Brain oxygen extraction fraction as an indicator for shunting operation in normal pressure hydrocephalus]

It is still difficult for neurosurgeons to determine which patients with suspected idiopathic normal pressure hydrocephalus (NPH) should undergo shunting. We need to find a more accurate indicator to predict the effect of shunting. We introduced a new preoperative examination of brain oxygen extraction fraction (OEF) and examined whether preoperative OEF value is effective for prediction of the surgical results. Global brain OEF was calculated from oxygen contents of arterial blood (AO2) and jugular venous blood (VjO2) selectively sampled from the right jugular bulb using the Seldinger method: OEF = (AO2-VjO2)/AO2. Since June 1996 we have treated 9 patients suspected of idiopathic and 10 patients suspected of secondary NPH. OEF in non-NPH patients with dilated ventricle (n = 10) and in infarct patients (n = 85) were 0.33 +/- 0.02 and 0.38 +/- 0.06, respectively. In contrast, OEF increased both in idiopathic NPH (0.42 +/- 0.04) and secondary NPH (0.45 +/- 0.02), and the NPH patients with the higher preoperative OEF values showed the better symptomatic recovery. The present study suggests that brain function may be reversible when OEF can be increased and that OEF can be a useful indicator for predicting the effect of a shunting operation in NPH.     

Endoscopic ventriculostomy versus shunt operation in normal pressure hydrocephalus: diagnostics and indication.

In contrast to the shunt operation the indication for an endoscopic ventriculostomy in patients diagnosed for normal pressure hydrocephalus is not scientifically established. Between September 1997 and December 1999 we operated on 48 patients diagnosed for normal pressure hydrocephalus. The diagnosis was established by means of the intrathecal lumbar or ventricular infusion test, the cerebrospinal fluid tap test and MRI-CSF flow studies pre- and postoperatively. In 37 patients (77%) we have implanted a ventriculo-peritoneal shunt, and in 11 patients (23%) we performed the endoscopic assisted third ventriculostomy. With our created NPH recovery rate and use of the clinical grading for normal pressure hydrocephalus created by Kiefer and Steudel we compared the operative results of both groups of patients. In patients with a pathologically increased resistance to CSF outflow in the lumbar infusion test a shunt implantation is indicated. Patients whose outflow resistance is increased in the ventricular infusion test but with a physiological lumbar infusion test are suspected for a functional aqueduct stenosis and should be treated by means of endoscopic assisted ventriculostomy.     

Continuous intraventricular pressure monitoring for diagnosis of normal-pressure hydrocephalus

Summary Objectives. Normal-pressure hydrocephalus (NPH) syndrome is treatable by implantation of a cerebrospinal fluid (CSF) shunt. However, diagnosis of NPH by clinical and radiological findings alone is unreliable, and co-existing structural dementia can contribute to low success rates after shunt implantation. The aim of our study was to investigate whether long-term results after shunt implantation in NPH improve when surgical candidates are selected by continuous intraventricular pressure monitoring (CIPM). Patients and methods. Ninety-two consecutive patients who were admitted with suspected NPH received CIPM for 48 h including an intraventricular steady-state infusion test to determine the resistance outflow. With positive CIPM, shunt implantation was performed and the patients were prospectively followed up for 1 to 10 years (median 6.5 years). Results. CIPM was negative in 37 patients. Fifty-five patients had a positive CIPM and received CSF shunt. 96.1% of them improved from gait disturbance, 77.1% from cognitive impairment and 75.7% from urinary dysfunction. Clinical improvement remained during long-term follow-up in all but 3 patients who showed a decline at 4, 5 and 7 years, respectively. CIPM-related complications (ventriculitis) occurred in only one patient. Conclusion. CIPM is a safe and valuable tool to establish a reliable diagnosis of NPH and to identify promising surgical candidates.     

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.     

Does the shunt opening pressure influence the effect of shunt surgery in normal pressure hydrocephalus?

Summary Thirteen patients with normal pressure hydrocephalus were operated upon with an externally manoeuvrable shunt system (Sophy SU8) in order to investigate its influence on clinical outcome, intracranial pressure and cranial CT parameters. The opening pressure was set at high at surgery and lowered stepwise at intervals of three months to medium and low. The clinical condition, intracranial pressure and cranial CT parameters were examined at the end of the 3 months interval on each pressure level.The patients improved within the first 3 months inspite of an unchanged mean intracranial pressure and remained in a stable clinical condition during the rest of the study period. The intracranial pressure was significantly reduced at 9 months. The ventricular index, Evans index, temporal horn and third ventricle width were reduced 3 months post-operatively and did not change significantly during the rest of the study. The pre-operative third ventricle width was correlated to high psychometric test results after shunt surgery. Reduction in ventricular index, Evans index and third ventricle width after surgery correlated to improvement in psychometric scoring.The clinical improvement after shunt surgery for normal pressure hydrocephalus is seen within 3 months and is independent of the adjusted valve pressure.     

正常压力性脑积水分流术后运动功能恢复的相关因素分析

目的 脑室腹腔分流术是正常压力性脑积水较理想的治疗方式,本研究旨在对分流术后运动功能恢复的相关因素进行分析.方法 26例患者行分流术,以发病时间、腰穿压力、腰穿后症状改善及术后12个月时运动功能的恢复为指标.结果 术后12个月时,发病时间较短,腰穿压力较高,腰穿后症状有改善者,运动功能的恢复较好.结论 发病时间较短,腰穿压力较高,腰穿后症状改善者,分流术多有效.     

Changes in intracranial pulse pressure amplitudes after shunt implantation and adjustment of shunt valve opening pressure in normal pressure hydrocephalus

Summary Background  We have previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (NPH) patients responding to shunt surgery. Whether or not shunt implantation or adjustment of the shunt valve opening pressure modifies the intracranial pulse pressure amplitudes in NPH patients remains to be established. This report summarises our observations. Patients and methods  Thirteen patients with NPH (idiopathic in nine and secondary in four) are presented in whom continuous intracranial pressure (ICP) monitoring was done before and after shunt implantation. In two, ICP monitoring was also done during adjustment of shunt valve opening pressure. The mean ICP and mean ICP wave amplitude (i.e. pulse pressure amplitudes) were determined in 6-s time windows. Results  After shunt implantation there was a fall in both mean ICP and mean ICP wave amplitude; the reduction in the two ICP parameters correlated significantly. However, mean ICP in the supine position was normal (i.e. <15 mmHg) in 12 of 13 patients before shunt placement, and remained normal after shunting. According to our criteria, the mean ICP wave amplitudes were elevated before shunting in 12 of 13 patients and became “normalised” the day after shunting in nine patients. The reduction in mean ICP wave amplitude after shunt was highly significant at the group level. Moreover, adjustment of shunt valve opening pressure modified the levels of mean ICP wave amplitudes. Conclusions  The present observations in 13 NPH patients indicate that shunt implantation reduces mean ICP wave amplitudes. Moreover, the level of reduction can be tailored by adjustment of the shunt valve opening pressure.     

Predictive value of temporary external lumbar drainage in normal pressure hydrocephalus

In a prospective study on the effect of shunting, 22 patients diagnosed as suffering from normal pressure hydrocephalus (NPH) were investigated by means of temporary external lumbar drainage (ELD). Five patients had to be excluded from the study because of complications of ELD or definitive shunting. ELD correctly predicted the outcome of shunting in all of the remaining 17 patients. The value of external lumbar drainage in NPH is discussed on the basis of personal experience and data from the literature. It seems to be a safe and valuable tool for predicting the outcome of definitive shunting procedures.     

Acute subdural hematoma after lumboperitoneal shunt placement in patients with normal pressure hydrocephalus

Acute subdural hematoma (SDH) is a rare but disastrous complication after lumboperitoneal shunt placement. Four of 206 adult patients with normal pressure hydrocephalus (1.9%) who underwent lumboperitoneal shunt placement suffered acute SDH following head trauma. The interval between shunt placement and acute SDH was one month to 7 years. Two patients had subdural effusion on computed tomography (CT) at 2- and 6-month follow up. All four patients required assistance in their daily activities before acute SDH onset. The traumatic event was a fall. On admission, CT revealed a large SDH that required surgical removal in two patients, of whom one had manifested subdural effusion after shunt placement. The other two patients had a small SDH. None of the four patients had cerebral contusions. Patients with lumboperitoneal shunts, especially those not capable of independent daily activities, are at risk for acute SDH after even minor head trauma.     

Ventriculo-atrial shunt insertion: pressure monitoring as an aid to accurate placement

The objective of this paper is to describe a new method to ensure accurate placement of a ventriculo-atrial shunt distal catheter. A technique is described using pressure waveform changes within the right side of the heart. Pressure monitoring is a new method of placing atrial catheters and is easy to perform.     

Torkildsen shunt as a salvage procedure for an infant with post-hemorrhagic hydrocephalus

IntroductionTorkildsen operation is a ventriculo-cisternal shunt that diverts the cerebrospinal fluid flow from one of the lateral ventricles, via a ventricular catheter, to the cisterna magna of the posterior fossa. It is the first described operation of CSF diversion for the treatment of hydrocephalus [1] (Scarff, 1963).Presentation of caseWe present the case of a premature infant who presented with post hemorrhagic hydrocephalus who underwent several failed CSF diversion surgeries before Torkildsen shunt procedure. The patient overcame the irregularities of CSF circulation that were observed before the operation and his post-operative course was uneventful, in terms of CSF –related complications.DiscussionWe summarize the historical data and the technical aspects of the procedure, and we present a brief literature review of the indications and limitations associated with it.ConclusionTorkildsen shunt can be effective in selected patients with hydrocephalus even in the modern era of computed tomography and magnetic resonance imaging. the procedure enables one to avoid a standard ventriculoperitoneal shunt, especially in cases it is not technically feasible.     

Regional cerebral blood flow and oxygen metabolism in normal pressure hydrocephalus after subarachnoid hemorrhage

To clarify the pathophysiology of normal pressure hydrocephalus (NPH) after subarachnoid hemorrhage, the authors measured cerebral blood flow (CBF), cerebral oxygen metabolic rates (CMRO2), the cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) in eight normal volunteers, six SAH patients with NPH, and seven patients without NPH by 15O-labeled gas and positron emission tomography (PET). In the NPH group, PET revealed a decrease in CBF in the lower regions of the cerebral cortex and a diffuse decrease in CMRO2. The decrease in CBF in the lower frontal, temporal, and occipital cortices was significantly greater in the NPH than in the non-NPH group. Reduction of CMRO2 was also more extensive in the NPH group, and both CBF and CMRO2 were more markedly decreased in the lower frontal region. OEF was increased in all areas in both of the patient groups, but the increase was not significant in most areas. CBF, CMRO2 and OEF did not significantly differ between the non-NPH group and the normal volunteers. There was no significant difference in CBV among the three groups. These results indicate that NPH involves impairment of cerebral oxygen metabolism in the lower regions of the cerebral cortex, particularly in the lower frontal region.     

Clinical guidelines for idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome characterized by gait disturbance, dementia, and/or urinary incontinence without causative disorders, and ventricular enlargement due to disturbance of the cerebrospinal fluid (SF) circulation. The number of patients with iNPH will increase with the aging of the population in Japan. However, iNPH is often difficult to differentiate from other senile disorders such as lumbar canal stenosis, parkinsonism, and so on. Clinical guidelines for iNPH are required to improve understanding and provide for patients' quality of life and social care. These guidelines propose three levels of iNPH: possible, probable, and definite. Possible iNPH includes one or more of the classical triad and ventricular dilation in middle aged and elderly patients with closing of the CSF space at high convexity on magnetic resonance imaging. Probable iNPH shows improvement of the symptoms after CSF removal in patients with possible iNPH. Definite iNPH shows clinical improvement after CSF shunt operation. The CSF tap test is a major diagnostic measure because of the simplicity and less invasiveness. Use of the programmable valve is recommended to decrease CSF overdrainage. These guidelines are helpful for the diagnosis and treatment of iNPH.     

Clinical study of ventriculo-lumbar perfusion in the patients of so-called normal pressure hydrocephalus (author's transl)

The cerebrospinal fluid dynamics were studied in the ten patients between 33 and 67 years old with signs of so-called normal pressure hydrocephalus by the technique of ventriculo-lumbar perfusion. The perfusion fluid with Ringer's solution or Hartmann's solution containing tracer amounts (25 mg/dl) of insulin. The inflow fluid warmed up to the body temperature was introduced by the infusion pump to the trigone of the lateral ventricle through the ventricular tube. The outflow fluid was collected from the lumbar subarachnoid space through the spinal needle inserted into the L4-5 interspace. The perfusion pressure was adjusted by raising and lowering the height of the outflow manometric pressure relative to the spinous process. The distribution volume of the perfusion system was the range of 94 - 209 ml (average 136 ml) and exceeded the normal range. The formation rate of cerebrospinal fluid was the range of 0.21 - 0.69 ml/min (average 0.39 ml/min) at the opening pressure, and nearly equal to the bulk absorption rate. There was the relationship between the bulk absorption rate and the perfusion pressure, and the regression coefficients in nine cases were lower than reported in normals. The clinical condition of seven of the nine patients demonstrating this absorptive deficit improved after cerebrospinal fluid shunting. The perfusion test was useful to recognize the cerebrospinal fluid dynamics and also to determine the indication of cerebrospinal fluid shunt in the patients of so-called normal pressure hydrocephalus.