[Evaluation of lumbar tap test combined with mean cerebral blood flow measurement and electroencephalographic topography on idiopathic normal pressure hydrocephalus patients].

PURPOSE: To improve the diagnostic precision of the lumbar tap test (LTT). SUBJECTS AND METHODS: Thirty one patients (mean age, 65.4 years; male to female ratio, 12:19) suspected of having idiopathic normal pressure hydrocephalus (INPH) were used in the study. They underwent LTT (20-30 ml of cerebrospinal fluid was drained through a puncture with a 18 G needle; evaluation within 3 days after LTT). Based on changes in symptoms after LTT, including dementia (evaluated according to the duration of time needed to accomplish No. 7 items in the N method psychofunction test) and gait disturbance (evaluated according to the duration and the number of steps needed to walk 4 m in a straight line), mean cerebral blood flow (mCBF) monitored with 133Xe-CT, and electroencephalographic topography (EEG-T). The patients were divided into symptom-improved [LTT (+)] and no change [LTT(-)] groups. Changing patterns of EEG-T and mCBF after LTT and the efficacy of V-P shunt at 1 month after shunt administration (effective: E; non-effective: NE) were analyzed and compared. Changing patterns of EEG-T and mCBF after LTT were categorized as improvement of both parameters (type A), that of mCBF only (type B), that of EEG-T only (type C), and no change in either parameter (type D). RESULTS: (1) Twenty patients were classified as LTT(+) and eleven as LTT(-). (2) The false positive rate was 25% (5/20) for LTT(+); the false negative rate was 27.3% (3/11) for LTT (-). (3) In all the patients, in relation to changing patterns of EEG-T and mCBF, 100% of type A patients (9/9), 75% of type B (6/8), 42.9% of type C (3/7), and 0% of type D (0/7) responded to shunting. (4) Increased rates (IR) of mCBF in 17 patients with improvement of mCBF were 24.2 +/- 10.6% in E patients and 8.9 +/- 5.2% in NE patients, demonstrating a significantly higher percentage in E patients (p < 0.005). The borderline of IR between E and NE was around 15%. CONCLUSION: (1) Although quantitative evaluation of symptoms (dementia and gait disturbance) before and after LTT, 27.3% of false negative and 25% of false positive were recognized. (2) According to changing patterns of EEG-T and mCBF after LTT, all type A patients responded to shunting (E), whereas type D patients were all categorized as NE. (3) When the IR of mCBF was 15% or more after LTT, such patients all responded to shunting. (4) The diagnostic precision of LTT in efficacy evaluation is improved when this test is combined with EEG-T and mCBF, in addition to quantitative evaluation of symptoms.

[Prognostic evaluation of glycerol-induced cerebral blood flow measurement in asymptomatic unruptured cerebral aneurysm treatment].

PURPOSE: To clarify the usefulness of glycerol-induced cerebral blood flow measurement (G-CBF) as a method for prognostic evaluation of an asymptomatic unruptured cerebral aneurysm (AUCA). SUBJECTS AND METHODS: Fifty-three patients (age: 26-72 years; ratio of males to females, 23: 30; 56 AUCAs) who were found to have an AUCA(s) on brain checkup at our hospital and then received treatment (direct or intravascular surgery) were the subject of our study. The patients underwent the N-type psychofunction test (NPT) and G-CBF. As the control group, G-CBF was also performed on 50 subjects (age: 36-73 years; ratio of males to females, 27; 23), who were found, by brain checkup, to have no intracranial disease. We investigated (1) the occurrence of post-treatment complications (symptoms/psychofunctional disorders) in the treated group, and compared (2) G-CBF between the complication-developing group, the non-complication-developing group, and the control group. RESULTS: (1) Complications were observed in 9 patients (17%), including convulsions in 2 patients, hemiparalysis in 1, disorientation in 3. Psychofunctional disorders (less than 80 points on the NPT score) were observed in all of the 9 patients developing complications, but could be determined as higher brain dysfunctions only in the 3 patients with disorientation. (2) The mean cerebral blood flow (mCBF) before glycerol administration was 34.17 +/- 4.82 ml/100 g/min in the complication-developing group, 32.41 +/- 7.29 ml/100 g/min in the non-complication-developing group, and 31.98 +/- 5.04 ml/100 g/min in the control group, showing no significant intergroup differences. The mean increased rate of cerebral blood flow (mIR) after glycerol administration was 7.05 +/- 3.96%, 23.63 +/- 5.5%, and 30.64 +/- 13.08%, respectively, showing a significantly lower increase in the complication-developing group (p < 0.01), particularly low in the frontal lobe. Paradoxical flow reactivity was observed in 2 patients, both of whom were in the complication-developing group. CONCLUSIONS: (1) The complication-developing group showed a significantly lower pre-treatment mIR (less than 10%), particularly low in the frontal lobe, (2) Paradoxical flow reactivity was observed only in the complication-developing group. (3) G-CBF was very useful for prognostic evaluation prior to the treatment of AUCA.