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Macrocephaly

Julie Kardos, MD, FAAP and Naline Lai, MD, FAAP
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Two Peds in A Pod Drs. Julie Kardos and Naline Lai review macrocephaly in infants, including etiology, presentation, work-up, and when to refer to a specialist.

Definition of macrocephaly is an occiptofrontal head circumference (HC)  >2 standard deviations for age (>97%ile)

  • Use special HC  charts if baby is premature

  • Note that craniosynostosis does not typically change HC

 

Three different ways a skull can become enlarged: 

1.     Excessive Fluid (Hydrocephalus)

2.     Excessive Brain Skull (Megalencephaly)

3.     Skull thickening (Genetic syndromes, Thalassemias)

 

  • Long babies (taller) have bigger heads, not fat babies, so check length more than weight!

  •  If you note failure to thrive, check other growth parameters because a large HC can imply hydrocephalus, which can affect feeding!

  • Causes of Macrocephaly requiring workup:

  1. Excessive Ventricular Fluid: Hydrocephalus occurs in 1 in 1,000 infants! 

Specific causes:  

  • Aqueductal stenosis ( which is the most common cause of congenital hydrocephalus),

  • Dandy walker, 

  • Arnold Chiari, 

  • Mass or tumor blocking CSF flow

  • Damage to drainage of CSF (via the arachnoid villi) from intraventricular hemorrhage  or meningitis) 

 

  1. Excessive Brain tissue:

Specific causes:  

  • Tay-sachs 

  • Glycogen storage disease

  • Tumors 

  • Tuberous sclerosis

  • Other syndromes Fragile X, Soto’s

 

  1. Thick skull: 

Specific causes:  

  • Skeletal dysplasias (rickets, OI, osteopetrosis, hypophosphatemia), 

  • Thalassemias (expanding bone marrow)

 

  • Causes of macrocephaly not requiring workup, i.e. normal variants:

1)   Familial macrocephaly- follows curve, family has big head

  • Assessment of familial macrocephaly:  Obtain The parents' occipito-frontal head  circumference (OFC) measurements (if possible). Use these measurements to calculate a standard score for use with the Weaver curves to assess  genetic contribution to macrocephaly.

 

Ed’s Note: A standard score is calculated for the child and each of the parents using the following formula: Standard score (SS) = (OFC - mean value)/standard deviation (SD). When calculating the parents' standard scores, the mean value and SD for an 18-year-old should be used. The average of the parents' SS and the child's SS are plotted on the Weaver curve. A genetic contribution to macrocephaly is suggested if the child's SS is within the range determined by the average parental score.

 

2) “Benign external HCP” is when you see excessive extra-axial fluid outside frontal lobe 

 

  • RED FLAGS associated with pathological causes of macrocephaly:

    •  vomiting 

    • lethargy 

    •  “sundowning” eyes 

    •  bulging fontanelle 

    •  poor feeding

    •  irritability

    •  seizures

    •  loss of balance or coordination

    •  developmental  delay

    •  syndromic features 

    • other systemic anomalies (congenital heart disease, heme anomalies)

 

  • Reassuring signs associated with benign macrocephaly:

  • No delays (though rolling and sitting might be harder and done later given a larger than normal  head!)

  • Following growth curves 

 

  • Anterior fontanelle  closes around 8-18 months, so ultrasound early if concerned to assess for excessive fluid associated with HCP

  • CT or MRI head can be done if fontanelle closes to eval for HCP 

  • If abnormal imaging, refer to NSG, and genetics if needed.

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Hippo Peds RAP August 2021 Written Summary 5 MB - PDF

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