Change in Morphological Features of Enlarged Subarachnoid Spaces Following Treatment in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Focally enlarged sulci (FES) are areas of proposed extraventricular fluid entrapment that may occur within idiopathic normal pressure hydrocephalus (iNPH) with radiographic evidence of disproportionately enlarged subarachnoid-space hydrocephalus (DESH), and should be differentiated from atrophy. PURPOSE: To evaluate for change in FES size and pituitary height after shunt placement in iNPH. STUDY TYPE: Retrospective. SUBJECTS: A total of 125 iNPH patients who underwent shunt surgery and 40 age-matched controls. FIELD STRENGTH/SEQUENCE: 1.5 T and 3 T. Axial T2w FLAIR, 3D T1w MPRAGE, 2D sagittal T1w. ASSESSMENT: FES were measured in three dimensions and volume was estimated by assuming an ellipsoid shape. Pituitary gland height was measured in the mid third of the gland in iNPH patients and controls. STATISTICAL TESTS: Wilcoxon signed-rank test for comparisons between MRI measurements; Wilcoxon rank sum test for comparison of cases/controls. Significance level was P < 0.05. RESULTS: Fifty percent of the patients had FES. FES volume significantly decreased between the pre and first postshunt MRI by a median of 303 mm3 or 30.0%. Pituitary gland size significantly increased by 0.48 mm or 14.4%. FES decreased significantly by 190 mm3 or 23.1% and pituitary gland size increased significantly by 0.25 mm or 6% between the first and last postshunt MRI. DATA CONCLUSION: Decrease in size of FES after shunt placement provides further evidence that these regions are due to disordered cerebrospinal fluid (CSF) dynamics and should not be misinterpreted as atrophy. A relatively smaller pituitary gland in iNPH patients that normalizes after shunt is a less-well recognized feature of altered CSF dynamics. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

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

BACKGROUND: Patients with the dementia subtype idiopathic normal pressure hydrocephalus (iNPH) may improve clinically following cerebrospinal fluid (CSF) diversion (shunt) surgery, though the predictors of shunt response remain debated. Currently, radiological features play an important role in the diagnosis of iNPH, but it is not well established which radiological markers most precisely predict shunt responsive iNPH. OBJECTIVE: To conduct a systematic review and meta-analysis to identify radiological predictors of shunt responsiveness, evaluate their diagnostic effectiveness, and recommend the most predictive radiological features. METHODS: Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR were searched for original studies investigating radiological predictors of shunt response in iNPH patients. Included studies were assessed using the ROBINS-1 tool, and eligible studies were evaluated using a univariate meta-analysis. RESULTS: Overall, 301 full-text papers were screened, of which 28 studies were included, and 26 different radiological features were identified, 5 of these met the inclusion criteria for the meta-analysis: disproportionately enlarged subarachnoid space (DESH), callosal angle, periventricular white matter changes, cerebral blood flow (CBF), and computerized tomography cisternography. The meta-analysis showed that only callosal angle and periventricular white matter changes significantly differentiated iNPH shunt responders from non-responders, though both markers had a low diagnostic odds ratio (DOR) of 1.88 and 1.01 respectively. None of the other radiological markers differentiated shunt responsive from shunt non-responsive iNPH. CONCLUSION: Callosal angle and periventricular changes are the only diagnostically effective radiological predictors of shunt responsive iNPH patients. However, due to the DORs approximating 1, they are insufficient as sole predictors and are advised to be used only in combination with other diagnostic tests of shunt response. Future research must evaluate the combined use of multiple radiological predictors, as it may yield beneficial additive effects that may allow for more robust radiological shunt response prediction.

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.

Association between the Onset of Idiopathic Normal Pressure Hydrocephalus Symptoms and Reduced Default Mode Network Connectivity.

OBJECTIVE: The aim was to examine the association between connectivity changes in the default mode network (DMN) and the progression of idiopathic normal pressure hydrocephalus (iNPH). METHODS: We retrospectively recruited cases of preclinical and clinical iNPH from 2,196 patients who had received whole-body 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scanning. We included 31 cases with asymptomatic ventriculomegaly with features of iNPH on MRI (AVIM; reported as preclinical iNPH) and 12 with iNPH. We performed a voxel-based analysis of the brain FDG-PET images of the AVIM and iNPH groups as well as for each background-matched normal control (NC) group, using Statistical Parametric Mapping 12. Volume of interest (VOI)-based analysis was also performed. We set the VOI as the region from the precuneus to the posterior cingulate cortices (PCC), and compared the mean regional standardized uptake value ratio (SUVR) between the AVIM and iNPH group FDG-PET/CT images and each corresponding NC group. RESULTS: The voxel-based analysis showed a greater decreased FDG uptake in the PCC in the iNPH group than in the AVIM group. The VOI-based analysis revealed no significant difference in the mean SUVR of the AVIM group and the corresponding NC group, but that of the iNPH group was significantly lower than that of its corresponding NC group. CONCLUSIONS: DMN connectivity was reduced in the clinical iNPH group but not in the preclinical group. These data suggest that alterations in the functional connectivity of the DMN are related to the onset of iNPH symptoms.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in normal pressure hydrocephalus misinterpreted as atrophy: autopsy and radiological evidence.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH), a feature of normal pressure hydrocephalus (NPH), is often misinterpreted as cortical atrophy. We report a 67-year-old man with features of NPH but not diagnosed because radiographic findings were interpreted as cortical atrophy. Autopsy showed findings consistent with NPH and no neurodegenerative disease. The second patient with DESH underwent shunt surgery. Entrapped fluid diminished after the surgery, confirming this is not atrophy, but due to a CSF dynamic process. Patients with DESH have tight sulci adjacent to the entrapped fluid pockets, distinguishing it from cortical atrophy. 18F-Fluorodeoxyglucose PET can help differentiate DESH from cortical atrophy.

Changes in brain morphology in patients in the preclinical stage of idiopathic normal pressure hydrocephalus.

BACKGROUND: Specific ventriculomegaly features, including tight high-convexity and medial subarachnoid spaces, are found on magnetic resonance images in patients with idiopathic normal pressure hydrocephalus (iNPH). However, some healthy elderly individuals with no typical triad symptoms of iNPH also exhibit specific magnetic resonance image features of iNPH. Therefore, this study quantitatively clarified the brain morphology of suspected iNPH patients with no objective triad symptoms (iNPH-NOS). METHODS: We recruited patients with suspected iNPH and divided them into two groups based on their iNPH grading scale scores: the iNPH-NOS group and the iNPH with apparent objective triad symptoms (iNPH-AOS) group. Data for normal controls (NC) were taken from the database used in our previous study. We compared the relative volumes of ventricle systems (VS), Sylvian fissures (SF), and sulci at high convexity and the midline (SHM), adjusted by the intracranial volume, of the iNPH-NOS, iNPH-AOS, and NC groups. Additionally, we compared the relative volumes of VS, SF, and SHM in iNPH-NOS patients between their first visit and follow-up 1 year later. RESULTS: Fifteen iNPH-NOS patients and 45 iNPH-AOS patients were recruited, and 24 NCs were found in the database. The relative volumes of VS and SF were significantly smaller than in NCs than in the iNPH-NOS and iNPH-AOS groups, and the relative volume of SHM was significantly larger in NCs. The relative volume of SHM was significantly larger in the iNPH-NOS group than in the iNPH-AOS group, but there were no significant differences in the relative volumes of VS and SF between these groups. In the iNPH-NOS group, the relative volumes of VS and SF were significantly smaller at the first visit than 1 year later, whereas the relative volume of SHM was significantly larger. In 6 of 15 iNPH-NOS patients, objective symptoms appeared during the observation period. CONCLUSIONS: Our results indicate that iNPH-NOS patients were in the transitional stage between normal and iNPH-AOS, both morphologically and clinically.

Imaging normal pressure hydrocephalus: theories, techniques, and challenges.

The pathophysiology of NPH continues to provoke debate. Although guidelines and best-practice recommendations are well established, there remains a lack of consensus about the role of individual imaging modalities in characterizing specific features of the condition and predicting the success of CSF shunting. Variability of clinical presentation and imperfect responsiveness to shunting are obstacles to the application of novel imaging techniques. Few studies have sought to interpret imaging findings in the context of theories of NPH pathogenesis. In this paper, the authors discuss the major streams of thought for the evolution of NPH and the relevance of key imaging studies contributing to the understanding of the pathophysiology of this complex condition.

Does Vascular Dementia Exist? Report of Two Cases Previously Diagnosed with Vascular Dementia Treated by Means of Ventriculoatrial Shunts.

Vascular dementia (VaD) is the second most common cause of dementia after Alzheimer's disease. While new therapeutic modalities have been available for Alzheimer's disease, there is currently no effective treatment for VaD. We encountered two cases with VaD who recovered their cognitive function to normal levels after ventriculoatrial shunt (VA shunt). Both cases complained cognitive impairment shortly after cerebral infarctions. Their brain images showed ventricular dilatation without the findings of disproportionately enlarged subarachnoid space hydrocephalus, which is regarded as characteristic for idiopathic normal pressure hydrocephalus (iNPH). Both cases were initially diagnosed as VaD by board neurosurgeons. However, since they showed positive response to lumbar tap test, VA shunts were performed. Both cases recovered their cognitive function to normal level. Their excellent cognitive outcomes after VA shunts indicate that many iNPH patients with lacunar infarcts may possibly be misdiagnosed as VaD.

Idiopathic normal pressure hydrocephalus: Validation of the DESH score as a prognostic tool for shunt surgery response.

OBJECTIVE: Several radiological markers have been linked to clinical improvement after shunt surgery for idiopathic normal pressure hydrocephalus (iNPH). However, iNPH has no pathognomonic feature, and patients are still diagnosed as probable, possible, or unlikely cases based on clinical symptoms, imaging findings, and invasive supplementary tests. The predictive value of the disproportionately enlarged subarachnoid space hydrocephalus (DESH) score is not yet conclusively determined, but it might offer a more accurate diagnostic method. The aim of the present retrospective cohort study was to validate the predictive power of the DESH score for clinical improvement after shunt surgery in iNPH patients. METHODS: We retrospectively obtained presurgical MRI and/or CT scans from 71 patients with iNPH who underwent ventriculoperitoneal shunt surgery. Radiological images were evaluated for Evans index (EI), corpus callosal angle (CA), tight high convexity (THC), Sylvian fissure dilation, and focal sulci dilation. These markers were aggregated to determine the DESH score. Patient journal entries were used to subjectively determine the extent of improvement in gait function, urinary incontinence, and/or cognition as a measure of shunt surgery response. RESULTS: Multiple logistic regression analysis, controlling for age and sex (α = 0.05), showed that DESH score was significantly correlated (OR 1.77) with subjective shunt-surgery response at a minimum of 1-month follow-up. Patients with higher DESH scores were more likely to have a favorable response to shunt surgery. CONCLUSION: Aggregating radiological markers into the DESH score is useful for predicting shunt responders among iNPH patients and can aid the selection of patients for surgery. These findings provide further support for the DESH score as a diagnostic tool for iNPH.

Idiopathic Normal Pressure Hydrocephalus With Multiple Sulcus Enlargements but No Ventricular Enlargement Resembling Brain Atrophy Over a Long Period Before Diagnosis: A Case Report.

The most common imaging findings in idiopathic normal pressure hydrocephalus (iNPH) are disproportionately enlarged subarachnoid space hydrocephalus, i.e., enlarged ventricles (Evans index >0.3), narrowing of the superior arcuate and median sulci, widening of the Sylvian fissure, and focal widening of the sulci of the brain. In the present study, we encountered an interesting case of a 73-year-old woman with iNPH with characteristic imaging findings of cerebral atrophy-like features and no prominent ventricular enlargement. Many cases might be difficult to diagnose as iNPH because of atypical imaging findings such as no prominent ventricular enlargement and so on. Even in cases with multiple atrophic sulcus openings without any prominent ventricular enlargement, the callosal angle and posterior commissure-level brain-ventricle ratio (BVR) could be helpful in the diagnosis, and bilateral opening of the occipitoparietal sulcus might be a key imaging finding.

Cerebrospinal fluid dynamics and discordant amyloid biomarkers.

Do MRI-based metrics of a CSF-dynamics disorder, disproportionately enlarged subarachnoid-space hydrocephalus (DESH), correlate with discordant amyloid biomarkers (low CSF ß-amyloid 1-42, normal Aß-PET scan)? Individuals ≥50 years from the Mayo Clinic Study of Aging, with MRI, 11C-Pittsburgh compound B (Aß) PET scans, and CSF phosphorylated-tau protein and Aß42, were categorized into 4 groups: normal and/or abnormal by CSF ß-amyloid 1-42 and Aß amyloid PET. Within groups, we noted MRI patterns of CSF-dynamics disorders and Aß-PET accumulation-change rate. One-hundred participants (21%) in the abnormal-CSF and/or normal-PET group had highest DESH-pattern scores and lowest CSF-phosphorylated-tau levels. Among normal amyloid-PET individuals, a 1-unit DESH-pattern score increase correlated with 30%-greater odds of abnormal amyloid CSF after age, and sex adjustment. Mean rate over time of amyloid-PET accumulation in abnormal-CSF and/or normal-PET individuals approximated individuals with normal amyloid values. Adjusting for phosphorylated-tau, abnormal CSF-amyloid and/or normal amyloid-PET individuals had higher mean amyloid-PET accumulation rates than normal individuals. CSF dynamics disorders confound ß-amyloid and phosphorylated-tau CSF-biomarker interpretation.

Preoperative Predictive Factors of Short-Term Outcome in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Surgical treatment of idiopathic normal pressure hydrocephalus (iNPH) by ventriculoperitoneal (VP) or lumboperitoneal (LP) shunting can achieve long-term recovery of activities of daily living; however, in a subset of patients, maintenance of independence lasted for <6 months. This study examined positive preoperative predictive factors of short-term outcome for shunted iNPH patients. METHODS: Over a 9-year period, consecutive patients from multiple centers diagnosed with probable iNPH underwent either VP or LP shunt surgery. Preoperative variables of age, symptom duration, iNPH severity, tap test response, and magnetic resonance imaging findings of disproportionately enlarged subarachnoid space hydrocephalus (DESH) or incomplete DESH were retrospectively evaluated in relation to 1-year postoperative outcome. RESULTS: Outcome for 154 shunt patients (12 VP, 142 LP) as measured by postoperative disability modified Rankin Scale (mRS) and iNPH-gait disturbance (GD) was the same regardless of age. Symptom duration was inversely correlated with both iNPH severity (P < 0.0001) and postoperative improvement at 1 year (P = 0.0015). Severity also correlated inversely with postoperative improvement at 1 year (P < 0.0001). Age was not significantly correlated with the degree of postoperative improvement (mRS: P = 0.487; iNPH grading scale [GD]: P = 0.725). Outcome at 1 year (mRS, gait domain, and activities of daily living significantly improved in patients with a good response to the tap test (P < 0.0001) Preoperative DESH correlated with improvement in mRS and GD (P < 0.0001). CONCLUSIONS: Mild preoperative iNPH severity, shorter preoperative symptom duration, good tap test response, and complete DESH were associated with good short-term postoperative outcome at 1 year. These positive factors may be useful for prediction of short-term surgical outcome in iNPH patients.

Role of DESH, callosal angle and cingulate sulcus sign in prediction of gait responsiveness after shunting in iNPH patients.

Primary endpoint of this single-centre, prospective consecutive cohort study was to evaluate DESH score, CA, CSS and Evans index of suspected iNPH patients against the reference standard of lumbar infusion test (LIT) and external lumbar drainage (ELD) in prediction of gait response after VP shunt implantation in patients with idiopathic normal pressure hydrocephalus (iNPH). Patients were assigned to NPH and non-NPH groups based on LIT and ELD results. Age-matched controls were added for group comparison. 32 NPH, 46 non-NPH and 15 control subjects were enrolled in the study. There were significant differences in mean preoperative DESH scores of NPH, non-NPH and control groups (6.3 ± 2.3 ([±SD]) (range 2-10) vs 4.5 ± 2.4 (range 0-10) vs 1.0 ± 1.2 (range 0-4)). Differences in mean CA and Evans index were not significant between NPH and non-NPH groups. CSS showed 62.5% sensitivity, 60.87% specificity, 52.63% PPV and 70% NPV for differentiation of NPH and non-NPH groups. A CA of 68 degrees had 48.49% sensitivity, 76.09% specificity, 59.26% PPV 67.31% NPV and DESH score of 4 had 93.75% sensitivity, 41.30% specificity, 52.63% PPV and 90.48% NPV for differentiation between NPH and non-NPH groups. The groups of probable iNPH patients with gait impairment diagnosed by high DESH score or positive functional testing did not overlap and DESH score did not correlate with gait improvement after ELD. DESH score should not be used as a simple diagnostic or prognostic marker of iNPH and we could not confirm the benefit of measurement of callosal angle and cingulate sulcus sign.

The Utility of Imaging Parameters in Predicting Long-Term Clinical Improvement After Shunt Surgery in Patients with Idiopathic Normal Pressure Hydrocephalus.

OBJECTIVE: It is difficult to predict which patients with idiopathic normal pressure hydrocephalus (iNPH) will improve after shunt surgery. This study investigated the association between preoperative imaging parameters in patients with iNPH and long-term outcome after shunt placement. METHODS: Patients with iNPH who showed a response to large-volume cerebrospinal fluid drainage and subsequently underwent ventriculoperitoneal shunt surgery were reviewed. Long-term patient-reported outcomes were obtained by telephone interview. Preoperative computed tomography and/or magnetic resonance imaging were retrospectively reviewed to determine associations between imaging parameters and clinical outcome. RESULTS: The final analysis included 37 patients. The median duration between shunt surgery and telephone interview was 30 months (range, 12-56 months). Gait improvement after shunting was present more often in patients without focally dilated sulci (95% vs. 71%, P = 0.04), but a statistically significant relationship was not established after logistic regression. Patients with cognitive improvement after shunting had a higher preoperative Evans index (mean 0.41 vs. 0.36, P < 0.01), and Evans index was a predictor of cognitive improvement (odds ratio = 1.40, scale of 0.01, P = 0.01). CONCLUSIONS: Higher Evans index is a predictor of long-term cognitive improvement after shunt placement; however, no cutoff value demonstrates sufficient accuracy for the selection of shunt candidates. None of the evaluated imaging features was predictive of long-term gait or urinary improvement. The utility of imaging to predict a response to shunting is limited, and no imaging feature alone can be used to exclude patients from shunt surgery.

Reconsidering Ventriculoperitoneal Shunt Surgery and Postoperative Shunt Valve Pressure Adjustment: Our Approaches Learned From Past Challenges and Failures.

Treatment for idiopathic normal pressure hydrocephalus (iNPH) continues to develop. Although ventriculoperitoneal shunt surgery has a long history and is one of the most established neurosurgeries, in the 1970s, the improvement rate of iNPH triad symptoms was poor and the risks related to shunt implantation were high. This led experts to question the surgical indication for iNPH and, over the next 20 years, cerebrospinal fluid (CSF) shunt surgery for iNPH fell out of favor and was rarely performed. However, the development of programmable-pressure shunt valve devices has reduced the major complications associated with the CSF drainage volume and appears to have increased shunt effectiveness. In addition, the development of support devices for the placement of ventricular catheters including preoperative virtual simulation and navigation systems has increased the certainty of ventriculoperitoneal shunt surgery. Secure shunt implantation is the most important prognostic indicator, but ensuring optimal initial valve pressure is also important. Since over-drainage is most likely to occur in the month after shunting, it is generally believed that a high initial setting of shunt valve pressure is the safest option. However, this does not always result in sufficient improvement of the symptoms in the early period after shunting. In fact, evidence suggests that setting the optimal valve pressure early after shunting may cause symptoms to improve earlier. This leads to improved quality of life and better long-term independent living expectations. However, in iNPH patients, the remaining symptoms may worsen again after several years, even when there is initial improvement due to setting the optimal valve pressure early after shunting. Because of the possibility of insufficient CSF drainage, the valve pressure should be reduced by one step (2-4 cmH2O) after 6 months to a year after shunting to maximize symptom improvement. After the valve pressure is reduced, a head CT scan is advised a month later.

CSF dynamics disorders: Association of brain MRI and nuclear medicine cisternogram findings.

Disproportionately enlarged subarachnoid space hydrocephalus (DESH), characterized by ventriculomegaly, high convexity/midline tight sulci, and enlarged sylvian fissures on brain MRI has been increasingly recognized as a distinct diagnostic imaging entity that falls within the larger category of idiopathic normal pressure hydrocephalus. Normal pressure hydrocephalus has been previously characterized as a CSF dynamics disorder based on abnormalities on nuclear medicine cisternography: radiotracer in the lateral ventricles and absent or delayed ascent of radiotracer over the cerebral convexity. The purpose of this work was to evaluate for differences in nuclear medicine cisternography between patients with vs without DESH and thereby provide support for the concept that DESH is a structural imaging marker of a CSF dynamics disorder. The study included 102 patients (mean age 71 years, range 46-86, 38 females), 58 patients with cisternogram performed to evaluate suspected normal pressure hydrocephalus (mean age 73 years, range 46-86 years, 24 female) and 44 patients evaluated for headache (mean age 68 years, range 60-82 years, 14 female). All patients had an MRI of the brain performed within 13 months of the cisternogram. Cisternogram imaging, typically acquired at 0.5, 1, 2, 4, and 24 h post injection, was evaluated for the time at which radiotracer reached the basal cisterns, presence of persistent radiotracer in the lateral ventricles, time radiotracer first entered the lateral ventricles, presence of radiotracer over the cerebral convexity, and time at which radiotracer was first visualized over the cerebral convexity. MRI features of ventriculomegaly (defined as Evans' index ≥ 0.3) and high convexity tight sulci (HCTS) were recorded. Based on the MRI features, patients were grouped according to presence or absence of DESH (ventriculomegaly and HCTS). Those without DESH were separated into groups of ventriculomegaly alone, HCTS alone, and neither ventriculomegaly nor HCTS. Cisternogram metrics were compared between MR-defined groups. Patients with DESH showed a higher frequency of radiotracer in the lateral ventricles and delayed or absent ascent over the cerebral convexity compared to those without DESH, higher frequency of ventricular radioactivity vs those with HCTS alone, and shorter time to ventricular radioactivity compared to those with ventriculomegaly alone. Patients with ventriculomegaly or HCTS alone had a higher frequency of radiotracer in the lateral ventricles and delayed ascent of radiotracer over the cerebral convexity compared to those with neither ventriculomegaly nor HCTS. These findings support DESH and the individual components of ventriculomegaly and HCTS as markers of disordered CSF dynamics.

The prevalence and clinical associations of disproportionately enlarged subarachnoid space hydrocephalus (DESH), an imaging feature of idiopathic normal pressure hydrocephalus in community and memory clinic based Singaporean cohorts.

INTRODUCTION: Disproportionately Enlarged Subarachnoid space Hydrocephalus (DESH) is considered as an important imaging feature of idiopathic normal pressure hydrocephalus (iNPH). METHOD: Subjects aged 60 and over in a memory clinic and a community-based cohort were assessed for the presence of ventriculomegaly, Sylvian dilatation, and high convexity tightness by neuroimaging, and a clinical triad of iNPH symptoms, i.e. cognitive, gait and urinary symptoms. RESULTS: In the memory clinic-based study (548 subjects), the prevalence of DESH was 1.1% and increased with age. The clinical triad was significantly more frequent in subjects with DESH (50%) compared to those with normal images (none), Sylvian dilatation (7%), and ventriculomegaly (12%). Gait disturbance was also significantly more frequent in DESH (83%) compared to those with normal images (2%), Sylvian dilatation (14%), and ventriculomegaly (26%). In the community-based cohort (946 subjects), the prevalence of DESH was 1.0% and increased with age. The clinical triad (11%) was significantly more common in subjects with DESH compared to those with normal images (none), Sylvian dilatation (2%), and ventriculomegaly (7%). Gait disturbance was also significantly more common in DESH (33%) compared to those with normal images (1%), Sylvian dilatation (4%), and ventriculomegaly (10%). CONCLUSION: The reported prevalence of DESH was approximately 1%, and increased with age. DESH and high convexity tightness were specifically associated with the clinical triad of iNPH. Of the triad, gait disturbance was associated to DESH and high convexity tightness.

Changes in cerebral glucose metabolism caused by morphologic features of prodromal idiopathic normal pressure hydrocephalus.

BACKGROUND: Decreased cerebral glucose metabolism has been reported in idiopathic normal pressure hydrocephalus (iNPH). However, the timing of appearance in the preclinical stage of iNPH remains unknown. Herein, we evaluated the changes in regional cerebral glucose metabolism with respect to the characteristic morphologic features of iNPH. METHODS: We performed a cross-sectional study in > 2000 elderly patients who received a whole body 18F-fluorodeoxyglucose-positron emission tomography/computed tomography scanning and recruited subjects with clinical and preclinical iNPH. We included 12 subjects with iNPH, 32 subjects with asymptomatic ventriculomegaly with features of iNPH on magnetic resonance imaging (AVIM), and 33 subjects with preclinical morphologic features of DESH (PMD). We previously reported that iNPH develops in the order of PMD (asymptomatic subjects with incomplete DESH), AVIM (asymptomatic subjects with DESH), and iNPH (symptomatic subjects with DESH). We measured the median regional standardized uptake value ratio (SUVR) on 18F-fluorodeoxyglucose-positron emission tomography/computed tomography images between the three groups and compared them with background-matched normal controls in the frontal lobes, temporal lobes, medial parietal lobes, striata, and thalami. RESULTS: In the frontal and temporal lobes, the SUVR distributions of the PMD, AVIM, and PMD groups were significantly lower than for each NC (p < 0.05 for all). In the medial parietal lobes, the SUVR distributions were significantly higher in PMD and AVIM groups (p < 0.05 for all). In the thalami and striata, the SUVR distributions were significantly lower in the iNPH group (p < 0.05 for all). CONCLUSIONS: Changes in brain glucose metabolism in the cortices are observed in preclinical iNPH, while metabolic decline in the basal ganglia is only detected in clinical iNPH.

The Tight Medial and High Convexity Subarachnoid Spaces Is the First Finding of Idiopathic Normal Pressure Hydrocephalus at the Preclinical Stage.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH) findings are often reported as characteristic radiological features of idiopathic normal pressure hydrocephalus (iNPH). However, the process of development of DESH remains unclear. The aim of the present study was to determine the dynamic deforming process and pathophysiology of iNPH. All patients >50 years of age who underwent whole body FDG-PET/CT scanning at Kindai University Hospital between May 2017 and April 2018 were included in this retrospective study, and their brain image findings and clinical information were assessed. We defined DESH-like findings, which had one or two equivocal features of the three components of DESH findings, as preclinical morphologic features of DESH (PMD). PMD were classified into six subtypes based on their component of DESH findings: PMD-T, only tight medial and high convexity subarachnoid spaces (TMC); PMD-S, only enlarged Sylvian fissures; PMD-V, only ventriculomegaly; PMD-TV, TMC and ventriculomegaly; PMD-TS, TMC and enlarged Sylvian fissures; PMD-SV, enlarged Sylvian fissures and ventriculomegaly. A total of 2196 cases (70.5 ± 9.3 years) were enrolled, with 54 cases (77.1 ± 5.9 years) with DESH findings, and 42 cases (72.9 ± 7.9 years) with PMD (five PMD-T, two PMD-V, 12 PMD-TV, 18 PMD-TS, and five PMD-SV). In each component of DESH, 35 of 42 (83.3%) cases with PMD had TMC. We suggest that the TMC is the first change on DESH findings in most iNPH cases, and may be an important part of the pathophysiology of iNPH.

Utility of Radiologic Variables to Predict the Result of Lumbar Infusion Test in the Diagnosis of Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Diagnosis of idiopathic normal pressure hydrocephalus is based in clinical data, radiologic variables, and invasive cerebrospinal fluid (CSF) testing, such as the lumbar infusion test. Several neuroimaging findings are inconclusively related to improvement after CSF shunt surgery. CSF tests are invasive and have complications. The aim of this study was to select radiologic variables related to a positive lumbar infusion test so as to avoid this test in patients. METHODS: Patients with possible idiopathic normal pressure hydrocephalus were reviewed. The collected radiologic data were cingulate sulcus sign, disproportionately enlarged subarachnoid space, callosal angle, and width of temporal horns. Two groups were established: group 1, comprising patients with resistance to CSF outflow <12 mm Hg/mL/minute, and group 2, comprising patients with resistance to CSF outflow >12 mm Hg/mL/minute. Negative and positive predictive values were determined. RESULTS: The study included 43 patients in group 1 and 64 patients in group 2. Group 2 significantly showed more acute callosal angle with higher accuracy cutoff value of 90.6°, lower width of temporal horns with higher accuracy cutoff value of 8 mm, and higher percentage of cingulate sulcus sign and disproportionately enlarged subarachnoid space. Matching the radiologic variables, positive predictive values were >80%; however, negative predictive values were low. CONCLUSIONS: Owing to high positive predictive values of matched radiological variables, the lumbar infusion test could be avoided in the diagnosis of idiopathic normal pressure hydrocephalus. However, when 1 or 2 of the variables are negative, this invasive test should be performed.