Large Heads (Macrocephaly)

Introduction

The average head circumference at birth is 33-35 cm and increases about 2 cm per month. Head circumference should be measured at each visit and plotted on a growth chart. Although head size often follows body growth, small infants may have large heads and vice versa. It is not unusual for the head circumference to cross percentiles during the first year of life, but if the infant has a large head, other family members' heads should be measured and plotted and a full developmental assessment and examination should be performed. Large heads are often a familial feature. The posterior fontanel usually closes at 6-8 weeks of life and the anterior fontanel between 12-18 months.

 

Evaluation

  1. History
    1. Developmental assessment
    2. Symptoms of increased intracranial pressure-lethargy, poor feeding, irritability, vomiting
    3. History of trauma, prematurity, infections.
    4. Family history of neurologic disorders
  2. Physical examination findings
    1. split sutures and bulging anterior fontanel
    2. prominent veins 
    3. setting sun eyes
    4. Abnormal tone and increased DTRs
    5. thorough skin inspection including evaluation for midline spinal lesions.
    6. Intracranial bruits 
    7. Retinal hemorrhages and evidence of chorioretinitis
    8. Pulse, blood pressure, respiratory rate 
    9. Transillumination
  3. CT and MRI will help define hydrocephalus, congenital malformation, vascular lesions, subdural collections of fluid, and degenerative changes. 
  4. Consultation of a neurosurgeon 

 

Link to WHO Growth Charts

 

Etiology of Large Heads

  1. Normal infant with familial large heads.
  2. Hydrocephalus
    1. hemorrhage
    2. trauma
    3. Congenital- aqueductal stenosis, congenital malformations such as Arnold Chiari malformation and Dandy Walker cysts. 
    4. Neoplasm
    5. infection- meningitis, encephalitis, abscess
  3. Rickets
  4. Subdural effusions or hematomas
  5. Hydranencephaly- absence of cerebral hemispheres. + transillumination
  6. Megalocephaly- increase in brain substance
    1. neurocutaneous syndromes 
    2. Cerebral gigantism
    3. Aminoacidurias
    4. Tay Sachs
    5. Leukodystophies
    6. Mucopolysaccharidosis

 

References

  1. Weinberg H. and Tunnessen W.  Megacephaly:Heeding the Head  Contemporary Pediatrics Oct 1996
  2. Rios A. Microcephaly. Peds in Review 1996
  3. Dias M.S. and Li V. Pediatric Neurosurgical Disease. Pediatric Clinics of North Americal 1998

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