Intensive Blood Pressure Treatment and Subclinical Brain Infarcts: A Secondary Analysis of SPRINT (Systolic Pressure Intervention Trial)

OBJECTIVE

Subclinical brain infarcts (SBI) increase the risk for stroke and dementia, but whether they should be considered equivalent to symptomatic stroke when determining blood pressure targets remains unclear. We tested whether intensive systolic blood pressure (SBP) treatment reduced the risk of new SBI or stroke and determined the association between SBI and cognitive impairment.

METHODS

In this secondary analysis of SPRINT (Systolic Pressure Intervention Trial), participants ≥50 years old, with SBP 130-180mmHg and elevated cardiovascular risk but without known clinical stroke, dementia, or diabetes, were randomized to intensive (<120mmHg) or standard (<140mmHg) SBP treatment. Brain magnetic resonance images collected at baseline and follow-up were read for SBI. The occurrence of mild cognitive impairment (MCI) or probable dementia (PD) was evaluated.

RESULTS

For 667 participants at baseline, SBI were identified in 75 (11%). At median 3.9 years follow-up, 12 of 457 had new SBI on magnetic resonance imaging (5 intensive, 7 standard), whereas 8 had clinical stroke (4 per group). Baseline SBI (subhazard ratio [sHR] = 3.90; 95% CI 1.49 to 10.24; p = 0.006), but not treatment group, was associated with new SBI or stroke. For participants with baseline SBI, intensive treatment reduced their risk for recurrent SBI or stroke (sHR = 0.050; 95% CI 0.0031 to 0.79; p = 0.033). Baseline SBI also increased risk for MCI or PD during follow-up (sHR = 2.38; 95% CI 1.23 to 4.61; p = 0.010).

INTERPRETATION

New cerebral ischemic events were infrequent, but intensive treatment mitigated the increased risk for participants with baseline SBI, indicating primary prevention SBP goals are still appropriate when SBI are present. ANN NEUROL 2024;95:866-875.

Intensive systolic blood pressure treatment remodels brain perivascular spaces: A secondary analysis of the Systolic Pressure Intervention Trial (SPRINT)

BACKGROUND

Brain perivascular spaces (PVS) are part of the glymphatic system and facilitate clearance of metabolic byproducts. Since enlarged PVS are associated with vascular health, we tested whether intensive systolic blood pressure (SBP) treatment affects PVS structure.

METHODS

This is a secondary analysis of the Systolic PRessure INtervention Trial (SPRINT) MRI Substudy: a randomized trial of intensive SBP treatment to goal < 120 mm Hg vs < 140 mm Hg. Participants had increased cardiovascular risk, pre-treatment SBP 130-180, and no clinical stroke, dementia, or diabetes. Brain MRIs acquired at baseline and follow-up were used to automatically segment PVS in the supratentorial white matter and basal ganglia using a Frangi filtering method. PVS volumes were quantified as a fraction of the total tissue volume. The effects of SBP treatment group and major antihypertensive classes on PVS volume fraction were separately tested using linear mixed-effects models while covarying for MRI site, age, sex, Black race, baseline SBP, history of cardiovascular disease (CVD), chronic kidney disease, and white matter hyperintensities (WMH).

RESULTS

For 610 participants with sufficient quality MRI at baseline (mean age 67 ± 8, 40 % female, 32 % Black), greater PVS volume fraction was associated with older age, male sex, non-Black race, concurrent CVD, WMH, and brain atrophy. For 381 participants with MRI at baseline and at follow-up (median ± IQR = 3.9 ± 0.4 years), intensive treatment was associated with decreased PVS volume fraction relative to standard treatment (interaction coefficient: -0.029 [-0.055 to -0.0029] p = 0.029). Reduced PVS volume fraction was also associated with exposure to calcium channel blockers (CCB).

CONCLUSIONS

PVS enlargement was partially reversed in the intensive SBP treatment group. The association with CCB use suggests that improved vascular compliance may be partly responsible. Improved vascular health may facilitate glymphatic clearance. Clincaltrials.gov: NCT01206062.

Diffusion tensor free water MRI predicts progression of FLAIR white matter hyperintensities after ischemic stroke

Background

The progression of FLAIR white matter hyperintensities (WMHs) on MRI heralds vascular-mediated cognitive decline. Even before FLAIR WMH progression, adjacent normal appearing white matter (NAWM) already demonstrates microstructural deterioration on diffusion tensor imaging (DTI). We hypothesized that elevated DTI free water (FW) would precede FLAIR WMH progression, implicating interstitial fluid accumulation as a key pathological step in the progression of cerebral small vessel disease.

Methods

Participants at least 3 months after an ischemic stroke or TIA with WMH on MRI underwent serial brain MRIs every 3 months over the subsequent year. For each participant, the WMHs were automatically segmented, serial MRIs were aligned, and a region of WMH penumbra tissue at risk was defined by dilating lesions at any time point and subtracting baseline lesions. Penumbra voxels were classified as either stable or progressing to WMH if they were segmented as new lesions and demonstrated increasing FLAIR intensity over time. Aligned DTI images included FW and FW-corrected fractional anisotropy (FATissue) and mean diffusivity (MDTissue). Logistic regression and area under the receiver-operator characteristic curve (AUC) were used to test whether baseline DTI predicted voxel-wise classification of stable penumbra or progression to WMH while covarying for clinical risk factors.

Results

In the included participants (n = 26, mean age 71 ± 9 years, 31% female), we detected a median annual voxel-wise WMH growth of 2.9 ± 2.6 ml. Each baseline DTI metric was associated with lesion progression in the penumbra, but FW had the greatest AUC of 0.732 (0.730 - 0.733) for predicting voxel-wise WMH progression pooled across participants.

Discussion

Baseline increased interstitial fluid, estimated as FW on DTI, predicted the progression of NAWM to WMH over the following year. These results implicate the presence of FW in the pathogenesis of cerebral small vessel disease progression.

Intensive Systolic Blood Pressure Treatment Remodels Brain Perivascular Spaces: A Secondary Analysis of SPRINT

Background

Brain perivascular spaces (PVS) are part of the glymphatic system and facilitate clearance of metabolic byproducts. Since enlarged PVS are associated with vascular health, we tested whether intensive systolic blood pressure (SBP) treatment affects PVS structure.

Methods

This is a secondary analysis of the Systolic PRessure INTervention (SPRINT) Trial MRI Substudy: a randomized trial of intensive SBP treatment to goal < 120 mm Hg vs. < 140 mm Hg. Participants had increased cardiovascular risk, pre-treatment SBP 130-180, and no clinical stroke, dementia, or diabetes. Brain MRIs acquired at baseline and follow-up were used to automatically segment PVS in the supratentorial white matter and basal ganglia using a Frangi filtering method. PVS volumes were quantified as a fraction of the total tissue volume. The effects of SBP treatment group and major antihypertensive classes on PVS volume fraction were separately tested using linear mixed-effects models while covarying for MRI site, age, sex, black race, baseline SBP, history of cardiovascular disease (CVD), chronic kidney disease, and white matter hyperintensities (WMH).

Results

For 610 participants with sufficient quality MRI at baseline (mean age 67±8, 40% female, 32% black), greater PVS volume fraction was associated with older age, male sex, non-Black race, concurrent CVD, WMH, and brain atrophy. For 381 participants with MRI at baseline and at follow-up (median = 3.9 years), intensive treatment was associated with decreased PVS volume fraction relative to standard treatment (interaction coefficient: -0.029 [-0.055 to -0.0029] p=0.029). Reduced PVS volume fraction was also associated with exposure to calcium channel blockers (CCB) and diuretics.

Conclusions

Intensive SBP lowering partially reverses PVS enlargement. The effects of CCB use suggests that improved vascular compliance may be partly responsible. Improved vascular health may facilitate glymphatic clearance. Clincaltrials.gov : NCT01206062.

Abstract 55: Intensive Blood Pressure Treatment Remodels Brain Perivascular Spaces: A Secondary Analysis Of The SPRINT MIND Trial

Introduction: Perivascular spaces (PVS) contribute to brain waste clearance pathways, possibly via arterial pulsatility, and are implicated in neurodegenerative disease. Aging, hypertension, and small vessel disease are associated with enlarged PVS, but the effect of intensive blood pressure (BP) control on PVS structure is unknown.

Methods: This is a secondary analysis of the SPRINT-MIND MRI substudy, in which participants with cardiovascular risk but without clinical stroke were randomized to intensive BP control (systolic <120) or standard control (<140) and underwent MRI brain at baseline and 4 years. An established spatial filtering algorithm was applied to T2 images to automatically segment PVS within the supratentorial white matter and basal ganglia. PVS volumes were calculated as a percentage of the tissue volume analyzed. We tested for an effect of intensive BP treatment over time on PVS volume fraction using mixed-effects linear models, including random effects for subject and site, and fixed effects for treatment, timepoint, treatment-by-time interaction, age, and sex.

Results: At randomization 658 participants had useable images (mean age = 67 years, 60% female), and PVS volume fraction was associated with age (Beta=0.0043; CI:0.0012 - 0.0076; p=0.007), white matter hyperintensity volume (B=0.18; 0.13 - 0.23; p<0.0001) and brain parenchymal fraction (B=0.011; 0.004 - 0.018; p=0.003). At mean follow-up of 3.9 years, 243 in the intensive treatment arm and 199 in the standard treatment arm had evaluable pre and post scans. PVS volume fractions were similar at randomization between treatment groups (1.38% vs 1.39%) but decreased with intensive treatment to 1.35% (p=0.022) while remaining stable with standard treatment (interaction p=0.040).

Discussion: Intensive BP treatment reduces the volume of perivascular spaces. These changes may reflect remodeling of waste clearance pathways and/or volume status.

Global changes in diffusion tensor imaging during acute ischemic stroke and post-stroke cognitive performance

Post-stroke cognitive impairment is related to the effects of the acute stroke and pre-stroke brain health. We tested whether diffusion tensor imaging (DTI) can detect acute, global effects of stroke and predict post-stroke cognitive performance. Patients with stroke or TIA enrolled in a prospective cohort study were included if they had 1) at least one DTI acquisition at acute presentation, 24 hours, 5 days, or 30 days, and 2) follow-up testing with the telephone Montreal Cognitive Assessment (T-MoCA) at 30 and/or 90 days. A whole brain, white-matter skeleton excluding the infarct was used to derive mean global DTI measures for mean diffusivity (MD), fractional anisotropy (FA), free water (FW), FW-corrected MD (MD_tissue), and FW-corrected FA (FA_tissue). In 74 patients with ischemic stroke or TIA, there was a transient 4.2% increase in mean global FW between acute presentation and 24 hours (p = 0.024) that returned to initial values by 30 days (p = 0.03). Each acute global DTI measure was associated with 30-day T-MoCA score (n = 61, p = 0.0011-0.0076). Acute global FW, MD, FA and FA_tissue were also associated with 90-day T-MoCA (n = 56, p = 0.0034-0.049). Transient global FW elevation likely reflects stroke-related interstitial edema, whereas other global DTI measures are more representative of pre-stroke brain health.

Abstract WP12: Evolution Of Regional Flair White Matter Hyperintensities After Ischemic Stroke: A Voxel-wise Approach

Background: White matter (WM) degeneration after ischemic stroke may herald post-stroke cognitive decline. FLAIR WM hyperintensity (WMH) reflects tissue injury and accumulates around the infarct and in remote regions. But WMH volumetry is insensitive to regional progression. We compared WMH volumetry to a voxel-wise (VW) approach for detecting FLAIR WMH change longitudinally after stroke.

Methods: Ischemic stroke patients enrolled in an observational cohort study underwent serial MRI acutely, at 1 month and every 3 months thereafter. Patients with 6 to 12-month follow-up were included. WMH lesion volumes were automatically segmented on serial FLAIR MRI. In the hemisphere contralateral to the infarct after 30 days, we compared longitudinal change in WMH volume to a VW regression of FLAIR signal change over time. Serial FLAIR images were nonlinearly aligned using a T1 intermediate. FLAIR intensities were normalized, corrected for local expansion/contraction, and smoothed. Within voxels identified as lesion at any timepoint, significant WMH change was determined relative to the normal appearing WM and converted to percent of total intracranial volume (TICV).

Results: 22 stroke patients (mean age 73, NIHSS 4, infarct volume 10.3cc) had on average 3 follow-ups over 343 days. In the non-stroke hemisphere, volumetry revealed lesion growth in 12 participants (55%) while VW analysis revealed FLAIR signal increase in 15 (68%). For volumetry, mean lesion increase was 0.01 ± 0.20% of TICV per year while VW FLAIR intensity increased in mean 0.11 ± 0.23% of total intracranial voxels. Volumetric growth was associated with the volume of VW signal increase (Std Beta = 0.51, p = 0.02). In the stroke hemisphere, WMH expansion of peri-infarct tissue, consistent with Wallerian degeneration, was present in 10 participants (45%). WMH regression, consistent with atrophy or infarct cavitation, was present in 14 participants (64%). Stroke hemisphere WMH expansion was associated with higher NIHSS (Std B = 0.58, p = 0.009) while regression was associated with larger infarct volumes (Std B = 0.80, p < 0.001).

Conclusions: In early chronic stroke, VW longitudinal WMH analysis detects progressive WM degradation with regional variation and may be more sensitive than gross volumetry.

Abstract TP18: Progressive White Matter Degeneration After Ischemic Stroke

Background: White matter degeneration after ischemic stroke may herald post-stroke cognitive decline. FLAIR white matter hyperintensity (WMH) reflects tissue injury and accumulates around the infarct and in remote regions. But WMH volumetry is insensitive to regional or short-term progression. We compared WMH volumetry to a voxel-wise approach for detecting FLAIR WMH change longitudinally after stroke.

Methods: Ischemic stroke patients enrolled in an observational cohort study underwent serial MRI acutely, at 1 month and every 3 months thereafter. Patients with 6 to 12-month follow-ups were included. WMH lesion volumes were automatically segmented on serial FLAIR MRI. In the hemisphere contralateral to the infarct from 30 days onward, we compared longitudinal change in WMH volume to a voxel-wise regression of FLAIR signal change over time. We used T1 images as an intermediate to nonlinearly align serial FLAIR images to individual templates. FLAIR intensities were normalized, corrected for local expansion/contraction, and smoothed. Within voxels identified as lesion at any timepoint, significant WMH change was determined relative to the normal appearing white matter and converted to a percentage of the intracranial volume.

Results: 22 ischemic stroke patients (mean age 73 ± 8 years, NIHSS 4 ± 4, infarct volume 10.3 ± 23 cc) had on average 3 follow-ups over 343 days. In the non-stroke hemisphere, volumetry revealed lesion growth in 12. Mean lesion increase was 0.01 ± 0.20% per year. In voxel-wise analysis 15 patients had increasing FLAIR signal. Intensity increased in mean 0.11 ± 0.23% of intracranial voxels. Lesion growth was associated with the volume of voxel-wise signal increase (Beta = 0.51, p = 0.018). In the stroke hemisphere, progressive WMH expansion of peri-infarct tissue, consistent with Wallerian degeneration, was present in 10 patients. WMH regression, consistent with atrophy and infarct cavitation, was present in 14. Stroke hemisphere WMH expansion was associated with initial NIHSS (B = 0.58, p = 0.0086) while regression was associated with acute infarct volume (B = 0.80, p < 0.001).

Conclusions: Voxel-wise longitudinal WMH analysis detects progressive white matter degradation and regional variation continuing 30 days after stroke.

Fluid-Attenuated Inversion Recovery Hyperintense Ischemic Stroke Predicts Less Favorable 90-Day Outcome after Intravenous Thrombolysis

INTRODUCTION

The absence of an ischemic lesion on MRI fluid-attenuated inversion recovery (FLAIR) is helpful in predicting stroke onset within 4.5 h. However, some ischemic strokes become visible on FLAIR within 4.5 h. We hypothesized that the early lesion visibility on FLAIR may predict stroke outcome 90 days after intravenous (IV) thrombolysis, independent of time.

MATERIALS AND METHODS

We analyzed data from acute ischemic stroke patients presenting over the last 10 years who were screened with MRI and treated with IV thrombolysis within 4.5 h from onset. Three independent readers assessed whether ischemic lesions seen on diffusion-weighted imaging were also FLAIR positive based on visual inspection. Multivariable regression analyses were used to obtain an adjusted odds ratio of favorable clinical and radiological outcomes based on FLAIR positivity.

RESULTS

Of 297 ischemic stroke patients, 25% had lesion visibility on initial FLAIR. The interrater agreement for the FLAIR positivity assessment was 84% (κ = 0.604, 95% CI: 0.557-0.652). Patients with FLAIR-positive lesions had more right hemispheric strokes (57 vs. 41%, p = 0.045), were imaged later (129 vs. 104 min, p = 0.036), and had less frequent favorable 90-day functional outcome (49 vs. 63%, p = 0.028), less frequent early neurologic improvement (30 vs. 58%, p = 0.001), and more frequent contrast extravasation to the cerebrospinal fluid space (44 vs. 26%, p = 0.008).

CONCLUSIONS

Early development of stroke lesion on FLAIR within 4.5 h of onset is associated with reduced likelihood of favorable 90-day outcome after IV thrombolysis.

Abstract P64: Longitudinal Brain Structural Changes After Stroke

Background: Stroke causes focal and diffuse structural brain changes that may contribute to subsequent cognitive decline and dementia. We hypothesize that MRI structural measures can detect continued cerebral degeneration over the first year after stroke. We identify predictors for progression of brain atrophy, leukoaraiosis and diffusion tensor imaging (DTI) metrics.

Methods: Patients with ischemic stroke were enrolled prospectively in an observational study that included serial brain MRI. Patients underwent MRI FLAIR and DTI at the time of acute stroke and were followed for at least 9 months with multiple MRIs between 30 days and 15 months post-stroke. We used FLAIR to measure brain atrophy as the percent brain parenchymal fraction (BPF) of the total intracranial volume (TICV) and white matter hyperintensity volume (WMHV) as a percentage of TICV. DTI was used to calculate Peak Skeletonized Mean Diffusivity (PSMD), a global measure of white matter integrity previously validated in cerebral small vessel disease. Longitudinal changes in BPF, WMHV or PSMD were measured from 30 days post-stroke onward using linear regression models that included age, stroke volume, baseline BPF and WMHV as predictors.

Results: Twenty-six patients had a median of 4 follow-ups over 9-15 months. Median age was 74 years (range 51-84) and 38% were women. Mean stroke volume was 4.5cc (0 - 30cc). Mean BPF was 78% (72 - 86%) and mean baseline WMHV was 1.1% (0.1 - 3.9%). BPF was associated with age and declined by 0.7% per year (t(111) = 2.7, p = 0.007). Progression was associated with baseline BPF (t(111) = -3.4, p < 0.001). WMHV in the non-stroke hemisphere was associated with age and increased by 0.10% per year (t(87) = -5.8, p < 0.001). Accumulation was associated with age (t(87) = 5.8, p < 0.001). PSMD was associated with baseline WMHV and had a relative increase of 1.9% per year in the non-stroke hemisphere and 4.5% in the stroke hemisphere (t(174) = -2.1, p = 0.03). Progression was associated with age (t(174) = 2.3, p = 0.03) and stroke volume (t(174) = 2.4, p = 0.02).

Conclusions: During the months after ischemic stroke, BPF, WMHV and PSMD can detect persistent structural changes that may reflect later phases of stroke injury or ongoing contributions of aging, silent ischemia, or neurodegeneration.

Abstract P56: Diffusion Tensor Imaging at the Time of Stroke is Associated With Cognitive Performance 4 Months Later

Introduction: Cognitive impairment after stroke is associated with stroke severity and baseline brain health. We hypothesized that acute diffusion tensor imaging (DTI) metrics would identify patients at risk for post-stroke cognitive impairment.

Methods: Patients were enrolled prospectively in an observational study that involves serial MRI and cognitive testing in patients with recent stroke and moderate white matter disease on MRI but without dementia. DTI was performed at the time of stroke; cognitive testing with the MOCA and the Telephone Interview for Cognitive Status (TICS) were performed 3 months later. DTI was used to calculate Peak Skeletonized Mean Diffusivity (PSMD), a measure of global white matter microstructural integrity previously validated in cerebral small vessel disease. Fractional anisotropy maps were skeletonized (figure panel A) and a histogram of the corresponding MD values was used to calculate the peak width in the non-stroke hemisphere (panel B). Linear regression was used to test whether acute PSMD in the non-stroke hemisphere, acute stroke volume, or baseline NIHSS predicted cognitive performance 3 months later.

Results: Fourteen patients followed-up at a median of 123 days. Patients had a median age of 73 years, mean baseline NIHSS of 1.2 (IQR 0-1.75), mean infarct volume of 4cc (range 0-16cc), mean MOCA of 25 (range 19-30), mean TICS of 33 (range 23-41), and 50% were women. Using multivariable linear regression, only acute PSMD predicted follow-up MOCA (std beta= -0.64, adj R 2 = 0.37, p= 0.013) while compared to baseline NIHSS, PSMD showed a stronger association with follow-up TICS score (std beta= -0.57 vs -0.44, p= 0.017; model adj R 2 = 0.476, p= 0.011)(Panel C).

Conclusions: In this cohort of patients with small strokes we found that acute contralateral PSMD provided a measure of brain health that appears to predict cognitive performance at 3 months better than stroke size or severity. These are preliminary findings from an ongoing study.

Abstract P353: FLAIR-Positive Acute Ischemic Stroke and Less Favorable 90-Day Outcome After IV Thrombolysis

Background and Purpose: It is well established that earlier treatment times are associated with better outcomes in acute stroke patients receiving thrombolysis. There is also an association between time from stroke onset and lesion visibility on FLAIR MRI. We hypothesized that lesion visibility on FLAIR, independent of time, may be a predictor of outcome in stroke patients with known onset.

Methods: We analyzed data from acute ischemic stroke patients presenting over the last 10 years who were screened with MRI and treated with IV thrombolysis within 4.5 hours from known onset. Three independent readers assessed whether acute ischemic lesions seen on Diffusion Weighted Imaging were also FLAIR-positive based on visual inspection. Multivariable regression analysis was used to obtain an adjusted odds ratio of favorable clinical and radiological outcomes based on FLAIR-positivity.

Results: Of 310 stroke patients, 24% had lesion visibility on initial FLAIR MRI. The interrater agreement for the FLAIR-positive assessment was 84% (κ=0.604, 95% CI 0.557-0.652). Patients with FLAIR-positive lesions were younger (67 vs 73 years, p=0.028), had more right hemispheric strokes (57% vs 42%, p=0.018), were imaged later (127 vs 104 minutes, p=0.010), had more frequent blood-brain barrier disruption (44% vs 26%, p=0.004), less frequent early neurologic improvement (30% vs 58%, p<0.001), and less frequent favorable 90-day functional outcome (49% vs 63%, p=0.039). Following multivariable logistic regression, older age, greater NIH Stroke Scale, lesion visibility on FLAIR, but not time-from-onset, were independently associated with less favorable outcome.

Conclusions: FLAIR-positive acute ischemic stroke within 4.5 hours of known onset was associated with less favorable 90-day outcome after IV thrombolysis. When compared with time, lesion visibility on FLAIR was more strongly associated with outcome.

Blood Pressure Control in Aging Predicts Cerebral Atrophy Related to Small-Vessel White Matter Lesions

Cerebral small-vessel damage manifests as white matter hyperintensities and cerebral atrophy on brain MRI and is associated with aging, cognitive decline and dementia. We sought to examine the interrelationship of these imaging biomarkers and the influence of hypertension in older individuals. We used a multivariate spatial covariance neuroimaging technique to localize the effects of white matter lesion load on regional gray matter volume and assessed the role of blood pressure control, age and education on this relationship. Using a case-control design matching for age, gender, and educational attainment we selected 64 participants with normal blood pressure, controlled hypertension or uncontrolled hypertension from the Northern Manhattan Study cohort. We applied gray matter voxel-based morphometry with the scaled subprofile model to (1) identify regional covariance patterns of gray matter volume differences associated with white matter lesion load, (2) compare this relationship across blood pressure groups, and (3) relate it to cognitive performance. In this group of participants aged 60–86 years, we identified a pattern of reduced gray matter volume associated with white matter lesion load in bilateral temporal-parietal regions with relative preservation of volume in the basal forebrain, thalami and cingulate cortex. This pattern was expressed most in the uncontrolled hypertension group and least in the normotensives, but was also more evident in older and more educated individuals. Expression of this pattern was associated with worse performance in executive function and memory. In summary, white matter lesions from small-vessel disease are associated with a regional pattern of gray matter atrophy that is mitigated by blood pressure control, exacerbated by aging, and associated with cognitive performance.

Thalamic-hippocampal-prefrontal disruption in relapsing-remitting multiple sclerosis

Background

Cortical, thalamic and hippocampal gray matter atrophy in relapsing–remitting MS (RRMS) is associated cognitive deficits. However, the role of interconnecting white matter pathways including the fornix, cingulum, and uncinate fasciculus (UF) is less well studied.

Objective

To assess MS damage to a hippocampal–thalamic–prefrontal network and the relative contributions of its components to specific cognitive domains.

Methods

We calculated diffusion tensor fractional anisotropy (FA) in the fornix, cingulum and UF as well as thalamic and hippocampal volumes in 27 RRMS patients and 20 healthy controls. A neuropsychological battery was administered and 4 core tests known to be sensitive to MS changes were used to assess cognitive impairment. To determine the relationships between structure and cognition, all tests were grouped into 4 domains: attention/executive function, processing speed, verbal memory, and spatial memory. Univariate correlations with structural measures and depressive symptoms identified potential contributors to cognitive performance and subsequent linear regression determined their relative effects on performance in each domain. For significant predictors, we also explored the effects of laterality and axial versus radial diffusivity.

Results

RRMS patients had worse performance on the Symbol Digit Modalities Test, but no significant impairment in the 4 cognitive domains. RRMS had reduced mean FA of all 3 pathways and reduced thalamic and hippocampal volumes compared to controls. In RRMS we found that thalamic volume and BDI predicted attention/executive function, UF FA predicted processing speed, thalamic volume predicted verbal memory, and UF FA and BDI predicted spatial memory.

Conclusions

Hippocampal–thalamic–prefrontal disruption affects cognitive performance in early RRMS with mild to minimal cognitive impairment, confirming both white and gray matter involvement in MS and demonstrating utility in assessing functional networks to monitor cognition.

•

We detect limbic white matter and gray matter insult in early RRMS patients with mild to minimal cognitive impairment.

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Thalamic atrophy and uncinate fasciculus microstructural changes are associated with cognitive performance in early RRMS.

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Depressive symptomatology also independently predicts cognitive performance

Detection of altered hippocampal morphology in multiple sclerosis-associated depression using automated surface mesh modeling

Depression is very common in multiple sclerosis (MS) but the underlying biological mechanisms are poorly understood. The hippocampus plays a key role in mood regulation and is implicated in the pathogenesis of depression. This study utilizes volumetric and shape analyses of the hippocampus to characterize neuroanatomical correlates of depression in MS. A cross-section of 109 female patients with MS was evaluated. Bilateral hippocampi were segmented from MRI scans (volumetric T1 -weighted, 1 mm(3) ) using automated tools. Shape analysis was performed using surface mesh modeling. Depression was assessed using the Center for Epidemiologic Studies-Depression (CES-D) scale. Eighty-three subjects were classified as low depression (CES-D 0-20) versus 26 subjects with high depression (CES-D ≥ 21). Right hippocampal volumes (P = 0.04) were smaller in the high depression versus the low depression groups, but there was no significant difference in left hippocampal volumes. Surface rendering analysis revealed that hippocampal shape changes in depressed patients with MS were clustered in the right hippocampus. Significant associations were found between right hippocampal shape and affective symptoms but not vegetative symptoms of depression. Our results suggested that regionally clustered reductions in hippocampal thickness can be detected by automated surface mesh modeling and may be a biological substrate of MS depression in female patients.

Fornix damage limits verbal memory functional compensation in multiple sclerosis

Selective atrophy of the hippocampus, in particular the left CA1 subregion, is detectable in relapsing-remitting MS (RRMS) and is correlated with verbal memory performance. We used novel high-resolution imaging techniques to assess the role that functional compensation and/or white matter integrity of mesial temporal lobe (MTL) structures may play in mediating verbal memory performance in RRMS. High-resolution cortical unfolding of structural MRI in conjunction with functional magnetic resonance imaging (fMRI) was used to localize MTL activity in 18 early RRMS patients and 16 healthy controls during an unrelated word-pairs memory task. Diffusion tensor imaging (DTI) and Tract-Based Spatial Statistics (TBSS) were used to assess the integrity of the fornix and the parahippocampal white matter (PHWM), the major efferents and afferents of the hippocampus. RRMS patients showed greater activity in hippocampal and extra-hippocampal areas during unrelated word-pair learning and recall. Increased hippocampal activity, particularly in the right anterior hippocampus and left anterior CA1 was associated with higher verbal memory scores. Furthermore, increased fractional anisotropy (FA) in the fornix was correlated with both greater fMRI activity in this region and better memory performance. Altered hippocampal fMRI activity in RRMS patients during verbal learning may result from both structural damage and compensatory mechanisms. Successful functional compensation for hippocampal involvement in RRMS may be limited in part by white matter damage to the fornix, consistent with the critical role of this pathway in the clinical expression of memory impairment in MS.

Optic disk and white matter abnormalities in a patient with a de novo 18p partial monosomy

PURPOSE

Neuro-ophthalmologic and neuroimaging features of partial chromosome 18p deletion syndromes have not yet been fully described.

METHODS

Careful neuro-ophthalmologic and neuroimaging evaluation of a young woman with a partial 18p deletion, including 3 Tesla MRI and diffusion tensor imaging, cytogenetic analysis on GTG-banded chromosomes, and 244K array CGH analysis.

RESULTS

This 17-year-old girl had modest mental retardation, facial dysmorphism, other characteristics typical of 18p deletion syndrome, and anomalous optic disks. MRI showed enlarged third and lateral ventricles, a thin corpus callosum and patchy white matter signal hyperintensities without enhancement, while diffusion tensor imaging (DTI) revealed significant abnormalities of the corpus callosum with relative sparing of the corticospinal tracts. She had a de novo 14.6 Mb deletion on chromosome 18p [del(18)(p11.2>pter)], a region including 143 genes, only 10 of which were likely candidates for phenotypic expression.

CONCLUSIONS

This young woman had clinical features similar to those described previously with the 18p deletion syndrome, including moderate mental retardation and dysmorphism without focal neurologic signs. She was myopic, like other 18p deletion patients, supporting the concept that 18p contains a candidate locus for myopia. She also had anomalous optic disks, a feature that may be more common in this syndrome than previously recognized. MRI revealed enlarged ventricles and white matter abnormalities that may be explained in part by haploinsufficiency of ADCYAP1 and LPIN2 in the deleted region of chromosome 18.

Smaller cornu ammonis 2-3/dentate gyrus volumes and elevated cortisol in multiple sclerosis patients with depressive symptoms

BACKGROUND

The hippocampus is likely involved in mood disorders, but in vivo evidence for the role of anatomically distinct hippocampal subregions is lacking. Multiple sclerosis, an inflammatory disease of the central nervous system, is linked to a high prevalence of depression as well as hippocampal damage and may thus provide important insight into the pathologic correlates of medical depression. We examined the role of subregional hippocampal volume for depression in relapsing-remitting multiple sclerosis.

METHODS

Anatomically defined hippocampal subregional volumes (cornu ammonis 1-3 [CA1-CA3] and the dentate gyrus [CA23DG], subiculum, entorhinal cortex) were measured using a high-resolution T2-weighted magnetic resonance imaging sequence in 29 relapsing-remitting multiple sclerosis patients and 20 matched healthy control subjects. Diurnal salivary cortisol was assessed at awakening, 4 pm, and 9 pm on 2 consecutive days. Subjects also completed the Beck Depression Inventory.

RESULTS

Multiple sclerosis patients showed smaller hippocampal volumes compared with control subjects, particularly in the CA1 and subiculum subregions. In addition, multiple sclerosis patients with depressive symptoms (Beck Depression Inventory score >13) also showed smaller CA23DG volumes and higher cortisol levels. Within the multiple sclerosis group, CA23DG volume was correlated with depressive symptoms and cortisol levels. There were no associations with number of previous steroid treatments, global atrophy, or disease duration.

CONCLUSIONS

This report provides in vivo evidence for selective association of smaller CA23DG subregional volumes in the hippocampus with cortisol hypersecretion and depressive symptoms in multiple sclerosis.