Voxel-based assessment of spinal tap test-induced regional cerebral blood flow changes in normal pressure hydrocephalus.
OBJECTIVE
Normal pressure hydrocephalus (NPH) is a cause of dementia that may be amended by medical intervention. Its diagnosis is therefore of major importance and the establishment of response criteria to cerebrospinal fluid (CSF) shunting is essential. One of these criteria is the clinical response to spinal tap. The accuracy of the spinal tap test could potentially be improved by adding neuroimaging of regional cerebral blood flow (rCBF) changes to the response criteria. Statistical parametric mapping (SPM) is a voxel-based method of image analysis that may be used to statistically assess the significance of rCBF changes. The objective of this study was to evaluate, by SPM, spinal tap test-induced rCBF changes in patients with NPH syndrome.


METHODS
Forty patients with NPH syndrome underwent hexamethylpropylene amine oxime (HMPAO) brain single photon emission computed tomography (SPECT) before and after a spinal tap test (1-day split-dose protocol). The differences in rCBF between these pairs of scans were analysed by SPM in the whole group and between subgroups divided according to gait improvement at the spinal tap test.


RESULTS
In the whole group of patients, there was no statistical difference between pre- and post-spinal tap SPECT images. SPM analysis of patients grouped as a function of their clinical response to the spinal tap test revealed a significant post-spinal tap rCBF increase in the bilateral dorsolateral frontal and left mesiotemporal cortex in clinically responding compared with non-responding patients.


CONCLUSIONS
According to SPM analysis, gait improvement at the spinal tap test in patients with NPH syndrome is associated with an rCBF increase localized in the bilateral dorsolateral frontal and left mesiotemporal cortex.
Dumarey
Nicolas E
NE
Department of Nuclear Medicine and PET/Biomedical Cyclotron Unit, Hôpital Erasme, Université Libre de Bruxelles, 808 route de Lennik, B-1070 Brussels, Belgium. ndumarey@ulb.ac.be
Massager
Nicolas
N
Laureys
Steven
S
Goldman
Serge
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging*; D015170:Cerebrospinal Fluid Pressure; D002560:Cerebrovascular Circulation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013129:Spinal Puncture / Q000379:methods*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods