Macrocephaly

Definition
Head circumference (HC) > 3 standard deviations above the mean for age and sex

* Normally HC increases by 2cm for the first 3 months, 1cm for the next 3 months, and 0.5cm for the next 6 months – 12cm in first year of life

Causes

  •  
    • Macrocrania (increased skull thickness)
    • Megalencephaly (increased brain size)
    • Hyrdrocephalus (increased ventricular size) –> lateral ventricles through foramen of Munro, 3rd ventricle, cerebral aqueduct, 4th ventricle, foramen of Magendie/Luschka
  • Communicating: impaired flow in subarachnoid space or impaired absorption of CSF (IVH)
    • Congenital – failure of arachnoid villi to develop
    • Acquired – postinfectious, posthemorrhagic, posttraumatic, neoplastic, idiopathic
  • Non-communicating: obstruction within ventricular system
    • Congenital – stenosis, obstruction, webs, Arnold-Chiari
    • Acquired – posinfectious, posthermorrhagic, neoplastic
  • Hydrocephalus
  • Tumor
  • Bleed – shaken baby, AVM
  • Familial macrocephaly (FHx)
  • Metabolic

History

  • Rate of head growth
  • Family history
  • Eye changes, nausea and vomitting, seizure, infection, cough, apnea, sleep disturbance, irritability, poor appetite and weight loss, lethargy, abuse
  • Development
  • Prior ICH, meningitis, mumps, encephalitis

Physical exam

  • HEENT
  • CVS
  • Skin
  • MSK (spine)
  • Neuro

Clinical features

  • Headache
  • Vomiting
  • Cranial nerve dysfunction
  • Visual dysfunction (CNII)
  • Papilledema
  • Endocrine dysfunction (distension of 3rd ventricle)
  • Ataxia, spasticity
  • Paresis of upward gaze (dilation of aqueduct compressing the periaqueductal grey – sunsetting)
  • Personality/behavioural changes
  • Lethargy/drowsiness
  • Diplopia (III/VI palsy)
  • Excessive head growth
  • Changes in vital signs
  • Hypothalamic changes

Differential diagnosis

  • Neonates: spina bifida, IVH, gram negative meningitis
  • Infants: glycogen storage diseases, subdural hematoma, hydrocephaly
  • Children: tumors, infections
  • Adolescents: tumors

Management

  • Identify cause
  • Treat cause
  • Place ventriculoperitoneal or venticulojugular shunt

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