Hydromechanical testing in non-communicating hydrocephalus to select patients for microsurgical third ventriculostomy.

To select adult patients with benign non-communicating hydrocephalus for microsurgical third ventriculostomy, cerebrospinal fluid (CSF) pressure, intercompartmental flow of CSF, and CSF draining capacity were measured in 14 patients with clinical high pressure hydrocephalus and 5 patients with clinical normal pressure hydrocephalus. The testing was of value in selecting patients with high pressure hydrocephalus for third ventriculostomy. Based on the clinical picture and the hydromechanical balance between the two separate CSF compartments one could distinguish two different patterns: (1) unbalanced high pressure hydrocephalus which improved after third ventriculostomy, and (2) balanced high pressure hydrocephalus which had to have a ventriculo-atrial shunt. All patients with normal pressure hydrocephalus had an almost balanced hydrocephalus, and the testing was shown to be of no value in this small group.