Investigations

A minimal series of investigations in hydrocephalus includes:

• skull X ray:
  • assess skull size, suture diastasis; may be obvious in infants
  • look for evidence of chronic raised pressure - erosion of the posterior clinoids
  • look for associated defects - e.g. basilar invagination
    
    
• CT scan including contrast - reveals pattern of ventricular enlargement and, frequently, the site and cause of obstruction:
  • generalised dilatation - suggests communicating hydrocephalus
  • lateral and 3rd ventricles dilated:
    • 4th ventricle normal - suggests aqueduct stenosis
    • 4th ventricle absent or deviated - suggests a posterior fossa mass
      
      
• ultrasonography through the anterior fontanelle in infants - demonstrates ventricular enlargement but is less informative than CT