Structural neuroimaging changes associated with subjective cognitive decline from a clinical sample.

BACKGROUND: Alzheimer's disease (AD) is characterized by progressive deterioration of cognitive functions. Some individuals with subjective cognitive decline (SCD) are in the early phase of the disease and subsequently progress through the AD continuum. Although neuroimaging biomarkers could be used for the accurate and early diagnosis of preclinical AD, the findings in SCD samples have been heterogeneous. This study established the morphological differences in brain magnetic resonance imaging (MRI) findings between individuals with SCD and those without cognitive impairment based on a clinical sample of patients defined according to SCD-Initiative recommendations. Moreover, we investigated baseline structural changes in the brains of participants who remained stable or progressed to mild cognitive impairment or dementia. METHODS: This study included 309 participants with SCD and 43 healthy controls (HCs) with high-quality brain MRI at baseline. Among the 99 subjects in the SCD group who were followed clinically, 32 progressed (SCDp) and 67 remained stable (SCDnp). A voxel-wise statistical comparison of gray and white matter (WM) volume was performed between the HC and SCD groups and between the HC, SCDp, and SCDnp groups. XTRACT ATLAS was used to define the anatomical location of WM tract damage. Region-of-interest (ROI) analyses were performed to determine brain volumetric differences. White matter lesion (WML) burden was established in each group. RESULTS: Voxel-based morphometry (VBM) analysis revealed that the SCD group exhibited gray matter atrophy in the middle frontal gyri, superior orbital gyri, superior frontal gyri, right rectal gyrus, whole occipital lobule, and both thalami and precunei. Meanwhile, ROI analysis revealed decreased volume in the left rectal gyrus, bilateral medial orbital gyri, middle frontal gyri, superior frontal gyri, calcarine fissure, and left thalamus. The SCDp group exhibited greater hippocampal atrophy (p < 0.001) than the SCDnp and HC groups on ROI analyses. On VBM analysis, however, the SCDp group exhibited increased hippocampal atrophy only when compared to the SCDnp group (p < 0.001). The SCD group demonstrated lower WM volume in the uncinate fasciculus, cingulum, inferior fronto-occipital fasciculus, anterior thalamic radiation, and callosum forceps than the HC group. However, no significant differences in WML number (p = 0.345) or volume (p = 0.156) were observed between the SCD and HC groups. CONCLUSIONS: The SCD group showed brain atrophy mainly in the frontal and occipital lobes. However, only the SCDp group demonstrated atrophy in the medial temporal lobe at baseline. Structural damage in the brain regions was anatomically connected, which may contribute to early memory decline.

Time discrimination and change detection could share a common brain network: findings of a task-based fMRI study.

Introduction: Over the past few years, several studies have described the brain activation pattern related to both time discrimination (TD) and change detection processes. We hypothesize that both processes share a common brain network which may play a significant role in more complex cognitive processes. The main goal of this proof-of-concept study is to describe the pattern of brain activity involved in TD and oddball detection (OD) paradigms, and in processes requiring higher cognitive effort. Methods: We designed an experimental task, including an auditory test tool to assess TD and OD paradigms, which was conducted under functional magnetic resonance imaging (fMRI) in 14 healthy participants. We added a cognitive control component into both paradigms in our test tool. We used the general linear model (GLM) to analyze the individual fMRI data images and the random effects model for group inference. Results: We defined the areas of brain activation related to TD and OD paradigms. We performed a conjunction analysis of contrast TD (task > control) and OD (task > control) patterns, finding both similarities and significant differences between them. Discussion: We conclude that change detection and other cognitive processes requiring an increase in cognitive effort require participation of overlapping functional and neuroanatomical components, suggesting the presence of a common time and change detection network. This is of particular relevance for future research on normal cognitive functioning in the healthy population, as well as for the study of cognitive impairment and clinical manifestations associated with various neuropsychiatric conditions such as schizophrenia.

Endolymphatic hydrops severity in magnetic resonance imaging evidences disparate vestibular test results.

OBJECTIVES: It has been suggested that in Ménière's disease (MD) a dissociated result in the caloric test (abnormal result) and video head-impulse test (normal result) probably indicates that hydrops affects the membranous labyrinth in the horizontal semicircular canal (HSC). The hypothesis in this study is that based on endolymphatic hydrops' cochleocentric progression, hydrops should also be more severe in the vestibule of these patients than in those for whom both tests are normal. METHODS: 22 consecutive patients with unilateral definite MD were included and classified as NN if both tests were normal or AN if the caloric test was abnormal. MRI evaluation of endolymphatic hydrops was carried out with a T2-FLAIR sequence performed 4h after intravenous gadolinium administration. The laterality and degree of vestibular endolymphatic hydrops and the presence or absence of cochlear endolymphatic hydrops were recorded. Demographic data, audiometric and vestibular evoked myogenic potentials were collected, and video head-impulse and caloric tests were performed. RESULTS: Patients in both groups (NN and AN) were similar in terms of demographic data and hearing loss. The interaural asymmetry ratio was significantly higher for ocular and cervical VEMP in patients in the AN group. There was a significantly higher degree of hydrops in the vestibule of the affected ear of AN patients (χ2; p=0.028). CONCLUSION: Significant canal paresis in the caloric test is associated with more severe endolymphatic hydrops in the vestibule as detected with gadolinium-enhanced MRI and with a more severe vestibular deficit. LEVEL OF EVIDENCE: 2a.

Grey matter hypometabolism and atrophy in Parkinson's disease with cognitive impairment: a two-step process.

The pathophysiological process underlying cognitive decline in Parkinson's disease is not well understood. Cerebral atrophy and hypometabolism have been described in patients with Parkinson's disease and dementia or mild cognitive impairment with respect to control subjects. However, the exact relationships between atrophy and hypometabolism are still unclear. To determine the extension and topographical distribution of hypometabolism and atrophy in the different cognitive states of Parkinson's disease, we examined 46 patients with Parkinson's disease (19 female, 27 male; 71.7 ± 5.9 years old; 14.6 ± 4.2 years of disease evolution; modified Hoehn and Yahr mean stage 3.1 ± 0.7). Cognitive status was diagnosed as normal in 14 patients, as mild cognitive impairment in 17 and as dementia in 15 patients. Nineteen normal subjects (eight female, 11 male; 68.1 ± 3.2 years old) were included as controls. (18)F-fluorodeoxyglucose positron emission tomography and magnetic resonance imaging scans were obtained, co-registered, corrected for partial volume effect and spatially normalized to the Montreal Neurological Institute space in each subject. Smoothing was applied to the positron emission tomography and magnetic resonance imaging scans to equalize their effective smoothness and resolution (10 mm and 12 mm full-width at half-maximum and Gaussian kernel, respectively). Z-score maps for atrophy and for hypometabolism were obtained by comparing individual images to the data set of control subjects. For each group of patients, a paired Student's t-test was performed to statistically compare the two Z-map modalities (P < 0.05 false discovery rate corrected) using the direct voxel-based comparison technique. In patients with mild cognitive impairment, hypometabolism exceeded atrophy in the angular gyrus, occipital, orbital and anterior frontal lobes. In patients with dementia, the hypometabolic areas observed in the group with mild cognitive impairment were replaced by areas of atrophy, which were surrounded by extensive zones of hypometabolism. Areas where atrophy was more extended than hypometabolism were found in the precentral and supplementary motor areas in both patients with mild cognitive impairment and with dementia, and in the hippocampus and temporal lobe in patients with dementia. These findings suggest that there is a gradient of severity in cortical changes associated with the development of cognitive impairment in Parkinson's disease in which hypometabolism and atrophy represent consecutive stages of the same process in most of the cortical regions affected.

Reversible cerebral vasoconstriction syndrome induced by adrenaline.

INTRODUCTION: Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by acute severe thunderclap headaches and evidence of multifocal, segmental, reversible vasoconstrictions of the cerebral arteries. Several precipitating factors have been identified and reported, including the use of recreational substances or sympathomimetic drugs and the postpartum state. CASE DESCRIPTION: Here we present the case of a woman who developed RCVS after the administration of adrenaline (epinephrine) in the setting of an anaphylactic reaction during antibiotic allergy testing. DISCUSSION: To our knowledge, this is the first reported case of RCVS following the administration of exogenous adrenaline. This case contributes to the understanding of the physiopathological mechanisms underlying reversible cerebral vasoconstriction.

Functional bold MRI: advantages of the 3 T vs. the 1.5 T.

We quantitatively evaluate the benefits of a higher field strength for functional brain MRI (fMRI) based on the blood oxygenation level-dependent contrast. The 3-T fMRI shows a higher sensitivity for the motor and somatosensory stimulation and more specific localization in the grey substance. The 3-T fMRI detects additional areas of activation with the motor paradigm.

Hepatic abnormalities in patients with chronic granulomatous disease.

UNLABELLED: Chronic granulomatous disease (CGD) is a rare congenital disorder characterized by repeated bacterial and fungal infections. Aside from a high incidence of liver abscess, little is known about hepatic involvement in CGD. The aim of this study was to describe the spectrum of liver abnormalities seen in CGD. The charts of 194 patients with CGD followed at the NIH were reviewed, with a focus on liver abnormalities. Liver enzyme elevations occurred on at least one occasion in 73% of patients during a mean of 8.9 years of follow-up. ALT elevations were generally transient. Although transient alkaline phosphatase (ALP) elevations were also common, persistent ALP elevations lasting up to 17.6 years were seen in 25% of patients. Liver abscess occurred in 35% of patients. Drug-induced hepatotoxicity was documented in 15% of patients but likely occurred more frequently. Hepatomegaly was found in 34% and splenomegaly in 56% of patients. Liver histology showed granulomata in 75% and lobular hepatitis in 90% of specimens. Venopathy of the portal vein was common (80%) and associated with splenomegaly. Venopathy of the central vein was also common (63%) and was associated with the number of abscess episodes. Nodular regenerative hyperplasia (NRH) was seen in 9 patients, including 6 of 12 autopsy specimens. CONCLUSION: Liver enzyme abnormalities occur frequently in patients with CGD. In addition to liver abscesses and granulomata, drug hepatotoxicity is likely underappreciated. Vascular lesions such as venopathy and--to a lesser extent--NRH are common. The cause and clinical consequences of venopathy await prospective evaluation.

CT and MRI of hepatic abscess in patients with chronic granulomatous disease.

OBJECTIVE: We describe the spectrum of radiologic appearances of hepatic abscesses in patients with chronic granulomatous disease (CGD), a hereditary immunodeficiency presenting in childhood that occurs at a rate of 1 in 200,000-250,000 live births and predisposes patients to infection with catalase-positive organisms. CONCLUSION: Hepatic abscesses in patients with CGD show an atypical radiologic appearance compared with sporadic hepatic abscesses, and they are characterized by homogeneous enhancement and multiseptal enhancement. In the appropriate clinical setting, the appearance of an enhancing mass should suggest the possibility of a CGD-related hepatic abscess.