Predictive assessment of shunt effectiveness in patients with idiopathic normal pressure hydrocephalus by determining regional cerebral blood flow on 3D stereotactic surface projections

Abstract

The regional cerebral blood flow (rCBF) and cerebral metabolism in patients with idiopathic normal pressure hydrocephalus (iNPH) remain to be studied in detail.Using single-photon emission computed tomography (SPECT), we compared the characteristic rCBF patterns in iNPH patients who did, or did not, respond to shunt operations.We studied 24 consecutive iNPH patients: 14 men and 10 women aged 68 to 88 years (mean 77.5 years). Using the Japanese normal pressure hydrocephalus grading scale, they were divided into responders and non-responders to shunt operations. Follow-up ranged from 10 to 36 months (mean 25 months). We obtained baseline single-photon emission computed tomography (SPECT) data on three-dimensional stereotactic surface projections (3D-SSP) before and after shunt operations, and compared rCBF in responders and non-responders.On statistical maps, responders manifested significantly lower rCBF in the basal frontal lobes and cingulate gyrus (anterior-dominant).The preoperative measurement of rCBF by 3D-SSP SPECT may help to identify iNHP patients expected to exhibit a good response to shunt operations.