Average at birth 35cm Normal Growth: 1cm/month for 1 st 6 months ½ cm/month from 6 months to 1 year Especially important first 3 years of age

Most concerning: 3 Standard Deviations above or below the mean >97 th Percentile: Macrocephaly <3 rd Percentile: Microcephaly Special Charts Down Syndrome Williams Syndrome Achondroplasia VLBW

Microcephaly: Small Head Macrocephaly: Large Head Micrencephaly: Small Brain Megalencephaly: Large Brain Brain growth determines ultimate cranium size

2.5% of all children Some with no neurologic problems Asymptomatic familial microcephaly Family history of small head size Normal development Normal neuro exam

Primary (genetic) Usually present at birth Secondary (environmental) Present at birth Develop later from postnatal insult

Autosomal Recessive Brain is small Otherwise normal architecture Mental retardation Otherwise unremarkable neuro exam

Abnormal neuroimaging Holoprosencephaly- failure of forebrain to divide into hemispheres. Midline facial defects Disruption of hypothalamic-pituitary axis Lissencephaly- smooth brain Seizures, spasticity, global dev delay

Rett Syndrome

Rubenstein Taybi Syndrome Broad Thumb-Hallux Syndrome

Cornelia de Lange

Miller Dieker

Prenatal Causes Drugs and alcohol, irradiation, intrauterine infections Perinatal asphyxia Severe malnutrition

Presenting signs/symptoms vary with age Communicating vs noncommunicating

Benign hydrocephalus H.C. normal or large at birth Increases to 98%ile, then parallels chart Normal neuro exam and development

Benign or idiopathic (AKA Familial Macrocephaly) Normal neuro exam No increased ICP No fluid collection Family history of large heads May have some subtle difficulty with coordination

Metabolic Inborn errors of metabolism Most autosomal recessive Significant dev delay with regression Mucopolysaccharidoses

Anatomic Increased number of cells Sotos syndrome (overgrowth syndrome) Neurocutaneous syndromes Most with developmental delay

Must entertain the worst Space-occupying lesions Tumor AVM Hemorrhage

Open fontanelle Ultrasound MRI Gives best information on brain parynchyma Best at posterior fossa CT Intracranial calcifications Hemorrhage Skull