Correlates of local cerebral blood flow (CBF) in normal pressure hydrocephalus patients before and after shunting - A retrospective analysis of [O-15]H2O PET-CBF studies in 65 patients

Objectives: Findings in local cerebral blood flow (rCBF) in Normal pressure hydrocephalus (NPH) have always been challenged by the variable and inconsistent relation to clinical symptoms before and after shunt treatment. [O-15]H2O PET data from a consecutive cohort of 65 idiopathic NPH patients were retrospectively analyzed questioning whether the functional status before and after shunt treatment might correlate with local blood flow. Patients and methods: Using statistical parametric mapping (SPM99, Wellcome Department of Cognitive Neurology, London), the [O-15]H2O uptake was correlated with the preoperative clinical scores, graded according to a modified Stein and Langfitt score. Furthermore, differences in the uptake in the pre-and post-shunt treatment study after seven to 10 days in patients with and without clinical improvement were studied. Results: A higher clinical score significantly correlated with a reduced tracer uptake in mesial frontal (k = 1239 voxel, Z = 4.41) and anterior temporal (k = 469, Z = 4.07) areas. In the mesial frontal areas, tracer uptake showed significant reciprocal changes in the clinically improved vs. the unimproved patients. Conclusion: Matched with the existing literature, the regional blood flow alterations are suggested relevant to the NPH syndrome and to post-treatment functional changes. The present rCBF findings warrant prospective studies on the accuracy of neuroimaging studies as they may provide a more specific insight into disease mechanisms. (c) 2008 Elsevier B.V. All rights reserved.