Abnormal brain diffusivity in participants with persistent neuropsychiatric symptoms after COVID-19

Objectives

We aimed to compare brain white matter integrity in participants with post-COVID-19 conditions (PCC) and healthy controls.

Methods

We compared cognitive performance (NIH Toolbox®), psychiatric symptoms and diffusion tensor imaging (DTI) metrics between 23 PCC participants and 24 controls. Fractional anisotropy (FA), axial (AD), radial (RD), and mean (MD) diffusivities were measured in 9 white matter tracts and 6 subcortical regions using MRICloud.

Results

Compared to controls, PCC had similar cognitive performance, but greater psychiatric symptoms and perceived stress, as well as higher FA and lower diffusivities in multiple white matter tracts (ANCOVA-p-values≤0.001–0.048). Amongst women, PCC had higher left amygdala-MD than controls (sex-by-PCC p=0.006). Regardless of COVID-19 history, higher sagittal strata-FA predicted greater fatigue (r=0.48-0.52, p<0.001) in all participants, and higher left amygdala-MD predicted greater fatigue (r=0.61, p<0.001) and anxiety (r=0.69, p<0.001) in women, and higher perceived stress (r=0.45, p=0.002) for all participants.

Conclusions

Microstructural abnormalities are evident in PCC participants averaged six months after COVID-19. The restricted diffusivity (with reduced MD) and higher FA suggest enhanced myelination or increased magnetic susceptibility from iron deposition, as seen in stress conditions. The higher amygdala-MD in female PCC suggests persistent neuroinflammation, which might contribute to their fatigue, anxiety, and perceived stress.

Comparison of Gadoterate Meglumine and Gadobutrol in the MRI Diagnosis of Primary Brain Tumors: A Double-Blind Randomized Controlled Intraindividual Crossover Study (the REMIND Study)

BACKGROUND AND PURPOSE

Effective management of patients with brain tumors depends on accurate detection and characterization of lesions. This study aimed to demonstrate the noninferiority of gadoterate meglumine versus gadobutrol for overall visualization and characterization of primary brain tumors.

MATERIALS AND METHODS

This multicenter, double-blind, randomized, controlled intraindividual, crossover, noninferiority study included 279 patients. Both contrast agents (dose = 0.1 mmol/kg of body weight) were assessed with 2 identical MRIs at a time interval of 2-14 days. The primary end point was overall lesion visualization and characterization, scored independently by 3 off-site readers on a 4-point scale, ranging from "poor" to "excellent." Secondary end points were qualitative assessments (lesion border delineation, internal morphology, degree of contrast enhancement, diagnostic confidence), quantitative measurements (signal intensity), and safety (adverse events). All qualitative assessments were also performed on-site.

RESULTS

For all 3 readers, images of most patients (>90%) were scored good or excellent for overall lesion visualization and characterization with either contrast agent; and the noninferiority of gadoterate meglumine versus gadobutrol was statistically demonstrated. No significant differences were observed between the 2 contrast agents regarding qualitative end points despite quantitative mean lesion percentage enhancement being higher with gadobutrol (P < .001). Diagnostic confidence was high/excellent for all readers in >81% of the patients with both contrast agents. Similar percentages of patients with adverse events related to the contrast agents were observed with gadoterate meglumine (7.8%) and gadobutrol (7.3%), mainly injection site pain.

CONCLUSIONS

The noninferiority of gadoterate meglumine versus gadobutrol for overall visualization and characterization of primary brain tumors was demonstrated.

Volumetric analysis of pelvic hematomas after blunt trauma using semi-automated seeded region growing segmentation: a method validation study

OBJECTIVE

Manually segmented traumatic pelvic hematoma volumes are strongly predictive of active bleeding at conventional angiography, but the method is time intensive, limiting its clinical applicability. We compared volumetric analysis using semi-automated region growing segmentation to manual segmentation and diameter-based size estimates in patients with pelvic hematomas after blunt pelvic trauma.

MATERIALS AND METHODS

A 14-patient cohort was selected in an anonymous randomized fashion from a dataset of patients with pelvic binders at MDCT, collected retrospectively as part of a HIPAA-compliant IRB-approved study from January 2008 to December 2013. To evaluate intermethod differences, one reader (R1) performed three volume measurements using the manual technique and three volume measurements using the semi-automated technique. To evaluate interobserver differences for semi-automated segmentation, a second reader (R2) performed three semi-automated measurements. One-way analysis of variance was used to compare differences in mean volumes. Time effort was also compared. Correlation between the two methods as well as two shorthand appraisals (greatest diameter, and the ABC/2 method for estimating ellipsoid volumes) was assessed with Spearman's rho (r).

RESULTS

Intraobserver variability was lower for semi-automated compared to manual segmentation, with standard deviations ranging between ±5-32 mL and ±17-84 mL, respectively (p = 0.0003). There was no significant difference in mean volumes between the two readers' semi-automated measurements (p = 0.83); however, means were lower for the semi-automated compared with the manual technique (manual: mean and SD 309.6 ± 139 mL; R1 semi-auto: 229.6 ± 88.2 mL, p = 0.004; R2 semi-auto: 243.79 ± 99.7 mL, p = 0.021). Despite differences in means, the correlation between the two methods was very strong and highly significant (r = 0.91, p < 0.001). Correlations with diameter-based methods were only moderate and nonsignificant. Mean semi-automated segmentation time effort was 2 min and 6 s and 2 min and 35 s for R1 and R2, respectively, vs. 22 min and 8 s for manual segmentation.

CONCLUSION

Semi-automated pelvic hematoma volumes correlate strongly with manually segmented volumes. Since semi-automated segmentation can be performed reliably and efficiently, volumetric analysis of traumatic pelvic hematomas is potentially valuable at the point-of-care.

Bayesian predictive modeling based on multidimensional connectivity profiling

Dysfunction of brain structural and functional connectivity is increasingly being recognized as playing an important role in many brain disorders. Diffusion tensor imaging (DTI) and functional magnetic resonance (fMR) imaging are widely used to infer structural and functional connectivity, respectively. How to combine structural and functional connectivity patterns for predictive modeling is an important, yet open, problem. We propose a new method, called Bayesian prediction based on multidimensional connectivity profiling (BMCP), to distinguish subjects at the individual level based on structural and functional connectivity patterns. BMCP combines finite mixture modeling and Bayesian network classification. We demonstrate its use in distinguishing young and elderly adults based on DTI and resting-state fMR data.

The roles of the “visual word form area” in reading

Activation of the left midfusiform gyrus in response to reading words and pseudowords is such a reliable finding in functional imaging that this region has been called "the visual word form area" (VWFA). However, this label has recently been challenged, because activation in VWFA is also observed in other lexical tasks. We evaluated whether VWFA is necessary, sufficient, or specialized for reading by examining how frequently acute lesions in VWFA disrupt tasks that require access to written word forms versus other lexical tasks. We administered lexical tasks with spoken and written input and output, and identified damage or dysfunction of VWFA and other regions of interest (ROI) on diffusion- and perfusion-weighted imaging (DWI and PWI) in 80 patients within 24 h of onset of acute left ischemic stroke. Associations between abnormalities in each region of interest and impairment on lexical tasks were evaluated with chi-squared tests. Damage or dysfunction of VWFA was not significantly associated with impairment of written word comprehension or lexical decision, but was significantly associated with impairment on all tasks requiring lexical output: oral reading and oral naming (visual or tactile input), and written naming. We account for these results and results from functional imaging by proposing that the left midfusiform gyrus normally has two roles in reading: (1) computation of location- and modality-independent grapheme sequences from written word stimuli, and (2) a modality-independent stage of lexical processing that links modality-specific input and output representations. VWFA is not necessary for the former because the right homologue of VWFA can immediately assume this role.

Accuracy and sensitivity of detection of activation foci in the brain via statistical parametric mapping: a study using a PET simulator

Statistical parametric mapping (SPM) is currently the most widely used method for analysis of functional activation images. This paper reports a quantitative evaluation of the sensitivity and accuracy of SPM, using a realistic simulator of PET image formation, which accounted for the main physical processes involved in PET, including attenuation, scatter, randoms, Poisson noise, and limited detector resolution. Activation foci of the brain were simulated by placing spheres of specified activities in particular locations. Using these data, the sensitivity and accuracy of SPM in detecting activation foci was measured for different versions of the SPM spatial normalization method and for an elastic warping method referred to as STAR (spatial transformation algorithm for registration). The STAR method resulted in relatively better registration and hence better detection of the activation foci. A secondary goal of the paper was to evaluate the improvement in detection sensitivity obtained by applying an atlas-based adaptive smoothing method instead of the usual Gaussian filtering method. The results indicate some limitations of statistical parametric mapping, assist in the correct interpretation of the SPM maps, and point to future research directions in functional image analysis.

Neuroimaging variables related to development of Secondary Attention Deficit Hyperactivity Disorder after closed head injury in children and adolescents

OBJECTIVE

To characterize children who develop Secondary Attention Deficit Hyperactivity Disorder (S-ADHD) after severe and moderate closed head injury (CHI) according to neuroimaging variables.

METHOD

Ninety-nine children from 4-19 years who suffered severe and moderate CHI were prospectively followed for a year after injury. Premorbid psychiatric status was determined by administration to the parent of a structured psychiatric interview. This interview was readministered 1 year after injury to determine the presence of post-closed head injury S-ADHD. An MRI was performed 3 months after injury to define lesion locations and volumes.

RESULTS

A set of multiple logistic regression models determined that the odds of developing S-ADHD were 3.64 times higher among children with thalamus injury, and 3.15 times higher among children with basal ganglia injury. There was no significant difference in lesion volumes in any of the locations of interest between the group who developed S-ADHD and the group who did not develop S-ADHD.

CONCLUSION

The data support an association between S-ADHD and injury in either or both the thalamus and basal ganglia, but they do not definitively demonstrate whether injury in either structure has an effect on S-ADHD in the absence of injury in the other.

Struggling over subjectivity: debates about the "self" and Alzheimer's disease

The current conception of Alzheimer's disease emerged in the 1970s and achieved wide acceptance and popularization because it effectively served political-economic interests, solved pragmatic, clinical, and psychological problems, and met philosophical and ethical concerns. But the very success of this widespread acceptance and popularization has produced a troubling dilemma regarding the subjectivity of the person diagnosed with Alzheimer's disease. A "loss of self" is implicit in the current Alzheimer's construct, and it has been argued that, consequently, the subjective experience of being and becoming old has become increasingly distressing. It has been further suggested that a response to this unintended assault on the self can be seen in the now burgeoning literature offering diverse representations of and debates about the "self" in Alzheimer's. What appears to be at stake in these competing voices is our very notion of what comprises the self and what constitutes subjective experience. Finally, one can speculate why, as a culture, we tell these stories about aging: it could be that, as a society as well as a community of gerontological thinkers and practitioners, our struggle with the nature of the self-in-Alzheimer's reflects our struggle to grapple with what it will be like, and what it will mean, to be and become old.

Comparative study of pentoxifylline vs antiaggregants in patients with transient ischaemic attacks

Out of 235 patients with recent cerebral transient ischaemic attacks, 208 subjects were available for final evaluation after 6 months' randomised treatment with either pentoxifylline (PTX 1200 mg/day) or a combination (ASAD) of acetylsalicylic acid (ASA, 1050 mg/day) and dipyridamole (D, 150 mg/day). Prevention of TIA, stroke or death attributable to previous events were endpoint criteria. The pentoxifylline group (n = 100) exhibited no recurrent episodes in 86 patients (86%). TIA occurred in 9 patients, stroke in 5 patients and there was 1 death. In the ASAD group (n = 108) no recurrence of ischaemic episodes was recorded in 82 cases (75.9%). TIA occurred in 20 patients, stroke in 6 patients and there were 3 deaths of vascular origin. Side effects were recorded in 4 ASAD and 1 PTX patients. The total rate of recurrence was 14% with PTX as compared to 24.1% with ASAD treatment.

Hereditary essential tremor in Buenos Aires (Argentina)

A descriptive trial of essential tremor in Buenos Aires city is proposed. It may be considered as the first one like this in Latin America. During a 15 year period, sixteen families with essential tremor diagnosis have been examined, making a total of 39 patients (20 males and 19 females). The disease was basically studied from its semiological, clinico-evolutive and therapeutical view point, following a protocol. Our results indicate -- a. The clinico-evolutive characteristics: its frequency (according to race, sex, social status, age of beginning and physiopathological type), morbidity and mortality, evolution, prognosis, triggering factors, longevity and multiparity. b. The different treatment given to our patients with discussion of their pharmacokinetic and pharmacodynamic basis and evaluation of the best responses. In this matter, it is concluded that both primidone (750 mg/daily) and/or propranolol (160-240 mg/daily) are undeniably the drugs of first choice for the treatment of this disease. A comparison of the clinico-therapeutic features of this tremor in Buenos Aires and other cities is done. The study of this syndrome in Buenos Aires does not give different results from those obtained in Europe and USA.

Preventive treatment of cerebral transient ischemia: comparative randomized trial of pentoxifylline versus conventional antiaggregants

A comparative study of the prevention of recurrences of cerebral transient ischemic attacks during a 6-month observation period was conducted in 73 patients treated with a combination of acetylsalicylic acid and dipyridamole (ASAD, 1,050 mg + 150 mg/day) and in 65 patients treated with pentoxifylline (PTX 1,200 mg/day, Trental 400 t.d.s.). The patients were randomly assigned to the treatments. Risk factor analysis showed high prevalence of arterial hypertension, hyperlipidemia and smoking in these patients. The two groups were matched in terms of age, sex, blood pressure and site of TIA origin (carotid 63% in the ASAD, 65% in the PTX group). 23 ASAD patients and 9 PTX patients suffered a recurrence. There were 4 nonfatal stroke events with ASAD and 2 with PTX. 80 recurrent TIAs were recorded in 19 ASAD patients compared with 19 such episodes in 9 PTX subjects. The morbidity rates (life table analysis) were significantly lower (p less than 0.05) in the PTX group. The results of the study point to a preventive effect of PTX in terms of the reduction in TIA recurrences.

Randomised trial of pentoxifylline versus acetylsalicylic acid plus dipyridamole in preventing transient ischaemic attacks

In a multicentre trial to compare the ability of a combination of acetylsalicylic acid and dipyridamole (1050 mg + 150 mg/day, group A) to prevent recurrence of transient ischaemic attacks (TIA) with that of pentoxifylline (1200 mg/day, group B), 36 patients received the combination and 30 pentoxifylline. There was no statistically significant difference between the groups as regards age, sex, blood pressure, site of origin of TIA, and incidence of other risk factors. The incidence of recurrent TIAs during 1 year of follow-up was 28% in group A and 10% in group B; this difference was significant (p less than 0.05). The incidence of permanent strokes was similar in the two groups but distinctly lower (4.5%) than that usually reported after untreated TIA.

[Paralysis of the conjugated lateral gaze of pontile origin: neuroanatomical discussion of the fasciculus longitudinalis medialis]

The case of a patient with paralysis of the lateral gaze to the left, paresis of both eyes when he tried to look upwards and a disfunction of the cerebellum to the left, is reported. During the evolution the paresia of both eyes when the patient looked upwards and the disfunction of the cerebellum disappeared, but the paralysis of the lateral gaze to the left, remained. Later on the patient went a little confuse, did not understand what other persons spoke to him, and speak badly. The necropsy showed one old infarct in the medial longitudinal fasciculus in the left, the same type of lesion in the ventral part of the upper pons which was also to the left and demyelinization of the motor lemniscus of the same side. It was also seen a more recent infarct in the transverse gyrus of the left cerebral hemisphere and also the white matter below it. The study of the medial longitudinal fasciculus by means of the secondary degeneration showed that it was crossed above the 6 degrees nuclei, but was straight to the contrary of what is said about it. The authors also observe that the cells of the interstitial nucleus of Cajal were in chromatolysis. These findings justify the syndrome and the absence of the internuclear anterior ophthalmoplegia to the right.

[Considerations on low pressure hydrocephalus]

The physiopathological conditions of the normal pressure hydrocephalus syndrome are analysed. Within a group of 21 patients with clinical sintomathology pertaining this entity, only were 10 selected with a clinical, radiological and cisternografic indubitable diagnosis. It has been noticed that in spite of the stricked selection only a 50% of them have been beneficed by the application of a low pressure valve. Then, the hypothesis that the disease is a multicausal syndrome appears, which by an identical physiopathologic process produces or exhibits a similar clinical, radiological and cisternographic picture. Only those patients on whom the mechanical problem is solved would be beneficed by neurosurgery.