An approach to a child with microcephaly Dr.Anita Lamichhane MD Resident (paediatrics) Shaikh Zayed Hospital Lahore
MicrocephalyA child whose head circumference is more thanthree standard deviations below the mean forage and sex
Normal head circumference at birth Male: 35cm(mean) range = 32---37 cm Female: 34cm(mean) Rate of growth of head circumference 2cm/month 1st three months of life 1cm/month 4-6 months of age 0.5cm/month 6-12 months of age 47cm at 1 yr of age 49 cm at 2 yrs of age
HC reflects brain volume, a small skull reflects a small brain. Incidence of moderate to severe mental retardation HC from 2-3 SD below the age is 33%. HC > 3 SD, incidence is 62% Not always associated with mental retardation
types of microcephaly Primary microcephaly Secondary microcephaly (non (genetic) genetic /acquired) primary defect in brain development prenatal onset prenatal onset postnatal onset postnatal onset
pathogenesis Occurs as a result of Small brain & poorly growing skull An abnormal neuronal migration during fetal development. Cytoarchitectural derangements. heterotopias of neuronal cells.
Microcephaly Vera an Autosomal recessive disorder severe hypoplasia of the frontal regions of the brain and skull. severe mental retardation.Note: HC alone should never be used to establish a prognosis for intellectual development.
Aicardi Syndrome females only Severe mental & development retardation agenesis of the corpus callosum seizures infantile Spasms gray matter heterotopias.
Bloom Syndrome Autosomal recessive a butterfly shaped facial rash. Microcephaly prone to develop Cancer. short stature Genetic diagnosis is available. DNA fragility
Downs Syndrome Trisomy 21 small low set ears and Microcephaly. incurving of the fifth finger. a single palmar crease ( simian up slanting Fissures, crease) epicanthal Folds, hypotonia flat facial profile,
Phenylketonuria Deficiency of phenylalanine hydroxylase in the liver Accumulation of phenylalanine in the blood Toxic to brain Causes microcephaly mental retardation cerebral palsy eczema mousy odor of urine
Contd… Diagnosed by increased serum phenylalanine in Blood Guthrie test ( 5th– 15th day of life) Treatment A diet low in phenylalanine
History Family history (for genetic cause) Exposure of radiation during pregnancy Maternal drug history Infection during pregnancy Maternal DM or PKU
Contd.. Difficult delivery: forceps delivery, meconium stained liquor cord around the neck and low Apgar Scores all raises the possibility of hypoxic ischemic encephalopathy Significant fever during neonatal period
h/o high-pitched cry poor feeding seizures increased movement of the arms and legs (spasticity)
Examination Introduction of oneself to the parents Size of the parents & other siblings head circumference Note the child’s alertness Look for any Dysmorphic feature ( intrauterine TORCH, de Lange, Rubinstein Taybi)
Child’s posture & symmetry of the movements ( voluntary & involuntary ) Inspect the skin for neurocutaneous stigmata Head circumference Height & weight & plot in the centile chart
Note the child’s overall growth generally small only head small examine the head for any scar marks ( surgical repair of Craniosynostosis, closure of Encephalocele)
Contd.. Shape of the head flat occiput of Autosomal recessive microcephaly Palpate the head for ridging along the suture line & any deformity of skull contour (Craniosynostosis) or bony defects ( repaired Encephalocele)
Anterior fontanelle a large AF occurs in trisomies congenital rubella hypothyroidism Petechiae or skin rash
Eye micropthalmos (TORCH) lens for cataract (TORCH, trisomies ) fundus for chorioretinitis (TORCH) glaucoma ( congenital rubella ) red reflex ( rubella)
hypotelorism (Holoprosencephaly)upward slant ( down syndrome)epicanthi fold ( trisomies )squint ( TORCH)pupils for anisocoria ( cong. Varicella )
Ears for hearing impairment ( TORCH ) neck for goiter hypothyroidism
Systemic examination CVS for congenital heart defects ( congenital rubella,trisomies ) Abdomen hepatosplenomegaly (TORCH) Genitalia micropenis with hypopitutarism structure ( cryptorchidism) Joint contractures Asses the gross and fine motor development– 180 degree maneuver
Investigations Serological tests for intrauterine TORCH infection Chromosomal analysis for Autosomal Trisomy syndrome Neonatal screening tests for PKU & congenital hypothyroidism
Urine test Metabolic screening to detect virus excretion with CMV CSF to detect intrauterine or perinatal TORCH infection
a) Skull x ray for cerebral calcification CMV --- periventricular Toxoplasmosis—diffuse to detect early closure of sutures
CT SCAN/ MRI for cerebral malformations evidence of perinatal asphyxia or intrauterine infection
Genetic studies are indicated in patients with Dysmorphic features
Microcephaly may be diagnosed before birth by prenatal ultrasound. Genetic counseling should be done
Management No treatment for microcephaly Baby’s head cannot be returned to a normal size & shape Includes focusing on preventing or minimizing deformities & maximizing the child’s capabilities at home & in the community.
Contd.. According to the cause. Anticonvulsants Physiotherapy Hearing & speech therapy Dietary management for failure to thrive Genetic counseling