformation of CNS– Prematurity / hypoplastic SGA
• Perinatal– Trauma/HIE
Etiology...
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• Postnatal– Hypothyroidism (congenital / juvenile)– Acquired postnatal CNS infection/trauma– PEM, deficiency of iodine/iron /zinc – Exogenous toxin: lead– Neurocutaneous syndromes: NF,TS– Neuromuscular disorders with CNS involvement – Neurodegenerative disorders may have a progressively
worsening course
• Idiopathic: largest group in mild MR
Etiology...
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Evaluation: History
• Ethnic origin /consanguinity
• Family h/o MR, dev delay, epilepsy, neurological deficit
• Gestational history
• Time and mode of delivery, requirement of resuscitation
• Developmental milestones
• School performance
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Developmental milestones• Milestones refer to the time of achievement of a particular
developmental skill.• Questions systematically elicited in all 4 domains
– Gross motor: head holding, roll over, sit with and without support, stand with and without support, walk, run, go up & down stairs, hop, skip
– Fine motor: reaching out for objects, grasp, transfer of objects from hand to hand ,feeding & writing skills
– Language: cooing, squealing, vowels ,consonants, non-specific & specific bisyllables
– Social: mother regard, social smile, stranger anxiety, waving bye, parallel play, indicating toilet needs
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Evaluation - Examination
• Head circumference: plotted on centile charts
• Cutaneous markers-café au lait spot, ash leaf macule,
adenoma sebaceum
• Dysmorphism: large ears, long face, prominent lower jaw in
fragile-X syndrome
• Detailed neurologic examination including eye
• Psychometric testing
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Syndromes with Mental Retardation
Side profile of a boy with fragile-X syndrome Down syndrome
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Adenoma Sebaceum
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Ash Leaf Macule
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Hypothyroidism
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Grades / Severity of MR
• Borderline (IQ:70-80): independent; employable
• Mild (IQ: 50-69): educable
• Moderate (IQ:35-49): trainable
• Severe/profound: dependent on caretakers
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Investigations • Screening for hypothyroidism-TSH / T4• Fragile-X molecular tests.• Neuroimaging-not mandatory;picks structural defects,
neurodegenerative • Karyotype-if dysmorphic,other congenital malformations• Screening for inborn errors of metabolism if clues on
evaluation– Intermittent/progressive deterioration, seizures, fresh
neurodeficits – Light pigmentation, photosensitivity, athetoid ,small OFC
suggests phenylketonuria (PKU)– Lens dislocation, tall stature, arachnodactyly, hemiparesis
suggests homocystinuria (HCU)
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Treatment• Rehabilitation
– Borderline /mild MR can be integrated with normal schools
– Moderate MR would need special schooling ;vocational training to achieve independence
• Treatment of co-morbidities: seizures, behavioral problems
• Treat for hypothyroidism
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Treatment...• PKU-special diet; HCU-pyridoxine, folate
• Genetic counseling / prevent recurrence-Downs/Fragile-X-– karyotype /molecular genetics in affected child– Explaining risk of recurrence based on inheritance– Prenatal diagnosis to know if fetus affected and
termination if the couple so desires