REGIONAL CEREBRAL BLOOD-FLOW IN NORMAL-PRESSURE HYDROCEPHALUS - DIAGNOSTIC AND PROGNOSTIC ASPECTS

Relative regional cerebral blood flow (rrCBF) was measured by single-p hoton emission tomography (SPET), using technetium-99m-d,l-hexamethylp ropylene amine oxime (HMPAO) as flow tracer, in 23 patients with norma l pressure hydrocephalus (NPH). 1000 MBq Tc-99m-HMPAO was given intrav enously and the rrCBF calculated as regional/cerebellar count level ra tios. The patients were examined before and 3-12 months after ventricu loperitoneal shunt surgery. rrCBF was also determined in ten healthy a ged matched volunteers who served as controls. The NPH patients had de creased rrCBF in the hippocampal regions and in the frontal and pariet al white matter as compared to the controls. The frontal/parietal rrCB F ratio correlated with both psychiatric disability and the preoperati ve degree of incontinence. Decreased flow in frontal white matter, fro ntoparietal and hippocampal grey matter and a low frontalparietal grey matter flow ratio preoperatively correlated with improvement in both Mini Mental State score and psychiatric disability after shunt surgery . After shunt surgery the rrCBF increased in the mesencephalon, fronta l grey and white matter, parietal white matter and hippocampus. The fl ow increase in hippocampal regions and frontal white matter correlated with improvement in psychiatric symptomatology. The results of this s tudy regarding the frontal and hippocampal rrCBF patterns, and the cli nical correlation, support the hypothesis that CBF changes in these re gions are of patohphysiological and prognostic importance in NPH.