Severe underweight and cerebral microbleeds

Relationship between obesity and structural brain abnormality: Accumulated evidence from observational studies

We aimed to evaluate the relationship between obesity and structural brain abnormalities assessed by magnetic resonance imaging using data from 45 observational epidemiological studies, where five articles reported prospective longitudinal results. In cross-sectional studies' analyses, the pooled weighted mean difference for total brain volume (TBV) and gray matter volume (GMV) in obese/overweight participants was -11.59 (95 % CI: -23.17 to -0.02) and -10.98 (95 % CI: -20.78 to -1.18), respectively. TBV was adversely associated with BMI and WC, GMV with BMI, and hippocampal volume with BMI, WC, and WHR. WC/WHR are associated with a risk of lacunar and white matter hyperintensity (WMH). In longitudinal studies' analyses, BMI was not statistically associated with the overall structural brain abnormalities (for continuous BMI: RR = 1.02, 95 % CI: 0.94-1.12; for categorial BMI: RR = 1.18, 95 % CI: 0.75-1.85). Small sample size of prospective longitudinal studies limited the power of its pooled estimates. A higher BMI is associated with lower brain volume while greater WC/WHR, but not BMI, is related to a risk of lacunar infarct and WMH. Future longitudinal research is needed to further elucidate the specific causal relationships and explore preventive measures.

No Impact of Body Mass Index on Outcome in Stroke Patients Treated with IV Thrombolysis BMI and IV Thrombolysis Outcome

Background and Purpose

The impact of excess body weight on prognosis after stroke is controversial. Many studies report higher survival rates in obese patients (“obesity paradox”). Recently, obesity has been linked to worse outcomes after intravenous (IV) thrombolysis, but the number and sample size of these studies were small. Here, we aimed to assess the relationship between body weight and stroke outcome after IV thrombolysis in a large cohort study.

Methods

In a prospective observational multicenter study, we analyzed baseline and outcome data of 896 ischemic stroke patients who underwent IV thrombolysis. Patients were categorized according to body mass index (BMI) as underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25–29.9 kg/m²), obese (30–34.9 kg/m²) or severely obese (>35 kg/m²). Using uni- and multivariate modeling, we assessed the relationship of BMI with favorable outcome (defined as modified Rankin Scale 0 or 1) and mortality 3 months after stroke as well as the occurrence of symptomatic intracerebral hemorrhages (sICH). We also measured the incidence of patients that had an early neurological improvement of >40% on the National Institutes of Health Stroke Scale (NIHSS) after 24 hours.

Results

Among 896 patients, 321 were normal weight (35.8%), 22 underweight (2.5%), 378 overweight (42.2%), 123 obese (13.7%) and 52 severely obese (5.8%). Three-month mortality was comparable in obese vs. non-obese patients (8.1% vs. 8.3%) and did not differ significantly among different BMI groups. This was also true for favorable clinical outcome, risk of sICH and early neurological improvement on NIHSS at 24 hours. These results remained unchanged after adjusting for potential confounding factors in the multivariate analyses.

Conclusion

BMI was not related to clinical outcomes in stroke patients treated with IVT. Our data suggest that the current weight-adapted dosage scheme of IV alteplase is appropriate for different body weight groups, and challenge the existence of the obesity paradox after stroke.

Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping

The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

Risk Factors Associated With Incident Cerebral Microbleeds According to Location in Older People: The Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study

IMPORTANCE

The spatial distribution of cerebral microbleeds (CMBs), which are asymptomatic precursors of intracerebral hemorrhage, reflects specific underlying microvascular abnormalities of cerebral amyloid angiopathy (lobar structures) and hypertensive vasculopathy (deep brain structures). Relatively little is known about the occurrence of and modifiable risk factors for developing CMBs, especially in a lobar location, in the general population of older people.

OBJECTIVE

To investigate whether lifestyle and lipid factors predict new CMBs in relation to their anatomic location.

DESIGN, SETTING, AND PARTICIPANTS

We enrolled 2635 individuals aged 66 to 93 years from the population-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study in a brain imaging study. Participants underwent a baseline magnetic resonance imaging (MRI) examination of the brain from September 1, 2002, through February 28, 2006, and returned for a second MRI examination from April 1, 2007, through September 30, 2011.

EXPOSURES

Lifestyle and lipid factors assessed at baseline included smoking, alcohol consumption, body mass index, and serum levels of total cholesterol, high- and low-density lipoprotein cholesterol, and triglycerides.

MAIN OUTCOMES AND MEASURES

Incident CMBs detected on MRIs, which were further categorized as exclusively lobar or as deep.

RESULTS

During a mean follow-up of 5.2 years, 486 people (18.4%) developed new CMBs, of whom 308 had lobar CMBs only and 178 had deep CMBs. In the multivariate logarithm-binomial regression model adjusted for baseline cardiovascular risk factors, including blood pressure, antihypertensive use, prevalent CMBs, and markers of cerebral ischemic small-vessel disease, heavy alcohol consumption (vs light to moderate consumption; relative risk [RR], 2.94 [95% CI, 1.23-7.01]) was associated with incident CMBs in a deep location. Baseline underweight (vs normal weight; RR, 2.41 [95% CI, 1.21-4.80]), current smoking (RR, 1.47 [95% CI, 1.11-1.94]), an elevated serum level of high-density lipoprotein cholesterol (RR per 1-SD increase, 1.13 [95% CI, 1.02-1.25]), and a decreased triglyceride level (RR per 1-SD decrease in natural logarithm-transformed triglyceride level, 1.17 [95% CI, 1.03-1.33]) were significantly associated with an increased risk for lobar CMBs exclusively but not for deep CMBs.

CONCLUSIONS AND RELEVANCE

Lifestyle and lipid risk profiles for CMBs were similar to those for symptomatic intracerebral hemorrhage and differed for lobar and deep CMBs. Modification of these risk factors could have the potential to prevent new-onset CMBs, particularly those occurring in a lobar location.

Susceptibility Weighted Imaging and Mapping of Micro-Hemorrhages and Major Deep Veins after Traumatic Brain Injury

Micro-hemorrhages are a common result of traumatic brain injury (TBI), which can be quantified with susceptibility weighted imaging and mapping (SWIM), a quantitative susceptibility mapping approach. A total of 23 TBI patients (five women, 18 men; median age, 41.25 years old; range, 21.69-67.75 years) with an average Glasgow Coma Scale score of 7 (range, 3-15) at admission were recruited at mean 149 d (range, 57-366) after injury. Susceptibility-weighted imaging data were collected and post-processed to create SWIM images. The susceptibility value of small hemorrhages (diameter ≤10 mm) and major deep veins (right septal, left septal, central septal, right thalamostriate, left thalamostriate, internal cerebral, right basal vein of Rosenthal, left basal vein of Rosenthal, and pial veins) were evaluated. Different susceptibility thresholds were tested to determine SWIM's sensitivity and specificity for differentiating hemorrhages from the veins. A total of 253 deep veins and 173 small hemorrhages were identified and evaluated. The mean susceptibility of hemorrhages was 435±206 parts per billion (ppb) and the mean susceptibility of deep veins was 108±56 ppb. Hemorrhages showed a significantly higher susceptibility than all deep veins (p<0.001). With different thresholds (250, 227 and 200 ppb), the specificity was 97%, 95%, and 92%, and the sensitivity was 84%, 90%, and 92%, respectively. These results show that SWIM could be used to differentiate hemorrhages from veins in TBI patients in a semi-automated manner with reasonable sensitivity and specificity. A larger cohort will be needed to validate these findings.