Hydrocephalic Parkinsonism: lessons from normal pressure hydrocephalus mimics

Disproportionately Enlarged Subarachnoid-Space Hydrocephalus on MRI in Pathologically Confirmed Progressive Supranuclear Palsy

Background and Objective

Several studies have shown that idiopathic normal-pressure hydrocephalus (iNPH) can mimic other neurodegenerative disorders, particularly progressive supranuclear palsy (PSP). In this study, we investigated iNPH clinical and neuroimaging features in patients with autopsy-confirmed PSP or Lewy body disease (LBD) by assessing the normal pressure hydrocephalus (NPH) triad of symptoms and imaging features of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) and Evans index (EI) on antemortem MRI scans.

Methods

Among our study participants (N = 190), the mean (SD) age was 76.8 (9.2) years and 134 (70.5%) were male. The patients had been followed at Mayo Clinic and had autopsy diagnosis of either PSP or LBD. Patients were excluded if they had Alzheimer disease or a history of a disorder that could cause hydrocephalus, such as chronic meningitis or neoplasia. The study included 101 patients with PSP and 89 with LBD. The frequency of DESH and a high EI on brain MRI were analyzed in PSP and LBD with logistic regression analyses, adjusting for age, sex, and brain weight. The NPH triad of symptoms was assessed relative to imaging findings.

Results

We found that DESH and high EI were similar between PSP and LBD. The mean age at death (PSP: 74.0 [8.2]; LBD: 80.0 [9.2]) and brain weight (PSP: 1,190 [123]; LBD: 1,300 [150]) were greater in LBD compared with PSP (p < 0.001 for each). The frequency of DESH was greater in LBD than PSP (13% vs 3%, p = 0.004), while a high EI was similar in PSP and LBD (36% vs 32%, p = 0.500). The adjusted odds ratios for DESH and high EI were similar between the 2 groups (DESH: adjusted ORs 0.3, 95% CI 0.06-1.25, p = 0.119; high EI: adjusted ORs 1.8, 95% CI 0.86-4.06, p = 0.120).

Discussion

These findings suggest that DESH and high EI, often considered biomarkers for iNPH, may lack specificity and may be found in a subset of patients with PSP or LBD leading to unnecessary neurosurgery for iNPH.

Biomechanical instability of the brain-CSF interface in hydrocephalus

Hydrocephalus, characterized by progressive expansion of the CSF-filled ventricles (ventriculomegaly), is the most common reason for brain surgery. 'Communicating' (i.e. non-obstructive) hydrocephalus is classically attributed to a primary derangement in CSF homeostasis, such as choroid plexus-dependent CSF hypersecretion, impaired cilia-mediated CSF flow currents, or decreased CSF reabsorption via the arachnoid granulations or other pathways. Emerging data suggest that abnormal biomechanical properties of the brain parenchyma are an under-appreciated driver of ventriculomegaly in multiple forms of communicating hydrocephalus across the lifespan. We discuss recent evidence from human and animal studies that suggests impaired neurodevelopment in congenital hydrocephalus, neurodegeneration in elderly normal pressure hydrocephalus and, in all age groups, inflammation-related neural injury in post-infectious and post-haemorrhagic hydrocephalus, can result in loss of stiffness and viscoelasticity of the brain parenchyma. Abnormal brain biomechanics create barrier alterations at the brain-CSF interface that pathologically facilitates secondary enlargement of the ventricles, even at normal or low intracranial pressures. This 'brain-centric' paradigm has implications for the diagnosis, treatment and study of hydrocephalus from womb to tomb.

Right putamen and claustrum infarction mimicking normal pressure hydrocephalus

A woman in her 70s presented with approximately 2 years of sudden-onset gait and cognitive problems. She had been diagnosed with normal pressure hydrocephalus (NPH) and underwent ventriculoperitoneal shunt (VPS) placement 1 year prior. Before VPS placement, brain imaging showed ventriculomegaly and chronic infarction of the right putamen and claustrum. A lumbar drain trial resulted in modest improvement of gait dysfunction. She underwent VPS placement for suspected NPH, but her symptoms remained unchanged. Examination revealed mild cognitive impairment, left-sided and lower body predominant parkinsonism, as well as disproportionately prominent postural instability. Gait analysis showed increased gait variability, reduced velocity and shortened step length bilaterally. Motor and gait abnormalities did not change after administration of levodopa. Her symptoms have remained stable for up to 52 months since symptom onset. We postulate that the infarction affecting the right putamen and claustrum could have led to a higher-level gait disorder mimicking NPH.

Is there a spinal tap responder in progressive supranuclear palsy? The first prospective study

OBJECTIVE

Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disease, and sometimes shows idiopathic normal pressure hydrocephalus (iNPH)-like presentations. We aimed to evaluate spinal tap responsiveness in patients with PSP, including the effect of sham spinal tap.

METHODS

Eleven patients with PSP, ten with probable/definite iNPH, and eight control patients were prospectively enrolled. All participants underwent sham spinal tap and spinal tap procedures. Gait was evaluated using wearable inertial sensors. We defined "tap responders" as individuals with a 10% or more improvement from baseline in any of the gait parameters (timed up-and-go test total time, stride length, and velocity during straight walking under single-task and cognitive dual-task conditions). We compared the ratio of responders in patients with PSP to patients with iNPH and controls.

RESULTS

The ratio of tap responders and the ratio of sham tap responders in patients with PSP were significantly higher than those in control patients, and not different from those in patients with iNPH. PSP patients with iNPH-like MRI features tended to respond to the spinal tap compared to those without such imaging features. Notably, one patient with PSP, who responded to the spinal tap beyond the effect of sham spinal tap, was treated by the shunt operation.

CONCLUSION

This is the first prospective study to demonstrate tap and shunt responsiveness in patients with PSP while highlighting the placebo effects of the spinal tap in patients with PSP or iNPH. Our findings suggest that some PSP patients have impaired cerebrospinal fluid circulation, contributing to a distinct component of the clinical spectrum.

[Clinical features and effects of shunt surgery in patients with progressive supranuclear palsy and idiopathic normal pressure hydrocephalus]

This study aimed to retrospectively review the frequency and clinical features of 13 patients with progressive supranuclear palsy (PSP) and idiopathic normal pressure hydrocephalus (iNPH). All patients were found to have PSP-Richardson's syndrome (PSP-RS). Shunt surgery was effective in 5 of 11 patients (45.5%). A comparison of these 5 patients who responded to shunt surgery versus the remaining 6 patients revealed a significant difference in the reduction of frontal lobe blood flow on cerebral perfusion single-photon emission computed tomography (SPECT) (P = 0.018). These results suggest that PSP-RS is common in patients with PSP and iNPH and indicate the usefulness of cerebral perfusion SPECT in estimating the effect of shunt surgery.

PSP-Richardson syndrome mimics: An overview and pragmatic approach

Progressive supranuclear palsy-Richardson syndrome (PSP-RS) is a sporadic atypical parkinsonian syndrome with levodopa-unresponsive axial-predominant parkinsonism, early postural instability, vertical supranuclear gaze palsy, dysarthria, executive dysfunction and behavioural changes. PSP-RS can be mimicked by numbers of other disorders, generally known as PSP mimics, or PSP-like syndromes. Their aetiological spectrum includes neurodegenerative (mostly genetic), vascular, infectious and drug-induced illnesses as well as other causes. Based on the available data, we have tried to create a definition of PSP-RS mimics: a syndrome resembling PSP-RS with at least one of the following red flags: 1) positive family history; 2) onset before 45 years of age; 3) rapid or stepwise progression; 4) acute or subacute onset; 5) atypical symptoms and/or signs; 6) normal or atypical brain MRI; 7) history of HIV or untreated syphilis, aortal surgery or recent therapy with dopamine-blocking agents. We have suggested a short diagnostic algorithm leading to the identification of PSP-RS mimics and the recommended diagnostic work-up. The key point of the diagnostic process is the early identification and treatment of potentially treatable PSP-RS mimics.

Higher prevalence of idiopathic normal pressure hydrocephalus-like MRI features in progressive supranuclear palsy: An imaging reminder of atypical parkinsonism

OBJECTIVES

The classic triad of idiopathic normal pressure hydrocephalus (NPH) encompass gait disturbance, cognitive impairment, and urinary incontinence. These symptoms overlap with parkinsonism but with distinct treatment. Lacking applicable differentiation also hampers the prediction to therapeutic response. Here, we try to clarify this issue among different Parkinsonian syndromes and propose some innovative thinking while approaching a patient with parkinsonism and hydrocephalus concomitantly.

METHODS

Twenty-four patients with clinical probable multiple system atrophy (MSA), 34 with probable progressive supranuclear palsy (PSP), and 58 with sex- and age-matched Parkinson's disease (PD) were enrolled. Evans' index (EI), callosal angle (CA), antero-posterior (AP) diameter of the midbrain, length of the midbrain tegmentum diameter (MB^Tegm ), and disproportionately enlarged subarachnoid space hydrocephalus (DESH) were evaluated using the conventional MRI. Logistic regression was applied to identify the independent variables in hydrocephalus.

RESULTS

Patients with PSP had higher mean EI than those with MSA and PD. Around 38.2% of patients with PSP had accompanied hydrocephalus (EI > 0.3). Parkinsonism subtypes (PD, MSA, or PSP), AP diameter of the midbrain, and MB^Tegm were significantly different among patients with and without hydrocephalus. After regression analysis, parkinsonism subtype stood out to be the most key risk factor of hydrocephalus. The comparison between patients with PSP with and without hydrocephalus did not disclose specific clinical characteristics or risk factors.

CONCLUSIONS

This study demonstrates that the presence of NPH-like MRI features is much higher in PSP patients, and this tendency is decided upon the determination of parkinsonism subtype. Sharing pathophysiological characteristics in these two diseases is implied. More diagnostic tools are needed to better differentiate the two diseases and decide the treatment. To closely observe hydrocephalic parkinsonism patients and well inform the possible limited shunting benefits if PSP core features appear, will be more pivotal and practical at present clinical practice.

Idiopathic normal pressure hydrocephalus: historical context and a contemporary guide

Idiopathic normal pressure hydrocephalus (NPH) was described in 1965 as a syndrome in which hydrocephalus develops but with a normal cerebrospinal fluid (CSF) pressure, causing shunt-responsive gait apraxia, cognitive impairment and urinary incontinence. Not all patients respond to shunting despite having the clinical syndrome with appropriate radiological features. This has led to considerable debate over subsequent decades regarding idiopathic NPH. It is now understood that asymptomatic communicating hydrocephalus can develop in many healthy older people, and that over time this can develop into a symptomatic state that sometimes responds to CSF shunting, but to a variable extent. This review looks at the historical background of NPH, the use of predictive tests, the current state of clinical evidence for the diagnosis and treatment of idiopathic NPH and the possible underlying causes, to provide a contemporary practical guide for assessing patients with the radiological features of idiopathic NPH.

The Overlap in Neuroimaging Findings Between Idiopathic Normal Pressure Hydrocephalus and Progressive Supranuclear Palsy

Background

The neuroimaging findings of brain stem atrophy resembling progressive supranuclear palsy (PSP) radiology are common in idiopathic normal pressure hydrocephalus (iNPH) subjects. Besides, recent studies report the existence of iNPH-like MRI findings in PSP subjects. We aimed to comparatively investigate the neuroimaging indices of iNPH and PSP in our patient groups in a detailed methodology.

Methods

Ultimately, 19 probable PSP patients and 18 patients with a definite diagnosis of iNPH were enrolled. The subjects were recruited retrospectively from those who had been admitted between 2017 and 2021 to the Movement Disorders Polyclinic and the Neurosurgery Clinic of the Diskapi Yildirim Beyazit Training and Education Hospital. MRI-based DESH score, Evans index, and the callosal angle (CA) have been calculated in all the individuals. Besides, quantitative MRI parameters of PSP were evaluated in every subject. Statistical analyses were performed using IBM SPSS Statistics 26.

Results

The comparative analyses regarding the radiological parameters of PSP did not reveal any difference between patient groups. On the other hand, the comparisons of the neuroimaging parameters of iNPH, yielded differences in the CA, CA score, and the total DESH score. However, the ROC curve analyses did not reveal a discriminative power at a value of "very good" or "excellent" in any of the indices.

Conclusions

We found that the neuroimaging features of iNPH and PSP highly overlapped between these patient groups. These results may provide indirect evidence regarding the coexistence of PSP and iNPH pathophysiology that has been deliberated in several recent reports.

Parkinsonism in idiopathic normal pressure hydrocephalus: is it time for defining a clinical tetrad?

Background

Association between parkinsonism and idiopathic normal pressure hydrocephalus (iNPH) still remains debated. There is already plenty of evidences in the literature suggesting that this clinical sign can be considered as an integral part of the clinical spectrum of iNPH patients.

Methods

We reviewed the possible pitfalls in the core clinical definition of iNPH based on available international diagnostic criteria, phenomenology of parkinsonism in iNPH, and neuroimaging supporting the presence of parkinsonism in iNPH.

Conclusions

We argue that the diagnostic definition of the iNPH “triad” should be possibly reconsidered as a “tetrad” also including parkinsonism.

Update on the Cognitive Presentations of iNPH for Clinicians

This mini-review focuses on cognitive impairment in iNPH. This symptom is one of the characteristic triad of symptoms in a condition long considered to be the only treatable dementia. We present an update on recent developments in clinical, neuropsychological, neuroimaging and biomarker aspects. Significant advances in our understanding have been made, notably regarding biomarkers, but iNPH remains a difficult diagnosis. Stronger evidence for permanent surgical treatment is emerging but selection for treatment remains challenging, particularly with regards to cognitive presentations. Encouragingly, there has been increasing interest in iNPH, but more research is required to better define the underlying pathology and delineate it from overlapping conditions, in order to inform best practise for the clinician managing the cognitively impaired patient. In the meantime, we strongly encourage a multidisciplinary approach and a structured service pathway to maximise patient benefit.

Pathologically verified corticobasal degeneration mimicking Richardson's syndrome coexisting clinically and radiologically shunt‐responsive normal pressure hydrocephalus

Background

Normal pressure hydrocephalus (NPH) manifests as gait instability, cognitive impairment, and urinary incontinence. This clinical triad of NPH sometimes occurs with ventriculomegaly in patients with neurodegenerative disease. Patients with pathologically verified neurodegenerative diseases, such as progressive supranuclear palsy (PSP), have received antemortem diagnoses of NPH.

Objectives

This study presents clinical and pathological features of a patient with pathologically verified corticobasal degeneration (CBD) coexisting with clinically shunt‐responsive NPH.

Methods

We performed clinical, radiological, and pathological evaluations in a patient with CBD whose antemortem diagnosis was PSP Richardson's syndrome (PSP‐RS) coexisting with shunt‐responsive NPH.

Results

A 59‐year‐old woman developed bradykinesia and gait instability and then frequent falls, urinary incontinence, and supranuclear vertical gaze palsy followed. At 63 years of age, her gait disturbance and urinary incontinence had deteriorated rapidly, and cognitive impairment was disclosed. There were typical findings of NPH with ventriculomegaly and disproportionately enlarged subarachnoid space hydrocephalus as well as a 2‐layer appearance with decreased and increased cerebral blood perfusion. Shunt placement ameliorated gait instability for more than 1 year and improved radiological indicators of NPH. However, atrophy of the midbrain progressed with time after transient increases in size. Although the antemortem diagnosis was probable PSP‐RS, pathological evaluation verified CBD. There were severe discontinuities of the ependymal lining of the lateral ventricles and subependymal rarefaction and gliosis with tau‐positive deposition.

Conclusions

Shunt surgery could ameliorate NPH symptoms in patients with 4‐repeat tauopathies. Careful assessments of clinical findings are necessary to predict the benefits of shunts as a therapeutic option for patients with neurodegenerative diseases coexisting with NPH.

Idiopathic normal pressure hydrocephalus-like MRI features in patients with progressive supranuclear palsy: a comparative case-control study

BACKGROUND

The occurrence of neurodegenerative disease in patients with normal pressure hydrocephalus (NPH) is emphasized in recent reports. Based on this common co-occurrence, some of the hydrocephalic disorders appearing in late adulthood have been hypothesized to result from initially unapparent parenchymal abnormalities of neurodegenerative origin. Among these diseases, progressive supranuclear palsy (PSP) has been specifically remarked on. We aimed to comparatively investigate the neuroimaging clues of iNPH in our PSP subjects.

METHODS

Eighteen patients with a clinical diagnosis of PSP, 44 with Parkinson's disease (PD), and 44 healthy control (HC) individuals were enrolled. The disproportionately enlarged subarachnoid space hydrocephalus (DESH) score, the Evans' index (EI), and the callosal angle (CA) were measured on the conventional magnetic resonance imaging (MRI). The comparative analyses were performed using IBM SPSS Statistics 26.

RESULTS

We found that dilated Sylvian fissures score (p = 0.016) and focal sulcal dilatation score (p = 0.037) were higher in the PSP group in comparison to HC whereas the CA score was higher in PSP subjects in comparison to both PD patients and HC (p = 0.000). Remarkably, the DESH score was also found to be higher in the PSP group in comparison to the age-matched HC group (p = 0.024).

CONCLUSIONS

We found that the NPH-like MRI features were more common in PSP subjects in comparison to PD subjects and age-matched HC. These results may provide critical contributions to the literature regarding the overlap between PSP and NPH.

Neuropathological findings in possible normal pressure hydro-cephalus: A post-mortem study of 29 cases with lifelines

Aims: There are very few detailed post-mortem studies on idiopathic normal-pressure hydrocephalus (iNPH) and there is a lack of proper neuropathological criteria for iNPH. This study aims to update the knowledge on the neuropathology of iNPH and to develop the neuropathological diagnostic criteria of iNPH. Methods: We evaluated the clinical lifelines and post-mortem findings of 29 patients with possible NPH. Pre-mortem cortical brain biopsies were taken from all patients during an intracranial pressure measurement or a cerebrospinal fluid (CSF) shunt surgery. Results: The mean age at the time of the biopsy was 70±8 SD years and 74±7 SD years at the time of death. At the time of death, 11/29 patients (38%) displayed normal cognition or mild cognitive impairment (MCI), 9/29 (31%) moderate dementia and 9/29 (31%) severe dementia. Two of the demented patients had only scarce neuropathological findings indicating a probable hydrocephalic origin for the dementia. Amyloid-β (Aβ) and hyperphosphorylated τ (HPτ) in the biopsies predicted the neurodegenerative diseases so that there were 4 Aβ positive/low Alzheimer's disease neuropathological change (ADNC) cases, 4 Aβ positive/intermediate ADNC cases, 1 Aβ positive case with both low ADNC and progressive supranuclear palsy (PSP), 1 HPτ/PSP and primary age-related tauopathy (PART) case, 1 Aβ/HPτ and low ADNC/synucleinopathy case and 1 case with Aβ/HPτ and high ADNC. The most common cause of death was due to cardiovascular diseases (10/29, 34%), followed by cerebrovascular diseases or subdural hematoma (SDH) (8/29, 28%). Three patients died of a postoperative intracerebral hematoma (ICH). Vascular lesions were common (19/29, 65%). Conclusions: We update the suggested neuropathological diagnostic criteria of iNPH, which emphasize the rigorous exclusion of all other known possible neuropathological causes of dementia. Despite the first 2 probable cases reported here, the issue of "hydrocephalic dementia" as an independent entity still requires further confirmation. Extensive sampling (with fresh frozen tissue including meninges) with age-matched neurologically healthy controls is highly encouraged.

Corticospinal tract abnormalities and ventricular dilatation: A transdiagnostic comparative tractography study

BACKGROUND

Microstructural alterations of corticospinal tract (CST) have been found in idiopathic normal pressure hydrocephalus (iNPH). No study, however, investigated the effect of ventricular dilatation on CST in Progressive Supranuclear Palsy (PSP).

OBJECTIVE

The aim of this study was to investigate CST diffusion profile in a large cohort of PSP patients with and without ventricular dilatation.

METHODS

Twenty-three iNPH patients, 87 PSP patients and 26 controls were enrolled. Evans index (EI) and ventricular volume (VV) were measured in all patients. CST tractography was performed to calculate FA, MD, AxD and RD in six different anatomical regions: medulla oblungata (MO), pons (P), cerebral peduncle (CP), posterior limb of internal capsule (PLIC), corona radiata (CR), subcortical white matter (SWM). ANCOVA was used for comparing CST diffusion profiles between the groups and association between CST microstructural metrics and measures of ventricular dilatation (EI and VV) was assessed.

RESULTS

Thirty-three PSP patients had ventricular dilatation (EI > 0.30, PSP-vd) while 54 PSP patients had normal ventricular system (EI ≤ 0.30, PSP-wvd). iNPH patients had the most marked FA and AxD increase in PLIC and CR of CST followed by PSP-vd, PSP-wvd and controls; RD was altered only in iNPH. A strong correlation was found between CST diffusion metrics and EI or VV.

CONCLUSIONS

Our findings confirm the microstructural changes of CST in iNPH patients and demonstrate for the first time similar alterations in PSP-vd patients, suggesting a crucial role of ventricular dilatation in the mechanical compression of CST.

Can Medial Temporal Impairment Be an Imaging Red Flag for Neurodegeneration in Disproportionately Enlarged Subarachnoid Space Hydrocephalus?

BACKGROUND

The differentiation of idiopathic normal pressure hydrocephalus (iNPH) from neurodegenerative diseases such as Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) is often challenging because of their non-specific symptoms. Therefore, various neuroradiological markers other than ventriculomegaly have been proposed. Despite the utility of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) for the appropriate selection of shunt surgery candidates, the specificity and neuropathology of this finding have not been sufficiently evaluated.

OBJECTIVE

Investigation of the clinicopathological features and comparison of the neuroradiological findings between DESH with postmortem neuropathological diagnoses (pDESH) and clinically-diagnosed iNPH (ciNPH) patients are the main purposes of this study.

METHOD

In addition to the retrospective evaluation of clinicopathological information, quantitative, semiquantitative, and qualitative magnetic resonance imaging (MRI) indices were compared between pathologically-investigated 10 patients with pDESH and 10 patients with ciNPHResults:Excluding one patient with multiple cerebral infarctions, the postmortem neuropathological diagnoses of the pathologically-investigated patients were mainly neurodegenerative diseases (five AD, one DLB with AD pathologies, one DLB, one argyrophilic grain disease, and one Huntington's disease). In addition to the common neuroradiological featuresConclusion:Hippocampal atrophy and deformation with temporal horn enlargement seem to be characteristic neuroradiological findings of long-standing severely demented patients with DESH and neurodegenerative diseases, mainly advanced-stage AD.

Clinical Outcome and Striatal Dopaminergic Function After Shunt Surgery in Patients With Idiopathic Normal Pressure Hydrocephalus

OBJECTIVE

To determine changes in clinical features and striatal dopamine reuptake transporter (DAT) density after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH).

METHODS

Participants with probable iNPH were assessed at baseline by means of clinical rating scales, brain MRI, and SPECT with [¹²³I]-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane (FP-CIT). Levodopa responsiveness was also evaluated. Patients who did or did not undergo lumboperitoneal shunt were clinically followed up and repeated SPECT after 2 years.

RESULTS

We enrolled 115 patients with iNPH. Of 102 patients without significant levodopa response and no signs of atypical parkinsonism, 92 underwent FP-CIT SPECT (58 also at follow-up) and 59 underwent surgery. We identified a disequilibrium subtype (phenotype 1) and a locomotor subtype (phenotype 2) of higher-level gait disorder. Gait impairment correlated with caudate DAT density in both phenotypes, whereas parkinsonian signs correlated with putamen and caudate DAT binding in patients with phenotype 2, who showed more severe symptoms and lower striatal DAT density. Gait and caudate DAT binding improved in both phenotypes after surgery (p < 0.01). Parkinsonism and putamen DAT density improved in shunted patients with phenotype 2 (p < 0.001). Conversely, gait, parkinsonian signs, and striatal DAT binding worsened in patients who declined surgery (p < 0.01).

CONCLUSIONS

This prospective interventional study highlights the pathophysiologic relevance of striatal dopaminergic dysfunction in the motor phenotypic expression of iNPH. Absence of levodopa responsiveness, shunt-responsive parkinsonism, and postsurgery improvement of striatal DAT density are findings that corroborate the notion of a reversible striatal dysfunction in a subset of patients with iNPH.

Hydrocephalic Dementia: Revisited with Multimodality Imaging and toward a Unified Imaging Approach

Objective  Overlap of normal pressure hydrocephalus (NPH) and pathology proven cases of dementia is known. The objective of this paper is to correlate both the clinical and multimodality imaging findings in patients with imaging diagnosis NPH and give a hypothesis for association of clinical findings.

Methods  This is a retrospective observational analysis of 13 cases patients who were referred to molecular imaging center for imaging in 2016 to 2019, and they were divided into four groups based on structural imaging findings. Group 1 had magnetic resonance imaging (MRI) findings of diffuse effacement of sulcal spaces (DESH) and flow void, whereas Group 4 had none of these two. Group 3 had MRI findings of DESH but no flow void, and Group 2 had flow void but no DESH. Clinical presentation, MRI-PET findings of four groups are assessed.

Results  Groups with presence of flow void showed hypometabolism in the medial frontal and medial temporal lobe. Groups with presence of DESH has effacement of parietal sulci showed parietal hypo metabolism with clinical presentation AD/mixed dementia and absence of parietal effacement showed FTD-like presentation. Groups without flow void or DESH showed only mild medial temporal hypometabolism and presented with classical signs of NPH. ASL perfusion changes are in correlation with metabolism on positron emission tomography (PET)-MRI.

Conclusion  This study has led us to hypothesize the lack of outflow of brain protein and their deposition in parenchyma based on pressure gradient would be easier explanation to go with cluster of findings. MR-PET and other investigations each had different specificity and sensitivity and different pattern of presentation.

Treatment for secondary deterioration in idiopathic normal pressure hydrocephalus in the later course of the disease: a retrospective analysis

BACKGROUND

Cerebrospinal fluid (CSF) shunting is a highly effective treatment for idiopathic normal pressure hydrocephalus (iNPH). However, secondary deterioration can occur at a later time. Thus, the current study aimed to evaluate the incidence rate and causes of secondary deterioration.

METHODS

A retrospective analysis was conducted on all patients with iNPH who were treated with implantation of a CSF shunt since 1993. A meticulous shunt workup was recommended to all patients who presented to our department with secondary deterioration during their follow-up visits. Data about the proportion of patients with such deterioration and its causes, subsequent treatment, and clinical outcome were obtained.

RESULTS

A total of 169 patients were included, and the mean follow-up time was 69.2 months. In total, 119 (70.4%) patients presented with a total of 153 secondary deteriorations. In 9 cases (5.9%), the deterioration was caused by delayed subdural hematoma and in 27 (22.1%) cases, by shunt dysfunction. Invasive shunt testing was commonly required to validate shunt failure. Moreover, 19 of 27 patients experienced a satisfactory improvement after revision surgery. In total, 86 deteriorations were attributed to nonsurgical causes, and the valve pressure was decreased in 79 patients, with only 16.5% presenting with a satisfactory improvement after lowering of valve pressure.

CONCLUSIONS

Most patients with shunted iNPH presented with deterioration in the later course of the disease. Shunt dysfunction was considered a cause of secondary deterioration. Moreover, shunt revision surgery was a highly effective treatment, and patients with deterioration should undergo screening procedures for shunt dysfunction, including invasive shunt testing.

Gaps, Controversies, and Proposed Roadmap for Research in Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus is considered common but remains underinvestigated. There are no uniformly accepted diagnostic criteria and therapeutic guidelines. We summarize the accumulated evidence regarding the definition, pathophysiology, diagnosis, and treatment of idiopathic normal pressure hydrocephalus, highlighting the many gaps and controversies, including diagnostic challenges, the frequent association with neurodegeneration and vascular disease, and the many unknowns regarding patient selection and outcome predictors. A roadmap to fill these gaps and solve the controversies around this condition is also proposed. More evidence is required with respect to diagnostic criteria, the value of ancillary testing, prospective population-based studies and novel trial designs. Furthermore, a need exists to develop new advanced options in shunt technology. © 2020 International Parkinson and Movement Disorder Society.

Progressive Supranuclear Palsy: A Crucial Co-occurrence in Normal Pressure Hydrocephalus or an Etiology of Hydrocephalic Presentation?

Co-occurrences of neurodegenerative diseases in normal pressure hydrocephalus (NPH) is a remarkable topic of discussion, which has been mentioned in recent studies and it was also emphasized by the International Society for Hydrocephalus and Cerebrospinal Fluid Disorder. In this report, I illustrate two remarkable cases which were initially diagnosed with idiopathic normal pressure hydrocephalus (iNPH) and ventriculoperitoneal (VP) shunt surgery was performed, which yielded significant improvement in the clinic of both patients in the short-term period. However, in the long-term follow-up, both of them deteriorated, and re-evaluation of the neurological examination and neuroimaging data yielded the full clinical picture of progressive supranuclear palsy (PSP). Via the illustration of these cases and related literature data, I rediscuss some related hypotheses about the co-occurrence of these two conditions of hydrocephalus and PSP. I also suggest some distinct discussions to be clarified in future studies.

Secondary deterioration in patients with normal pressure hydrocephalus after ventriculoperitoneal shunt placement: a proposed algorithm of treatment

Background

After ventriculoperitoneal shunt surgery for idiopathic normal pressure hydrocephalus (iNPH) with adjustable gravitational valves, a certain proportion of patients develop secondary clinical worsening after initial improvement of clinical symptoms. The aim of this study was to analyze this group of patients with secondary deterioration and to evaluate the performed shunt management.

Methods

For this investigation, we retrospectively reviewed our NPH registry for patients included between 1999 and 2013 with a decrease by a minimum of two points in the Kiefer score in the first year of follow up and an increase of two points in the Kiefer score between the second and the fifth year after shunt surgery (secondary deterioration). Then, we analyzed the patient’s shunt management (adapting the valve pressure setting, shuntography, valve replacement, catheter replacement, implant an adjustable gravitational unit). Additionally, we searched for risk factors for secondary deterioration.

Results

Out of 259 iNPH patients, 53 (20%) patients showed secondary deterioration on an average of 2.7 (2–4 years) years after shunt surgery. Fourteen (26%) patients with secondary deterioration improved after shunt or valve management and 58% remained without clinical benefit after management. We had a drop-out rate of 15% due to incomplete datasets. Our shunt management reduced the rate of secondary deterioration from 20 to 15%. On the basis of our findings, we developed an algorithm for shunt management. Risk factors for secondary deterioration are the age of the patient at the time of shunting, newly diagnosed neurodegenerative diseases, and overdrainage requiring adjusting the valve to higher-pressure levels.

Conclusion

Twenty percent of patients with iNPH were at risk for secondary clinical worsening about 3 years after shunt surgery. About one-fourth of these patients benefited for additional years from pressure level management and/or shunt valve revision. Our findings underline the need for long-term follow-ups and intensive shunt management to achieve a favorable long-term outcome for patients with iNPH and VPS.

Solving the Riddle of "Idiopathic" in Idiopathic Intracranial Hypertension and Normal Pressure Hydrocephalus: An Imaging Study of the Possible Mechanisms - Monro-Kellie 3.0

Background

Idiopathic intracranial hypertension (IIH) and normal pressure hydrocephalus (NPH) represent a cluster of typical clinical and imaging findings, with no evident etiological cause noted. In this study, we have proposed a model for IIH and NPH called Monroe-Kellie 3.0 (MK 3.0). IIH and NPH may be entities which represent opposite sides of the same coin with venous system and cerebrospinal fluid (CSF) as core drivers for both these entities.

Materials and Methods

IIH and NPH volume data were collected, voxel-based morphometry analysis was performed without normalization, and the distribution of the individual volumes of gray matter, white matter, and CSF was statistically analyzed. Visual morphometry analyses of segmented data were performed, and the findings in routine magnetic resonance imaging (MRI) were noted to build a model for IIH and NPH.

Results

In IIH and NPH when the volumes were compared with controls, the distribution was similar. Furthermore, the morphometric changes noted in the MRI and segmented volume data were analyzed and the results were suggestive of changes in elastic property of brain causing a remodeling of brain shape and resulting in minor brain shift in the skull vault, and the resulting passive displacement of CSF which has been termed as MK 3.0.

Conclusion

This model helps to put the clinical and imaging findings and complications of treatment in single perspective.

Decreased Expression of hsa-miR-4274 in Cerebrospinal Fluid of Normal Pressure Hydrocephalus Mimics with Parkinsonian Syndromes

Background: Patients presenting with the classical idiopathic normal pressure hydrocephalus (iNPH) triad often show additional parkinsonian spectrum signs. Accurate differential diagnosis strongly influences the long-term outcome of cerebrospinal fluid (CSF) shunting.

Objective: The aim of this study was to find potential CSF microRNA (miRNA) biomarkers for NPH mimics with parkinsonian syndromes that can reliably distinguish them from iNPH patients.

Methods: Two cohorts of 81 patients (cohort 1, n = 55; cohort 2, n = 26) with possible iNPH who were treated in two centers between January 2011 and May 2014 were studied. In both cohorts, CSF samples were obtained from patients clinically diagnosed with iNPH (n = 21 and n = 10, respectively), possible iNPH with parkinsonian spectrum (PS) (n = 18, n = 10, respectively), possible iNPH with Alzheimer’s disease (AD) (n = 16), and non-affected elderly individuals (NC) (n = 6). A three-step qRT-PCR analysis of the CSF samples was performed to detect miRNAs that were differentially expressed in the groups.

Results: The expression of hsa-miR-4274 in CSF was decreased in both cohorts of PS group patients (cohort 1: p < 0.0001, cohort 2: p < 0.0001), and was able to distinguish PS from iNPH with high accuracy (area under the curve = 0.908). The CSF concentration of hsa-miR-4274 also correlated with the specific binding ratio of ioflupane (¹²³I) dopamine transporter scan (r = –0.494, p = 0.044). By contrast, the level of hsa-miR-4274 was significantly increased in the PS group after CSF diversion.

Conclusion: Levels of CSF hsa-miR-4274 can differentiate PS from patients with iNPH, AD, and NC. This may be clinically useful for diagnostic purposes and predicting shunt treatment responses.

Gait analysis in PSP and NPH

Objective

To test whether quantitative gait analysis of gait under single- and dual-task conditions can be used for a differential diagnosis of progressive supranuclear palsy (PSP) and idiopathic normal-pressure hydrocephalus (iNPH).

Methods

In this cross-sectional study, temporal and spatial gait parameters were analyzed in 38 patients with PSP (Neurological Disorders and Stroke and Society for Progressive Supranuclear Palsy diagnostic criteria), 27 patients with iNPH (international iNPH guidelines), and 38 healthy controls. A pressure-sensitive carpet was used to examine gait under 5 conditions: single task (preferred, slow, and maximal speed), cognitive dual task (walking with serial 7 subtractions), and motor dual task (walking while carrying a tray).

Results

The main results were as follows. First, both patients with PSP and those with iNPH exhibited significant gait dysfunction, which was worse in patients with iNPH with a more broad-based gait (p < 0.001). Second, stride time variability was increased in both patient groups, more pronounced in PSP (p = 0.009). Third, cognitive dual task led to a greater reduction of gait velocity in PSP (PSP 34.4% vs iNPH 16.9%, p = 0.002). Motor dual task revealed a dissociation of gait performance: patients with PSP considerably worsened, but patients with iNPH tended to improve.

Conclusion

Patients with PSP seem to be more sensitive to dual-task perturbations than patients with iNPH. An increased step width and anisotropy of the effect of dual-task conditions (cognitive vs motor) seem to be good diagnostic tools for iNPH.

Deconstructing normal pressure hydrocephalus: Ventriculomegaly as early sign of neurodegeneration

Idiopathic normal pressure hydrocephalus (NPH) remains both oversuspected on clinical grounds and underconfirmed when based on immediate and sustained response to cerebrospinal fluid diversion. Poor long-term postshunt benefits and findings of neurodegenerative pathology in most patients with adequate follow-up suggest that hydrocephalic disorders appearing in late adulthood may often result from initially unapparent parenchymal abnormalities. We critically review the NPH literature, highlighting the near universal lack of blinding and controls, absence of specific clinical, imaging, or pathological features, and ongoing dependence for diagnostic confirmation on variable cutoffs of gait response to bedside fluid-drainage testing. We also summarize our long-term institutional experience, in which postshunt benefits in patients with initial diagnosis of idiopathic NPH persist in only 32% of patients at 36 months, with known revised diagnosis in over 25% (Alzheimer's disease, dementia with Lewy bodies, and progressive supranuclear palsy). We postulate that previously reported NPH cases with "dual" pathology (ie, developing a "second" disorder) more likely represent ventriculomegalic presentations of selected neurodegenerative disorders in which benefits from shunting may be short-lived, with a consequently unfavorable risk-benefit ratio. Ann Neurol 2017;82:503-513.