Pathophysiology of cerebral circulatory disorders in idiopathic normal pressure hydrocephalus.

This study was conducted to elucidate the pathologic conditions of cerebral circulatory disorders in idiopathic normal pressure hydrocephalus (iNPH). Among 44 possible iNPH patients, 40 patients underwent shunt surgery based on diagnostic flow charts plotted by the Southern Tohoku method and were evaluated to be shunt-effective at the end of the first post-surgical month. The cerebral blood flow (CBF) was measured by N-isopropyl-((123)I)-P-iodo-amphetamine single photon emission computed tomography (mean, mCBF; cortical region, cCBF; thalamus-basal ganglia region, tbCBF on autoradiography [ARG] method) and the perfusion patterns of the cerebral cortex were measured based on three-dimensional stereotactic surface projection (3D-SSP) Z-score images, before and 1 month after the surgery in all 40 subjects. The mCBF rose significantly from 32.1 +/- 2.74 ml/100 g/min before surgery to 39.8 +/- 3.02 ml/100 g/min after surgery (p < 0.03). Investigation of the change of CBF revealed reductions in the cCBF (3 cases), tbCBF (9 cases), and cCBF + tbCBF (28 cases), with the reduced-cCBF group totaling 31 cases and the reduced-tbCBF group totaling 37 cases. Investigation of cerebral cortex hypoperfusion by 3D-SSP Z-score revealed 31 cases with hypoperfusion (frontal lobe type [19 cases], occipitotemporal lobe type [5 cases], mixed type [7 cases]) and nine cases with cortical normoperfusion (N). The pattern of reduction of the cortical blood flow on ARG method was favorably correlated with the pattern of hypoperfusion of the cerebral cortex on 3D-SSP Z-score images before surgery. A reduction of blood flow was found in the thalamus-basal ganglia region of all N type cases. The blood flow improved in 19 of 31 (61.3%) cases of the reduced-cCBF group and in 32 of 37 (86.5%) cases of the reduced-tbCBF group. All of the cases without detectable improvement exhibited increased blood flow in non-reduction areas. Investigation of the hypoperfusion patterns of the cerebral cortex on 3D-SSP Z-score images, revealed a reduction or disappearance of the hypoperfusion site in 19 of 31 (61.3%) cases, either no-change or a shift of the hypoperfusion site in 12 of 31 (38.7%) cases, and a correlation between the pattern of cortical blood flow reduction on ARG method and the pattern of cerebral cortex hypoperfusion on 3D-SSP Z-score images after surgery. Cerebral circulatory disorders in iNPH manifest as either of two pathophysiological conditions: the "circulatory disorder of the cerebral cortical region" and the "circulatory disorder of the thalamus-basal ganglia region." Various patterns develop according to the disease stage.

[Reinvestigation of CSF outflow resistance value in idiopathic normal pressure hydrocephalus--comparing epidural pressure monitoring with lumbar subarachnoid cerebrospinal fluid pressure monitoring].

PURPOSE: To compare the cerebrospinal fluid (CSF) outflow resistance values (Ro) with epidural pressure (EDP) monitoring and lumbar subarachnoid CSF pressure (L-CSFP) monitoring. SUBJECTS AND METHODS: The subjects were 14 patients with possible iNPH (age: 59-74 years old, ratio of male and female 8:6). All the patients were subjected to an infusion test by a single bolus injection method (1 ml/sec., deltaV: 5 ml, t2: 2 min) as prescribed in the Standard of SINPHONI. EDP was monitored by continuous monitoring and the L-CSFP values By intermittent simple glass tube method (SINPHONI) were measured simultaneously. The Ro (RoEDP, RoL-CSFP) calculated from both methods, (1) the correlation of Ro and (2) the Ro threshold in a shunt effective group (E: nine cases) and a non effective group (NE, five cases) were compared. RESULTS: (1) Although a favorable correlation was found between both Ro measurements (r=0.784), the RoEDP was always higher than the RoL-CSFP. (2) The mean Ro values in the E and NE groups were 36.8 +/- 15.7 mmHg/ml/min, and 10 +/- 2.05 mmHg/ml/min for Ro-EDP, 22.1 +/- 13.95 mmg/ml/min and 6.4 +/- 1.7 mmHg/ml/min for RoL-CSFP, respectively. The approximate thresholds in the E and NE groups were 15 mmHg/ml/min for RoEDP and 10 mmHg/ml/min for RoL-CSFP. CONCLUSION: (1) Although the RoEDP is always higher than the RoL-CSFP, a favorable correlation is found between the RoEDP and RoL-CSFP, (2) The Ro thresholds of the E and NE groups in the infusion test are about 15 mmHg/ml/min for RoEDP and 10 mmHg/ml/min for RoL-CSFP. (3) After this, Ro calculation ought to execute by standard of SINPHONI and the Ro threshold of the E and NE groups is about 10 mmHg/ml/min.

[Significance of shunt efficacy decision of SPECT on idiopathic normal pressure hydrocephalus].

PURPOSE: The purpose of this study was to investigate the significance of the shunt-effect evaluation of SPECT in idiopathic normal pressure hydrocephalus (iNPH). SUBJECTS AND METHODS: The subjects were 15 patients with possible iNPH, aged 62-83 (mean 75.3, the ratio of males to females to 6:9), who were treated at our department during the period from June to September, 2004. All patients received the lumbar tap test (LTT) at the outpatient section before surgery. An L-P shunt was conducted on patients whose the LTT positive or negative with cerebrospinal fluid outflow resistance value (Ro) was 10 mmHg/ml/min. or higher patients. As for SPECT, a 3D-SSP Z-score, as well as an mCBF, was conducted before and after the LTT and within one month after surgery. Comparisons were made for (1) the shunt effect, (2) mCBF before and after the LTT and after surgery, (3) mean cerebral blood flow increase rate (mIR) after the LTT, and (4) 3D-SSP before and after surgery. RESULTS: (1) The shunt was effective for all the patients. (2) The mCBF levels was 30.8 +/- 4.02 ml/100 g/min. before the LTT, 37.1 +/- 100 g/min. after the LTT, and 38.6 +/- 3.4 ml/100 g/min. after surgery. A significant increase in mCBF was observed both after the LTT and after surgery (p < 0.05). (3) The mean mIR after the LTT was 21.2 +/- 8.01%, with all the patients showing 10% or higher. (4) The ischemic patterns in the SD-SSP Z-score before surgery were the frontal type (F: 10 cases, 66.7%), the occipitotemporal type (OT: 3 cases, 20%), and the mixed type (M: 2 cases, 13.3%), but not the parietal localized type. The post-operative course showed no-change in 4 cases, disappearance-reduction in 9 cases, and shift to OT in 2 cases. CONCLUSION: The evaluation factors in the measurement of the cerebral blood flow for evaluation of the shunt effect were the following two items. (1) The mIR of mCBF after the LIT was 10% or higher. (2) As for the preoperative cerebral ischemic patterns, there were many F cases and no parietial localized types found.