Transcranial Doppler for evaluation of idiopathic intracranial hypertension

OBJECTIVES: The value of transcranial Doppler (TCD) ultrasonography in assessing patients with Idiopathic Intracranial Hypertension (IIH) is uncertain. We sought to determine the contribution of TCD to their evaluation. MATERIALS AND METHODS: Twenty-three patients with suspected IIH underwent TCD. Mean blood flow (BFV), peak systolic (PSV) and end-diastolic (EDV) velocities, and pulsatility (PI) and resistance (RI) indexes were obtained in the middle cerebral (MCA) and vertebral (VA) arteries and compared (Student's t-test) between patients with confirmed IIH and controls. IIH patients and controls were comparable in terms of age, gender and weight. RESULTS: The mean +/- SD BFV(MCA), PSV(MCA), EDV(MCA) and PI(VA) in the 13 IIH patients were higher than in the ten controls (59 +/- 6.8, 94 +/- 28.5, 43 +/- 12.4, 0.86 +/- 0.16 and 50 +/- 8.6, 72 +/- 25.8, 32 +/- 11.5, 0.58 +/- 0.45 respectively, P < 0.05) but still within normal values. The mean +/- SD PI(MCA), RI(MCA) and RI(VA) values in the IIH patients and controls were similar. CONCLUSIONS: TCD parameters had no useful unique features for monitoring IIH patients.     

Intraoperative monitoring of cerebral blood flow during ventricular shunting in hydrocephalic pediatric patients

Several studies have demonstrated lowered cerebral blood flow (CBF) in patients with hydrocephalus and symptoms of raised intracranial pressure. Ventricular shunting in such cases permits a sudden increase in CBF. The pathophysiology of functional brain deficit secondary to hydrocephalus is little understood. Improvement of the patient's clinical status after drainage of CSF suggests that cerebral dysfunction is not necessarily due to permanent brain damage. In fact, it improves rapidly after ventricular taps. In view of this it would be helpful to monitor cerebral perfusion. The transcranial Doppler (TCD) ultrasonography technique allows real-time monitoring of the intracranial circulation and makes it possible to evaluate the physiopathological correlation between ventricular dilatation and CBF. Continuous monitoring of the middle cerebral artery (MCA) by TCD was performed in three hydrocephalic children (2 months, 14 months, and 8 years old) during a ventricular-peritoneal shunt operative procedure. A TC-2000S device provided by an IMP-F fixed probe was utilized. In all patients, when the lateral ventricle was shunted and the CSF could flow away, a clear and sudden increase of flow velocity above 30% was detected. The pulsatility index (PI) was also pathologically increased in all patients. A gradual normalization of this index was revealed after the shunting procedure. Our experience has to be considered preliminary, but nonetheless, it suggests a clear correlation between hydrocephalic disease and concomitant CBF alterations. A more consistent number of monitoring performances by TCD during operative procedures will improve our understanding of the role of CBF in the development of functional deficits in hydrocephalic disease.Presented at the Consensus Conference: Hydrocephalus '92, Assisi, Italy, 26–30 April 1992     

脑静脉窦血栓经颅多普勒超声监测的临床意义

目的探讨经颅多普勒超声(TCD)监测上矢状窦血栓患者颅内压(ICP)的可行性,研究TCD动脉、静脉参数及频谱形态与ICP的关系,以指导临床治疗、评价疗效及判定预后。方法选择18例上矢状窦血栓形成住院患者,取入院第1、7及14天为观察点,动态监测患者的ICP、脑灌注压(CPP)、波动指数(PI)、阻力指数(RI)、大脑中动脉(MCA)和大脑中深静脉(dMCV)平均血流速度(Vm)以及TCD频谱形态,并与对照组相比较,同时进行相关性分析。结果上矢状窦血栓患者各观察点参数与对照组相比均有显著性差异(t=6.32,P<0.05),随着ICP的升高,患者的dMCV平均血流速度、PI及RI呈上升趋势,MCA平均血流速度和CPP呈下降趋势,在第7天达到高峰,持续到两周时略有恢复,但仍维持在较高水平。ICP与P1呈明显正相关(P<0.01,r=0.859);ICP与MCA-Vm呈明显负相关(P<0.01.r=-0.638);ICP与dMCV-Vm无相关性(r=0.07,P>0.05)。随着ICP的升高,动脉频谱表现为舒张期和收缩期血流的不同步下降,静脉频谱呈现血流升高的特征,表现为血流量与血管径的同步增加。结论TCD对临床可疑脑静脉窦血栓形成的患者是一种有效的筛选检测手段,TCD动态监测脑静脉窦血栓患者动脉和静脉血流的同步变化可以评估ICP增高的程度和脑部灌注情况,为临床治疗提供科学依据。     

急性脑梗死各临床亚型患者的脑血管反应性的变化

目的 探讨急性脑梗死各临床亚型患者脑血管反应性(CVR)的变化.方法 将70例急性脑梗死患者分为3个亚组:动脉硬化性血栓形成性脑梗死(AI)组(22例)、腔隙性脑梗死(LI)组(33例)和心源性脑梗死(CI)组(15例).应用经颅多普勒超声(TCD)检测各组患者双侧大脑中动脉(MCA)的平均流速(Vm)、脉动指数(PI)、阻力指数(RI)指标,通过屏气试验测定屏气指数(BHI);并与20名正常对照组进行比较. 结果与正常对照组相比,AI组Vm、PI、RI均显著升高(P<0.05～0.01),BHI明显降低(P<0.01);LI组Vm、BHI均显著降低(均P<0.05);而CI组各参数与正常对照组相比差异无统计学意义. 结论急性脑梗死各亚组的CVR改变并不相同,AI、LI组CVR损害更为明显,CVR检测对急性脑梗死各亚型的血液动力学研究有重要意义.     

Intraventricular administration of hepatocyte growth factor treats mouse communicating hydrocephalus induced by transforming growth factor beta1

Communicating hydrocephalus may occur spontaneously in elderly patients or occur as a complication of meningitis or intracranial hemorrhage, typically as a result of fibrosis along the route of cerebrospinal fluid (CSF) flow. Hepatocyte growth factor (HGF) has anti-fibrotic properties and is a promising candidate for the treatment of various fibrotic diseases. Thus, the goal of this study was to examine the effect of exogenous HGF (30 microg of human recombinant (hr) HGF intraventricularly for 7 or 14 days) in a model of hr transforming growth factor beta1-induced communicating hydrocephalus in C57BL/6 mice. HGF treatment resulted in a reduction of ventriculomegaly, as demonstrated by magnetic resonance imaging, and improved spatial memory. Further, ink passage test demonstrated improvement of normalized CSF in flow in mice receiving HGF treatment as opposed to delayed CSF flow in the hydrocephalic mice at baseline. Finally, histological examination in hydrocephalic mice undergoing HGF treatment revealed reduction of collagen fibers in the meninges and normalization of their structures. These results indicate that exogenous HGF may be of utility in the treatment of hydrocephalus in humans.     

Optimal Values of Flow Velocity on Transcranial Doppler in Grading Middle Cerebral Artery Stenosis in Comparison With Magnetic Resonance Angiography

BACKGROUND AND PURPOSE: To investigate the optimal values of flow velocity on transcranial Doppler (TCD) in grading the severity of middle cerebral artery (MCA) stenosis in comparison with magnetic resonance angiography (MRA). METHODS: Both TCD and MRA examinations were performed on 148 asymptomatic patients. The peak flow velocities of each MCA were recorded. Severity of MCA stenosis on MRA was classified as normal-mild (< 50% lumen diameter reduction), moderate (50%-75%), and severe-void (> 75% and void of flow signal). RESULTS: Among 296 MCAs evaluated, normal-mild stenosis was found in 75 (25%), moderate stenosis in 112 (38%), and severe stenosis in 109 (37%). The mean of systolic velocity (Vs) of MCA differed significantly among these three groups: mean Vs = 121.83 +/- 22.52 cm/s in the normal-mild group; 155.96 +/- 21.62 cm/s for the moderate group; and 199.39 +/- 43.86 cm/s for the severe group (P < .001). The optimal cutoff velocity for detection of MCA (> 50%) stenosis was found at Vs > 140 cm/s on TCD (area under the ROC curve is 0.87, P < 0.001). The best cutoff points for grading severity of on TCD were 140 cm/s and 180 cm/s. CONCLUSION: TCD enables grading of the severity of MCA stenosis according to the flow velocity. This method provides a noninvasive and reliable method for grading MCA stenosis and allows longitudinal monitoring of the relationship between clinical outcome and hemodynamic change.     

Value of transcranial Doppler indices in predicting raised ICP in infantile hydrocephalus

Cerebral hemodynamic changes in infants with progressive hydrocephalus have been studied with the transcranial Doppler (TCD) technique. Several authors have referred to the correlation between the hemodynamic changes and increased intracranial pressure (ICP). Despite conflicting conclusions on the value of pulsatility index (PI) measurements for monitoring infantile hydrocephalus, these pulsatility indices are the most commonly used for this purpose. Although clinical signs of raised ICP are highly variable and unreliable in infants, assumptions have been made in most of the studies about the presence of elevated ICP on the basis of the patient's clinical state. Few studies have reported on actual ICP values, however, and a direct relationship between ICP and TCD changes has never been adequately demonstrated. In the present study, this relationship was investigated in long-term simultaneous TCD/ICP measurements, in an attempt to develop a noninvasive method of monitoring the effect of ICP on intracranial hemodynamics. Two groups of data sets were established. Group I consisted of pre- and postoperative (shunt implantation) TCD/ICP measurements. Group II were long-term simultaneous TCD/ICP recordings showing significant ICP variations. In most of the postoperative measurements there was a decrease in the average PI and RI values. The correlation between PI or RI and ICP in the long-term simultaneous recordings, however, was generally poor. The risk of obtaining false positive or false negative PI or RI values in short-term measurements was also demonstrated. It can be concluded from our results, besides the wide range of reference values for the Doppler indices and extracranial influences upon them, that the present Doppler indices are inadequate for monitoring the complex intracranial dynamic responses in patients with raised ICP.     

Long-term results of hydrocephalus with myelomeningocele

This paper reviews long-term follow-up studies of 78 hydrocephalic patients with myelomeningocele. Seventy-eight (95%) out of 82 patients with myelomeningocele had hydrocephalus. CT, MRI, CT cisternography, and monitoring of intracranial pressure (ICP) with infusion methods were performed to evaluate the indication of shunt insertion or shunt independency. These hydrocephalic patients consisted of the following two groups: (1) Early treated group. Sixty-four cases received initial cerebrospinal fluid (CSF) diversion operation within 2 years of life. Sixty-three patients had a ventriculoperitoneal (VP) or a ventriculoatrial (VA) shunt. All the patients of this group showed progressive signs and symptoms of increased ICP due to hydrocephalus. The mean age at the initial shunt placement was 10 weeks. The mean value of Evans' index before shunting was 47%, which corresponded to moderate ventriculomegaly. 48% of this group showed slit-like ventricles on postoperative CT scans, where 52% had normal or only mildly dilated ventricles subsequent to shunting. There were two instances (3%) of the so-called "slit ventricle syndrome" and one instance of "isolated fourth ventricle", who had undergone multiple shunt revisions. Shunt revisions were performed on fifty-two occasions in this group. The mean number of shunt revisions per child was 2.8. Sixty among 64 patients of this group were suitable for evaluating shunt dependency with long-term follow-up period. Forty-two out of 60 patients were considered to be shunt dependent, who underwent multiple shunt revisions after 6 months of age. These patients had signs and symptoms of increased ICP, neurological deterioration, and enlarged ventricles when their shunts were blocked. There were four cases of slowly progressive (shunt dependent) hydrocephalus, who did not show clinical signs and symptoms of shunts malfunction in spite of progressive ventriculomegaly and abnormal findings of CT cisternography and ICP monitoring. Only two patients (3%) proved to be shunt independent. Consistently their ventricles were mildly dilated. These results suggest a very low incidence of true arrest of hydrocephalus after shunt operation. (2) Late treated group. Fourteen cases were diagnosed or treated for hydrocephalus after 7 years of age. Six out of fourteen patients had remarkable hydrocephalus whose Evans' index exceeded 51%. The mean value of Evans' index was 48% in this group. Six patients had progressive signs and symptoms of hydrocephalus and were shunted. ICP monitoring and studies of CSF dynamics revealed abnormal findings in ten out of 14 cases in spite of preservation of good intelligence.(ABSTRACT TRUNCATED AT 400 WORDS)     

高血压合并无症状性大脑中动脉狭窄患者的药物干预研究

目的探讨在降血压治疗的同时联合应用辛伐他汀和阿司匹林对高血压合并无症状性大脑中动脉狭窄患者的干预作用和脑血管事件的预防效果。方法177例高血压合并大脑中动脉狭窄患者,其中90例应用辛伐他汀(每晚20mg)和阿司匹林肠溶片(75mg/d)进行治疗(干预组),通过经颅多普勒超声检查分别观察治疗前及治疗后1～3年大脑中动脉收缩期血流速度峰值、搏动指数、阻力指数、频谱形态,同时检测治疗前后血压、血脂等项生化指标的变化,并与87例对照者进行比较。结果治疗第1年,干预组患者大脑中动脉收缩期血流速度峰值、搏动指数、阻力指数及频谱形态等与治疗前差异无统计学意义(P>0.05);随访至第2,3年,上述各项指标均改善(P<0.01),频谱形态明显好转。随访结束时,两组患者大脑中动脉上述指标间差异有高度统计学意义(均P<0.01),干预组患者脑血管事件发生率为11.11%(10/90),低于对照组的24.14%(21/87)(P<0.01)。结论在有效降低血压的同时,联合应用辛伐他汀和阿司匹林可稳定并延缓高血压患者大脑中动脉狭窄的进程,对降低脑血管事件的发生率具有良好的作用。     

The Role of Transcranial Doppler in Symptomatic Striatocapsular Small Deep Infarction

BACKGROUND AND PURPOSE: The transcranial Doppler (TCD) findings in symptomatic small deep infarction are not well known. The aim of this study was to evaluate the role of TCD in striatocapsular small deep infarctions (SSDIs). METHODS: The cerebral angiography and TCD findings were analyzed on 100 patients with symptomatic cerebral infarcts on the middle cerebral artery (MCA) territory. The sensitivity, specificity, and accuracy of TCD in detecting the MCA lesions were compared between lacunar group (the patients with lacunar syndrome and SSDIs on magnetic resonance image) and nonlacunar group. RESULTS: Thirty-eight patients were classified as the lacunar group, whereas 62 patients as the nonlacunar group. On angiography, occlusive lesion of MCA was found in 18 of the lacunar group and 24 patients of the nonlacunar group. The degree of MCA stenosis was higher in the nonlacunar group (80.8% +/- 21.2%) than the lacunar group (60.4% +/- 21.6%). The accuracy of TCD for the detection of MCA stenosis was not different between the groups. However, the sensitivity of TCD in the lacunar group was lower (72%) than in the nonlacunar group (88%), and it might have been due to the difference in the degree of MCA stenosis among the groups. CONCLUSION: Occlusive lesions of the MCA should be considered as a potential cause of SSDIs. In this respect, TCD may be used for screening candidates for conventional angiography in those patients. High rate of mild-degree stenosis of MCA in patients with SSDIs, however, caused a risk for missing such stenosis on TCD.     

Normal pressure hydrocephalus. Part 1. Dynamic study of CSF circulation in patients with normal pressure hydrocephalus (author's transl)

To clarify the pathogenesis of normal pressure hydrocephalus (NPH), quantitative measurement of CSF dynamics was attempted using RI techniques. In this study results concerning RI ventriculography and RI transfer test from CSF to plasma were reported. "Barrier ratio" and regional cerebral blood flow study in NPH will be reported elsewhere. Fifty-three patients with chronic communicating hydrocephalus wer devided into two groups. Thus, twenty-seven cases were diagnosed as NPH according to clinical symptoms and signs, and others were considered as mere chronic communicating hydrocephalus without any NPH characteristics. Results are as follows: 1) 169Yb--DTPA ventriculography; In NPH group, there was longer retention of RI injected into lateral ventricle, and RI activity was not detected in the cisterna magna 60 minutes after the injection. These findings show remarkable delay of CSF flow in NPH patients. 2) Transfer test of 169Yb--DTPA from CSF to plasma; Immediately after the RI injection, Transfer ratio of RI activity from CSF to plasma was measured. It was revealed that intraventricular RI was more rapidly transfered to plasma in NPH group compared with in the control group, suggesting accelerated trans-ependymal absorption of RI in NPH group.     

Transcranial Doppler and real-time cranial sonography in neonatal hydrocephalus

Nine hydrocephalic infants who were less than 1 year old and 7 age-matched control subjects were examined by real-time and transcranial Doppler sonography to evaluate cerebral blood flow and to correlate it to ventricular size. These 16 infants were placed in one of three groups: infants in group 1 (n = 7) had a normal ventricular size, infants in group 2 (n = 3) had a progressively increasing ventricular size, and infants in group 3 (n = 6) had ventriculomegaly with either stable or decreasing ventricular size or a functioning ventriculoperitoneal shunt. All scans performed on group-2 infants showed markedly increased ventricular size and increased pulsatility index, while those on group-1 infants showed a normal ventricular size and pulsatility index. However, the scans of group-3 infants revealed increased ventricular size and pulsatility index for all groups. Regression analysis of the data showed rather weak correlations between ventricular size and pulsatility index for all groups. The regression data suggest that ventricular size is not the main determinant of cerebral blood flow in the neonate with hydrocephalus and that intracranial pressure may be a more critical factor. These data suggest that pulsatility index, as measured by transcranial Doppler, can be clinically more important than just the anatomical data alone in the evaluation of hydrocephaly. This points to a possible use of transcranial Doppler sonography in the evaluation of hydrocephalic patients for placement of ventriculoperitoneal shunts.     

Cerebrovascular CO2 reactivity in migraine with aura and without aura. A transcranial doppler study

Inntroduction – We studied by means of Transcranial Doppler (TCD) recordings the CO₂ cerebrovascular reactivity in migraine patients during the headache-free period. Material & methods - In three groups of subjects (15 controls, 15 suffering from migraine with aura and 15 from migraine without aura) the middle cerebral artery (MCA) mean flow velocity (MFV) was recorded under basal condition and hypocapnia induced by hyperventilation. Relative MFV, PI (Pulsatility Index) changes and Reactivity Index (RI) were calculated. Results - Reactivity Index values were: 0.019 ± 0.007 (mean ± SD) in control subjects: 0.029 ± 0.008 in migraine with aura; 0.022 ± 0.008 in migraine without aura. Statistical analysis showed a significantly (P < 0.05) increased RI in migraine with aura group. Conclusion – Cerebrovascular CO₂ reactivity is increased during the interictal period in migraine with aura patients.     

中、重型颅脑损伤患者脑血流动力学变化与颅内压、脑灌注压的相关性研究

目的 探讨经颅多普勒（TCD）无创检测中、重型颅脑损伤患者的脑血流动力学变化与颅内压和脑灌注压的关系。方法 前瞻性研究52例急性中、重型颅脑损伤患者的双侧大脑中动脉血流动力学状态，TCD检测脑血流动力学参数包括收缩期血流速度（Vp）、舒张期血流速度（Vd）、平均血流速度（Vm）、搏动指数（PI）、阻力指数（RI），持续监测颅内压（ICP）和脑灌注压（CPP）、平均动脉血压（MABP）。对脑血流动力学参数、MABP与ICP、CPP进行相关性分析。结果 PI、RI与ICP正相关系数分别为PI：r=0．881（P＜0．0001）；RI：r=0．789（P＜0．0001），ICP和CPP与PI、RI、Vd、Vm、MABP多元逐步回归分析发现PI与ICP，CPP与PI、MABP关系最为密切（P＜0．0001）。结论 无创脑血流动力学检测可实时反映ICP和CPP的变化，可作为ICP和CPP监测的一种有效方法，具有无创、安全、价廉的特点，易于临床推广应用。     

Transcranial Doppler Markers of Diffusion-Perfusion Mismatch

BACKGROUND AND PURPOSE: During the evaluation of acute ischemic stroke with diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively), the presence of salvageable brain tissue is suggested by the occurrence of a perfusion-diffusion "mismatch." DWI and PWI, however, are not universally available and have inherent inconveniences, which justify a search for practical diagnostic alternatives. The purpose of this study is to investigate whether there are transcranial Doppler (TCD) markers of mismatch. METHODS: Retrospective analysis of 22 patients with acute ischemic stroke affecting the middle cerebral artery (MCA) territory, who had a TCD performed within 24 hours of magnetic resonance imaging (MRI) with DWI and PWI. RESULTS: MRI and TCD were performed on average 10.8 +/- 9.2 hours apart. Time from symptom onset to MRI and TCD completion were 1.6 +/- 1.6 and 2 +/- 1.9 days, respectively. MCA and intracranial internal carotid artery (ICA) cerebral blood flow velocity (CBFV) asymmetry, together with a large ICA-to-MCA gradient, were associated with the presence of mismatch. The combined use of 2 TCD parameters (MCA CBFV asymmetry of > or = 30% and ICA-to-MCA gradient > or = 20 cm/sec) had a sensitivity of 75%, specificity of 80%, positive predictive value of 82%, and negative predictive value of 73% at detecting mismatch cases. CONCLUSIONS: Diffusion-perfusion mismatch appears to be associated with interhemispheric asymmetry between MCA and ICA CBFVs, and a large CBFV gradient between the ICA and MCA on the affected side. Prospective studies are required to verify these observations and to determine whether TCD can be used to follow patients with mismatch.     

Indications for shunt insertion or III ventriculostomy in hydrocephalic children, guided by lumbar and intraventricular infusion tests

The best therapeutic management for infantile hydrocephalus is not always obvious. Traditionally, shunt insertion has been performed when CSF dynamics have been considered abnormal. However, in cases of noncommunicating hydrocephalus endoscopic III ventriculostomy (ETV) has become a well-established treatment modality, but despite clinical and radiological information clinical improvement is not obtained in all cases. A reliable preoperative investigative procedure helping to select hydrocephalic children for ETV, shunt insertion or no operation, is urgently needed. We report three cases of infantile hydrocephalus, in which our operative management was guided by the results of cerebrospinal (CSF) infusion tests. With a lumbar infusion test we assessed the CSF resorption capacity, and thus whether shunting was indicated. Comparing the results with those of an intraventricular infusion test, we assessed the presence of any structural blockage of the CSF circulation between the ventricles and the subarachnoid compartment, which would indicate a possible effect of an ETV. Performance of both a lumbar infusion test and a subsequent intraventricular infusion test in hydrocephalic children seems to provide valuable information for the decision-making on surgery. Received: 31 August 1998     

How does CSF dynamics change after shunting?

Objective –  Hydrocephalus is much more complex than a simple disorder of cerebrospinal fluid (CSF) circulation. Shunting primarily corrects disturbed fluid flow which may have an impact on cerebral blood flow and metabolism. We studied hydrocephalic patients before and after shunting to characterize changes in their CSF compensatory parameters.
Material and methods –  We selected 25 patients and studied them retrospectively. All patients had ventriculomegaly and clinical symptoms of normal pressure hydrocephalus. After shunting, they were still presenting with some adverse symptoms, mainly headaches, slow improvement or no improvement of ventriculomegaly. Therefore, they underwent further infusion studies to assess shunt function. In all cases, the shunts were confirmed to be draining CSF adequately. Parameters of CSF dynamics: baseline intracranial pressure (ICP), resistance to CSF outflow, cerebrospinal elasticity, content of vasogenic pressure waves (pulse, respiratory and B waves) and compensatory reserve assessed as moving correlation coefficient between mean CSF pressure and pulse amplitude (RAP), were compared before and after shunting.
Results –  Mean ICP and resistance to CSF outflow decreased ( P  < 0.003) after shunting. All vasogenic pressure waves decreased ( P  < 0.005). Compensatory reserve (RAP) significantly improved ( P  < 0.005).
Conclusion –  A functioning shunt has an important impact on CSF circulation and pressure–volume compensation. Infusion studies can demonstrate the return of disturbed CSF dynamics to normal values even if clinical or radiological changes are not dramatic.     

Assay of immune complexes in infantile hydrocephalus among Nigerians

The immune complexes in infantile hydrocephalic CSF in Nigerian children using a laser nephelometer were quantified. The values obtained were relatively low when compared with the serum levels. There was no evidence of selective admixture or of a breakdown of blood-brain-barrier (BBB). The low levels of immune complexes, when associated with implantation of shunt device for treatment of the hydrocephalus, may be a predisposing factor that can lead to overwhelming infection among this group of patients in a developing country like Nigeria. Between the hydrocephalic fluid and lumbar CSF, an IgG gradient was found.     

Simultaneous recording of cerebrospinal fluid pressure and middle cerebral artery blood flow velocity in patients with suspected symptomatic normal pressure hydrocephalus.

CSF pressure (intracranial pressure, in one patient lumbar pressure) was monitored continuously for one night in 23 patients with suspected symptomatic normal pressure hydrocephalus (NPH) to identify patients who might benefit from subsequent shunt surgery. In 20 patients middle cerebral artery (MCA) blood flow velocity by means of transcranial Doppler sonography (TCD) and CSF pressure were recorded simultaneously. In three patients transcranial Doppler signals were insufficient. Spontaneous changes in CSF pressure always paralleled changes in the TCD signal. Equivalents of B-waves as well as intermediate waves (in between B- and A-waves), and C-waves could be identified easily and always appeared in phase. The Doppler signal, however, could not be used to evaluate the absolute changes in CSF pressure. Fast Fourier Transform of the Doppler signal was a useful tool to indicate the relative frequency of B-wave equivalents. In five patients the injection of 10ml saline into the ventricle raised intracranial pressure considerably, but hardly affected the MCA blood flow velocity. Continuous TCD monitoring might be useful as a noninvasive screening procedure in patients with suspected symptomatic NPH before continuous invasive CSF pressure measurements are performed.     

Cerebral energy metabolism in experimental canine hydrocephalus

Cerebral energy metabolism, its relationship to the stage and extent of hydrocephalus, and the effect of cerebrospinal fluid (CSF) removal on it were studied in experimental canine hydrocephalus produced by intracisternal injection of kaolin by using phosphorus-31 (P-31) magnetic resonance (MR) spectroscopy and MR imaging, P-31 MR spectra were serially obtained before and after CSF removal, maximally on eight occasions over a period of nearly 5 h. There was a decrease in the ratio of creatine phosphate to inorganic phosphate, used as an indicator of the bioenergetic state, in acute and subacute stages of hydrocephalus as compared with the control. An animal in the subacute stage, when periventricular edema was most prominent, exhibited the most predominent decrease in this ratio at 14 days after hydrocephalic insult. The recovery of the ratio toward the control level was seen in the chronically hydrocephalic animal. There was no change in adenosine triphosphate (ATP) levels in any stage of hydrocephalus. Serial spectra obtained after the withdrawal of ventricular CSF showed no change in the bioenergetic state of the brain in any stage of hydrocephalus. There was no relationship between either the extent of hydrocephalus or the ventricular CSF pressure and the change in the bioenergetic state or the levels of any of the phosphorus compounds. These findings may indicate the alteration of the mitochondrial energy metabolism in hydrocephalus, which may explain the mechanism of hydrocephalic syndrome.