Acta Neurochir (2002) [Suppl] 8 I: 55-57 © Springer-Verlag 2002 Neuropsychological Sequels to Changes in Global Cerebral Blood Flow and Cerebrovascular Reserve Capacity after Shunt Treatment in Chronic Hydrocephalus - A Quantitative PET -Study P. Klingel, N. Riickertl, M. Schuhmannt, G. Berding\ T. Brinker\ W. H. Knapp\ and M. Samii 1 1 Departments of Neurosurgery, Medical School and Nordstadt Hospital Hannover, Hannover, Germany 2 Protestant University of Applied Sciences, Hannover, Germany 3 Department of Nuclear Medicine, Medical School Hannover, Hannover, Germany Summary Aim. To study relationship of neuropsychological deficits in chronic hydrocephalus before and after shunting with dynamics in cerebral blood flow. In 27 patients (65 ± 13 yrs) with idiopathic chronic hydro- cephalus II selected neuropsychological tests, providing a wide range of psychomotor functions, were performed before, one week (early) and 7 months (late) after shunting. Parallel global cortical blood flow (CBF) and cerebrovascular reserve capacity (CVR) were determined by dynamic 15-0-water PET studies (Siemens ECA T 951/31) before and after application of acetazolamide (I g). Test raw data and changes after treatment were compared with global and regional blood flow values by polynomial regression. No relationship of test profiles with hemodynamics before surgery was found. After one week, improvement of gait was related to an increase in cerebrovascular reserve capacity (p = 0.05). After 7 months changes in mental tests were related to changes in hemo- dynamics: again increases in CVR were significantly related to im- provements in visual attention and verbal memory (p < 0.01). Early improvement of hemodynamic reserve was related to im- provement in gait, whereas mental improvement was particularly related to increases in global CVR at later periods after shunting. These results indicate that neurological sequels in idiopathic chronic hydrocephalus after shunting may actually depend on consecutive improvement of cerebral hemodynamics. Keywords: Hydrocephalus; psychometry; cerebral hemodynamics; follow-up. Introduction Both experimental and clinical findings have in- dicated that neurological impairment in chronic hy- drocephalus may be related to disturbances in cerebral blood flow [2, 3]. Also, clinical findings showed that in shunt-responsive hydrocephalus increases in global and regional cerebral blood flow have occurred [7]. U sing a variety of common neuropsychological tests, providing a wide range of psychometric tasks, we wanted to study, whether psychomotor changes after shunt treatment were related to early and late changes in cerebral hemodynamics of chronic hydrocephalus patients. Material and Methods 27 patients (65 ± 13 yrs) with clinical and radiological pre- sentation of chronic hydrocephalus were investigated. All patients suffered from psychomental deterioration, motor disturbances, whereas incontinence was variable feature. Almost all patients were treated by ventriculoperitoneal shunting (COD MAN- MEDOS®-programmable, CODMAN-MEDOS®-medium-high (100 ± 10 mmH2 0) and PUDENZ-SCHULTE® medium-pressure valves) except one endoscopic ventriculostomy. Cortical cerebral blood flow (CBF) and cerebrovascular reserve capacity (CVR) were determined by dynamic 15-0-water PET studies (Siemens ECA T 951/31) before and after application of acetazolamide (I g). Global and regional CBF was calculated (ml/l 00 ml/min) from the time course of tissue and blood activity using a one-compartment-model (Kety-Schmidt) based on the ROI-technique on a representative slice at the level of the basal ganglia. Regions of interest were manually defined corresponding to the territories of the anterior (ACA), me- dial (MCA) and posterior cerebral artery (PCA) of both hemi- spheres. Cerebrovascular reserve capacity (CVR) was determined after application (i. v.) of I g acetazolamide (DIAMOX®) over 5 min after a time interval of IS minutes post injection as the relative difference in CBF of baseline and during stimulation (percent change). Measurement was done one week (early) and seven months (late) after shunt insertion and at parallel intervals, II neuro- psychological tests providing a wide range of cognitive and psycho- motor functions [4] were performed: Auditory attention ("Digit- span"); verbal memory and learning ("Luria 10 words-list"); visual attention ("Digit-symbol"), visuomotor tracking ("number connec- tion"), motor precision Cline-tracing") and psychomotor velocity ("serial dotting") and evaluation of balance- and gait-profiles (lO-m-