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

BACKGROUND: The regional cerebral blood flow (rCBF) and cerebral metabolism in patients with idiopathic normal pressure hydrocephalus (iNPH) remain to be studied in detail.
PURPOSE: 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.
MATERIALS AND METHODS: 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.
RESULTS: On statistical maps, responders manifested significantly lower rCBF in the basal frontal lobes and cingulate gyrus (anterior-dominant).
CONCLUSIONS: The preoperative measurement of rCBF by 3D-SSP SPECT may help to identify iNHP patients expected to exhibit a good response to shunt operations.