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