White matter diffusion is higher in Binswanger disease than in idiopathic normal pressure hydrocephalus

Shared CSF Biomarker Profile in Idiopathic Normal Pressure Hydrocephalus and Subcortical Small Vessel Disease

Introduction

In this study, we examine similarities and differences between 52 patients with idiopathic normal pressure hydrocephalus (iNPH) and 17 patients with subcortical small vessel disease (SSVD), in comparison to 28 healthy controls (HCs) by a panel of cerebrospinal fluid (CSF) biomarkers.

Methods

We analyzed soluble amyloid precursor protein alpha (sAPPα) and beta (sAPPβ), Aβ isoforms −38, −40, and −42, neurofilament light protein (NFL), glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), matrix metalloproteinases (MMP −1, −2, −3, −9, and −10), and tissue inhibitors of metalloproteinase 1 (TIMP1). Radiological signs of white matter damage were scored using the age-related white matter changes (ARWMC) scale.

Results

All amyloid fragments were reduced in iNPH and SSVD (p < 0.05), although more in iNPH than in SSVD in comparison to HC. iNPH and SSVD showed comparable elevations of NFL, MBP, and GFAP (p < 0.05). MMPs were similar in all three groups except for MMP-10, which was increased in iNPH and SSVD. Patients with iNPH had larger ventricles and fewer WMCs than patients with SSVD.

Conclusion

The results indicate that patients with iNPH and SSVD share common features of subcortical neuronal degeneration, demyelination, and astroglial response. The reduction in all APP-derived proteins characterizing iNPH patients is also present, indicating that SSVD encompasses similar pathophysiological phenomena as iNPH.

Lumbar and ventricular CSF concentrations of extracellular matrix proteins before and after shunt surgery in idiopathic normal pressure hydrocephalus

Background

Idiopathic normal pressure hydrocephalus (iNPH) is a reversible CNS disease characterized by disturbed cerebrospinal fluid (CSF) dynamics. Changes in the extracellular matrix (ECM) composition might be involved in the pathophysiology of iNPH. The aim of this study was to explore possible differences between lumbar and ventricular CSF concentrations of the ECM markers brevican and neurocan, matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) and their relation to clinical symptoms in iNPH patients before and after shunt surgery.

Methods

Paired lumbar and ventricular CSF was collected from 31 iNPH patients, before and four months after shunt surgery. CSF was analysed for concentrations of tryptic peptides originating from brevican and neurocan using a mass spectrometry-based panel, and for MMP-1, -2, -9, -10 and TIMP-1 using fluorescent or electrochemiluminescent immunoassays.

Results

Brevican and neurocan peptide levels were not influenced by CSF origin, but MMP-1, -2, -10 and TIMP-1 were increased (p ≤ 0.0005), and MMP-9 decreased (p ≤ 0.0003) in lumbar CSF compared with ventricular CSF. There was a general trend of ECM proteins to increase following shunt surgery. Ventricular TIMP-1 was inversely correlated with overall symptoms (rho = − 0.62, p < 0.0001). CSF concentrations of the majority of brevican and neurocan peptides were increased in iNPH patients with a history of cardiovascular disease (p ≤ 0.001, AUC = 0.84–0.94) compared with those without.

Conclusion

Levels of the CNS-specific proteins brevican and neurocan did not differ between the lumbar and ventricular CSF, whereas the increase of several CNS-unspecific MMPs and TIMP-1 in lumbar CSF suggests contribution from peripheral tissues. The increase of ECM proteins in CSF following shunt surgery could indicate disturbed ECM dynamics in iNPH that are restored by restitution of CSF dynamics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00256-1.

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.

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.

Counting-backward test for executive function in idiopathic normal pressure hydrocephalus

OBJECTIVES

The aim of this study was to develop and validate a bedside test for executive function in patients with idiopathic normal pressure hydrocephalus (INPH).

MATERIALS AND METHODS

Twenty consecutive patients with INPH and 20 patients with Alzheimer's disease (AD) were enrolled in this study. We developed the counting-backward test for evaluating executive function in patients with INPH. Two indices that are considered to be reflective of the attention deficits and response suppression underlying executive dysfunction in INPH were calculated: the first-error score and the reverse-effect index. Performance on both the counting-backward test and standard neuropsychological tests for executive function was assessed in INPH and AD patients.

RESULTS

The first-error score, reverse-effect index and the scores from the standard neuropsychological tests for executive function were significantly lower for individuals in the INPH group than in the AD group. The two indices for the counting-backward test in the INPH group were strongly correlated with the total scores for Frontal Assessment Battery and Phonemic Verbal Fluency. The first-error score was also significantly correlated with the error rate of the Stroop colour-word test and the score of the go/no-go test. In addition, we found that the first-error score highly distinguished patients with INPH from those with AD using these tests.

CONCLUSION

The counting-backward test is useful for evaluating executive dysfunction in INPH and for differentiating between INPH and AD patients. In particular, the first-error score may reflect deficits in the response suppression related to executive dysfunction in INPH.

Implementation of a new CSF dynamic device: a multicenter feasibility study in 562 patients

OBJECTIVES

The cerebrospinal fluid (CSF) infusion test is frequently used when selecting hydrocephalus patients for shunt surgery. Very little has been reported regarding adverse events. We present a prospective feasibility study.

METHODS

Standardized devices for measuring CSF dynamics were built and 562 patients investigated: Needles were placed by lumbar puncture (LP). An automatic CSF infusion protocol was performed. Course of events during the investigation as well as adverse events were registered.

RESULTS

Preoperative evaluation of normal-pressure hydrocephalus was the most common indication (63%), followed by evaluation of shunt function (23%) and intracranial pressure recordings (14%). The LP was successfully performed in all but nine cases with 24 patients (4.3%) reporting major discomfort. Ringer infusion was performed in 474 investigations, and a valid measurement of the outflow resistance was received in 439 (93%). During the infusion phase, 17 (4%) patients reported severe headache. Infusion volume was significantly higher in patients having subjective symptoms during the infusion phase compared with those without adverse events. During 269 preoperative CSF tap tests, six (2%) patients had severe headache. Post-investigational headache was reported by 83 (15%) patients at the 24-h follow-up. No serious adverse events were observed.

CONCLUSION

Infusion testing was safe and without serious adverse events with a high rate of successful procedures. The investigation was associated with expected mild to moderate discomfort.

Ventriculomegaly and balance disturbances in patients with TIA

OBJECTIVES

Dilated ventricles and gait disturbances are common in the elderly, and these are also features of the treatable syndrome idiopathic normal pressure hydrocephalus (INPH). Many studies report an association between hypertension, vascular disease and INPH. The objective of this study was to study the frequency of ventriculomegaly, with or without hydrocephalic symptoms, in patients who had suffered from a transitory ischaemic attack (TIA).

METHODS

Gait, Romberg sign, tandem standing and one-leg stance were consecutively evaluated in elderly > 24 h after a TIA. Ventricular size, white matter lesions and atrophy were assessed on computed tomography scans. Exclusion criteria were conditions possibly influencing the balance tests.

RESULTS

eventy-six patients with TIA out of 105 were included. Ventriculomegaly [Evans Index (EI) > 0.30] was observed in 19.7% and very large ventricles (EI > 0.33) in 7.9%. Ventriculomegaly was found in 58% of the patients with a previous 'history of balance or gait disturbance', but only in 12% of those without any prior disturbance (chi-square test; P = 0.0009). Three out of 76 patients with TIA (3.9%) fulfilled both radiological and clinical criteria for 'possible INPH'.

CONCLUSION

Ventriculomegaly is a common finding in elderly. One out of 20 patients with TIA may suffer from INPH, existing before and independent of the TIA diagnosis. Therefore, patients presenting with ventriculomegaly and gait/balance disturbances not attributable to other causes should be referred to a hydrocephalus centre or a neurologist with special interest in INPH.

Diffusion tensor imaging reveals supplementary lesions to frontal white matter in idiopathic normal pressure hydrocephalus

BACKGROUND

Idiopathic normal-pressure hydrocephalus (INPH) is associated with white matter lesions, but the extent and severity of the lesions do not cohere with symptoms or improvement after shunting, implying the presence of further, yet undisclosed, injuries to white matter in INPH.

OBJECTIVE

To apply diffusion tensor imaging (DTI) to explore white matter lesions in patients with INPH before and after drainage of cerebrospinal fluid (CSF).

METHODS

Eighteen patients and 10 controls were included. DTI was performed in a 1.5T MRI scanner before and after 3-day drainage of 400 mL of CSF. Regions of interest included corpus callosum, capsula interna, frontal and lateral periventricular white matter, and centrum semiovale. White matter integrity was quantified by assessing fractional anisotropies (FA) and apparent diffusion coefficients (ADC), comparing them between patients and controls and between patients before and after drainage. The significance level corresponded to .05 (Bonferroni corrected).

RESULTS

Decreased FA in patients was found in 3 regions (P<.002, P<.001, and P<.001) in anterior frontal white matter, whereas elevated ADC was found in genu corpus callosum (P<.001) and areas of centrum semiovale associated with the precentral gyri (P<.002). Diffusion patterns in these areas did not change after drainage.

CONCLUSION

DTI reveals subtle injuries-interpreted as axonal loss and gliosis-to anterior frontal white matter where high-order motor systems between frontal cortex and basal ganglia travel, further supporting the notion that motor symptoms in INPH are caused by a chronic ischemia to the neuronal systems involved in the planning processes of movements.