Continuous intraventricular pressure monitoring for diagnosis of normal-pressure hydrocephalus

Adult Hydrocephalus: Natural History, Clinical Outcomes, Quality of Life, and Health Economics

Adult hydrocephalus comprise a family of disorders characterized by a cerebrospinal fluid dynamic disturbance and a shared core symptomatology. Idiopathic normal pressure hydrocephalus (iNPH) has gained an increasing scientific attention over the past decades and is the most studied type of adult hydrocephalus. While knowledge of iNPH have accumulated and expanded, literature is still meagre in other, more uncommon adult hydrocephalus. In this focused review, we describe the most important advances in the literature on natural course, outcomes, quality of life and health economics with a focus on iNPH, the type of adult hydrocephalus where substantial research data exist.

Idiopathic normal pressure hydrocephalus: a systematic review and a streamlined six-step algorithm endorsed by the Italian Society of Neurosurgery (SINCH)

INTRODUCTION

Idiopathic normal pressure hydrocephalus (iNPH) is a treatable neurodegenerative disorder characterized by a triad of gait disturbance, cognitive impairment, and urinary incontinence. Early diagnosis and timely intervention are crucial for optimal outcomes. However, the diagnosis of iNPH remains challenging due to its variable presentation and overlap with other neurological conditions.

EVIDENCE ACQUISITION

A comprehensive review of the literature was conducted to identify current diagnostic criteria and treatment strategies for iNPH. Based on this review, a novel, six-step algorithm was developed to streamline the diagnostic process and improve patient outcomes.

EVIDENCE SYNTHESIS

The proposed algorithm includes the following six steps: 1) suspect diagnosis of iNPH: Identification of core clinical features (gait disturbance, cognitive impairment, and urinary incontinence) and radiological evidence of ventricular enlargement; 2) investigate probable iNPH: detailed neuropsychological assessment, gait analysis, and urodynamic studies to confirm the diagnosis; 3) high-volume lumbar puncture: evaluation of the clinical response to CSF drainage, including improvements in gait, cognition, and urinary function; 4) evaluation after HVLP: assessment of the duration and magnitude of symptom improvement after lumbar puncture; 5) shunt surgery: indication for shunt surgery in patients with a positive response to CSF drainage; 6) infusion test and intracranial pressure measurement: alternative diagnostic tools for cases where the diagnosis remains uncertain.

CONCLUSIONS

The proposed algorithm provides a structured approach to the diagnosis and management of iNPH. By combining clinical, radiological, and neurophysiological assessments, clinicians can improve diagnostic accuracy and optimize patient outcomes. Further research is needed to validate this algorithm in larger patient populations and to develop more sensitive and specific biomarkers for iNPH.

Standardizing the large-volume "tap test" for evaluating idiopathic normal pressure hydrocephalus: a systematic review

INTRODUCTION

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by the clinical triad of gait, cognitive, and urinary dysfunction associated with ventriculomegaly on neuroimaging. Clinical evaluation before and after CSF removal via large volume lumbar puncture (the "tap test") is used to determine a patient's potential to benefit from shunt placement. Although clinical guidelines for iNPH exist, a standardized protocol detailing the procedural methodology of the tap test is lacking.

EVIDENCE ACQUISITION

Using PRISMA guidelines, a systematic review of PubMed and Embase identifying studies of the tap test in iNPH was performed, centered on four clinical questions (volume of CSF to remove, type of needle for lumbar puncture, which clinical assessments to utilize, and timing of assessments). A modified Delphi approach was then applied to develop a consensus standardized tap test protocol for the evaluation of idiopathic normal pressure hydrocephalus.

EVIDENCE SYNTHESIS

Two hundred twenty-two full-text articles encompassing a total of 80,322 participants with iNPH met eligibility and were reviewed. Variations in the tap test protocol resulted in minimal concordance among studies. A standardized protocol of the tap test was iteratively developed over a two-year period by members of the International Parkinson and Movement Disorders Society Normal Pressure Hydrocephalus Study Group until expert consensus was reached.

CONCLUSIONS

The literature shows significant variability in the procedural methodology of the tap test. The proposed protocol was subsequently developed to standardize clinical management, improve patient outcomes, and better align future research in idiopathic normal pressure hydrocephalus.

The effectiveness of various CSF diversion surgeries in idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

Background

Idiopathic normal pressure hydrocephalus (iNPH) is commonly treated using cerebrospinal fluid (CSF) diversion procedures, most commonly ventriculoperitoneal (VP) but also lumboperitoneal (LP), ventriculoatrial (VA) shunting, and endoscopic third-ventriculostomy (ETV). Despite the prevalence of these interventions and recent advancements in iNPH diagnostic processes, there is limited up-to-date evidence regarding surgical outcomes.

Methods

A systematic review and meta-analysis were conducted to analyse the effects of CSF diversion surgeries among iNPH patients. The primary outcome was efficacy of the CSF diversion procedure, defined as symptomatic improvement, and secondary outcomes included surgical complications. Several major databases were searched for original studies from inception up to June 4, 2024, which were evaluated using random-effects meta-analyses, meta-regression, and influence analyses. This study was registered with PROSPERO: CRD42023458526.

Findings

Out of the 1963 studies screened, 54 were included in this review, and 4811 patients were pooled. Overall, more than 74% of patients experienced improvement after surgical treatment (95% CI: 70-78%). VP shunting demonstrated an efficacy of 75% (95% CI 70-79%), VA shunting at 75% (95% CI: 70-80%), and LP shunting at 70% (95% CI: 52-83%). ETV had a success rate of 69% (95% CI: 58-78%). Gait improvement was high at 72% (95% CI: 67-77%), while urinary and cognitive dysfunction each improved in approximately 50% of patients. The efficacy of surgery did not increase between 2005 and 2024 (p = 0.54). Complications occurred in 20.6% of cases, with a surgery revision rate of 15.1%.

Interpretation

This meta-analysis found that the overall efficacy of CSF diversion procedures for iNPH remained unchanged from 2005 to 2024, with 74% of cases showing improvement. No procedure was found to be clearly superior, and only half of the patients saw improvements in urinary and cognitive dysfunction. The stagnant efficacy over time and frequent complications highlight the need for improved patient selection criteria to best identify those most likely to benefit from CSF shunting.

Funding

None for this study.

Invasive Preoperative Investigations in Idiopathic Normal Pressure Hydrocephalus: A Comprehensive Review

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder characterized by the triad of gait disturbance, cognitive impairment, and urinary incontinence. The condition is diagnosed mainly in older adults and is associated with ventricular enlargement without an increase in cerebrospinal fluid pressure. The clinical assessment involves a detailed medical history, physical examination, and cognitive testing. Neuroimaging is an essential part of the diagnostic workup for iNPH. However, to determine the suitability of patients for shunt surgery, a range of invasive preoperative investigations are employed. This narrative review aims to provide a comprehensive analysis of the current literature on invasive preoperative investigations in iNPH, focusing primarily on the lumbar infusion test, cerebrospinal fluid drainage tests, and continuous intracranial pressure monitoring. The strengths and limitations of each method, as well as their potential impact on treatment outcomes, are discussed.

Clinical predictors of shunt response in the diagnosis and treatment of idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

Background

Positive shunt response (SR) remains the gold standard for diagnosing idiopathic normal pressure hydrocephalus (iNPH). However, multiple pathologies mimic iNPH symptoms, making it difficult to select patients who will respond to shunt surgery. Although presenting features, extended lumbar drainage (ELD), infusion test (IT), intracranial pressure monitoring (ICPM), and tap test (TT) have been used to predict SR, uncertainty remains over which diagnostic test to choose.

Objective

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

Methods

Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR were searched for original studies investigating clinical predictors of SR in iNPH patients. Included studies were assessed using the QUADAS-2 tool, and eligible studies were evaluated using univariate and bivariate meta-analyses.

Results

Thirty-five studies were included. Nine studies discussed the diagnostic use of presenting clinical features, 8 studies ELD, 8 studies IT, 11 studies ICPM, and 6 studies TT. A meta-analysis of 21 eligible studies was conducted for TT, ELD, IT, and ICPM. ICPM yielded the highest diagnostic effectiveness, with diagnostic odds ratio (DOR) = 50.9 and area under curve (AUC) = 0.836. ELD yielded DOR = 27.70 and AUC = 0.753, IT had DOR = 5.70 and AUC = 0.729, and TT scored DOR = 3.86 and AUC = 0.711.

Conclusion

Intraparenchymal ICPM is statistically the most effective diagnostic test, followed by ELD, IT, and lastly TT. Due to the higher accessibility of TT and IT, they are recommended to be used first line, using a timed-up-and-go improvement ≥ 5.6 s or a Rout cut-off range between 13 and 16 mmHg, respectively. Patients who test negative should ideally be followed up with ICPM, using mean ICP wave amplitude \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 4 mmHg, or 1- to 4-day ELD with an MMSE cut-off improvement \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 3. Future research must use standardized methodologies for each diagnostic test and uniform criteria for SR to allow better comparison.

The Dilemma of Hydrocephalus in Prolonged Disorders of Consciousness

Prolonged disorders of consciousness (DOC) are considered to be among the most severe outcomes after acquired brain injury. Medical care for these patients is mainly focused on minimizing complications, given that treatment options for patients with unresponsive wakefulness or minimal consciousness remain scarce. The complication rate in patients with DOC is high, both in the acute hospital setting, as in the rehabilitation or long-term care phase. Hydrocephalus is one of these well-known complications and usually develops quickly after acute changes in cerebrospinal fluid (CSF) circulation after different types of brain damage. However, hydrocephalus may also develop with a significant delay, weeks, or even months after the initial injury, reducing the potential for natural recovery of consciousness. In this phase, hydrocephalus is likely to be missed in DOC patients, given that their limited behavioral responsiveness camouflages the classic signs of increased intracranial pressure or secondary normal-pressure hydrocephalus. Moreover, the development of late-onset hydrocephalus may exceed the period of regular outpatient follow-up. Several controversies remain about the diagnosis of clinical hydrocephalus in patients with ventricular enlargement after severe brain injury. In this article, we discuss both the difficulties in diagnosis and dilemmas in the treatment of CSF disorders in patients with prolonged DOC and review evidence from the literature to advance an active surveillance protocol for the detection of this late, but treatable, complication. Moreover, we advocate a low threshold for CSF diversion when hydrocephalus is suspected, even months or years after brain injury.

The oscillatory flow of the cerebrospinal fluid in the Sylvian aqueduct and the prepontine cistern measured with phase contrast MRI in children with hydrocephalus-a preliminary report

INTRODUCTION

Recognizing patients with ventriculomegaly who are at risk of developing acute hydrocephalus presents a challenge for the clinician. The association between disturbed cerebrospinal fluid flow (CSF) and impaired brain compliance may play a role in the pathogenesis of hydrocephalus. Phase contrast MRI is a noninvasive technique which can be used to assess CSF parameters. The aim of the work is to evaluate the effectiveness of phase contrast MRI in recognizing patients at risk of acute hydrocephalus, based on measuring the pulsatile CSF flow parameters in the Sylvian aqueduct and prepontine cistern in children with ventriculomegaly.

AIM

The aim of the work is to characterize the parameters of cerebrospinal fluid (CSF) flow in the Sylvian aqueduct and prepontine cistern in children with ventriculomegaly with regard to patient age and symptoms. We hypothesize that the relationship between CSF flow parameters in these two regions will vary according to analyzed factors and it will allow to recognize children at risk of hydrocephalus.

MATERIALS AND METHODS

A group of 26 children with ventriculomegaly (five girls and 21 boys) underwent phase contrast MRI examinations (Philips 3T Achieva with Q-flow integral application). Amplitudes of average and peak velocities of the CSF flow through the Sylvian aqueduct and prepontine cistern were used to calculate ratios of oscillation and peak velocities, respectively. The relationship between the oscillation coefficient, the peak velocity coefficient, and stroke volume was then assessed in accordance with age and clinical symptoms.

RESULTS

The peak velocity coefficient was significantly higher in patients with hyper-oscillating flow through the Sylvian aqueduct (3.04 ± 3.37 vs. 0.54 ± 0.28; p = 0.0094). Moreover, these patients tended to develop symptoms more often (p = 0.0612). No significant age-related changes were observed in CSF flow parameters.

CONCLUSION

Phase contrast MRI is a useful tool for noninvasive assessment of CSF flow parameters. The application of coefficients instead of direct values seems to better represent hemodynamic conditions in the ventricular system. However, further studies are required to evaluate their clinical significance and normal limits.

Revisiting secondary normal pressure hydrocephalus: does it exist? A review

OBJECTIVE There are several etiologies that can lead to the development of secondary normal pressure hydrocephalus (sNPH). The aim of this study was to evaluate the etiology, diagnosis, treatment, and outcome in patients with sNPH and to highlight important differences between the separate etiologies. METHODS A comprehensive review of the literature was performed to identify studies conducted between 1965 and 2015 that included data regarding the etiology, treatment, diagnosis, and outcome in patients with sNPH. Sixty-four studies with a total of 1309 patients were included. The inclusion criteria of this study were articles that were written in English, included more than 2 patients with the diagnosis of sNPH, and contained data regarding the etiology, diagnosis, treatment, or outcome of NPH. The most common assessment of clinical improvement was based on the Stein and Langfitt grading scale or equivalent improvement on other alternative ordinal grading scales. RESULTS The main etiologies of sNPH were subarachnoid hemorrhage (SAH) in 46.5%, head trauma in 29%, intracranial malignancies in 6.2%, meningoencephalitis in 5%, and cerebrovascular disease in 4.5% of patients. In 71.9% of patients the sNPH was treated with ventriculoperitoneal shunt placement, and 24.4% had placement of a ventriculoatrial shunt. Clinical improvement after shunt placement was reported in 74.4% and excellent clinical improvement in 58% of patients with sNPH. The mean follow-up period after shunt placement was 13 months. Improvement was seen in 84.2% of patients with SAH, 83% of patients with head trauma, 86.4% of patients with brain tumors, 75% of patients with meningoencephalitis, and 64.7% of patients with NPH secondary to stroke. CONCLUSIONS Secondary NPH encompasses a diverse group of clinical manifestations associated with a subset of patients with acquired hydrocephalus. The most common etiologies of sNPH include SAH and traumatic brain injury. Secondary NPH does indeed exist, and should be differentiated from idiopathic NPH based on outcome and on clinical, pathophysiological, and epidemiological characteristics, but should not be considered as a separate entity.

Mortality and risk of dementia in normal-pressure hydrocephalus: A population study

INTRODUCTION

We examined mortality, dementia, and progression of hydrocephalic symptoms among untreated individuals with idiopathic normal-pressure hydrocephalus (iNPH) in a population-based sample.

METHODS

A total of 1235 persons were examined between 1986 and 2012. Shunted individuals were excluded. We examined 53 persons with hydrocephalic ventricular enlargement (probable iNPH: n = 24, asymptomatic or possible iNPH: n = 29). Comparisons were made with individuals without hydrocephalic ventricular enlargement.

RESULTS

The 5-year mortality was 87.5% among those with probable iNPH. The hazard ratio (HR) for death was 3.8 (95% confidence interval [CI]: 2.5-6.0) for probable iNPH. Those with possible iNPH and asymptomatic hydrocephalic ventricular enlargement had increased risk of developing dementia, HR 2.8 (95% CI: 1.5-5.2). Only two individuals with hydrocephalic ventricular enlargement remained asymptomatic.

DISCUSSION

In the present sample, persons with clinical and imaging signs of iNPH had excess mortality and an increased risk of dementia. The data also suggest that radiological signs of iNPH might be more important than previously supposed.

Repeated assessment of suspected normal pressure hydrocephalus in non-shunted cases. A prospective study based on the constant rate lumbar infusion test

BACKGROUND

Only a few reports have been published on the natural history of non-shunted patients suspected of having NPH. The aim of this study is to follow up a group of such cases.

METHODS

It was possible to follow up 27 patients who had not been qualified for shunting after the primary diagnosis. An assessment of Hakim's triad was performed, together with an analysis of radiological parameters and the results of lumbar infusion tests (LITs), both on admission and at the later date (on average, after 5.6 months). All parameters were analyzed with respect to periventricular lucency (PVL), atrophy, type of NPH, and the age of the patients.

RESULTS

There were no deteriorations and six patients improved. Those who were over 50 and who had no PVL or secondary NPH tended to improve more frequently. Significant improvement of dementia was noted (p = 0.042) in all cases, and in the group of patients without PVL (p = 0.04). The size of the ventricles did not change significantly. The values of the resistance to outflow (R), elastance (E), and ICP remained stable.

CONCLUSIONS

Analysis of our series revealed that the patients suspected of having NPH who had not been qualified for shunting did not deteriorate, while some of them even improved significantly as far as the level of dementia was concerned. As the CT and LIT parameters remained stable, there were no indications for repeating these examinations, at least within the period of nearly 6 months, which followed the primary diagnosis.

Diagnosis and prognosis in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a communicating hydrocephalus, of unknown pathophysiology, characterized by the classical triad of dementia, urinary incontinence, and ataxia. The most popular treatment option is shunt surgery, although it is not a cure. The diagnosis of the disorder is challenging as it may mimic a lot of other neurological conditions and has no distinct biomarker. It becomes even more challenging as majority of the cases are diagnosed by invasive cerebrospinal fluid (CSF) removal tests. However, a careful history taking, a keen and detailed physical examination, and pertinent imaging studies can lead to an early diagnosis. The gait symptoms respond the most to surgery. The predictors deciding the postsurgical prognosis has been discussed. Improved shunting modalities and novel shunt materials with valve adjustments have improved the precision of the shunting procedures. Still we have lot more to achieve in terms of early diagnosis and definitive management of iNPH.

Natural course of idiopathic normal pressure hydrocephalus

OBJECTIVES

The natural course of idiopathic normal pressure hydrocephalus (iNPH) has not been thoroughly studied. The consequences of postponing shunt treatment are largely unknown. We aimed to describe the effects of waiting for more than 6 months before surgery and to compare the outcome with that seen in patients who waited for less than 3 months.

METHODS

33 patients (iNPHDelayed) underwent an initial investigation (Pre-op 1), followed by re-examination, just prior to surgery, after waiting for at least 6 months (Pre-op 2). Outcome was evaluated after 3 months of treatment. 69 patients who were surgically treated within 3 months after Pre-op 1 and who were also evaluated after 3 months of treatment constituted a comparison group (iNPHEarly). Evaluations were done with the iNPH scale and the modified Rankin Scale (mRS). iNPHDelayed patients were prospectively studied with regard to outcome, whereas the comparison group iNPHEarly was defined and analysed retrospectively.

RESULTS

iNPHDelayed patients deteriorated significantly during their wait for surgery, with progression of symptom severity ranging from +7 to -47 on the iNPH scale, and from 0 to +3 on the mRS (both p<0.001). The magnitude of change after surgery was similar in the groups, but since the symptoms of iNPHDelayed patients had worsened while waiting, their final outcome was significantly poorer.

CONCLUSIONS

The natural course of iNPH is symptom progression over time, with worsening in gait, balance and cognitive symptoms. This deterioration is only partially reversible. To maximise the benefits of shunt treatment, surgery should be performed soon after diagnosis.

Natural history of idiopathic normal-pressure hydrocephalus

Natural history of idiopathic normal-pressure hydrocephalus (INPH) is not clear. We performed a literature search for studies that looked into the outcome of unshunted INPH patients trying to answer the following questions: Do all INPH patients deteriorate without shunt? If yes, at what rate? Do some NPH patients improve without shunt? If yes, to what extent? Six studies objectively described the outcome of 102 INPH patients. Result shows that without surgery, most INPH patients had measurable deterioration as early as 3 months following initial assessment. A small number of patients might improve without shunt, however the extent of improvement is not clear. The homogeneity of the findings of the cohort studies provided high evidence supporting the rule of shunt surgery in INPH patients.

Simultaneous measurements of intracranial pressure parameters in the epidural space and in brain parenchyma in patients with hydrocephalus

Object

In this study, the authors compare simultaneous measurements of static and pulsatile pressure parameters in the epidural space and brain parenchyma of hydrocephalic patients.

Methods

Simultaneous intracranial pressure (ICP) signals from the epidural space (ICPEPI) and the brain parenchyma (ICPPAR) were compared in 12 patients undergoing continuous ICP monitoring as part of their diagnostic workup for hydrocephalus. The static ICP was characterized by mean ICP and the frequency of B waves quantified in the time domain, while the pulsatile ICP was determined from the cardiac beat–induced single ICP waves and expressed by the ICP pulse pressure amplitude (dP) and latency (dT; that is, rise time).

Results

The 12 patients underwent a median of 22.5 hours (range 5.9–24.8 hours) of ICP monitoring. Considering the total recording period of each patient, the mean ICP (static ICP) differed between the 2 compartments by ≥ 5 mm Hg in 8 patients (67%) and by ≥ 10 mm Hg in 4 patients (33%). In contrast, for every patient the ICP pulse pressure readings from the 2 compartments showed near-identical results. Consequently, when sorting patients to shunt/no shunt treatment according to pulsatile ICP values, selection was independent of sensor placement. The frequency of B waves also compared well between the 2 compartments.

Conclusions

The pulsatile ICP is measured with equal confidence from the ICPEPI and ICPPAR signals. When using the pulsatile ICP for evaluation of hydrocephalic patients, valid measurements may thus be obtained from pressure monitoring in the epidural space. Recorded differences in the mean ICP between the epidural space and the brain parenchyma are best explained by differences in the zero setting of different sensors.

Diagnostic Intracranial Pressure Monitoring and Surgical Management in Idiopathic Normal Pressure Hydrocephalus

OBJECTIVE

To review our experience of managing idiopathic normal pressure hydrocephalus (iNPH) during the 6-year period from 2002 to 2007, when intracranial pressure (ICP) monitoring was part of the diagnostic workup.

METHODS

The review includes all iNPH patients undergoing diagnostic ICP monitoring during the years 2002 to 2007. Clinical grading was done prospectively using a normal pressure hydrocephalus (NPH) grading scale (scores from 3 to 15). The selection of patients for surgery was based on clinical symptoms, enlarged cerebral ventricles, and findings on ICP monitoring. The median follow-up time was 2 years (range, 0.3–6 years). Both static ICP and pulsatile ICP were analyzed.

RESULTS

A total of 214 patients underwent the diagnostic workup, of whom 131 went on to surgery. Although 1 patient died shortly after treatment, 103 of the 130 patients (79%) improved clinically. This improvement lasted throughout the observation period. The static ICP observed during ICP monitoring was a poor predictor of the response to surgery. In contrast, among 109 of 130 patients with increased ICP pulsatility (ie, ICP wave amplitude &gt;4 mm Hg on average and &gt;5 mm Hg in &gt;10% of recording time), 101 (93%) were responders (ie, increase in the NPH score of &gt;2). Correspondingly, only 2 of 21 (10%) without increased ICP pulsatility were responders. Superficial wound infection was the only complication of ICP monitoring and occurred in 4 (2%) patients.

CONCLUSION

Surgical results in iNPH were good with almost 80% of patients improving after treatment. The data indicate that improvement after surgery can be anticipated in 9 of 10 iNPH patients with abnormal ICP pulsatility, but in only 1 of 10 with normal ICP pulsatility. Diagnostic ICP monitoring had a low complication rate.

CEREBROSPINAL FLUID DRAINAGE AND DYNAMICS IN THE DIAGNOSIS OF NORMAL PRESSURE HYDROCEPHALUS

INTRODUCTION

Because of the difficulty in distinguishing idiopathic normal pressure hydrocephalus (INPH) from other neurodegenerative conditions unrelated to cerebrospinal fluid (CSF) dynamics, response to CSF shunting remains highly variable. We examined the utility of CSF drainage and CSF pressure (Pcsf) dynamics in predicting response to CSF shunting for patients with INPH.

METHODS

Fifty-one consecutive INPH patients underwent continuous lumbar Pcsf monitoring for 48 hours followed by 72 hours of slow CSF drainage before ventriculoperitoneal shunting. Response to CSF drainage and B-wave characteristics were assessed via multivariate proportional-hazards regression analysis.

RESULTS

Improvement in 1, 2, or all 3 INPH symptoms was observed in 35 (69%), 28 (55%), and 11 (22%) patients, respectively, after CSF shunt implantation by 12 months after surgery. A positive response to CSF drainage was found to be an independent predictor of shunt responsiveness (relative risk, 0.30; 95% confidence interval, 0.09–0.98; P = 0.05). There was no difference in Pcsf wave characteristics between the shunt-responsive and -nonresponsive groups, regardless of whether 1-, 2-, or 3-symptom improvement was used to define response to CSF shunting.

CONCLUSION

In this study of 51 INPH patients who underwent Pcsf monitoring with waveform analysis and CSF drainage followed by shunt surgery, there was no correlation between specific Pcsf wave characteristics and objective symptomatic improvement after shunt placement. Pcsf monitoring with B-wave analysis contributes little to the diagnostic dilemma with INPH patients. Clinical response to continuous CSF drainage over a 72-hour period suggests a high likelihood of shunt responsiveness.

Multivariate analysis of intracranial pressure (ICP) signal using principal component analysis

The diagnosis and treatment of hydrocephalus and other neurological disorders often involve the acquisition and analysis of large amount of intracranial pressure (ICP) signal. Although the analysis and subsequent interpretation of this data is an essential part of the clinical management of the disorders, it is typically done manually by a trained clinician, and the difficulty in interpreting some of the features of this complex time series can sometimes lead to issues of subjectivity and reliability. This paper presents a method for the quantitative analysis of this data using a multivariate approach based on principal component analysis, with the aim of optimising symptom diagnosis, patient characterisation and treatment simulation and personalisation. In this method, 10 features are extracted from the ICP signal and principal components that represent these features are defined and analysed. Results from ICP traces of 40 patients show that the chosen features have relevant information about the ICP signal and can be represented with a few components of the PCA (approximately 91% of the total variance of the data is represented by the first four components of the PCA) and that these components can be helpful in characterising subgroups in the patient population that would otherwise not have been apparent. The introduction of supplementaty (non-ICP) variables has offered insight into additional groupings and relationships which may prove to be a fruitful avenue for exploration.

Normal pressure hydrocephalus

Normal Pressure Hydrocephalus first became recognized as a treatable, reversible disorder in the 1960s. The classic triad of magnetic apraxia, urinary incontinence, and dementia remain relevant into the 21(st) century as being the basis for symptomatic diagnosis and predicting potential benefit from ventriculoperitoneal shunting, though they have been greatly augmented by the addition of modern neuroimaging, particularly MRI. Modern criteria recognize a wider range of diagnostic criteria, and new positive and negative prognostic indicators for treatment benefit have been discovered, though the mainstay remains initial drainage of a large volume of cerebrospinal fluid and monitoring for clinical improvement. Even with our advances in understanding both primary and secondary normal pressure hydrocephalus, diagnosis, management, and counseling remain challenging in this disorder.