Computerized tomographic study of normal Evans index in adult Nigerians

Normative parameters of the Evans Index using Computer Tomography in the Saudi population

OBJECTIVES

To calculate The Evans Index (EI) in normal Individuals. Ventricular enlargement is referred to as hydrocephalus. Computer tomography (CT) scans are commonly used to investigate such intracranial pathologies. The EI is an important parameter for diagnosing hydrocephalus.

METHODS

We included all patients who underwent Computer tomography (CT) scan of the brain that was reported as normal. The mean EI was calculated for the whole sample stratified by age, gender, and ethnicity. Patients with an initial report indicating any intracranial pathology, such as hydrocephalus, tumors, hemorrhages, or neurodegenerative disorders, were excluded.

RESULTS

A total of 1,330 brain CT scans carried out at our institution were reviewed retrospectively from August 2021 to December 2021. A total of 423 CT scans were screened after excluding 25 patients with abnormal imaging findings and 14 repeated images for the same patients. A total of 384 patients were included. The mean EI for the entire sample was 0.2550±0.0277. There was a minimal but statistically significant difference based on gender, with a mean EI of 0.2588±0.0274 for males and 0.2517±0.0276 for females (p=0.012). There was no statistically significant difference between Saudi and non-Saudi patients. EI increased progressively with age in both genders.

CONCLUSION

Our EI values were similar to many of those reported in other countries, which supports the use of the 0.3 cutoff for the diagnosis of hydrocephalus, regardless of gender, age, or ethnicity.

Toward the "Perfect" Shunt: Historical Vignette, Current Efforts, and Future Directions

As a concept, drainage of excess fluid volume in the cranium has been around for more than 1000 years. Starting with the original decompression-trepanation of Abulcasis to modern programmable shunt systems, to other nonshunt-based treatments such as endoscopic third ventriculostomy and choroid plexus cauterization, we have come far as a field. However, there are still fundamental limitations that shunts have yet to overcome: namely posture-induced over- and underdrainage, the continual need for valve opening pressure especially in pediatric cases, and the failure to reinstall physiologic intracranial pressure dynamics. However, there are groups worldwide, in the clinic, in industry, and in academia, that are trying to ameliorate the current state of the technology within hydrocephalus treatment. This chapter aims to provide a historical overview of hydrocephalus, current challenges in shunt design, what members of the community have done and continue to do to address these challenges, and finally, a definition of the "perfect" shunt is provided and how the authors are working toward it.

Neuroophthalmological manifestations of congenital aqueductal stenosis

OBJECTIVE

Congenital aqueductal stenosis (CAS) is a common etiology of hydrocephalus that occurs in a subset of infants and may be linked to an increased incidence of ophthalmological abnormalities and delayed developmental milestones. Although hydrocephalus is common and widely studied, sparse literature exists on patients with isolated (no identifiable genetic link) CAS along with analysis of ophthalmological manifestations. In this study, the authors sought to describe the ophthalmological abnormalities and delayed developmental milestones of patients with isolated CAS.

METHODS

Data of patients with CAS were prospectively entered and monitored in a surgical database maintained by the Department of Neurological Surgery at Children's Hospital of Pittsburgh from January 2005 to October 2016. Patients with a family history of congenital hydrocephalus, positive testing for genetic forms of aqueductal stenosis, other congenital abnormalities suggesting an underlying genetic syndrome, and stenosis/obstruction due to secondary causes were excluded from this study. Prenatal and perinatal history, CSF diversion history, and a variety of outcomes, including ophthalmological deficits and developmental milestones, were collected and analyzed.

RESULTS

A total of 41 patients with isolated CAS were identified, with a mean follow-up duration of 6 years. Among that cohort, 26 patients (63.4%) developed neuroophthalmological complications, which were further stratified. Fourteen patients (34.1%) developed strabismus and 11 (26.8%) developed astigmatism, and 1 patient (2.4%) with papilledema was recorded. Among patients with ophthalmological abnormalities, 76.9% had delayed developmental milestones (p = 0.045).

CONCLUSIONS

Patients with CAS were found to have increased risk of ophthalmological abnormalities requiring correction, along with an increased risk of delayed developmental milestones. Importantly, there was a significant correlation between the development of ophthalmological abnormalities and delayed developmental milestones that was independent of CSF diversion history. Larger patient cohort studies are required to explore whether earlier development of hydrocephalus, as is the case in CAS, causes elevated rates of neurological and ophthalmological complications, and if earlier CSF diversion correlates with improved outcomes.

The association of disproportionately enlarged subarachnoid space hydrocephalus with cognitive deficit in a general population: the Ohasama study

Disproportionately enlarged subarachnoid space hydrocephalus (DESH) is the characteristic feature of idiopathic normal pressure hydrocephalus. We aimed to characterize the prevalence, development, and association of DESH to cognitive deficit in a large population. We reviewed the data of 1384 subjects eligible for the present study among 1590 participants who underwent magnetic resonance imaging (MRI) in the Ohasama Study, a population-based study in Ohasama, Japan. The participants with Mini-Mental State Examination (MMSE) score <  = 25 were assumed to have cognitive deficit and DESH was evaluated by reviewing the MRIs. We assessed the association between DESH, Evans index (EI), and cognitive deficit using multivariate logistic regression models adjusted for relevant confounders. Furthermore, we evaluated the new development of DESH and the deterioration of cognitive function in the participants with DESH. There were nine participants with DESH (0.65%), seven of whom showed cognitive deficit. DESH was significantly associated with cognitive deficit in multivariate regression analyses (odds ratio; 8.50 [95% confidence interval: 1.61–44.88]). In the 669 participants who underwent follow-up MRI, we found four participants newly presenting with DESH; the development of DESH was observed before/after the presence of EI > 0.3. We also found two participants with existing DESH showing no remarkable worsening in MMSE and EI. The present study demonstrated a positive association between the presence of DESH and cognitive deficit. DESH can develop independently of EI > 0.3, and ventricular enlargement in combination with DESH may be an important factor in the worsening of cognitive deficit.

Evans index among adult Ghanaians on normal head computerized tomography scan

Introduction

Normal-Pressure Hydrocephalus (NPH) is a neurological condition which is made up of a clinical triad of gait disturbance, dementia and urinary incontinence and can be reversed by ventricular shunting. Currently, some guidelines suggest the use of Evans' index (EI) for diagnosis of hydrocephalus radiologically. Most of the studies are based on the Western population data. None of these studies have been performed in the Ghanaian population setting yet. The aim of this study was to quantitatively establish normal borderline value for Evans Index in the Ghanaian adult population with respect to age and sex.

Methods

This study was retrospectively conducted on normal enhanced head CT scan images of 266 males and 241 females. EI was calculated as the linear ratio of Maximum Anterior Horn Width (MAHW) of the frontal horns of the lateral ventricles at the level of foramina of Monroe and the Maximum Intracranial Diameter (MICD) of the inner skull. Student T-test, ANOVA and Pearson's correlation were used to analyze the data. A test for a relationship was performed with a scatter plot and a linear regression was performed based on age, sex and different EI of ventricular size.

Results

The mean and median value of EI was 0.24 ± 0.02. There was no statistically significant difference in the EI values between males and females, (p-value = 0.61). A steady increase in EI with age was observed. There was a strong correlation coefficient r = 0.89 of EI and age, which suggested a strong linear relationship between EI and Age. The overall linear relationship model was EI = 0.1879 + 0.0011∗Age.

Conclusions

The mean EI of 0.24 ± 0.02 in our study agrees with adapted international guidelines cut-off value for normal adult patients of (<0.30) and can be a useful tool in determining ventricular enlargement particularly in resource limited settings.

Head and Brain Postmortem Computed Tomography-Autopsy Correlation in Hospital Deaths

The use of postmortem computed tomography (PMCT) to support autopsy pathology has increased in recent decades. To some extent, PMCT has also been contemplated as a potential alternative to conventional postmortem examination. The purpose of this study was to investigate the ability of PMCT to detect specific pathologic findings in the head and brain in natural hospital deaths.We examined postmortem CT images and autopsy data from 31 subjects who died at SUNY (State University of New York) Upstate University Hospital between 2013 and 2018. Each subject underwent a noncontrast PMCT and a traditional autopsy. A neuroradiologist analyzed PMCT images for head and brain abnormalities. The autopsies were performed by pathologists who were aware of the radiology results.In our series, PMCT was able to detect the majority of the significant space-occupying lesions, although it was not always reliable in ascertaining their nature. Postmortem computed tomography revealed findings usually challenging to detect at autopsy. Unfortunately, there were also situations in which PMCT was misleading, showing changes that were difficult to interpret, or that could be related to postmortem events. Therefore, we conclude PMCT should be used as an adjunct rather than a substitute to autopsy.

Diagnostic performance and interobserver agreement of the callosal angle and Evans' index in idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic performance and interobserver agreement of the callosal angle and Evans' index in idiopathic normal pressure hydrocephalus (iNPH).

METHODS

A systematic search of MEDLINE and EMBASE was performed to find studies assessing the diagnostic performance or interobserver agreement of the callosal angle and Evans' index in iNPH. Pooled sensitivity and specificity of the two radiologic indices were calculated. The area under the curve (AUC) was obtained based on a hierarchical summary receiver operating characteristic curve. The diagnostic performances of both radiologic indices were compared in subgroup analysis. To evaluate interobserver agreement, the pooled correlation coefficient was calculated.

RESULTS

Ten original articles (874 patients) were included. The pooled sensitivity and specificity of the callosal angle in the diagnosis of iNPH were 91% (95% CI, 86-94%) and 93% (95% CI, 89-96%), respectively. The pooled sensitivity and specificity of Evans' index were 96% (95% CI, 47-100%) and 83% (95% CI, 77-88%), respectively. Subgroup analysis demonstrated a significant higher specificity of the callosal angle than that of Evans' index (p < 0.01). The AUC of the callosal angle and Evans' index were 0.97 (95% CI, 0.95-0.98) and 0.87 (95% CI, 0.84-0.90), respectively. The pooled correlation coefficients for the callosal angle and Evans' index were 0.92 (95% CI, 0.82-0.96) and 0.92 (95% CI, 0.83-0.97), respectively.

CONCLUSIONS

Our meta-analysis demonstrated a high performance of the callosal angle in the diagnosis of iNPH. Evans' index showed reasonable diagnostic performance with high sensitivity but low specificity. Interobserver agreements were excellent in both radiologic indices.

KEY POINTS

• Callosal angle showed high diagnostic performance in idiopathic normal pressure hydrocephalus. • Evans' index showed reasonable diagnostic performance with high sensitivity but low specificity. • Interobserver agreements were excellent in both callosal angle and Evans' index.

Novel multi-linear quantitative brain volume formula for manual radiological evaluation of brain atrophy

Objectives

The brain atrophy commonly occurs in elderly and in some childhood conditions making the techniques for quantifying brain volume needful. Since the automated quantitative methods of brain volume assessment have limited availability in developing countries, it was the purpose of this study to design and test an alternative formula that is applicable to all healthcare levels.

Methods

The multi-linear diagonal brain fraction formula (DBF) was designed from dimensions of brain relative to skull and ventricles. To test a developed formula, a total of 347 subjects aged between 0 and 18 years who had brain CT scans performed recruited and subjected to a systematic measurement of their brains in a diagonal brain fashion.

Results

Out of 347 patients evaluated, 62 subjects (17.8 %) were found to be cases of brain atrophy. The three radiological measurements which included sulcal width (SW), ventricular width (VW) and Evans Index (EI) were concurrently performed. SW and VW showed good age correlation. Similar tests were extended to diagonal brain fraction (DBF) and skull vertical horizontal ratio (VHR) in which DBF showed significant age correlation.

Conclusions

The DBF formula shows significant ability of differentiating changes of brain volume suggesting that it can be utilized as an alternative brain fraction quantification method bearing technical simplicity in assessing gross brain volume.

Advances in knowledge

The designed formula is unique in that it captures even the possible asymmetrical volume loss of brain through diagonal lines. The proposed scores being in term of ratios give four grades of brain atrophy.

Neuroimaging in the Diagnosis of Chronic Traumatic Encephalopathy: A Systematic Review

OBJECTIVE

Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repeated subconcussive and concussive head injury. Clinical features include cognitive, behavioral, mood, and motor impairments. Definitive diagnosis is only possible at postmortem. Here, the utility of neuroimaging in the diagnosis of CTE is evaluated by systematically reviewing recent evidence for changes in neuroimaging biomarkers in suspected cases of CTE compared with controls.

DATA SOURCES

Providing an update on a previous systematic review of articles published until December 2014, we searched for articles published between December 2014 and July 2016. We searched PubMed for studies assessing neuroimaging changes in symptomatic suspected cases of CTE with a history of repeated subconcussive or concussive head injury or participation in contact sports involving direct impact to the head. Exclusion criteria were case studies, review articles, and articles focusing on repetitive head trauma from military service, head banging, epilepsy, physical abuse, or animal models.

MAIN RESULTS

Seven articles met the review criteria, almost all of which studied professional athletes. The range of modalities were categorized into structural magnetic resonance imaging (MRI), diffusion MRI, and radionuclide studies. Biomarkers which differed significantly between suspected CTE and controls were Evans index (P = 0.05), cavum septum pellucidum (CSP) rate (P < 0.0006), length (P < 0.03) and ratio of CSP length to septum length (P < 0.03), regional differences in axial diffusivity (P < 0.05) and free/intracellular water fractions (P < 0.005), single-photon emission computed tomography perfusion abnormalities (P < 0.01), positron emission tomography (PET) signals from tau-binding, glucose-binding, and GABA receptor-binding radionuclides (P < 0.0001, P < 0.005, and P < 0.005, respectively). Important limitations include low specificity in identification of suspected cases of CTE across studies, the need for postmortem validation, and a lack of generalizability to nonprofessional athletes.

CONCLUSIONS

The most promising biomarker is tau-binding radionuclide PET signal because it is most specific to the underlying neuropathology and differentiated CTE from both controls and patients with Alzheimer disease (P < 0.0001). Multimodal imaging will improve specificity further. Future research should minimize variability in identification of suspected cases of CTE using published clinical criteria.

Evaluation of the Evan's and Bicaudate Index for Rural Population in Central India using Computed Tomography

Introduction:

Evans index (EI) and Bicaudate index (BCI) are practical markers of ventricular volume and are helpful radiological markers in the diagnosis of normal pressure hydrocephalus. Worldwide, variation exists in normative studies for both these indices. Most of the studies conducted for EI and BCI are based on the Western population data. No study has been performed on the rural population of Central India. The purpose of this study is to develop normative data on EI and BCI that can be extrapolated for future reference.

Materials and Methods:

This was a retrospective study conducted from December 2018 to May 2019 in MGIMS Hospital, Sevagram, Maharashtra, India, which is a rural hospital in Central India. All patients with either a head injury or neurological complaints although with normal computed tomography (CT) brain were included in the study. Patients with diagnosed neurological disorder, clinical features suggesting hydrocephalus, or intracranial pathology on CT brain were excluded from the study. Five hundred and eleven patients were selected for this study, and EI and BCI was calculated for them.

Results:

The mean value of EI and BCI in our study was 0.2707 and 0.1121, respectively. Both indices showed a statistically significant difference between males and females. The value of both indices increased with age.

Conclusion:

Although our study is in agreement with the cutoff value of EI to diagnose dilated lateral ventricles as 0.3 for age <70 years, cutoff value of EI for the older population should be reconsidered to 0.34.

Emerging advances of in vivo detection of chronic traumatic encephalopathy and traumatic brain injury

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder that is of epidemic proportions in contact sports athletes and is linked to subconcussive and concussive repetitive head impacts (RHI). Although postmortem analysis is currently the only confirmatory method to diagnose CTE, there has been progress in early detection techniques of fluid biomarkers as well as in advanced neuroimaging techniques. Specifically, promising new methods of diffusion MRI and radionucleotide PET scans could aid in the early detection of CTE.The authors examine early detection methods focusing on various neuroimaging techniques. Advances in structural and diffusion MRI have demonstrated the ability to measure volumetric and white matter abnormalities associated with CTE. Recent studies using radionucleotides such as flortaucipir and 18F-FDDNP have shown binding patterns that are consistent with the four stages of neurofibrillary tangle (NFT) distribution postmortem. Additional research undertakings focusing on fMRI, MR spectroscopy, susceptibility-weighted imaging, and singlephoton emission CT are also discussed as are advanced MRI methods such as diffusiontensor imaging and arterial spin labeled. Neuroimaging is fast becoming a key instrument in early detection and could prove essential for CTE quantification. This review explores a global approach to in vivo early detection.Limited data of in vivo CTE biomarkers with postmortem confirmation are available. While some data exist, they are limited by selection bias. It is unlikely that a single test will be sufficient to properly diagnosis and distinguish CTE from other neurodegenerative diseases such as Alzheimer disease or Frontotemporal Dementia. However, with a combination of fluid biomarkers, neuroimaging, and genetic testing, early detection may become possible.

Factors Associated with Ventriculoperitoneal Shunt Failures in the First 30 Postoperative Days in Pediatric Patients

OBJECTIVE

Placing of a ventriculoperitoneal shunt (VPS) is one of the most common procedures performed by neurosurgeons. Surgical revision of VPS is a significant cause of patient morbidity and mortality. This study was aimed to provide an analysis of factors related to VPS failures in the first 30 postoperative days in a pediatric cohort.

METHODS

This was a retrospective cohort study of 83 pediatric patients (<18 years old), shunted for the first time at a referral care center, between January 2012 and December 2016. Univariate analysis was used to detect potential predictors of VPS failures within the first 30 postoperative days and in the first 6 months of follow-up. Kaplan-Meier survival curves were used to examine the occurrence of VPS failures over time.

RESULTS

During the first 30 postoperative days, VPS failures occurred in 21 patients (25.3%). Intraventricular hemorrhage (IVH) (odds ratio [OR], 4.41; 95% confidence interval [CI], 1.44-13.48), cerebrospinal fluid (CSF) alterations (OR, 5.11; 95% CI, 1.37-19.1), and previous external ventricular drain (EVD) (OR, 7.05; 95% CI, 1.18-41.8) were significantly associated with shunt failure during the first postoperative month. Kaplan-Meier survival analysis showed decreased shunt survival for patients with IVH, both during the first 30 days after surgery (P = 0.005, log-rank), and during the 6 months after surgery (P = 0.005, log-rank).

CONCLUSIONS

In this study, we found that in pediatric patients, IVH was associated with VPS failure within the first 30 postoperative days and decreased shunt survival over time. Further larger prospective randomized studies are needed to better understand these results.