Fact-sheet: Communicating hydrocephalus


Updated on 01/22/2025 at 9:45 AM

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Definition

Hydrocephalus is ventriculomegaly related to a mismatch between production and resorption of cerebrospinal fluid (CSF).

Communicating hydrocephalus is characterized by ventricular dilatation without obstruction to CSF flow and may be:

  • due to impaired CSF resorption secondary to: subarachnoid hemorrhage
  • infectious meningitis
  • carcinomatous leptomeningitis
  • or without impaired CSF resorption in cases of: chronic active "normal pressure" hydrocephalus
  • choroid plexus papilloma

Clinical features

Chronic hydrocephalus (normal pressure hydrocephalus) is characterized by Hakim's triad, which combines:

  • Gait disturbances (short-stepped gait, with postural instability and a frozen, akinetic appearance, retropulsion, and decomposed turning)
  • Cognitive impairment, dominated by memory disturbances affecting recent events while remote memories are preserved, at least initially.
  • Sphincter disturbances, of the urinary type.

Clinical improvement after withdrawal of at least 30 mL of CSF is an additional argument in favor of the diagnosis of chronic hydrocephalus

MRI

In cases of impaired CSF resorption, look for signs or history of:

  • subarachnoid hemorrhage
  • infectious meningitis
  • carcinomatous leptomeningitis

Chronic active "normal pressure" hydrocephalus:

  • Enlargement of all 4 ventricles with dilatation of the temporal horns
  • Evans' index > 0.3

Index d Evans Ventriculomégalie

  • Callosal angle <90°

Angle calloso marginal Hydrocéphalie communicante

  • Possible enlargement of sulci in elderly subjects, with enlargement of the Sylvian fissures
  • Signs of transependymal CSF resorption
  • Flow artifact present from the 3rd to the 4th ventricle
  • Absence of obstruction at the foramen of Magendie or the cisterna magna, and absence of aqueductal stenosis (which is dilated)

Choroid plexus papilloma