The phenotype of idiopathic normal pressure hydrocephalus-a single center study of 429 patients

Idiopathic normal pressure hydrocephalus: associations between CSF biomarkers, clinical symptoms, and outcome after shunt surgery

BACKGROUND

The neurochemical alterations in cerebrospinal fluid (CSF) associated with the typical symptomatology in idiopathic normal pressure hydrocephalus (iNPH) and their association with outcome after shunt surgery are unsettled.

AIM

To explore associations between concentrations of CSF biomarkers reflecting amyloid- and tau pathology, neuronal degeneration as well as astrocytic activation and the characteristic symptomatology in iNPH and to examine whether these biomarkers can predict the postoperative outcome in all patients and in patients without evidence of Alzheimer's disease (AD) pathology.

METHODS

This explorative study included 81 patients diagnosed with iNPH at the Hydrocephalus research unit, Sahlgrenska. Symptoms were assessed using the iNPH-scale and standardized clinical tests measuring gait, balance, cognition and urinary incontinence before and median 8 months after shunt surgery. Pre-operative lumbar CSF concentrations of Aβ38, Aβ40, Aβ42, ratio Aβ42/Aβ40, sAPPα, sAPPβ, T-tau, P-tau, MCP-1, and NFL were analyzed. A low Aβ42/Aβ40 ratio defined patients with AD pathology. Correlation and regression analyses between biomarker concentrations and clinical symptoms at baseline as well as postoperative change in symptoms after surgery, were performed.

RESULTS

Higher NFL correlated with more pronounced impairment in all clinical tests, i.e. included measures of gait, balance, cognition and urinary incontinence (rp=0.25-0.46, p < 0.05). Higher T-tau and P-tau correlated with poorer performance in cognitive tests (rp=0.26-0.39, p < 0.05). No biomarker could differentiate between improved and unimproved patients in the whole sample or in AD-pathology negative patients. Low ratio Aβ42/Aβ40 lacked predictive value. A higher preoperative P-tau was weakly correlated with less pronounced overall clinical improvement (rp = -0.238, p = 0.036).

CONCLUSIONS

Axonal degeneration, as indicated by elevated NFL, is probably involved in the generation of the full iNPH tetrade of symptoms and tau pathology more specifically with iNPH cognitive impairment. No CSF biomarker could identify shunt responders. CSF evidence of Alzheimer pathology should not be used to exclude patients from shunt surgery.

Decrease of excessive daytime sleepiness after shunt treatment for normal pressure hydrocephalus

Sleepiness and apathy are often reported in patients with normal pressure hydrocephalus. However, research on outcomes after shunt surgery has mainly focused on the classical triad symptoms, that is, gait, cognition, and bladder dysfunction. This study aimed to describe the effects of shunt treatment on excessive daytime sleepiness and whether there was a relation to changes in ventricular volume. Pre- and postsurgical excessive daytime sleepiness was investigated using the Epworth sleepiness scale in a sample of 32 patients with normal pressure hydrocephalus who underwent shunt surgery. Data were gathered before surgery and at 1, 2, and 3 months after surgery and with different settings of the shunt. In the total sample, the Epworth sleepiness scale improved by a median of 1.5 points at 1 month after surgery, p = 0.026. The improvement was predominately found in the group (n = 6) with high presurgical daytime sleepiness (Epworth sleepiness scale >12) (median = 12 points, p = 0.035) compared with a median change of 0 points (p = 0.47) in the group with Epworth sleepiness scale ≤12 (n = 26). Between the postsurgical follow-ups, no further change in the Epworth sleepiness scale score was observed. The Epworth sleepiness scale score did not correlate with clinical tests nor with ventricular volume. Daytime sleepiness seems to be another domain of normal pressure hydrocephalus symptomatology in addition to the classical triad that is responsive to treatment, at least when pronounced. The Epworth sleepiness scale is a quick test to administer and could be a valuable addition to pre-surgical screening for treatable symptoms.

Physical activity and gait in patients with idiopathic normal pressure hydrocephalus: a literature review

Background

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by impaired gait and cognition, and urinary incontinence. Even though iNPH still lacks standardized diagnostic criteria, many patients may potentially benefit from treatment which are often invasive procedures.

Objectives

To provide an overview of the current state of research on physical activity behavior and gait in patients with iNPH, and examine potential changes after treatment (i.e., shunt surgery, spinal tap test or lumbar drainage).

Methods

This literature review was carried out based on the PRISMA statement and we searched PubMed, Web of Science and Scopus databases in April 2023.

Results

In total, 32 studies were included: 29 focusing on gait, 2 focusing on gait and physical activity, and 1 focusing on physical activity. All studies reported improvements in gait, such as reduced gait ataxia or shuffling gait and greater variability of gait cycle length, after an intervention or treatment. Improvements may depend on patients' age, symptom duration, and treatment method, among others.

Conclusion

Improvements in gait after iNPH treatment (e.g., shunt surgery) are well documented, whereas results on physical activity behavior in iNPH patients are inconsistent. More research on physical activity and gait outcomes before and after treatment is needed, also with regard to treatment success.

Hakim's disease: an update on idiopathic normal pressure hydrocephalus

INTRODUCTION

Idiopathic normal pressure hydrocephalus (iNPH) increases with age but is still underdiagnosed and undertreated. In the last decade, iNPH research has expanded into understanding broader contributions to iNPH, the role of cerebrospinal fluid (CSF), and imaging biomarkers to aid early detection, help diagnosis and differentiation from iNPH mimics, and aid with outcome prediction.

EVIDENCE ACQUISITION

We performed a literature search on the PubMed database. English language articles published between 2015-2024 were included. The strategies focused on iNPH and specific terms related to the topics of this review.

EVIDENCE SYNTHESIS

We first addressed the ambiguity of current classification terminology and reviewed the newly proposed classification system. This review has shown that prevalence is higher than previously reported. We have reviewed imaging and found numerous highly sensitive and specific imaging markers to aid diagnosis and differentiate from common mimics. CSF biomarkers have revealed that amyloid β and tau levels were lower in iNPH patients, which helped with differentiation from iNPH mimics, and that other emerging inflammatory markers need to be studied further. We also found numerous promising genetic markers in familial iNPH involved in cilial dysfunction, neuroinflammation, and neurodegeneration. Literature also reported the frequent presence of spinal stenosis, and studies reported better iNPH outcomes when these were addressed.

CONCLUSIONS

This has shown that there is a need for the development of a structured and standardized classification system, iNPH assessment protocol with standardized testing, and standardized biomarkers to aid diagnosis and treatment, and that this needs an interdisciplinary team approach.

When and how are complications suspected after shunt surgery in patients with normal pressure hydrocephalus?

PURPOSE

The follow-up routine for patients with idiopathic normal pressure hydrocephalus (iNPH) after shunt surgery differs across medical centers. Shunt surgery is not without risks, with complications emerging at various times after the procedure. The aim was to explore the timing and methods of detecting complications following ventriculoperitoneal shunt surgery for iNPH.

METHODS

This retrospective study examined patients who underwent shunt surgery for iNPH at Uppsala University Hospital between 2011 and 2018. The cohort comprised 491 patients. Postoperative complications within the first 12 months were recorded from medical records. Complications were classified by type, and the method or event that first indicated the complication was documented.

RESULTS

Of the 491 patients, 102 (20.8%) experienced complications during the one-year follow-up period, with a shunt revision rate of 15.5% (76 patients requiring reoperation). Subdural hematomas/hygromas were the most common complications, with 27 cases; only three required surgical intervention. Most complications were identified through additional appointments triggered by patient-reported symptoms (31.4%), while the planned follow-up routine with CT scans and planned follow-up visits together accounted for 56% of the detections. The 3-month and 12-month follow-up visits detected similar proportions of complications (12.7% and 11.8%, respectively).

CONCLUSION

The majority of the complications were detected at a planned visit or investigation. Given the cognitive impairments in iNPH patients and that signs of shunt dysfunction can be subtle, a structured follow-up routine is important for timely detection of complications. The findings suggest that both CT scans and planned follow-up visits are critical components of effective postoperative monitoring.

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.

Symptoms and signs did not predict outcome after surgery: a prospective study of 143 patients with idiopathic normal pressure hydrocephalus

OBJECTIVE

To determine the utility of symptoms, signs, comorbidities and background variables for the prediction of outcome of treatment in iNPH.

METHODS

A prospective observational study of consecutively included iNPH patients, who underwent neurological, physiotherapeutic and neuropsychological assessments before and after shunt surgery. The primary outcome measure was the total change on the iNPH scale, and patients were defined as improved postoperatively if they had improved by at least five points on that scale.

RESULTS

143 iNPH patients were included, and 73% of those were improved after surgery. None of the examined symptoms or signs could predict which patients would improve after shunt surgery. A dominant subjective complaint of memory problems at baseline was predictive of non-improvement. The reported comorbidities, duration of symptoms and BMI were the same in improved and non-improved patients. Each of the symptom domains (gait, neuropsychology, balance, and continence) as well as the total iNPH scale score improved significantly (from median 53 to 69, p < 0.001). The proportions of patients with shuffling gait, broad-based gait, paratonic rigidity and retropulsion all decreased significantly.

DISCUSSION

This study confirms that the recorded clinical signs, symptoms, and impairments in the adopted clinical tests are characteristic findings in iNPH, based on that most of them improved after shunt surgery. However, our clinical data did not enable predictions of whether patients would respond to shunt surgery, indicating that the phenotype is unrelated to the reversibility of the iNPH state and should mainly support diagnosis. Absence of specific signs should not be used to exclude patients from treatment.

Freezing of gait in idiopathic normal pressure hydrocephalus

BACKGROUND

Reports of freezing of gait (FoG) in idiopathic normal pressure hydrocephalus (iNPH) are few and results are variable. This study's objective was to evaluate the frequency of FoG in a large cohort of iNPH patients, identify FoG-associated factors, and assess FoG's responsiveness to shunt surgery.

METHODS

Videotaped standardized gait protocols with iNPH patients pre- and post-shunt surgery (n = 139; median age 75 (71-79) years; 48 women) were evaluated for FoG episodes by two observers (Cohens kappa = 0.9, p < 0.001). FoG episodes were categorized. Mini-mental state examination (MMSE) and MRI white matter hyperintensities (WMH) assessment using the Fazekas scale were performed. CSF was analyzed for Beta-amyloid, Tau, and Phospho-tau. Patients with and without FoG were compared.

RESULTS

Twenty-two patients (16%) displayed FoG at baseline, decreasing to seven (8%) after CSF shunt surgery (p = 0.039). The symptom was most frequently exhibited during turning (n = 16, 73%). Patients displaying FoG were older (77.5 vs. 74.6 years; p = 0.029), had a slower walking speed (0.59 vs. 0.89 m/s; p < 0.001), a lower Tinetti POMA score (6.8 vs. 10.8; p < 0.001), lower MMSE score (21.3 vs. 24.0; p = 0.031), and longer disease duration (4.2 vs. 2.3 years; p < 0.001) compared to patients not displaying FoG. WMH or CSF biomarkers did not differ between the groups.

CONCLUSIONS

FoG is occurring frequently in iNPH patients and may be considered a typical feature of iNPH. FoG in iNPH was associated with higher age, longer disease duration, worse cognitive function, and a more unstable gait. Shunt surgery seems to improve the symptom.

From one to many: Hypertonia in schizophrenia spectrum psychosis an integrative review and adversarial collaboration report

Different types of resistance to passive movement, i.e. hypertonia, were described in schizophrenia spectrum disorders (SSD) long before the introduction of antipsychotics. While these have been rediscovered in antipsychotic-naïve patients and their non-affected relatives, the existence of intrinsic hypertonia vs drug-induced parkinsonism (DIP) in treated SSD remains controversial. This integrative review seeks to develop a commonly accepted framework to specify the putative clinical phenomena, highlight conflicting issues and discuss ways to challenge each hypothesis and model through adversarial collaboration. The authors agreed on a common framework inspired from systems neuroscience. Specification of DIP, locomotor paratonia (LMP) and psychomotor paratonia (PMP) identified points of disagreement. Some viewed parkinsonian rigidity to be sufficient for diagnosing DIP, while others viewed DIP as a syndrome that should include bradykinesia. Sensitivity of DIP to anticholinergic drugs and the nature of LPM and PMP were the most debated issues. It was agreed that treated SSD should be investigated first. Clinical features of the phenomena at issue could be confirmed by torque, EMG and joint angle measures that could help in challenging the selectivity of DIP to anticholinergics. LMP was modeled as the release of the reticular formation from the control of the supplementary motor area (SMA), which could be challenged by the tonic vibration reflex or acoustic startle. PMP was modeled as the release of primary motor cortex from the control of the SMA and may be informed by subclinical echopraxia. If these challenges are not met, this would put new constraints on the models and have clinical and therapeutic implications.

Longitudinal neuropsychological trajectories in idiopathic normal pressure hydrocephalus: a population-based study

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a progressive syndrome affecting gait, incontinence, and cognition in a significant number of older adults. Still, prospective studies on early development of symptoms are scarce.

AIM

To investigate how neuropsychological functions develop before and in already diagnosed iNPH over a two-year period in a population-based material.

METHOD

A sample of 104 participants (median [IQR] 75 [72-80] years old) from the general population underwent CT-imaging and clinical assessment at baseline and follow-up. We used the iNPH symptom scale covering four domains (Neuropsychology, Gait, Balance, Incontinence) and additional tests of executive functions. Morphological signs were rated with the iNPH Radscale. Non-parametric statistics with Bonferroni corrections and a significance-level of p < 0.05 were used.

RESULTS

Median (IQR) time to follow-up was 25 (23-26) months. Effect size (ES) for individuals who developed iNPH (n = 8) showed a large (ES r = -0.55) decline in the Gait domain and on the Radscale (ES r = -0.60), with a medium deterioration in declarative memory (ES r = -0.37). Those having iNPH at baseline (n = 12) performed worse on one executive sub-function i.e., shifting (p = 0.045).

CONCLUSION

Besides deterioration in gait and radiology, our results suggest that a neuropsychological trajectory for those developing iNPH includes a reduction in declarative memory. Executive dysfunction was limited to those already having iNPH at baseline. These findings could suggest that memory impairments are included in the early development of iNPH.

Clinical Features of Idiopathic Normal Pressure Hydrocephalus: Critical Review of Objective Findings

Background

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by the classic clinical triad of gait, cognitive, and urinary dysfunction, albeit incomplete in a relevant proportion of patients. The clinical findings and evolution of these symptoms have been variably defined in the literature.

Objectives

To evaluate how the phenomenology has been defined, assessed, and reported, we performed a critical review of the existing literature discussing the phenomenology of iNPH. The review also identified the instrumental tests most frequently used and the evolution of clinical and radiologic findings.

Methods

The review was divided into 3 sections based on gait, cognitive, and urinary dysfunction. Each section performed a literature search using the terms "idiopathic normal pressure hydrocephalus" (iNPH), with additional search terms used by each section separately. The number of articles screened, duplicates, those meeting the inclusion criteria, and the number of articles excluded were recorded. Findings were subsequently tallied and analyzed.

Results

A total of 1716 articles with the aforementioned search criteria were identified by the 3 groups. A total of 81 full-text articles were reviewed after the elimination of duplicates, articles that did not discuss phenomenological findings or instrumental testing of participants with iNPH prior to surgery, and articles with fewer than 10 participants.

Conclusions

"Wide-based gait" was the most common gait dysfunction identified. Cognitive testing varied significantly across articles, and ultimately a specific cognitive profile was not identified. Urodynamic testing found detrusor overactivity and "overactive bladder" as the most common symptom of urinary dysfunction.

Ventricular volume in relation to lumbar CSF levels of amyloid-β 1–42, tau and phosphorylated tau in iNPH, is there a dilution effect?

Background

Levels of the biomarkers amyloid-β 1–42 (Aβ42), tau and phosphorylated tau (p-tau) are decreased in the cerebrospinal fluid (CSF) of patients with idiopathic normal pressure hydrocephalus (iNPH). The mechanism behind this is unknown, but one potential explanation is dilution by excessive CSF volumes. The aim of this study was to investigate the presence of a dilution effect, by studying the relationship between ventricular volume (VV) and the levels of the CSF biomarkers.

Methods

In this cross-sectional observational study, preoperative magnetic resonance imaging (MRI) and lumbar CSF was acquired from 136 patients with a median age of 76 years, 89 men and 47 females, selected for surgical treatment for iNPH. The CSF volume of the lateral and third ventricles was segmented on MRI and related to preoperative concentrations of Aβ42, tau and p-tau.

Results

In the total sample VV (Median 140.7 mL) correlated weakly (rs = − 0.17) with Aβ42 (Median 534 pg/mL), but not with tau (Median 216 pg/mL) nor p-tau (Median 31 pg/mL). In a subgroup analysis, the correlation between VV and Aβ42 was only present in the male group (rs = − 0.22, p = 0.038). Further, Aβ42 correlated positively with tau (rs = 0.30, p = 0.004) and p-tau (rs = 0.26, p = 0.012) in males but not in females.

Conclusions

The findings did not support a major dilution effect in iNPH, at least not in females. The only result in favor for dilution was a weak negative correlation between VV and Aβ42 but not with the other lumbar CSF biomarkers. The different results between males and females suggest that future investigations of the CSF pattern in iNPH would gain from sex-based subgroup analysis.

Value of MRI-based semi-quantitative structural neuroimaging in predicting the prognosis of patients with idiopathic normal pressure hydrocephalus after shunt surgery

OBJECTIVES

To explore the value of structural neuroimaging in predicting the prognosis of shunt surgery for idiopathic normal-pressure hydrocephalus (iNPH) using two different standard semi-quantitative imaging scales.

METHODS

A total of 47 patients with iNPH who underwent shunt surgery at our hospital between 2018 and 2020 were included in this study. The modified Rankin Scale (mRS) and iNPH grading scale (iNPHGS) were used to evaluate and quantify the clinical symptoms before and after shunt surgery. The disproportionately enlarged subarachnoid space hydrocephalus (DESH) and iNPH Radscale scores were used to evaluate the preoperative MR images. The primary endpoint was improvement in the mRS score a year after surgery, and the secondary endpoint was the iNPHGS after 1 year. The preoperative imaging features of the improved and non-improved groups were compared.

RESULTS

The rates of the primary and secondary outcomes were 59.6% and 61.7%, respectively, 1 year after surgery. There were no significant differences in preoperative DESH score, iNPH Radscale, Evans' index (EI), or callosal angle (CA) between the improved and non-improved groups. Significant correlations were observed between the severity of gait disorder and EI and the CA.

CONCLUSIONS

The value of structural neuroimaging in predicting the prognosis of shunt surgery is limited, and screening for shunt surgery candidates should not rely only on preoperative imaging findings.

KEY POINTS

• Early shunt surgery can significantly improve the clinical symptoms and prognosis of patients with idiopathic normal-pressure hydrocephalus (iNPH). • Structural imaging findings have limited predictiveness for the prognosis of patients with iNPH after shunt surgery. • Patients should not be selected for shunt surgery based on only structural imaging findings.

Gait, falls, cognitive function, and health-related quality of life after shunt-treated idiopathic normal pressure hydrocephalus-a single-center study

BACKGROUND

Normal pressure hydrocephalus (NPH) is a neurological disorder, characterized by gait- and balance disturbance, cognitive deterioration, and urinary incontinence, combined with ventricular enlargement. Gait ability, falls, cognitive status, and health-related quality of life pre and post surgery have not previously been studied at Karolinska University Hospital.

METHODS

One hundred and eighteen patients with iNPH that underwent shunt surgery at Karolinska University Hospital during the years from 2016 to 2018 were included. Results of walking tests, test for cognitive function, and self-estimated health-related quality of life, before and 3 months after surgery, were collected retrospectively as a single-center study.

RESULTS

Walking ability, cognitive function, and health-related quality of life significantly increased 3 months after shunt surgery. A positive significant correlation was seen between a higher self-estimated quality of life and walking ability.

CONCLUSIONS

Patients with suspected iNPH treated with shunt surgery at Karolinska University Hospital improved their walking ability and cognitive functioning 3 months after shunt surgery. A positive significant correlation was seen between a higher self-estimated quality of life and walking ability but not with increased cognitive function. We then concluded that the selection of patients for shunting maintained a high standard.

Psychiatric Comorbidities in Patients With Idiopathic Intracranial Hypertension: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Psychiatric disease is a frequent comorbidity in idiopathic intracranial hypertension (IIH) and has been associated with a poor subjective outcome. No prospective studies have investigated psychiatric comorbidities in new-onset IIH. Our primary aim was to investigate disease severity in IIH depending on comorbid psychiatric disease. Important secondary outcomes were disease severity after 6 months and prevalence of psychiatric diseases in IIH.

METHODS

This prospective, observational cohort study consecutively included patients with clinically suspected, new-onset IIH from 2 headache centers. A standardized diagnostic workup was completed to confirm or exclude IIH according to the revised Friedman criteria: semi-structured interview, neurologic and neuro-ophthalmologic examination, lumbar puncture with opening pressure (OP), and neuroimaging. Exclusion criteria were known IIH, secondary intracranial hypertension, missing data, and pregnancy. Disease severity was evaluated based on papilledema, visual fields, OP, and headache in patients with IIH without psychiatric disease (IIH-P) compared with patients with IIH with psychiatric disease (IIH+P). A blinded neuro-ophthalmologist assessed visual outcomes. Age- and sex-matched prevalence rates of psychiatric diseases in the general population were found in national reports.

RESULTS

A total of 258 patients were screened; 69 were excluded. A total of 189 patients with clinically suspected IIH were then evaluated with the diagnostic workup and IIH was confirmed in 111 patients (58.7%). A total of 45% of patients with IIH had a psychiatric comorbidity. Visual fields were worse in patients with IIH+P at baseline (-8.0 vs -6.0 dB; p = 0.04) and after 6 months (-5.5 vs -4.0 dB; p < 0.01) compared with IIH-P. Highly prevalent psychiatric disorders were major depressive disorder (24.3%; n = 27), anxiety or stress-related disorders (24.3%; n = 27), and emotionally unstable personality disorder (6.3%; n = 7). Substance abuse (1.8%), schizophrenia (0.9%), and bipolar disorder (0.9%) were rare. In the general population, prevalence estimates of major depressive disorder and emotionally unstable personality disorder were 1.8%-3.3% and 2%, respectively.

DISCUSSION

Visual fields were significantly worse at baseline and 6 months in IIH+P compared with IIH-P. Psychiatric comorbidities, particularly depression and emotionally unstable personality disorder, were highly prevalent in IIH. Increased awareness of psychiatric disease as a marker for worse visual status may improve patient care.

CSF tap test in idiopathic normal pressure hydrocephalus: still a necessary prognostic test?

Objective

To assess whether gait, neuropsychological, and multimodal MRI parameters predict short-term symptom reversal after cerebrospinal fluid (CSF) tap test in idiopathic normal pressure hydrocephalus (iNPH).

Methods

Thirty patients (79.3 ± 5.9 years, 12 women) with a diagnosis of probable iNPH and 46 healthy controls (74.7 ± 5.4 years, 35 women) underwent comprehensive neuropsychological, quantitative gait, and multimodal MRI assessments of brain morphology, periventricular white-matter microstructure, cortical and subcortical blood perfusion, default mode network function, and white-matter lesion load. Responders were defined as an improvement of at least 10% in walking speed or timed up and go test 24 h after tap test. Univariate and multivariable tap test outcome prediction models were evaluated with logistic regression and linear support vector machine classification.

Results

Sixteen patients (53%) respondedpositively to tap test. None of the gait, neuropsychological, or neuroimaging parameters considered separately predicted outcome. A multivariable classifier achieved modest out-of-sample outcome prediction accuracy of 70% (p = .028); gait parameters, white-matter lesion load and periventricular microstructure were the main contributors.

Conclusions

Our negative findings show that short-term symptom reversal after tap test cannot be predicted from single gait, neuropsychological, or MRI parameters, thus supporting the use of tap test as prognostic procedure. However, multivariable approaches integrating non-invasive multimodal data are informative of outcome and may be included in patient-screening procedures. Their value in predicting shunting outcome should be further explored, particularly in relation to gait and white-matter parameters.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11168-x.

Physical Capacity and Activity in Patients With Idiopathic Normal Pressure Hydrocephalus

Introduction

Most patients with idiopathic normal pressure hydrocephalus (iNPH) improve gait after surgery. However, knowledge on physical capacity and activity after shunt surgery is limited. One of the aims of this study was to evaluate the effect of shunt surgery in patients with iNPH on short-distance walking, functional exercise capacity, functional strength, and variables of activity and sleep, 3 and 6 months postoperatively. Another aim was to evaluate the effect of a physical exercise program. Additionally, we studied how changes in short-distance walking were correlated with functional exercise capacity and voluntary walking.

Methods

In total, 127 patients were consecutively included and randomized to the exercise group (n = 62) or the control group (n = 65). Participants in the exercise group underwent the supervision of a 12-week exercise program. All patients were assessed before surgery, at 3 and 6 months postoperatively with the 10-m walk test (10MWT), the 6-min walk test (6MWT), 30-s chair stand test (30sCST), and with the actigraphic recordings of activity variables measured for a total of 24 h/day for at least 3 days.

Results

All patients improved at 3 months postoperatively in the 10MWT (p < 0.001), 6MWT (p < 0.001), and 30sCST (p < 0.001). These results were maintained after 6 months. Actigraphic recordings for voluntary walking (steps per minute) were improved and nighttime sleep (%) increased after 6 months (p = 0.01, p = 0.04). There were no significant differences between the exercise group and the control group, except for the postoperative change in the proportion of daytime sleep after 3 months, which was slightly more reduced compared to baseline in the exercise group (p = 0.04). Changes after 3 months in the 10MWT and 6MWT were moderately correlated (ρ= −0.49, p = 0.01) whereas the correlation between the 10MWT and voluntary walking was weak (ρ = −0.34, p = 0.01).

Conclusion

Shunt surgery improved short-distance walking, functional exercise capacity, functional strength, and voluntary walking. An exercise program did not affect these outcomes. Short-distance walking was weakly correlated with voluntary walking, indicating improved physical capacity does not directly translate to increased physical activity. Further research should address how interventions should be tailored to promote physical activity after shunt surgery.

Trial Registration

clinicaltrials.gov, Id: NCT02659111.

Shunt Surgery Efficacy Is Correlated With Baseline Cerebrum Perfusion in Idiopathic Normal Pressure Hydrocephalus: A 3D Pulsed Arterial-Spin Labeling Study

This study investigated the relationship between preoperative cerebral blood flow (CBF) in patients with idiopathic normal pressure hydrocephalus (INPH) and preoperative clinical symptoms and changes of clinical symptoms after shunt surgery. A total of 32 patients with diagnosed INPH and 18 age-matched healthy controls (HCs) were involved in this study. All subjects underwent magnetic resonance imaging (MRI), including 3D pulsed arterial-spin labeling (PASL) for non-invasive perfusion imaging, and clinical symptom evaluation at baseline, and all patients with INPH were reexamined with clinical tests 1 month postoperatively. Patients with INPH had significantly lower whole-brain CBF than HCs, with the most significant differences in the high convexity, temporal lobe, precuneus, and thalamus. At baseline, there was a significant correlation between the CBF in the middle frontal gyrus, calcarine, inferior and middle temporal gyrus, thalamus, and posterior cingulate gyrus and poor gait manifestation. After shunting, improvements were negatively correlated with preoperative perfusion in the inferior parietal gyrus, inferior occipital gyrus, and middle temporal gyrus. Preoperative CBF in the middle frontal gyrus was positively correlated with the severity of preoperative cognitive impairment and negatively correlated with the change of postoperative MMSE score. There was a moderate positive correlation between anterior cingulate hypoperfusion and improved postoperative urination. Our study revealed that widely distributed and intercorrelated cortical and subcortical pathways are involved in the development of INPH symptoms, and preoperative CBF may be correlative to short-term shunt outcomes.

The timed up and go test in idiopathic normal pressure hydrocephalus: a Nationwide Study of 1300 patients

BACKGROUND

The aim of this study was to describe the outcome measure timed up and go (TUG) in a large, nationwide cohort of patients with idiopathic normal pressure hydrocephalus (iNPH) pre- and post-operatively. Furthermore, to compare the TUG test to the 10-m walk test (10MWT), the iNPH scale, the modified Rankin scale (mRS) and the Mini Mental State Examination (MMSE), which are commonly applied in clinical assessment of iNPH.

METHODS

Patients with iNPH (n = 1300), registered in the Swedish Hydrocephalus Quality Registry (SHQR), were included. All data were retrieved from the SHQR except the 10MWT, which was collected from patient medical records. Clinical scales were examined pre- and 3 months post-operatively. Data were dichotomised by sex, age, and preoperative TUG time.

RESULTS

Preoperative TUG values were 19.0 [14.0-26.0] s (median [IQR]) and 23 [18-30] steps. Post-operatively, significant improvements to 14.0 [11.0-20.0] s and 19 [15-25] steps were seen. TUG time and steps were higher in women compared to men (p < 0.001) but there was no sex difference in improvement rate. Worse preoperative TUG and younger age favoured improvement. TUG was highly correlated to the 10MWT, but correlations of post-operative changes were only low to moderate between all scales (r = 0.22-0.61).

CONCLUSIONS

This study establishes the distribution of TUG in iNPH patients and shows that the test captures important clinical features that improve after surgery independent of sex and in all age groups, confirming the clinical value of the TUG test. TUG performance is associated with performance on the 10MWT pre- and post-operatively. However, the weak correlations in post-operative change to the 10MWT and other established outcome measures indicate an additional value of TUG when assessing the effects of shunt surgery.

Imaging features associated with idiopathic normal pressure hydrocephalus have high specificity even when comparing with vascular dementia and atypical parkinsonism

Background

Vascular dementia (VaD) and atypical parkinsonism often present with symptoms that can resemble idiopathic normal pressure hydrocephalus (iNPH) and enlarged cerebral ventricles, and can be challenging differential diagnoses. The aim was to investigate frequencies of imaging features usually associated with iNPH and their radiological diagnostic accuracy in a sample containing the relevant differential diagnoses VaD, progressive supranuclear palsy (PSP), multiple system atrophy parkinsonian type (MSA-P), and healthy controls.

Methods

Nine morphological imaging features usually associated with iNPH were retrospectively investigated in MR images of 55 patients with shunt-responsive iNPH, 32 patients with VaD, 30 patients with PSP, 27 patients with MSA-P, and 39 age-matched healthy controls. Logistic regression and receiver operating characteristic curves were used to assess diagnostic accuracy, sensitivity, and specificity for each imaging finding.

Results

In a logistic regression model using iNPH diagnosis as a dependent variable, the following imaging features contributed significantly to the model: callosal angle (OR = 0.95 (0.92–0.99), p = 0.012), Evans’ index * 100 (OR = 1.51 (1.23–1.86), p < 0.001), enlarged Sylvian fissures (OR = 6.01 (1.42–25.40), p = 0.015), and focally enlarged sulci (OR = 10.18 (1.89–55.02), p = 0.007). Imaging features with 95% specificity for iNPH were: callosal angle ≤ 71°, temporal horns ≥ 7 mm, Evans’ index ≥ 0.37, iNPH Radscale ≥ 9, and presence of DESH, bilateral ventricular roof bulgings or focally enlarged sulci. A simplified version of the iNPH Radscale with only four features resulted in equally high diagnostic accuracy as the original iNPH Radscale.

Conclusions

There is a notable overlap between some of the commonly used imaging markers regarding iNPH, VaD and atypical parkinsonism, such as PSP. However, this study shows that the specificity of imaging markers usually associated with iNPH was high even when comparing with these challenging differential diagnoses. The callosal angle was the single imaging feature with highest diagnostic accuracy to discriminate iNPH from its mimics. A simplified rating scale using only a few selected features could be used with retained specificity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00270-3.

Anterior callosal angle correlates with gait impairment and fall risk in iNPH patients

BACKGROUND

In idiopathic normal pressure hydrocephalus (iNPH), gait and balance impairment is the most frequent symptom, and it is often associated with a higher fall risk. In a prior study, the anterior callosal angle (ACA) was validated as a reliable marker to discriminate iNPH from Alzheimer's disease and healthy controls. However, the potential correlation between the ACA with clinical symptoms and functional outcomes has not been assessed. The objective of this study is to determine the utility of the ACA in predicting gait improvement after ventriculoperitoneal (VP) shunting.

METHODS

Patients with probable iNPH who underwent shunt placement at a single institution were prospectively enrolled from May 2015 to May 2019. Patients were assessed preoperatively and at 6 months postoperatively following a standard clinical and MRI protocol. Callosal angle (CA) and ACA were calculated from 3 T MRI preoperatively and at 6 months postoperatively. CA and ACA were tested for correlation with clinical scores.

RESULTS

Forty-seven patients with probable INPH who completed 6-month postoperative follow-up were enrolled in the study. Baseline ACA was significantly correlated with preoperative fall risk, gait, and balance impairment assessed with Tinetti POMA scale. Additionally, baseline ACA differentiated patients who experienced improvement at Tinetti POMA scale after surgery.

CONCLUSIONS

The baseline ACA is a useful neuroradiological marker to differentiate patients by fall risk and has significant correlation with the improvement in gait and balance impairment following surgery. This study demonstrated that the ACA may be a complementary tool to the CA in predicting shunt responsiveness in iNPH.

MRI diffusion and perfusion alterations in the mesencephalon and pons as markers of disease and symptom reversibility in idiopathic normal pressure hydrocephalus

Introduction

Core symptomatology in idiopathic normal pressure hydrocephalus (iNPH) points at dysfunction in the mesencephalon and pons indicating pathological changes in these regions, but only a few studies have addressed the issue. The aim of this study was to investigate diffusion (ADC) and perfusion patterns pre- and postoperatively in these areas in iNPH.

Methods

Twenty iNPH patients and 15 healthy controls were included. Patients underwent a clinical examination and brain MRI pre- and 3–6 months postoperatively. The MRI-scan included diffusion and dynamic susceptibility contrast perfusion weighted sequences. Regions of interest in the mesencephalon and pons were drawn on a FLAIR sequence and co-registered to ADC maps and perfusion data.

Results

There were no significant differences in pre or postoperative ADC compared to the control group, however postoperative ADC increased by 10% (p = 0.026) in the mesencephalon and 6% (p = 0.016) in the pons in all patients and also in the subgroup of shunt responders by 11% (p = 0.021) and 4% (p = 0.020), respectively. Preoperative relative cerebral blood flow (rCBF) was similar in iNPH patients and controls. Postoperatively, rCBF increased in shunt responders by 6% (p = 0.02) in the mesencephalon and 11% (p = 0.004) in the pons. This increase correlated with the degree of clinical improvement (r_s = 0.80, p = 0.031 and r_s = 0.66, p = 0.021, respectively).

Conclusion

The postoperative increase in ADC and the correlation between postoperative increase in rCBF and clinical improvement in the mesencephalon and pons shown in this study point at an involvement of these areas in the core pathophysiology and its reversibility in iNPH.

Magnetic Resonance Imaging Biomarkers Distinguish Normal Pressure Hydrocephalus From Progressive Supranuclear Palsy

BACKGROUND

Idiopathic normal pressure hydrocephalus and PSP share several clinical and radiological features, making differential diagnosis, at times, challenging.

OBJECTIVES

To differentiate idiopathic normal pressure hydrocephalus from PSP using MR volumetric and linear measurements.

METHODS

Twenty-seven idiopathic normal pressure hydrocephalus patients, 103 probable PSP patients, and 43 control subjects were consecutively enrolled. Automated ventricular volumetry was performed using Freesurfer 6 on MR T₁ -weighted images. Linear measurements, such as callosal angle and a new measure, termed MR Hydrocephalic Index, were calculated on MR T₁ -weighted images. Receiver operating characteristic analyses were used for differentiating between patient groups. Generalizability and reproducibility of the results were validated, dividing each participant group in two cohorts used as training and testing subsets.

RESULTS

Ventricular volumes and linear measurements (callosal angle and Magnetic Resonance Hydrocephalic Index) revealed greater ventricular enlargement in patients with idiopathic normal pressure hydrocephalus than in PSP patients and controls. PSP patients had ventricular volume larger than controls. Automated ventricular volumetry and Magnetic Resonance Hydrocephalic Index were the most accurate measures (98.5%) in differentiating patients with idiopathic normal pressure hydrocephalus from PSP patients, whereas callosal angle misclassified several PSP patients and showed low positive predictive value (70.0%) in differentiating between these two diseases. All measurements accurately differentiated idiopathic normal pressure hydrocephalus patients from controls. Accuracy values obtained in the training set (automated ventricular volumetry, 98.4%; Magnetic Resonance Hydrocephalic Index, 98.4%; callosal angle, 87.5%) were confirmed in the testing set.

CONCLUSIONS

Our study demonstrates that AVV and Magnetic Resonance Hydrocephalic Index were the most accurate measures for differentiation between idiopathic normal pressure hydrocephalus and PSP patients. Magnetic Resonance Hydrocephalic Index is easy to measure and can be used in clinical practice to prevent misdiagnosis and ineffective shunt procedures in idiopathic normal pressure hydrocephalus mimics. © 2020 International Parkinson and Movement Disorder Society.

Survival in treated idiopathic normal pressure hydrocephalus

OBJECTIVE

To describe survival and causes of death in 979 treated iNPH patients from the Swedish Hydrocephalus Quality Registry (SHQR), and to examine the influence of comorbidities, symptom severity and postoperative outcome.

METHODS

All 979 patients operated for iNPH 2004-2011 and registered in the SHQR were included. A matched control group of 4890 persons from the general population was selected by Statistics Sweden. Data from the Swedish Cause of Death Registry was obtained for patients and controls.

RESULTS

At a median 5.9 (IQR 4.2-8.1) year follow-up, 37% of the iNPH patients and 23% of the controls had died. Mortality was increased in iNPH patients by a hazard ratio of 1.81, 95% CI 1.61-2.04, p < 0.001. More pronounced symptoms in the preoperative ordinal gait scale and the Mini-mental State Examination were the most important independent predictors of mortality along with the prevalence of heart disease. Patients who improved in both the gait scale and in the modified Rankin Scale postoperatively (n = 144) had a similar survival as the general population (p = 0.391). Deaths due to cerebrovascular disease or dementia were more common in iNPH patients, while more controls died because of neoplasms or disorders of the circulatory system.

CONCLUSIONS

Mortality in operated iNPH patients is 1.8 times increased compared to the general population, a lower figure than previously reported. The survival of iNPH patients who improve in gait and functional independence is similar to that of the general population, indicating that shunt surgery for iNPH, besides improving symptoms and signs, can normalize survival.

A prospective study on gait dominant normal pressure hydrocephalus

OBJECT

We characterize idiopathic normal pressure hydrocephalus (NPH) following treatment with lumbar puncture (LP) and shunt placement through clinical evaluation and quantitative ProtoKinetics Zeno walkway assessments. We evaluate the symptomology by determining gait characteristics altered by treatment.

METHODS

Patients at Barrow Neurological Institute (BNI) who underwent a LP, removing 30-32 mL cerebrospinal fluid) followed by ventriculoperitoneal shunt placement in February 2015 to February 2017 were analyzed for gait impairments. Inclusion in the study required a diagnosis of NPH, no conflicting comorbidities, and pre-LP, post-LP, and 6-month post-shunt assessments. Analyses of gait and balance data recorded by physical therapists and the ProtoKinetics Zeno Walkway at pre-LP, post-LP, and post-shunt were performed.

RESULTS

A total of 28 patients were included and one-way analysis of variance and Tukey-Kramer HSD was performed. Among the 15 clinical assessments, nine were significantly altered. Using the ProtoKinetics Zeno Walkway, 7 out of 10 characteristics recorded were considered significantly different among the three data sets. Furthermore, there were more significant differences between pre-LP assessments and post-shunt assessments in comparison to differences between pre-LP assessments and post-LP assessments.

CONCLUSIONS

Our results indicate that certain gait characteristics better fit NPH than others. By focusing on the features that are caused by NPH and alleviated by LP and/or shunt placement, a more definitive NPH diagnosis can be attained. Additionally, our findings confirm a cumulative effect of continuous drainage via shunt placement may lead to increased improvement in NPH symptoms over LP results.

Repeated Cerebrospinal Fluid Removal Procedure in Older Patients With Idiopathic Normal Pressure Hydrocephalus Ineligible for Surgical Treatment

OBJECTIVES

To evaluate the effects of repeated cerebrospinal fluid (CSF) tap procedures in idiopathic normal pressure hydrocephalus (iNPH) patients ineligible for surgical treatment.

DESIGN

Prospective, monocentric, pilot study.

SETTING

University hospital.

PARTICIPANTS

Thirty-nine patients aged 75 years and older, ineligible for shunting surgical intervention.

INTERVENTION

Repeated CSF taps.

MEASUREMENTS

All patients underwent a comprehensive geriatric assessment before and after each CSF tap. Adverse events were recorded.

RESULTS

No major side effect was reported. Eleven patients showed no response to the first CSF tap test and were excluded. In the remaining 28 patients, all physical and cognitive functions improved after the drainage procedures, except for continence (which seemed poorly influenced). According to clinical judgment, the mean time frame of benefit between CSF taps was 7 months. Patients withdrawing from the protocol during the clinical follow-up showed a worsening of functional and cognitive performances after the interruption.

CONCLUSIONS/IMPLICATIONS

Periodic CSF therapeutic taps are safe, allow a better control of iNPH symptoms, and prevent functional decline in geriatric patients.

Absence of Disproportionately Enlarged Subarachnoid Space Hydrocephalus, a Sharp Callosal Angle, or Other Morphologic MRI Markers Should Not Be Used to Exclude Patients with Idiopathic Normal Pressure Hydrocephalus from Shunt Surgery

BACKGROUND AND PURPOSE

Several studies have evaluated the use of MR imaging markers for the prediction of outcome after shunt surgery in idiopathic normal pressure hydrocephalus with conflicting results. Our aim was to investigate the predictive value of a number of earlier proposed morphologic MR imaging markers in a large group of patients with idiopathic normal pressure hydrocephalus.

MATERIALS AND METHODS

One hundred sixty-eight patients (mean age, 70 ± 9.3 years) with idiopathic normal pressure hydrocephalus, subjected to standardized quantification of clinical symptoms before and after shunt surgery, were included in the study. Outcome was calculated using a composite score. Preoperative T1, FLAIR, and flow-sensitive images were analyzed regarding the presence of 13 different morphologic MR imaging markers.

RESULTS

The median Evans index was 0.41 (interquartile range, 0.37-0.44). All patients had an aqueductal flow void sign present and white matter hyperintensities. The median callosal angle was 68.8° (interquartile range, 57.7°-80.8°). Dilated Sylvian fissures were found in 69%; focally dilated sulci, in 25%; and widening of the interhemispheric fissure, in 55%. Obliteration of the sulci at the convexity was found in 36%, and 36% of patients were characterized as having disproportionately enlarged subarachnoid space hydrocephalus. Sixty-eight percent of patients improved after surgery. None of the investigated MR imaging markers were significant predictors of improvement after shunt surgery.

CONCLUSIONS

Disproportionately enlarged subarachnoid space hydrocephalus, a small callosal angle, and the other MR imaging markers evaluated in this study should not be used to exclude patients from shunt surgery. These markers, though they may be indicative of idiopathic normal pressure hydrocephalus, do not seem to be a part of the mechanisms connected to the reversibility of the syndrome.