Is the placement of shunts in patients with idiopathic normal pressure hydrocephalus worth the risk? Results of a study based on continuous monitoring of intracranial pressure

Treatment of iNPH: novel insights

This review advocates for a shift from traditional symptom-based diagnosis of idiopathic normal pressure hydrocephalus (iNPH) to a deeper investigation into its underlying pathophysiological mechanisms, particularly the role of altered cerebral hydrodynamics as an important pathological hallmark. We explore the heterogeneity of iNPH, emphasizing its frequent overlap and cooccurrence with neurodegenerative conditions like Alzheimer and Parkinson disease, and subcortical vascular encephalopathy, complicating diagnosis and treatment strategies. The lumbar infusion test emerges as a useful diagnostic tool, offering quantitative insights into CSF outflow resistance that should be considered as a useful biomarker related to cerebral hydrodynamics and iNPH pathophysiology. Furthermore, we propose the hypothesis that shunt placement, by regulating brain fluid mechanics, may also serve as a form of neuromodulation, potentially enhancing neuronal function and mitigating clinical symptoms. This review advocates for an interdisciplinary, physics-based and patient-centered approach that emphasizes early detection, accurate diagnostics, and personalized treatment plans to enhance patient outcomes and quality of life, particularly in the aging population.

SV, Borchert R, Russo S, Eide PK. Radiological predictors of shunt response in the diagnosis and treatment of idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

BACKGROUND

Patients with the dementia subtype idiopathic normal pressure hydrocephalus (iNPH) may improve clinically following cerebrospinal fluid (CSF) diversion (shunt) surgery, though the predictors of shunt response remain debated. Currently, radiological features play an important role in the diagnosis of iNPH, but it is not well established which radiological markers most precisely predict shunt responsive iNPH.

OBJECTIVE

To conduct a systematic review and meta-analysis to identify radiological predictors of shunt responsiveness, evaluate their diagnostic effectiveness, and recommend the most predictive radiological features.

METHODS

Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR were searched for original studies investigating radiological predictors of shunt response in iNPH patients. Included studies were assessed using the ROBINS-1 tool, and eligible studies were evaluated using a univariate meta-analysis.

RESULTS

Overall, 301 full-text papers were screened, of which 28 studies were included, and 26 different radiological features were identified, 5 of these met the inclusion criteria for the meta-analysis: disproportionately enlarged subarachnoid space (DESH), callosal angle, periventricular white matter changes, cerebral blood flow (CBF), and computerized tomography cisternography. The meta-analysis showed that only callosal angle and periventricular white matter changes significantly differentiated iNPH shunt responders from non-responders, though both markers had a low diagnostic odds ratio (DOR) of 1.88 and 1.01 respectively. None of the other radiological markers differentiated shunt responsive from shunt non-responsive iNPH.

CONCLUSION

Callosal angle and periventricular changes are the only diagnostically effective radiological predictors of shunt responsive iNPH patients. However, due to the DORs approximating 1, they are insufficient as sole predictors and are advised to be used only in combination with other diagnostic tests of shunt response. Future research must evaluate the combined use of multiple radiological predictors, as it may yield beneficial additive effects that may allow for more robust radiological shunt response prediction.

Motor skills, cognitive impairment, and quality of life in normal pressure hydrocephalus: early effects of shunt placement

Background

Traditionally, clinical findings of normal pressure hydrocephalus are mainly characterized by the Hakim triad. The aim of this study is to evaluate the performance of patients suffering from idiopathic normal pressure hydrocephalus (iNPH) in a more holistic manner regarding motor skills, cognitive impairment, and quality of life.

Methods

In total, 30 individuals diagnosed with iNPH as well as a reference group with another 30 individuals were included. The iNPH patients and the reference group were age, educational, and morbidity matched. A standardized test battery for psychomotor skills, gait, neuropsychological abilities as well as questionnaires for quality of life was applied. The iNPH group was tested prior to surgery, at 6 weeks, and 3 months postoperatively. The reference group was tested once.

Results

Patients showed a significant improved performance in various items of the test battery during the first 3 months postoperatively. This included neuropsychological evaluation, motor skills including gait and upper motor function as well as the quality of life of the patients. Compared to reference individuals, neuropsychological aspects and quality of life of iNPH patients improved in some parts nearly to normal values.

Conclusion

Our findings underline that shunt surgery does not only improve the symptoms in iNPH patients but also ameliorates the quality of life to a great extent close to those of age and comorbidity matched reference individuals. This data enables an optimized counseling of iNPH patients regarding the expectable outcome after shunt surgery especially regarding cognitive performance, motor skills as well as life quality.

How to Choose a Shunt for Patients with Normal Pressure Hydrocephalus: A Short Guide to Selecting the Best Shunt Assembly

Most patients with hydrocephalus are still managed with the implantation of a cerebrospinal fluid (CSF) shunt in which the CSF flow is regulated by a differential-pressure valve (DPV). Our aim in this review is to discuss some basic concepts in fluid mechanics that are frequently ignored but that should be understood by neurosurgeons to enable them to choose the most adequate shunt for each patient. We will present data, some of which is not provided by manufacturers, which may help neurosurgeons in selecting the most appropriate shunt. To do so, we focused on the management of patients with idiopathic “normal-pressure hydrocephalus” (iNPH), as one of the most challenging scenarios, in which the combination of optimal technology, patient characteristics, and knowledge of fluid mechanics can significantly modify the surgical results. For a better understanding of the available hardware and its evolution over time, we will have a second look at the design of the first DPV and the reasons why additional devices were incorporated to control for shunt overdrainage and its related complications. We try to persuade the reader that a clear understanding of the physical concepts of the CSF and shunt dynamics is key to understand the pathophysiology of iNPH and to improve its treatment.

Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus (Third Edition): Endorsed by the Japanese Society of Normal Pressure Hydrocephalus

Among the various disorders that manifest with gait disturbance, cognitive impairment, and urinary incontinence in the elderly population, idiopathic normal pressure hydrocephalus (iNPH) is becoming of great importance. The first edition of these guidelines for management of iNPH was published in 2004, and the second edition in 2012, to provide a series of timely, evidence-based recommendations related to iNPH. Since the last edition, clinical awareness of iNPH has risen dramatically, and clinical and basic research efforts on iNPH have increased significantly. This third edition of the guidelines was made to share these ideas with the international community and to promote international research on iNPH. The revision of the guidelines was undertaken by a multidisciplinary expert working group of the Japanese Society of Normal Pressure Hydrocephalus in conjunction with the Japanese Ministry of Health, Labour and Welfare research project. This revision proposes a new classification for NPH. The category of iNPH is clearly distinguished from NPH with congenital/developmental and acquired etiologies. Additionally, the essential role of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in the imaging diagnosis and decision for further management of iNPH is discussed in this edition. We created an algorithm for diagnosis and decision for shunt management. Diagnosis by biomarkers that distinguish prognosis has been also initiated. Therefore, diagnosis and treatment of iNPH have entered a new phase. We hope that this third edition of the guidelines will help patients, their families, and healthcare professionals involved in treating iNPH.

Ventriculoperitoneal Shunt Complications in the European Idiopathic Normal Pressure Hydrocephalus Multicenter Study

BACKGROUND

Ventriculoperitoneal shunt (VP-shunt) is the standard of treatment for idiopathic normal pressure hydrocephalus (iNPH). However, a thorough investigation of VP-shunt complications in this population is lacking.

OBJECTIVE

To present the analysis and the rates of complications progressively occurring during the first year after shunt surgery in the patients with iNPH included in the European multicenter (EU-iNPH) study.

METHODS

Patients (n = 142) were prospectively included in the EU-iNPH study by 13 institutions. All patients received a programmable VP-shunt. One hundred fifteen patients completed the 12-mo follow-up. Reexaminations were performed 1, 3, and 12 mo after surgery. Data regarding symptomatic over- or underdrainage, infections, malposition, subdural collections, and shunt surgery were collected and analyzed.

RESULTS

Thirty patients (26%) experienced symptoms due to shunt underdrainage. Symptomatic overdrainage was reported in 10 (9%). Shunt adjustments were made in 43 (37%). Shunt malposition was recognized as the primary cause of shunt malfunction in 8 (7%), while only 1 infection (0.9%) occurred. Subdural hematoma was diagnosed in 7 (6%) and was treated by increasing the opening pressure of the valve in 5 patients. Hygroma was diagnosed in 10 (9%), requiring surgery in 1 patient. Overall, 17 patients (15%) underwent 19 shunt surgeries.

CONCLUSION

The advances in valve technology, a careful opening pressure setting, and rigorous follow-up allow a significant reduction of complications, which can be usually managed nonsurgically within the first 3 to 6 mo.

Characterization of spontaneous hydrocephalus development in the young atherosclerosis-prone mice

Little has been reported on whether abnormal lipid metabolism affects hydrocephalus, although congenital malformations and infectious diseases are major causal factors for hydrocephalus development. In a study on the pathogenesis of atherogenesis in mice, we unexpectedly discovered that hydrocephalus occurred in partial apolipoptotein E (apoE) and low-density lipoprotein receptor (LDLR) double-knockout (apoE/LDLR) mice fed either chow or a high-fat and high-cholesterol diet between the ages of 4 and 12 weeks. In the 12-week-old high-fat and high-cholesterol group, the incidence rate was as high as 15%. Transcription levels of transforming growth factor-β1 (TGF-β1), Smad3, Smad4, and Smad7 in the cortex of the hydrocephalic cerebrum were significant downregulated in 4-week-old mice, but were increased in the 8 and 12-week-old groups compared with that of age-matched nonhydrocephalic mice. The mRNA level of tissue inhibitor of metalloproteinases 1 was significantly increased, whereas matrix metalloproteinase-9 was lower in hydrocephalic mice of all ages. The translation level of TGF-β1 increased in the hydrocephalic brains of 8 and 12-week-old mice. This study provides primary evidence for the connection between lipid metabolic disorder and hydrocephalus development. This may suggest that both hyperglyceridemia and hypercholesterolemia are harmful factors in hydrocephalus development because of adverse effects on TGF-β1/Smad signaling in the brain.

Whole Brain Parcellation with Pathology: Validation on Ventriculomegaly Patients

Numerous brain disorders are associated with ventriculomegaly; normal pressure hydrocephalus (NPH) is one example. NPH presents with dementia-like symptoms and is often misdiagnosed as Alzheimer's due to its chronic nature and nonspecific presenting symptoms. However, unlike other forms of dementia NPH can be treated surgically with an over 80% success rate on appropriately selected patients. Accurate assessment of the ventricles, in particular its sub-compartments, is required to diagnose the condition. Existing segmentation algorithms fail to accurately identify the ventricles in patients with such extreme pathology. We present an improvement to a whole brain segmentation approach that accurately identifies the ventricles and parcellates them into four sub-compartments. Our work is a combination of patch-based tissue segmentation and multi-atlas registration-based labeling. We include a validation on NPH patients, demonstrating superior performance against state-of-the-art methods.

The Prediction of Shunt Response in Idiopathic Normal-Pressure Hydrocephalus Based on Intracranial Pressure Monitoring and Lumbar Infusion

BACKGROUND

Intracranial pressure (ICP) monitoring and infusion studies have long been used in the preoperative workup of patients with suspected idiopathic normal-pressure hydrocephalus (iNPH). We have analysed the predictive values of different measures derived from both investigations, emphasising the differences between responders and nonresponders.

MATERIALS AND METHODS

ICP monitoring and lumbar infusion studies were routinely performed during a 6-year period. Shunting was proposed when the resistance to cerebrospinal fluid outflow (ROUT) >12 mmHg/ml/min and/or a minimum 15 % of slow waves were detected. The outcome was evaluated 6 months after surgery. Recorded data from ICP monitoring were mean pressure and pulse amplitude, the total percentage of slow waves and the presence of different types of slow waves following the classification proposed by Raftopoulos et al. Recorded data from lumbar infusion studies were mean values of pressure and pulse amplitude during three epochs (basal, early infusion and plateau), ROUT and the pulsatility response to the increase in mean pressure during the infusion. This response was quantified by two pulse amplitude indexes: the pulse amplitude index during the early infusion stage (A1) and the pulse amplitude index during the plateau stage (A2).

RESULTS

Thirty shunted patients were evaluated at the end of the follow-up and 23 (76.7 %) of them improved. Differences in the percentage of slow waves, ROUT and both pulsatility indexes were not statistically significant. The proportion of patients with great symmetrical waves and pulse amplitude during the early infusion stage were higher in responders (p < 0.05). The predictive analysis yielded the highest accuracy, with ROUT and A1 as a logical "OR" combination.

CONCLUSION

The combined use of ICP monitoring and lumbar infusion to forecast the response to shunting in patients with suspected iNPH did not improve the accuracy provided by any of them alone.

Elective ICP monitoring: how long is long enough?

BACKGROUND

Intracranial pressure monitoring is commonly undertaken to assess and manage acute patients following head injury. However, ICP monitoring can also be a useful diagnostic tool in the management of CSF dynamics in elective patients. To date, there is little published research to suggest how long these elective patients require ICP monitoring in order to gain an accurate picture of a patient's ICP dynamics. At the author's institution, a minimum of 48-h data collection is currently undertaken in patients with a suspected ICP abnormality.

METHODS

A retrospective audit was undertaken comparing overall median ICP and overall median pulse amplitude data at three time points, 24 h, 48 h and total time analysed (if longer than 48 h). Paired T-test was used to assess if there were statistically significant differences between 24-h versus 48-h monitoring and total duration of monitoring. All patients admitted over a 6-month period for ICPM who met the inclusion/exclusion criteria were included.

RESULTS

Eighteen patients met the criteria. Median age was 45.8 years, range 22-83 years, 12 female and 6 male. No complications were experienced as a result of ICPM. Diagnosis included NPH, IIH, suspected shunt malfunction and Chiari malformation. The results demonstrated that there is no statistical difference between 24 h and 48 h or longer for both overall median ICP and pulse amplitude.

CONCLUSION

The results of this study demonstrate that ICP monitoring of elective adult patients using a Spiegelberg intraparenchymal bolt for 24 h gives an accurate picture of a patient's ICP dynamics compared with longer periods of monitoring.

The effect of shunt surgery on neuropsychological performance in normal pressure hydrocephalus: a systematic review and meta-analysis

We conducted a systematic review of the literature and used meta-analytic techniques to evaluate the impact of shunt surgery on neuropsychological performance in patients with normal pressure hydrocephalus (NPH). Twenty-three studies with 1059 patients were identified for review using PubMed, Web of Science, Google scholar and manual searching. Inclusion criteria were prospective, within-subject investigations of cognitive outcome using neuropsychological assessment before and after shunt surgery in patients with NPH. There were statistically significant effects of shunt surgery on cognition (Mini-Mental State Examination; MMSE), learning and memory (Rey Auditory Verbal Learning Test; RAVLT, total and delayed subtests), executive function (backwards digit span, phonemic verbal fluency, trail making test B) and psychomotor speed (trail making test A) all in the direction of improvement following shunt surgery, but with considerable heterogeneity across all measures. A more detailed examination of the data suggested robust evidence for improved MMSE, RAVLT total, RAVLT delayed, phonemic verbal fluency and trail making test A only. Meta-regressions revealed no statistically significant effect of age, sex or follow-up interval on improvement in the MMSE. Our results suggest that shunt surgery is most sensitive for improving global cognition, learning and memory and psychomotor speed in patients with NPH.

Results of Isotope Cisternography in 175 Patients with a Suspected Hydrocephalus

OBJECTIVE

Normal pressure hydrocephalus (NPH) is a syndrome characterized by gait disturbance, memory impairment and urinary incontinence. The isotope cisternography (ICG) became less useful because of low accuracy and complications. We tried to evaluate the safety and value of the ICG.

METHODS

We retrospectively collected data on ICG of 175 consecutive patients with a suspected hydrocephalus. We classified the ICG into four types by the ventricular reflux and circulation time. The ventricular size was measured by Evans index and the width of the third ventricle.

RESULTS

There were three complications including one case of paraplegia. Type 4 was the most common type, observed in 53%. Type 3 (33%), type 2 (7%), and type 1 (7%) were observed less often. Type 4 was more common in patients with large ventricles. Types of the ICG were not related to the causes of hydrocephalus, gender, or age of the patients. Shunting was more frequently performed in type 4 (71%), compared to type 1 (17%), type 2 (33%), and type 3 (46%). Surgery was more common when the cause was vascular. After the shunt surgery, 33.0% were graded as the improved. Although there were some improvements even in the not-improved patients, they still needed many helps. The improvement was related to the preoperative state.

CONCLUSION

ICG may bring a serious complication, however the incidence is very low. Although the predictability of response rate on the shunting is doubtful, ICG is a cheap and useful tool to select surgical candidates in NPH.

Ventriculoperitoneal shunt placement in poor-grade patients with chronic normal pressure hydrocephalus after aneurysmal subarachnoid haemorrhage

OBJECTIVE

The aim of this study was to analyse the shunt placement in patients who had normal pressure hydrocephalus after poor-grade aneurysmal subarachnoid haemorrhage (aSAH).

METHODS

Patients diagnosed with NPH after poor-grade aSAH were divided into a treatment group and control group, based on whether they had received ventriculoperitoneal shunt placement. The treatment group was then divided into an improvement group and non-improvement group according to their recovery. The Glasgow Outcome Scale and Mini Mental Scale Examination were used for 3 month and 1 year follow-up rehabilitation measures.

RESULTS

Of the 46 total patients, significant improvement was observed at the 3 month and 1 year follow-ups (p < 0.01) after shunt implantation in the treatment group compared to the control group. Furthermore, patients who were younger (p = 0.022), had better neurological function (higher Glasgow Coma Score, p < 0.01) and less severe hydrocephalus (lower EI, p < 0.01) appears to be more likely to benefit from the shunt.

CONCLUSIONS

Patients who had NPH due to poor-grade aSAH would benefit from shunt placement when given the correct candidates and timely management of shunt malfunction. Additionally, the curative effect of the shunt should have been regarded as a long-term goal of rehabilitation in these patients.

Preoperative prognostic value of MRI findings in 108 patients with idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

MR imaging is used in the diagnostic evaluation of patients with idiopathic normal pressure hydrocephalus. The aim of this study was to describe the prevalence of several imaging features and their prognostic use in the selection of shunt candidates with idiopathic normal pressure hydrocephalus.

MATERIALS AND METHODS

Preoperative MR imaging scans of the brain were retrospectively evaluated in 108 patients with idiopathic normal pressure hydrocephalus who had undergone a standardized, clinical evaluation before and 12 months after shunt surgery. The MR imaging features investigated were the Evans index, callosal angle, narrow sulci at the high convexity, dilation of the Sylvian fissure, diameters of the third ventricle and temporal horns, disproportionately enlarged subarachnoid space hydrocephalus, flow void through the aqueduct, focal bulging of the roof of the lateral ventricles, deep white matter hyperintensities, periventricular hyperintensities, and focal widening of sulci and aqueductal stenosis.

RESULTS

In logistic regression models, with shunt outcome as a dependent variable, the ORs for the independent variables, callosal angle, disproportionately enlarged subarachnoid space hydrocephalus, and temporal horns, were significant (P < .05), both in univariate analyses and when adjusted for age, sex, and previous stroke.

CONCLUSIONS

A small callosal angle, wide temporal horns, and occurrence of disproportionately enlarged subarachnoid space hydrocephalus are common in patients with idiopathic normal pressure hydrocephalus and were significant predictors of a positive shunt outcome. These noninvasive and easily assessed radiologic markers could aid in the selection of candidates for shunt surgery.

Normal pressure hydrocephalus: a qualitative study on outcome

OBJECTIVE

To describe the natural history and shunt outcome in patients with normal pressure hydrocephalus (NPH) and the variables that influence both.

METHOD

Motor and cognitive parameters of 35 patients with NPH, as well as shunt surgery status, were registered at two time points (T0 and T1).

RESULTS

Thirteen patients underwent shunt surgery. Favorable outcome in gait function occurred in 5 of 35 patients and was related to younger age, absence of cardiovascular risk factors (CVRF) and white matter lesions (WML), and shunt surgery. Cognitive outcome was favorable in 9 of 35 patients and associated with shunt surgery (trend level). Of the patients subjected to surgery, favorable outcome in motor function was related to younger age at T0 and absence of CVRF and WML (trend level).

CONCLUSION

Shunt surgery had a significant effect on gait and less on cognition. Favorable outcome in gait was also associated with younger age and absence of CVRF and WML.

Cognitive disturbances and neuropsychological changes after surgical treatment in a cohort of 185 patients with idiopathic normal pressure hydrocephalus

Although idiopathic normal pressure hydrocephalus (iNPH) is considered a treatable dementia, there is still some controversy regarding the cognitive improvement in these patients. The main aims of this study were to analyze baseline cognitive status and to study the neuropsychological changes after surgical treatment in a sample of 185 consecutive iNPH patients. An additional aim was to identify the variables that influenced the cognitive outcome. Specific tests assessing memory, attention, visual scanning, executive functions (EFs), and motor speed were used before and 6 months after shunting. The cognitive domains most affected at baseline were memory, EFs, attention, and psychomotor speed. After shunting, significant differences in the group as a whole were found in all tests except Digits Forward and Trail Making Part B. However, less than 50% of patients showed a significant improvement when analyzed individually. Previous global cognitive status assessed by Mini-Mental State Examination baseline scores was the best predictor for the cognitive outcome.

Subdural effusions with hydrocephalus after severe head injury: successful treatment with ventriculoperitoneal shunt placement: report of 3 adult cases

Background. Subdural collections of cerebrospinal fluid (CSF) with associated hydrocephalus have been described by several different and sometimes inaccurate terms. It has been proposed that a subdural effusion with hydrocephalus (SDEH) can be treated effectively with a ventriculoperitoneal shunt (V-P shunt). In this study, we present our experience treating patients with SDEH without directly treating the subdural collection. Methods. We treated three patients with subdural effusions and hydrocephalus as a result of a head injury. All the patients were treated with a V-P shunt despite the fact that there was an extra-axial CSF collection with midline shift. Results. In all of the patients, the subdural effusions subsided and the ventricular dilatation improved in the postoperative period. The final clinical outcome remains difficult to predict and depends not only on the successful CSF diversion but also on the primary and secondary brain insult. Conclusion. Subdural effusions with hydrocephalus can be safely and effectively treated with V-P shunting, without directly treating the subdural effusion which subsides along with the treatment of hydrocephalus. However, it is extremely important to make an accurate diagnosis of an SDEH and differentiate this condition from other subdural collections which require different management.

Lack of shunt response in suspected idiopathic normal pressure hydrocephalus with Alzheimer disease pathology

To determine the impact of cortical Alzheimer disease pathology on shunt responsiveness in individuals treated for idiopathic normal pressure hydrocephalus (iNPH), 37 patients clinically diagnosed with iNPH participated in a prospective study in which performance on neurologic, psychometric, and gait measures before and 4 months after shunting was correlated with amyloid β plaques, neuritic plaques, and neurofibrillary tangles observed in cortical biopsies obtained during shunt insertion. No complications resulted from biopsy acquisition. Moderate to severe pathology was associated with worse baseline cognitive performance and diminished postoperative improvement on NPH symptom severity scales, gait measures, and cognitive instruments compared to patients lacking pathology.

Cognitive and motor improvement after retesting in normal-pressure hydrocephalus: a real change or merely a learning effect?

Object

The test-retest method is commonly used in the management of patients with normal-pressure hydrocephalus (NPH). One of the most widely used techniques in the diagnosis of this condition is evaluation of the patient's response to CSF evacuation by lumbar puncture (a so-called tap test or spinal tap). However, interpretation of improved results in subsequent evaluations is controversial because higher scores could reflect a real change in specific abilities or could be simply the result of a learning effect.

Methods

To determine the effect of testing-retesting in patients with NPH, the authors analyzed changes documented on 5 neuropsychological tests (the Toulouse-Pieron, Trail Making Test A, Grooved Pegboard, Word Fluency, and Bingley Memory tests) and several motor ability scales (motor performance test, length of step, and walking speed tests) in a series of 32 patients with NPH who underwent the same battery on 4 consecutive days. The same tests were also applied in 30 healthy volunteers. In both groups, the authors used the generalized least-squares regression method with random effects to test for learning effects. To evaluate possible differences in response depending on the degree of cognitive impairment at baseline, the results were adjusted by using the Mini-Mental State Examination scores of patients and controls when these scores were significant in the model.

Results

In patients with NPH there were no statistically significant differences in any of the neuropsychological or motor tests performed over the 4 consecutive days, except in the results of the Toulouse-Pieron test, which were significantly improved on Day 3. In contrast, healthy volunteers had statistically significant improvement in the results of the Toulouse-Pieron test, Trail Making Test A, and Grooved Pegboard test but not in the remaining neuropsychological tests. Patients in the healthy volunteer group also exhibited statistically significant improvement in the motor performance test but not in step length or walking speed.

Conclusions

No learning effect was found in patients with NPH on any of the neuropsychological or motor tests. Clinical improvement after retesting in these patients reflects real changes, and this strategy can therefore be used in both the diagnosis and evaluation of surgical outcomes.

Ongoing search for diagnostic biomarkers in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus is a syndrome, which typically has a clinical presentation of gait/balance disturbance, often accompanied by cognitive decline and/or urinary incontinence. Its diagnosis is based on relevant history and clinical examination, appropriate imaging findings and physiological testing. The clinical picture of idiopathic normal pressure hydrocephalus may occasionally be difficult to distinguish from that of Alzheimer’s dementia, subcortical ischemic vascular dementia and Parkinson’s disease. The aim of this article is to systematically review the literature from the last 29 years in order to identify cerebrospinal fluid (CSF) or imaging biomarkers that may aid in the diagnosis of the syndrome. The authors concluded that no CSF or imaging biomarker is currently fulfilling the criteria required to aid in the diagnosis of the condition. However, a few studies have revealed promising CSF and imaging markers that need to be verified by independent groups. The reasons that the progress in this field has been slow so far is also commented on, as well as steps required to apply the current evidence in the design of future studies within the field.

In vivo assessment of hydrocephalus shunt

OBJECTIVES

Over a 3-year period, we have performed 312 tests in 197 shunted patients. The data have been analyzed retrospectively to: (1) investigate the parameters describing CSF dynamics that correlate with shunt under-drainage and (2) estimate accuracy of this method.

METHODS

Constant rate infusion tests into shunt prechamber were performed.

RESULTS

In 161 of the 312 infusion tests, results indicated under-draining shunts. Patients in the under-draining group had higher baseline and plateau CSF pressures, higher resistance to CSF outflow and higher levels of baseline pulse amplitude waveform. During the test, a significantly greater vasogenic waves and lower compensatory reserve was noticed in patients with blocked shunts. In 21 patients with suggestion of shunt blockage and who subsequently underwent operative revision of the shunt, reports of intraoperative shunt patency were available. Shunt blockage was confirmed intra-operatively during surgery in 19 cases.

CONCLUSIONS

In vivo shunt testing is easy, safe and clinically useful, aiding decision in difficult clinical situations, where shunt malfunction is suspected but not certain. It also has satisfactory positive predictive power.

Noninvasive biomarkers in normal pressure hydrocephalus: evidence for the role of neuroimaging

Object

Normal pressure hydrocephalus (NPH) represents a treatable form of dementia. Recent estimates of the incidence of this condition are in the region of 5% of patients with dementia. The symptoms of NPH can vary among individuals and may be confused with those of patients with multi-infarct dementia, dementia of the Alzheimer type, or even Parkinson disease. Traditionally the diagnosis of NPH could only be confirmed postoperatively by a favorable outcome to surgical diversion of CSF. The object of this literature review was to examine the role of structural and functional imaging in providing biomarkers of favorable surgical outcome.

Methods

A Medline search was undertaken for the years 1980–2006, using the following terms: normal pressure hydrocephalus, adult hydrocephalus, chronic hydrocephalus, imaging, neuroimaging, imaging studies, outcomes, surgical outcomes, prognosis, prognostic value, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy.

Results

The query revealed 16 studies that correlated imaging with surgical outcomes offering accuracy results. Three studies fulfilled the statistical criteria of a biomarker. A dementia Alzheimer-type pattern on SPECT in patients with idiopathic NPH, the presence of CSF flow void on MR imaging, and the N-acetylaspartate/choline ratio in patients with the secondary form are able to predict surgical outcomes with high accuracy.

Conclusions

There is at present Level A evidence for using MR spectroscopy in patients with secondary NPH, and Level B evidence for using SPECT and phase-contrast MR imaging to select patients with idiopathic NPH for shunt placement. The studies, however, need to be repeated by other groups. The current work should act as a platform to design further studies with larger sample sizes.

Normal pressure hydrocephalus: Diagnostic and predictive evaluationon

In typical cases, normal pressure hydrocephalus (NPH) manifests itself with the triad of gait disturbance, which begins first, followed by mental deterioration and urinary incontinence associated with ventriculomegaly (on CT or MRI) and normal cerebrospinal fluid (CSF) pressure. These cases present minor diagnostic difficulties and are the most likely to improve after shunting. Problems arise when NPH shows atypical or incomplete clinical manifestations (25–50% of cases) or is mimicked by other diseases. In this scenario, other complementary tests have to be used, preferentially those that can best predict surgical outcome. Radionuclide cisternography, intracranial pressure monitoring (ICP) and lumbar infusion tests can show CSF dynamics malfunction, but none are able to confirm whether the patient will benefit from surgery. The CSF tap test (CSF-TT) is the only procedure that can temporarily simulate the effect of definitive shunt. Since the one tap CSF-TT has low sensitivity, it cannot be used to exclude patients from surgery. In such cases, we have to resort to a repeated CSF-TT (RTT) or continuous lumbar external drainage (LED). The most reliable prediction would be achieved if RTT or LED proved positive, in addition to the occurrence of B-waves during more than 50% of ICP recording time. This review was based on a PubMed literature search from 1966 to date. It focuses on clinical presentation, neuroimaging, complementary prognostic tests, and differential diagnosis of NPH, particularly on the problem of selecting appropriate candidates for shunt.

Lumbar subcutaneous shunt: a novel technique for therapeutic decision making in normal pressure hydrocephalus (NPH) and benign intracranial hypertension (BIH)

Selecting patients who will benefit from a permanent CSF diversion procedure in benign intracranial hypertension (BIH) or communicating hydrocephalus due to normal pressure hydrocephalus (NPH) has inherent problems. The percutaneous introduction of a lumbar subcutaneous shunt (LSS) under local anaesthesia facilitates both a prolonged CSF drainage under aseptic conditions and also elicits an adequate clinical response. We describe the technique of a lumbar subcutaneous shunt and our experience with its use in patients with BIH and NPH. Postprocedure changes in the patients' clinical status were noted. Patients with a transient clinical improvement underwent a subsequent definitive CSF diversion; those with a sustained clinical improvement or no change in symptoms had no further procedure.

Cervical spine disease may result in a negative lumbar spinal drainage trial in normal pressure hydrocephalus: case report

OBJECTIVE

In this case report, we present a patient with normal pressure hydrocephalus in whom a lumbar drainage trial yielded a false-negative result secondary to cervical spondylosis.

CLINICAL PRESENTATION

An 80-year-old woman presented with classic symptoms of normal pressure hydrocephalus as well as evidence of cervical myelopathy. Magnetic resonance imaging of the brain and spine showed enlarged ventricles and single-level cervical canal narrowing.

INTERVENTION

An initial lumbar drainage trial was performed, which revealed negative results. The patient then underwent cervical decompression and fusion. Despite this procedure, the patient's symptoms continued to worsen. A repeat lumbar drainage trial was performed with positive results. Subsequently, a ventriculoperitoneal shunt was placed, resulting in significant improvement of her symptoms.

CONCLUSION

This case report illustrates how altered cerebrospinal fluid flow dynamics may impact the accuracy of the lumbar spinal drainage trial in patients with normal pressure hydrocephalus.

Intracranial pressure monitoring with the Neurodur-P epidural sensor: a prospective study in patients with adult hydrocephalus or idiopathic intracranial hypertension

OBJECT

Continuous intracranial pressure (ICP) monitoring using an epidural sensor is a common technique used in selected neurosurgical patients. The aim of this study was to assess the safety and accuracy of the Neurodur-P epidural sensor in the clinical setting.

METHODS

The zero drift, as well as the medical and technical complications, of using the Neurodur-P sensor placed in the epidural space was evaluated in 106 patients with hydrocephalus of varying causes or with suspected intracranial hypertension.

RESULTS

The median duration of ICP monitoring was 8 days (interquartile range [IQR] 6-12 days). In 78 (73.6%) of the 106 patients the pressure reading was recorded at sensor removal. No zero drift was observed in 28 sensors. The median drift was 0 mm Hg with an IQR of -1 to 1 mm Hg. No significant differences were found between patients monitored for < or = 5 days and those monitored for > 5 days (t = 535, p = 0.100). No correlation was found between zero drift and monitoring time (r = 0.153, p = 0.181). Of the 83 patients with a follow-up computed tomography scan, 3 showed a < 1 ml collection of blood at the catheter tip. No clinical infections could be attributed to the devices. Only 1 sensor malfunctioned.

CONCLUSIONS

Continuous ICP monitoring using the Neurodur-P sensor is safe, reliable, and easy to perform. At present, using this device is the authors' standard method for the long-term monitoring of patients with alterations in complex cerebrospinal fluid dynamics or with implanted shunts.

Intra-abdominal pressure: the neglected variable in selecting the ventriculoperitoneal shunt for treating hydrocephalus

OBJECTIVE

In the selection of a ventriculoperitoneal cerebrospinal fluid shunt, the intra-abdominal pressure (IAP) is traditionally neglected as a result of the idea that its value is close to 0 mmHg. Our aim was to explore the relationship between body mass index (BMI) and IAP with the goal of providing clinically relevant data that could help neurosurgeons to estimate IAP and select the appropriate shunt for patients with hydrocephalus and especially those with normal-pressure hydrocephalus syndrome.

METHODS

Sixty patients requiring the placement of a ventriculoperitoneal shunt were included in the study. We determined weight, BMI, and IAP. IAP was measured through an intraperitoneal catheter during the shunt surgery. To determine whether a linear relationship existed between quantitative variables, linear regression analysis was used.

RESULTS

BMI was 28.1 +/- 4.8 kg/m2. Eighteen patients (30%) had normal weight, 21 (35%) were moderately overweight, and 21 (35%) were obese. IAP was related to patient BMI. A significant positive linear correlation was identified between BMI and IAP (r = 0.52; P = 0.018) with a slope of 0.31 (P < 0.001) and an intercept of -5.5.

CONCLUSION

In our study, we determined that IAP had a strong positive linear relationship with BMI. This correlation was independent of sex. An IAP of 0 mmHg can, therefore, only be assumed for patients with a normal BMI who are recumbent. In obese or overweight patients, neurosurgeons should take IAP into account when selecting both the most adequate differential pressure valve to be implanted and in which distal cavity to place the distal catheter to avoid shunt underdrainage induced by high IAP.

A mathematical model of survival in a newly inserted ventricular shunt

OBJECT

The object of this study was to mathematically model the prognosis of a newly inserted shunt in pediatric or adult patients with hydrocephalus.

METHODS

A structured search was performed of the English-language literature for case series reporting shunt failure, patient mortality, and shunt removal rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to predict the outcome of a shunt after insertion. Separate models were used to predict shunt survival rates for children (patients < 17 years old) and adults.

RESULTS

Shunt survival rates in children and adults were calculated for 1 year (64.2 and 80.1%, respectively), 5 years (49.4 and 60.2%, respectively), and the median (4.9 and 7.3 years, respectively). The longer-term rates predicted by the model agree closely with those reported in the literature.

CONCLUSIONS

This model gives a comprehensive view of the fate of a shunt for hydrocephalus after insertion. The advantages of this model compared with Kaplan-Meier survival curves are discussed. The model used in this study may provide useful prognostic information and aid in the early evaluation of new shunt designs and techniques.

Have we made progress in preventing shunt failure? A critical analysis

OBJECT

The goal of this study was to determine whether failure rates of hydrocephalus shunts have fallen over the years as a result of experience or technical improvements.

METHODS

A structured search was performed of the English language literature for case series reporting failure rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to analyze failure rates statistically for temporal trends. Separate models were used for children (< 17 years old) and adults.

RESULTS

In children, the shunt failure rate was 31.3% for the 1st year and 4.5% per year thereafter. There were no significant changes in either rate over time. Although 1st-year failure rates in adults have fallen slightly over time, late failure rates have risen.

CONCLUSIONS

Progress in preventing shunt failures has not been made over the last several decades. Any improvements made in shunt materials or insertion techniques have been overshadowed by biological and other factors.

Post-surgical changes in brain metabolism detected by magnetic resonance spectroscopy in normal pressure hydrocephalus: results of a pilot study

BACKGROUND

Adult normal pressure hydrocephalus (NPH) is one of the few potentially treatable causes of dementia. Some morphological and functional abnormalities attributed to hydrocephalus improve following treatment.

OBJECTIVES

We focused on analysis of changes in cerebral metabolites using proton magnetic resonance spectroscopy (1H-MRS) after NPH treatment, and its clinical and cognitive correlation.

METHODS

1H-MRS, neuropsychological and clinical status examinations were performed before and 6 months after shunting in 12 adults with idiopathic NPH. We obtained N-acetyl-aspartate (NAA), choline (Cho), myoinositol (MI) and creatine (Cr) values.

RESULTS

After surgery, NAA/Cr was significantly increased. Moreover, NAA/Cr values were related to cognitive deterioration.

CONCLUSION

MRS could be a marker of neuronal dysfunction in NPH.

Shunts in normal-pressure hydrocephalus: do we place too many or too few?

OBJECT

The average 65-year-old patient with moderate dementia can look forward to only 1.4 quality-adjusted life years (QALYs), that is, longevity times quality of life. Some of these patients suffer from normal-pressure hydrocephalus (NPH) and respond dramatically to shunt insertion. Currently, however, NPH cannot be diagnosed with certainty. The authors constructed a Markov decision analysis model to predict the outcome in patients with NPH treated with and without shunts.

METHODS

Transition probabilities and health utilities were obtained from a review of the literature. A sensitivity analysis and Monte Carlo simulation were applied to test outcomes over a wide range of parameters. Using shunt response and complication rates from the literature, the average patient receiving a shunt would gain an additional 1.7 QALYs as a result of automatic shunt insertion. Even if 50% of patients receiving a shunt have complications, the shunt response rate would need to be less than 5% for empirical shunt insertion to do more harm than good. Authors of most studies have reported far better statistics.

CONCLUSIONS

In summary, many more patients with suspected NPH should be considered for shunt insertion.

Estimated incidence of normal-pressure hydrocephalus and shunt outcome in patients residing in assisted-living and extended-care facilities

Object

The primary objective of this study was to estimate the prevalence of idiopathic normal-pressure hydrocephalus (NPH), both diagnosed and undiagnosed, among residents of assisted-living and extended-care facilities, by using a practical screening tool. A secondary objective was to evaluate prospectively the diagnosis and outcome of surgical treatment in a subset of patients residing in healthcare facilities who were at risk for idiopathic NPH.

Methods

A retrospective chart analysis was performed using the medical records from four nursing homes. The final analysis included 147 patient records. Symptomatology and comorbidity were evaluated, as was the ability to perform activities of daily living. In a subset of 17 patients residing in healthcare facilities, the authors applied a standard idiopathic NPH diagnostic and management protocol and followed up the patients 1 year after treatment.

The estimated incidence of suspected idiopathic NPH among all patients in the retrospective survey ranged from 9 to 14%, depending on the diagnostic criteria used. Among the cohort of 17 patients available for an in-hospital study and 1-year follow up, 11 received shunts and seven of these showed either transient or sustained improvement.

Conclusions

A valid and practical diagnostic method is needed to identify idiopathic NPH accurately before admitting patients to a healthcare facility. Data from a prospective study of 17 patients residing in healthcare facilities indicated that supplementary tests remain predictive of a positive response to shunt insertion but cannot predict whether a favorable outcome will be sustained in a population of patients who have been confined to a wheelchair for a prolonged period of time. This finding supports the notion of a finite window of opportunity for successful treatment of idiopathic NPH and the imperativeness of an early diagnosis.

Functional and magnetic resonance imaging correlates of corpus callosum in normal pressure hydrocephalus before and after shunting

BACKGROUND

Normal pressure hydrocephalus (NPH) is associated with corpus callosum abnormalities.

OBJECTIVES

To study the clinical and neuropsychological effect of callosal thinning in 18 patients with idiopathic NPH and to investigate the postsurgical callosal changes in 14 patients.

METHODS

Global corpus callosum size and seven callosal subdivisions were measured. Neuropsychological assessment included an extensive battery assessing memory, psychomotor speed, visuospatial and frontal lobe functioning.

RESULTS

After surgery, patients showed improvements in memory, visuospatial and frontal lobe functions, and psychomotor speed. Two frontal corpus callosum areas, the genu and the rostral body, were the regions most related to the clinical and neuropsychological dysfunction. After surgery, total corpus callosum and four of the seven subdivisions presented a significant increase in size, which was related to poorer neuropsychological and clinical outcome.

CONCLUSION

The postsurgical corpus callosum increase might be the result of decompression, re-expansion and increase of interstitial fluid, although it may also be caused by differences in shape due to cerebral reorganisation.

Predicting the outcome of shunt surgery in normal pressure hydrocephalus

We studied retrospectively the effectiveness of the repeated lumbar CSF tap test (RTT), lumbar external CSF drainage (LED) and radioisotope cisternography (RIC) in predicting the outcome of shunt surgery, as well as the diagnostic and prognostic value of periventricular hyperintensity (PVH) and of the classic clinical triad in normal pressure hydrocephalus. Two hundred and seventy patients were referred to the Departments of Neurosurgery, in Nancy, France and in Istanbul, Turkey. The decision to perform surgery was based on the clinical presentation (all patients had at least two symptoms of the classic clinical triad), neuroimaging examinations and the results of the RTT (taps were performed on three consecutive days and at each tap a minimum of 30 to 40 cc of CSF was removed), the LED (drainage was performed for 3 days and the volume of CSF drained daily was a minimum of 150 to 250 cc) or the RIC. After all shunt procedures, postoperative assessments verified improvements in 88% of the RTT group, 91% of the LED group and 66% of the RIC group. Gait disturbance had improved in 90% at the end of the second and twelfth month follow-up. Cognitive dysfunction had improved in 79% at the second and in 77% at the twelfth month follow-up. Urinary incontinence had improved in 66% at the second and in 62% at the twelfth month follow-up. From the surgical point of view, the greatest difficulty is not to make the diagnosis, but rather to identify the appropriate patients to operate on. The decision to perform shunt surgery should be based on strict clinical findings associated with CT and MRI criteria and especially with positive RTT or LED test results.

Normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a reversible disorder characterized by gait impairment, subcortical dementia, and urinary urgency and incontinence associated with impaired cerebrospinal fluid circulation and ventriculomegaly. Treatment with shunt surgery is most likely to increase mobility, and may also improve dementia and urinary symptoms. An international, independent study group recently published guidelines for the diagnosis and management of idiopathic NPH. This article helps geriatricians identify patients who might have NPH, and care for these patients after shunt placement.

Intracerebroventricular passive immunization in transgenic mouse models of Alzheimer's disease

Since uncontrolled production of beta-amyloid (Abeta) is considered a key seeding event underlying progression of Alzheimer's disease (AD), elimination of excessive Abeta and preventing its reaccumulation constitute the primary therapeutic goal in preventing and treating AD. To date, immunoneutralization has been the most effective strategy in removing pre-existing cerebral Abeta. Both active and systemic passive immunizations are known to reduce cerebral Abeta and improve memory in transgenic murine models of AD. However, active immunization is associated with adverse effects such as encephalitis with perivascular inflammation and hemorrhage, while passive immunization has the potential to disrupt cerebral vasculature that is laden with amyloid and exposed to high levels of antibody in the blood. Intriguingly, intracerebroventricular passive immunization established in the authors' laboratory circumvented these problems. The authors demonstrated that a single intracerebroventricular injection of anti-Abeta antibody reduced the cerebral Abeta burden and Abeta-related astrocytosis, retarded reaccumulation of Abeta and restored Abeta-induced depletion of presynaptic SNAP-25, for at least 1 month and reduced inflammatory reactions for 1 week in AD murine models without producing inflammation, microhemorrhage or systemic histotoxicity. These facts suggest that intracerebroventricular anti-Abeta may be a safe method for the rapid clearance of pre-existing Abeta and retarding reaccumulation of Abeta in AD. Intracerebroventricular administration via a catheter and reservoir, may be combined with the development of humanized monoclonal antibody against Abeta. Intraventricular shunts and ventriculostomy are frequently employed with acceptable risk-to-benefit ratios in the treatment of various brain disorders, while humanized antibodies are currently used in clinical trials of brain diseases such as multiple sclerosis and lymphoma.

Impact of Cerebrovascular Disease on the Surgical Treatment of Idiopathic Normal Pressure Hydrocephalus

OBJECTIVE:

The influence of cerebrovascular disease (CVD) on the short- and long-term results of surgery was evaluated in a series of consecutive patients with idiopathic normal-pressure hydrocephalus (iNPH).

METHODS:

Patients with suspected iNPH admitted to our department between June 1996 and June 2003 were evaluated with four clinical and handicap scales. CVD and risk factors for vascular disease were rated. All patients underwent intracranial pressure monitoring via a spinal catheter. Sixty-six patients received a ventriculoperitoneal shunt with a programmable valve. Prospective assessments were programmed at 2 weeks and 3 months after surgery (short-term follow-up). Long-term follow-up evaluations were arranged in June 2004 with patients and/or relatives and health/home care assistants.

RESULTS:

At the short-term follow-up examination, a significant clinical improvement was globally present in 89% of the patients (P &lt; 0.05). CVD, such as leucoaraiosis or previous strokes, were present in 71% of the patients. Patients both with and without CVD and/or risk factors for vascular disease presented a significant improvement (P &lt; 0.05) after shunting; 85 and 100% of the patients with and without CVD, respectively. At the long-term follow-up examination (mean, 52 ± 24.8 mo), 24% of the patients were dead and 8% had experienced stroke. Globally, 60% of the patients were still improved (P &lt; 0.05); 52 and 79% of the patients with and without CVD, respectively.

CONCLUSION:

A high success rate in treatment of iNPH is possible in patients with and without CVD. Despite poorer short- and long-term treatment outcome of iNPH patients with CVD, a long-lasting improvement in their quality of life favors surgery.

Short-term medical management of hydrocephalus

Hydrocephalus is an excess accumulation of cerebrospinal fluid in or around the brain that can be produced by a broad spectrum of disorders. It can develop at any age and its incidence is increasing, both in infants and adults. Although the standard treatment of hydrocephalus is cerebrospinal fluid shunting, there are certain circumstances in which medical treatment, alone or in combination with shunting, has been suggested as an alternative. This review aims to present and discuss the indications for pharmacological treatment in the medical management of hydrocephalus, and the drugs most frequently used. Carbonic anhydrase inhibitors, loop diuretic agents, osmotic agents and fibrinolytic therapy are discussed. The most suitable drug seems to be acetazolamide, alone or in combination with furosemide. At present, osmotic agents are no longer used in the treatment of hydrocephalus. Fibrinolytic therapy administered directly into the ventricular system may not avoid the need for shunt placement, but may help in the management of hydrocephalus by preventing or reducing the rate of catheter obstruction and accelerating clot resolution.