Superior ophthalmic vein thrombosis: What radiologist and clinician must know?

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Incidental SOVT: good prognosis, self-limited and treated by anticoagulation.

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Post-traumatic and surgical SOVT: good prognosis, treated by anticoagulation.

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Septic SOVT: secondary to infections, high risk, requires specific interventions.

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Aseptic SOVT: secondary to inflammatory diseases, need to treat underlying etiology.

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CT and MRI are vital to the correct diagnosis and management of patients with SOVT.

Purpose

Superior ophthalmic vein thrombosis (SOVT) is an extremely rare condition. Few studies have been published about clinical aspects of this condition. In this study, we have studied the symptoms, underlying etiologies, treatment, pathogenesis and complication of the SOVT and we tried to classify it based on the etiology, treatment, and prognosis.

Methods

We reviewed the patients’ data from a tertiary academic referral center. Each patient with SOVT was then reviewed for symptoms associated with SOVT, underlying etiology, treatment protocol, treatment response, complications, possible pathogens, and final outcome.

Results

Twenty-four cases of SOVT were included in this study. Overall, 13 cases were diagnosed as right-sided SOVT, out of which, eight had simultaneous right-sided cavernous sinus thrombosis (CST). Eighteen cases were diagnosed to have left-sided SOVT, out of which, 11 had simultaneous left-sided CST.

Conclusions

The SOVT can be secondary to different mechanisms. The SOVT secondary to trauma, recent surgery and coagulopathy are mostly non-aggressive, and can be managed by conservative therapy and anticoagulation. The SOVT in patients with orbital cellulitis, history of active sinusitis or paranasal sinus surgery are aggressive presenting with acute orbital swelling, abscess and visual loss. This type of SOVT can be complicated by extension to the cavernous sinus and intracranial structures. These patients require urgent antibiotics therapy and sinus surgery. The most severe type of SOVT is caused by mucormycosis which may also extend intracranially resulting in stroke and is often life-threatening.

Reduced sound-evoked and resting-state BOLD fMRI connectivity in tinnitus

The exact neurophysiological basis of chronic tinnitus, which affects 10-15% of the population, remains unknown and is controversial at many levels. It is an open question whether phantom sound perception results from increased central neural gain or not, a crucial question for any future therapeutic intervention strategies for tinnitus. We performed a comprehensive study of mild hearing-impaired participants with and without tinnitus, excluding participants with co-occurrences of hyperacusis. A right-hemisphere correlation between tinnitus loudness and auditory perceptual difficulty was observed in the tinnitus group, independent of differences in hearing thresholds. This correlation was linked to reduced and delayed sound-induced suprathreshold auditory brain responses (ABR wave V) in the tinnitus group, suggesting subsided rather than exaggerated central neural responsiveness. When anatomically predefined auditory regions of interest were analysed for altered sound-evoked BOLD fMRI activity, it became evident that subcortical and cortical auditory regions and regions involved in sound detection (posterior insula, hippocampus), responded with reduced BOLD activity in the tinnitus group, emphasizing reduced, rather than increased, central neural gain. Regarding previous findings of evoked BOLD activity being linked to positive connectivities at rest, we additionally analysed r-fcMRI responses in anatomically predefined auditory regions and regions associated with sound detection. A profound reduction in positive interhemispheric connections of homologous auditory brain regions and a decline in the positive connectivities between lower auditory brainstem regions and regions involved in sound detection (hippocampus, posterior insula) were observed in the tinnitus group. The finding went hand-in-hand with the emotional (amygdala, anterior insula) and temporofrontal/stress-regulating regions (prefrontal cortex, inferior frontal gyrus) that were no longer positively connected with auditory cortex regions in the tinnitus group but were instead positively connected to lower-level auditory brainstem regions. Delayed sound processing, reduced sound-evoked BOLD fMRI activity and altered r-fcMRI in the auditory midbrain correlated in the tinnitus group and showed right hemisphere dominance as did tinnitus loudness and perceptual difficulty. The findings suggest that reduced central neural gain in the auditory stream may lead to phantom perception through a failure to energize attentional/stress-regulating networks for contextualization of auditory-specific information. Reduced auditory-specific information flow in tinnitus has until now escaped detection in humans, as low-level auditory brain regions were previously omitted from neuroimaging studies.

TRIAL REGISTRATION

German Clinical Trials Register DRKS0006332.

Longitudinal structural cerebral changes related to core CSF biomarkers in preclinical Alzheimer's disease: A study of two independent datasets

Alzheimer's disease (AD) is characterized by an accumulation of β-amyloid (Aβ₄₂) accompanied by brain atrophy and cognitive decline. Several recent studies have shown that Aβ₄₂ accumulation is associated with gray matter (GM) changes prior to the development of cognitive impairment, in the so-called preclinical stage of the AD (pre-AD). It also has been proved that the GM atrophy profile is not linear, both in normal ageing but, especially, on AD. However, several other factors may influence this association and may have an impact on the generalization of results from different samples. In this work, we estimate differences in rates of GM volume change in cognitively healthy elders in association with baseline core cerebrospinal fluid (CSF) AD biomarkers, and assess to what these differences are sample dependent. We report the dependence of atrophy rates, measured in a two-year interval, on Aβ₄₂, computed both over continuous and categorical values of Aβ₄₂, at voxel-level (p < 0.001; k < 100) and corrected for sex, age and education. Analyses were performed jointly and separately, on two samples. The first sample was formed of 31 individuals (22 Ctrl and 9 pre-AD), aged 60–80 and recruited at the Hospital Clinic of Barcelona. The second sample was a replica of the first one with subjects selected from the ADNI dataset. We also investigated the dependence of the GM atrophy rate on the basal levels of continuous p-tau and on the p-tau/Aβ₄₂ ratio. Correlation analyses on the whole sample showed a dependence of GM atrophy rates on Aβ₄₂ in medial and orbital frontal, precuneus, cingulate, medial temporal regions and cerebellum. Correlations with p-tau were located in the left hippocampus, parahippocampus and striatal nuclei whereas correlation with p-tau/Aβ₄₂ was mainly found in ventral and medial temporal areas. Regarding analyses performed separately, we found a substantial discrepancy of results between samples, illustrating the complexities of comparing two independent datasets even when using the same inclusion criteria. Such discrepancies may lead to significant differences in the sample size needed to detect a particular reduction on cerebral atrophy rates in prevention trials. Higher cognitive reserve and more advanced pathological progression in the ADNI sample could partially account for the observed discrepancies. Taken together, our findings in these two samples highlight the importance of comparing and merging independent datasets to draw more robust and generalizable conclusions on the structural changes in the preclinical stages of AD.

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GM atrophy rates depends differently on values of CSF Aβ₄₂ than on CSF p-tau in the preclinical stage of AD.

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Discrepant results were obtained. Although nominally equivalent, samples might reflect different time-windows in the AD continuum.

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It is necessary a further effort to standardize CSF-biomarkers measures and thresholds to make different samples to be directly comparable.

Evaluation of early-phase [18F]-florbetaben PET acquisition in clinical routine cases

Objectives

In recent years several [¹⁸F]-labelled amyloid PET tracers have been developed and have obtained clinical approval. There is accumulating evidence that early (post injection) acquisitions with these tracers are equally informative as conventional blood flow and metabolism studies for diagnosis of Alzheimer's disease, but there have been few side-by-side studies. Therefore, we investigated the performance of early acquisitions of [¹⁸F]-florbetaben (FBB) PET compared to [¹⁸F]-fluorodeoxyglucose (FDG) PET in a clinical setting.

Methods

All subjects were recruited with clinical suspicion of dementia due to neurodegenerative disease. FDG PET was undertaken by conventional methods, and amyloid PET was performed with FBB, with early recordings for the initial 10 min (early-phase FBB), and late recordings at 90–110 min p.i. (late-phase FBB). Regional SUVR with cerebellar and global mean normalization were calculated for early-phase FBB and FDG PET. Pearson correlation coefficients between FDG and early-phase FBB were calculated for predefined cortical brain regions. Furthermore, a visual interpretation of disease pattern using 3-dimensional stereotactic surface projections (3D-SSP) was performed, with assessment of intra-reader agreement.

Results

Among a total of 33 patients (mean age 67.5 ± 11.0 years) included in the study, 18 were visually rated amyloid-positive, and 15 amyloid-negative based on late-phase FBB scans. Correlation coefficients for early-phase FBB vs. FDG scans displayed excellent agreement in all target brain regions for global mean normalization. Cerebellar normalization gave strong, but significantly lower correlations. 3D representations of early-phase FBB visually resembled the corresponding FDG PET images, irrespective of the amyloid-status of the late FBB scans.

Conclusions

Early-phase FBB acquisitions correlate on a relative quantitative and visual level with FDG PET scans, irrespective of the amyloid plaque density assessed in late FBB imaging. Thus, early-phase FBB uptake depicts a metabolism-like image, suggesting it as a valid surrogate marker for synaptic dysfunction, which could ultimately circumvent the need for additional FDG PET investigation in diagnosis of dementia.

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Early-phase [¹⁸F]-florbetaben uptake depicts a metabolism-like image

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Strong relative quantitative and visual correlations of early-phase [¹⁸F]-florbetaben uptake with FDG images

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A two-phase [¹⁸F]-florbetaben protocol might give combined neurodegeneration and amyloid pathology biomarker information

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Early-phase [¹⁸F]-florbetaben PET could ultimately circumvent the need for an additional FDG-PET in the dementia work-up.

Evoked itch perception is associated with changes in functional brain connectivity

Chronic itch, a highly debilitating condition, has received relatively little attention in the neuroimaging literature. Recent studies suggest that brain regions supporting itch in chronic itch patients encompass sensorimotor and salience networks, and corticostriatal circuits involved in motor preparation for scratching. However, how these different brain areas interact with one another in the context of itch is still unknown. We acquired BOLD fMRI scans in 14 atopic dermatitis patients to investigate resting-state functional connectivity before and after allergen-induced itch exacerbated the clinical itch perception in these patients. A seed-based analysis revealed decreased functional connectivity from baseline resting state to the evoked-itch state between several itch-related brain regions, particularly the insular and cingulate cortices and basal ganglia, where decreased connectivity was significantly correlated with increased levels of perceived itch. In contrast, evoked itch increased connectivity between key nodes of the frontoparietal control network (superior parietal lobule and dorsolateral prefrontal cortex), where higher increase in connectivity was correlated with a lesser increase in perceived itch, suggesting that greater interaction between nodes of this executive attention network serves to limit itch sensation via enhanced top-down regulation. Overall, our results provide the first evidence of itch-dependent changes in functional connectivity across multiple brain regions.

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Atopic dermatitis patients were subjected to allergen-induced itch.

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Evoked itch reduced functional connectivity between itch-related brain regions.

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Evoked itch increased functional connectivity within frontoparietal control network.

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The above changes in functional connectivity correlated with perceived itch level.

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Itch sensation may be top-down regulated by frontoparietal control network.