average at birth 35cm normal growth: 1cm/month for 1 st 6 months ½ cm/month from 6 months to 1 year...
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Average at birth 35cmNormal Growth:
1cm/month for 1st 6 months½ cm/month from 6 months to 1 year
Especially important first 3 years of age
Head Circumference
Most concerning: 3 Standard Deviations above or below the mean>97th Percentile: Macrocephaly<3rd Percentile: Microcephaly
Special ChartsDown SyndromeWilliams SyndromeAchondroplasiaVLBW
Head Circumference
Microcephaly: Small HeadMacrocephaly: Large HeadMicrencephaly: Small BrainMegalencephaly: Large BrainBrain growth determines ultimate cranium
size
Head Circumference
2.5% of all childrenSome with no neurologic problems
Asymptomatic familial microcephalyFamily history of small head sizeNormal developmentNormal neuro exam
Microcephaly
Primary (genetic)Usually present at birth
Secondary (environmental)Present at birthDevelop later from postnatal insult
Microcephaly
Autosomal RecessiveBrain is small
Otherwise normal architectureMental retardation
Otherwise unremarkable neuro exam
Primary Microcephaly Vera
Abnormal neuroimagingHoloprosencephaly- failure of forebrain to
divide into hemispheres. Midline facial defectsDisruption of hypothalamic-pituitary axis
Lissencephaly- smooth brainSeizures, spasticity, global dev delay
Microcephaly w Anatomic Abnormalities
Microcephaly: Syndromes
Rubenstein Taybi SyndromeBroad Thumb-Hallux Syndrome
Prenatal CausesDrugs and alcohol, irradiation, intrauterine
infectionsPerinatal asphyxiaSevere malnutrition
Secondary Microcephaly
Benign hydrocephalusH.C. normal or large at birthIncreases to 98%ile, then
parallels chartNormal neuro exam and
development
Hydrocephalus
Benign or idiopathic (AKA Familial Macrocephaly)Normal neuro examNo increased ICPNo fluid collectionFamily history of large headsMay have some subtle difficulty with
coordination
Megalencephaly
MetabolicInborn errors of metabolismMost autosomal recessiveSignificant dev delay with regressionMucopolysaccharidoses
Megalencephaly
AnatomicIncreased number of cellsSotos syndrome (overgrowth syndrome)Neurocutaneous syndromesMost with developmental delay
Megalencephaly