Hydrocephalic oedema in normal-pressure hydrocephalus.

The hydrocephalic oedema in normal-pressure hydrocephalus (NPH) was evaluated by measurement of the relaxation time of protons of the water molecules of brain tissue. Patients with NPH were divided into two groups: shunt responders and shunt non-responders. In the group of shunt responders both T1 and T2 of periventricular white matter were significantly prolonged compared to those of controls, and shortened after shunting. Both T1 and T2 of white matter were significantly longer than of gray matter, while a reversed relationship was seen in normal controls. However, in the group of shunt non-responders, T1 of white matter was significantly prolonged, while T2 of the same area not. There was no change in either T1 or T2 of this region after shunting. Both T1 and T2 were almost the same in white and gray matter in shunt non-responders. It is suggested that periventricular abnormalities seen in various diseases may be distinguished on the basis of the relaxation behavior of protons of tissue water.