Placebo-Controlled Effectiveness of Idiopathic Normal Pressure Hydrocephalus Shunting: A Randomized Pilot Trial

Guidelines for Diagnosis and Management of Idiopathic Normal Pressure Hydrocephalus

In 1965, Hakim and Adams described 3 patients with normal pressure hydrocephalus who responded to treatment with a ventriculoatrial shunt. Afterward the adoption of shunt treatment without clear diagnostic criteria and surgical techniques resulted in poor outcomes with significant complications. The clinical practice guidelines for the diagnosis and treatment of idiopathic normal pressure hydrocephalus were first published by the Japanese Neurosurgical Society in 2004 and the international guidelines were published in 2005. Both guidelines led to diagnosis and treatment algorithms and significantly improved outcomes, along with decreased surgical risk. These guidelines should be reevaluated and updated on a regular basis.

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.

Adult Hydrocephalus Clinical Subtypes

Adult hydrocephalus comprises 4 pragmatic categories: (1) transition; (2) unrecognized congenital; (3) acquired; and (4) suspected idiopathic normal pressure hydrocephalus. Each of these groups has unique clinical presentations and care needs that require the involvement of adult neurosurgeons for diagnosis and treatment. Patients in all 4 of these categories benefit from longitudinal care for monitoring of their symptoms or assessing response to treatment.

Effect of ventricular volume on cerebrospinal fluid Alzheimer's disease biomarkers in patients with idiopathic normal pressure hydrocephalus

BackgroundIdiopathic normal pressure hydrocephalus (iNPH) is a common disorder in aging populations. Alzheimer's disease (AD) is a significant comorbidity in iNPH patients, and the presence of AD pathology is associated with worse shunting outcomes. Cerebrospinal fluid (CSF) concentrations of AD-associated biomarkers in iNPH patients are universally reduced and the exact mechanism related to this is unknown.ObjectiveOur aim was to study the effects of ventricular volume on CSF AD-associated biomarker levels in iNPH patients, to determine whether a dilution effect occurs and to assess if brain AD pathology contributes to this effect.MethodsA total of 153 iNPH patients had lumbar CSF samples available for analysis, along with brain MRIs of sufficient quality. Automated image analysis software was used to determine the volume of different brain segments. Volumes normalized for age, sex and head size were used for analysis. Brain biopsy data on AD pathology was also available.ResultsNone of the intracerebral ventricular volumes correlated with CSF levels of AD-associated biomarkers, indicating no dilution effect was present in this context. However, in iNPH patients positive for amyloid-β pathology in the biopsy, the volume of the fourth ventricle correlated inversely with all investigated biomarkers.ConclusionsIntracerebral ventricular volumes do not correlate with AD biomarker levels in CSF, arguing against a dilution effect. However, in patients with AD pathology, the volume of the fourth ventricle is inversely correlated with CSF T-Tau and P-Tau181 levels, suggesting a complex relationship between brain AD pathology, CSF flow and CSF volume in iNPH patients.

Efficacy and safety of idiopathic normal pressure hydrocephalus shunting: a systematic review and meta-analysis

OBJECTIVE

Shunting is commonly used in patients with idiopathic normal pressure hydrocephalus (iNPH). However, evidence comparing the relative effectiveness and safety of different iNPH shunting methods is lacking. Therefore, this systematic review investigated the efficacy and safety of different iNPH shunts.

METHODS

The PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science databases were systematically searched for articles comparing iNPH shunting from inception to July 29th, 2023 to identify randomized controlled trails or cohort studies comparing iNPH shunting with placebo or other treatment. Evidence was summarized using fixed and randomized effects frequentist meta-analysis when the I2 was <50% and >50%, respectively. Subgroup analysis based on different study designs and surgical procedures was conducted to explore sources of heterogeneity. The sensitivity analyses were conducted by systematically excluding each study to determine the potential effect of individual studies on overall risk.

RESULTS

Eleven studies including 1417 participants were initially identified. All included randomized controlled trials had a high risk of bias, while cohort studies had a low risk of bias. Ventriculoperitoneal (VP) shunting was effective at decreasing the times of 10m walks (MD=-2.52, 95% CI: -4.78 to -0.26, I2=0), while lumboperitoneal (LP) shunting was effective at improving cognitive level (MD=1.29, 95% CI: 1.09 to 1.49, I2=0), 10 m walks (MD=-32.20, 95% CI: -48.07 to -16.33), and bladder control (MD=-0.25, 95% CI: -0.35 to -0.15, I2=76). Regarding adverse events, the VP and LP groups showed no differences in subdural hematoma, intracranial infection, intracranial hemorrhage, tube-related complications, or seizures. Compared with VP shunting, ventriculoatrial shunting was associated with a higher risk of subdural hematoma.

CONCLUSION

VP and LP are the best medical treatments for patients with iNPH.

A Rare Case of Shunt Malfunction Due to the Needle Guard Coming Off During Ventriculoperitoneal Shunt Surgery

We report a rare case of shunt valve failure due to obstruction during ventriculoperitoneal (VP) shunt surgery for hydrocephalus after subarachnoid hemorrhage due to aneurysm rupture. The hydrocephalus shunt surgery was started normally, and there was no bending or twisting of the valve, nor blood contamination. However, after irrigation of the shunt valve, the shunt valve obstructed and malfunctioned before catheter connection and insertion into the subcutaneous space. Shunt valves are rarely damaged during surgery. In this case, the cause of the malfunction could not be identified during surgery, and it was necessary to use a shunt valve made by another company for patient safety. The surgery was completed without incident, but the cause of the obstruction, which was discovered after surgery, was that the needle guard inside the valve had come off from the bottom. The CODMAN CERTAS Plus Programmable Valve (CCPPV) in particular has excellent functionality, but the regular type needle guard is attached to the bottom of the valve pump. Therefore, it cannot withstand the handling during surgery that other valves tolerate. In the future, improvements in medical equipment and more careful operation of shunt valves by surgeons are required for risk management during surgery.

Shunting for idiopathic normal pressure hydrocephalus

BACKGROUND

Normal pressure hydrocephalus (NPH) occurs when the brain ventricles expand, causing a triad of gait, cognitive, and urinary impairment. It can occur after a clear brain injury such as trauma, but can also occur without a clear cause (termed idiopathic, or iNPH). Non-randomised studies have shown a benefit from surgically diverting ventricular fluid to an area of lower pressure by cerebrospinal fluid (CSF)-shunting in iNPH, but historically there have been limited randomised controlled trial (RCT) data to confirm this.

OBJECTIVES

To determine the effect of CSF-shunting versus no CSF-shunting in people with iNPH and the frequency of adverse effects of CSF-shunting in iNPH.

SEARCH METHODS

We searched the Cochrane Dementia and Cognitive Improvement Group's register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), Embase (Ovid SP), PsycINFO (Ovid SP), CINAHL (EBSCOhost), Web of Science Core Collection (Clarivate), LILACS (BIREME), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform on 15 February 2023.

SELECTION CRITERIA

We included only RCTs of people who had symptoms of gait, cognitive, or urinary impairment with communicating hydrocephalus (Evans index of > 0.3) and normal CSF pressure. Control groups included those with no CSF shunts or those with CSF shunts that were in 'inactive' mode.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures. Where necessary, we contacted study authors requesting data not provided in the papers. We assessed the overall certainty of the evidence using GRADE.

MAIN RESULTS

We included four RCTs, of which three were combined in a meta-analysis. The four RCTs included 140 participants (73 with immediate CSF-shunting and 67 controls who had delayed CSF-shunting) with an average age of 75 years. Risk of bias was low in all parallel-group outcomes evaluated apart from gait speed, cognitive function (general cognition and Symbol Digit Test) (some concerns) and adverse events, which were not blind-assessed. CSF-shunting probably improves gait speed at less than six months post-surgery (standardised mean difference (SMD) 0.62, 95% confidence interval (CI) 0.24 to 0.99; 3 studies, 116 participants; moderate-certainty evidence). CSF-shunting may improve qualitative gait function at less than six months post-surgery by an uncertain amount (1 study, 88 participants; low-certainty evidence). CSF-shunting probably results in a large reduction of disability at less than six months post-surgery (risk ratio 2.08, 95% CI 1.31 to 3.31; 3 studies, 118 participants; moderate-certainty evidence). The evidence is very uncertain about the effect of CSF-shunting on cognitive function at less than six months post-CSF-shunt surgery (SMD 0.35, 95% CI -0.04 to 0.74; 2 studies, 104 participants; very low-certainty evidence). The evidence is also very uncertain about the effect of CSF-shunt surgery on adverse events (1 study, 88 participants; very low-certainty evidence). There were no data regarding the effect of CSF-shunting on quality of life.

AUTHORS' CONCLUSIONS

We found moderate-certainty evidence that CSF-shunting likely improves gait speed and disability in iNPH in the relative short term. The evidence is very uncertain regarding cognition and adverse events. There were no longer-term RCT data for any of our prespecified outcomes. More studies are required to improve the certainty of these findings. In addition, more information is required regarding patient ethnicity and the effect of CSF-shunting on quality of life.

Assessing CT-based Volumetric Analysis via Transfer Learning with MRI and Manual Labels for Idiopathic Normal Pressure Hydrocephalus

Background

Brain computed tomography (CT) is an accessible and commonly utilized technique for assessing brain structure. In cases of idiopathic normal pressure hydrocephalus (iNPH), the presence of ventriculomegaly is often neuroradiologically evaluated by visual rating and manually measuring each image. Previously, we have developed and tested a deep-learning-model that utilizes transfer learning from magnetic resonance imaging (MRI) for CT-based intracranial tissue segmentation. Accordingly, herein we aimed to enhance the segmentation of ventricular cerebrospinal fluid (VCSF) in brain CT scans and assess the performance of automated brain CT volumetrics in iNPH patient diagnostics.

Methods

The development of the model used a two-stage approach. Initially, a 2D U-Net model was trained to predict VCSF segmentations from CT scans, using paired MR-VCSF labels from healthy controls. This model was subsequently refined by incorporating manually segmented lateral CT-VCSF labels from iNPH patients, building on the features learned from the initial U-Net model. The training dataset included 734 CT datasets from healthy controls paired with T1-weighted MRI scans from the Gothenburg H70 Birth Cohort Studies and 62 CT scans from iNPH patients at Uppsala University Hospital. To validate the model's performance across diverse patient populations, external clinical images including scans of 11 iNPH patients from the Universitatsmedizin Rostock, Germany, and 30 iNPH patients from the University of Alabama at Birmingham, United States were used. Further, we obtained three CT-based volumetric measures (CTVMs) related to iNPH.

Results

Our analyses demonstrated strong volumetric correlations (ϱ=0.91, p<0.001) between automatically and manually derived CT-VCSF measurements in iNPH patients. The CTVMs exhibited high accuracy in differentiating iNPH patients from controls in external clinical datasets with an AUC of 0.97 and in the Uppsala University Hospital datasets with an AUC of 0.99.

Discussion

CTVMs derived through deep learning, show potential for assessing and quantifying morphological features in hydrocephalus. Critically, these measures performed comparably to gold-standard neuroradiology assessments in distinguishing iNPH from healthy controls, even in the presence of intraventricular shunt catheters. Accordingly, such an approach may serve to improve the radiological evaluation of iNPH diagnosis/monitoring (i.e., treatment responses). Since CT is much more widely available than MRI, our results have considerable clinical impact.

Cerebrospinal fluid shunt surgery reduces the risk of developing dementia and Alzheimer's disease in patients with idiopathic normal pressure hydrocephalus: a nationwide population-based propensity-weighted cohort study

BACKGROUND

Patients with idiopathic normal-pressure hydrocephalus (iNPH) are predisposed to developing dementing disorders. Cerebrospinal fluid (CSF) shunt implantation is a treatment used to improve the motor and cognitive disabilities of these patients; however, its effect on the risk of developing dementing disorders remains unclear. We conducted a population-based propensity-weighted cohort study to investigate whether CSF shunt surgery may reduce the risk of subsequently developing dementia, Alzheimer's disease (AD), and vascular dementia in iNPH patients.

METHODS

Patients aged ≥ 60 years who were diagnosed with iNPH (n = 2053) between January 2001 and June 2018 were identified from the Taiwan National Health Insurance Research Database. Various demographic characteristics (age, sex, and monthly income) and clinical data (incidence year, comorbidities, and Charlson comorbidity index) were collected and divided into the shunt surgery group (SSG) and the non-shunt surgery group (NSSG). Stabilized inverse probability of treatment weighting by using the propensity score was performed to achieve a balanced distribution of confounders across the two study groups. The cumulative incidence rate and risk of dementing disorders were estimated during a 16-year follow-up period.

RESULTS

After weighting, the data of 375.0 patients in SSG and 1677.4 patients in NSSG were analyzed. Kaplan-Meier curve analysis indicated that the cumulative incidence rate of AD (p = 0.009), but not dementia (p = 0.241) and vascular dementia (p = 0.761), in SSG was significantly lower than that in NSSG over the 16-year follow-up period. Cox proportional hazards regression analysis revealed that SSG had a reduced hazard ratio (HR) for developing AD [HR (95% CI) 0.17 (0.04-0.69)], but not for dementia [HR (95% CI) 0.83 (0.61-1.12)] and vascular dementia [HR (95% CI) 1.18 (0.44-3.16)], compared with NSSG. Further Fine-Gray hazard regression analysis with death as a competing event demonstrated that SSG had a reduced subdistribution HR (sHR) for developing dementia [sHR (95% CI) 0.74 (0.55-0.99)] and AD [sHR (95% CI) 0.15 (0.04-0.61)], but not for vascular dementia [sHR (95% CI) 1.07 (0.40-2.86)].

CONCLUSION

CSF shunt surgery is associated with reduced risks of the subsequent development of dementia and AD in iNPH patients. Our findings may provide valuable information for assessing the benefit-to-risk profile of CSF shunt surgery.