Brain microbleeds: Epidemiology and clinical implications

Systematic Review on the Role of Lobar Cerebral Microbleeds in Cognition

BACKGROUND

Cerebral microbleeds (CMBs) are small round/oval lesions seen in MRI-specific sequences. They are divided in deep and lobar according to their location. Lobar CMBs (L-CMBs) are commonly associated with amyloid angiopathy. Although CMBs have been considered clinically silent for a long time, a growing body of evidence has shown that they could play a crucial role in cognitive functioning.

OBJECTIVE

The aim of this systematic review was to estimate the role of L-CMBs in cognitive performance.

METHODS

We selected, from the Cochrane Library, Embase, PubMed, and ScienceDirect databases, clinical studies, published from January 2000 to January 2020 and focused on the association between L-CMBs and cognitive functions. The inclusion criteria were: 1) participants grouped according to presence or absence of CMBs, 2) extensive neuropsychological examination, 3) CMBs differentiation according to topographical distribution, and 4) MRI-based CMB definition (< 10 mm and low signal in T2*/SWI). The impact of L-CMBs was separately assessed for executive functions, visuospatial skills, language, and memory.

RESULTS

Among 963 potentially eligible studies, six fulfilled the inclusion criteria. Four studies reported a greater reduction in executive performances in participants with L-CMB and two studies showed a statistically significant association between visuospatial dysfunction and L-CMBs. No association was found between hippocampal memory or language abilities and L-CMBs.

CONCLUSION

Lobar CMBs are associated with a reduction of processing speed and visuospatial performances, thus suggesting the contribution of vascular amyloid deposition to this cognitive profile. This occurrence enables us to suspect an underlying Alzheimer's disease pathology even in absence of typical hippocampal memory impairment.

Central Nervous System Injury in Patients With Severe Acute Respiratory Syndrome Coronavirus 2: MRI Findings

Due to the presence of a new and rapidly spreading coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the World Health Organization declared the coronavirus disease 2019 (COVID-19) outbreak a pandemic on March 11, 2020. This new disease has a multisystemic effect that predominantly targets the respiratory system; however, neurologic symptoms have been documented in approximately 36% of patients with confirmed COVID-19. During the period of March 2020 to March 2021, 481 brain MRI studies were performed by medical request. Of these, 9.7% (n = 47) were hospitalized with a diagnosis of COVID-19 pneumonia confirmed by SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) test with the following findings: microbleeds, osmotic demyelination, arterial thrombosis, ischemic infarcts, venous thrombosis, metabolic cerebellar syndrome, posterior reversible leukoencephalopathy, abnormal signal intensity in the frontal lobes and olfactory bulbs, microangiopathy, gliosis, and findings consistent with hypoxic-ischemic encephalopathy. In patients with histories of malignant central nervous system (CNS) tumors, the most frequent histological lineage being high-grade glioma, 100% progression was identified with respect to previous imaging studies, without other significant findings. In two patients, a brain MRI was performed due to altered alertness, identifying only involutive changes in the brain parenchyma; MRI was repeated 72 hours later, after a lack of improvement in higher functions, without identifying imaging findings. To date, limited studies have documented CNS abnormalities related to COVID-19 using MRI. Therefore, the purpose of this study is to present abnormal imaging findings in patients with SARS-CoV-2 infection and their clinical correlations.

Clinical and radiological features of cerebral amyloid angiopathy-related inflammation

OBJECTIVES

We want to report the clinical and radiological features of our cohort of patients diagnosed with cerebral amyloid angiopathy-related inflammation (CAA-RI) according to the Boston Criteria and additionally to disclose some atypical clinical characteristics observed in some of them to provide more knowledge about this novel entity.

METHODS

We describe 5 patients with probable CAA-RI according to a validation study of proposed criteria for the diagnosis of CAA-RI at University Hospital Josep Trueta of Girona. We consider some clinical characteristics which include the response to immunotherapy, CSF findings, and MRI features. The patient's neurologic outcomes were assessed using the modified Rankin Scale (mRS).

RESULTS

We collected 5 patients admitted for probable CAA-RI. Most were women and the median age was 72 years. The median mRS score at the onset of disease was 1. Parietal lobes were most affected clinically as well as radiologically. Two patients had intracranial hemorrhage. Decreased levels of CSF amyloid beta 42 and 40 protein were observed. Corticosteroids were used in four patients and a remarkable improvement was observed in all of them.

CONCLUSIONS

CAA-RI is a condition that predominantly affects parietal lobes according to our case series and this involvement seems to be directly related to a greater burden of microbleeds, cortical siderosis, WMH, and lobar hemorrhages on these lobes. Decreased levels of CSF amyloid beta protein plus increased total tau protein should be considered as part of the diagnostic criteria of CAA-RI. We recommend corticosteroids using, as they have been demonstrated to be very effective in managing CAA-RI.