Cortical superficial siderosis describes a distinct pattern of blood-breakdown product deposition limited to cortical sulci over the convexities of the cerebral hemispheres, sparing the brainstem, cerebellum and spinal cord. Although cortical superficial siderosis has many possible causes, it is emerging as a key feature of cerebral amyloid angiopathy, a common and important age-related cerebral small vessel disorder leading to intracerebral haemorrhage and dementia. In cerebral amyloid angiopathy cohorts, cortical superficial siderosis is associated with characteristic clinical symptoms, including transient focal neurological episodes; preliminary data also suggest an association with a high risk of future intracerebral haemorrhage, with potential implications for antithrombotic treatment decisions. Thus, cortical superficial siderosis is of relevance to neurologists working in neurovascular, memory and epilepsy clinics, and neurovascular emergency services, emphasizing the need for appropriate blood-sensitive magnetic resonance sequences to be routinely acquired in these clinical settings. In this review we focus on recent developments in neuroimaging and detection, aetiology, prevalence, pathophysiology and clinical significance of cortical superficial siderosis, with a particular emphasis on cerebral amyloid angiopathy. We also highlight important areas for future investigation and propose standards for evaluating cortical superficial siderosis in research studies.

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Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary angiopathy caused by mutations in the NOTCH3 gene. The clinical course is highly variable. Little is known about the long-term prognosis and the causes of death in CADASIL patients. Likewise, the impact of gender and NOTCH3 genotype on disease progression remains largely unexplored. We identified 411 subjects (196 men, 215 women) with a definite diagnosis of CADASIL. Age at onset for stroke, immobilization and death as well as the causes of death and clinical status at onset of the cause of death were determined systematically. Weibull regression models were used to calculate times to event, with gender and NOTCH3 genotype as covariates. At the time of the study, 73 patients had died. The median age at onset for stroke was 50.7 years [95% confidence interval (CI) = 48.2-53.1 years] in men and 52.5 years (95% CI = 50.0-54.9 years) in women (P = n.s.). The median ages at onset for inability to walk without assistance [men 58.9 years (95% CI = 56.6-61.3 years); women 62.1 years (59.7-64.4 years)], bedriddenness [men 62.1 years (59.6-64.7 years), women 66.5 years (63.9-69.1 years); and death [men 64.6 years (61.7-67.6 years); women 70.7 years (67.6-73.9 years)] were significantly lower in men than in women (all P < or = 0.01). The median survival time of men was significantly shorter than expected from German life tables (64.6 versus 69.3 years, P = 0.01). In contrast, the median survival time of women was not significantly reduced (70.7 versus 72.2 years). The C117F mutation was associated with a lower age at death and the C174Y mutation with a lower age at onset for stroke, immobilization and death (adjusted P values <0.05). At onset of the cause of death, 78% of the subjects were completely dependent. Sixty-three per cent were confined to bed. Pneumonia was the most frequent cause of death (38%), followed by sudden unexpected death (26%) and asphyxia (12%). We conclude that male sex is a risk factor for early immobilization and death in CADASIL. Our findings suggest possible genotype-phenotype correlations with regard to disease progression. The data presented may serve as source material for counselling CADASIL patients and for designing future interventional trials.

Cerebral small vessel disease is the most common cause of vascular cognitive impairment. It typically manifests with lacunar infarcts and ischaemic white matter lesions. However, little is known about how these lesions relate to the cognitive symptoms. Previous studies have found a poor correlation between the burden of ischaemic lesions and cognitive symptoms, thus leaving much of the variance in cognitive performance unexplained. The objective of the current study was to investigate the relationship between the location of subcortical ischaemic lesions and cognitive symptoms in small vessel disease. We applied a voxel-based lesion-symptom mapping approach to data from 215 patients with CADASIL, a genetically defined small vessel disease with mutations in the NOTCH3 gene. All patients were examined by magnetic resonance imaging and comprehensive neuropsychological testing. Lacunar lesions and white matter lesions were segmented on three-dimensional T(1) and fluid-attenuated inversion recovery sequences, respectively. One hundred and forty-five subjects had a total of 854 lacunar lesions (range 1-13 per individual). The normalized volume of white matter hyperintensities ranged from 0.0425% to 21.5% of the intracranial cavity. Significant clusters for cognitive performance were detected for both lacunar lesions and white matter hyperintensities. The most prominent results were obtained on a compound score for processing speed, the predominantly affected cognitive domain in this group of patients. Strategic locations included the anterior parts of the thalamus, the genu and anterior limb of the internal capsule, the anterior corona radiata and the genu of the corpus callosum. By combining the lesion-symptom mapping data with information from a probabilistic white matter atlas we found that the majority of the processing speed clusters projected on the anterior thalamic radiation and the forceps minor. In multivariate models that included demographic parameters, brain atrophy and the volume of ischaemic lesions, regional volumes of lacunar lesions and white matter hyperintensities in the anterior thalamic radiation predicted performance in processing speed tasks, whereas there was no independent contribution of the global volume of ischaemic lesions. These observations emphasize the importance of lesion location for both lacunar and ischaemic white matter lesions. Our findings further highlight the anterior thalamic radiation as a major anatomical structure impacting on processing speed. Together these findings provide strong support for a central role of frontal-subcortical circuits in cerebral small vessel disease and vascular cognitive impairment.

Hepatic glucose production by gluconeogenesis is the main source of glucose during fasting and contributes significantly to hyperglycemia in diabetes mellitus. Accordingly, glucose metabolism is tightly controlled by a variety of hormones including insulin, epinephrine, glucagon, and glucocorticoids (GCs) acting on various cell types. GC effects are mediated by the GC receptor (GR), a ligand-dependent transcription factor, which in the liver and kidney controls gluconeogenesis by induction of gluconeogenic enzymes. To specifically study the contribution of GC on liver carbohydrate metabolism, we generated mice with an inactivation of the GR gene exclusively in hepatocytes using the Cre/loxP technology. Half of the mutant mice die within the first 2 d after birth most likely due to hypoglycemia. Adult mice have normal blood sugar under basal conditions but show hypoglycemia after prolonged starvation due to reduced expression of genes involved in gluconeogenesis. We further demonstrate that absence of GR in hepatocytes limits the development of hyperglycemia in streptozotocin-induced diabetes mellitus probably due to impaired induction of gluconeogenesis. These findings show the essential role of GR function in liver glucose metabolism during fasting and in diabetic mice and indicate that liver-specific GC antagonists could be beneficial in control of diabetic hyperglycemia.

NOTCH3 pathogenic variant position is the most important determinant of CADASIL disease severity, with EGFr 7-34 pathogenic variant predisposing to a later onset of stroke and longer survival.

This study identifies brain atrophy as an important aspect of the disease process in CADASIL and establishes significant correlations with multiple clinical aspects including cognition. Age and systolic blood pressure are risk factors for brain volume loss during follow-up. Percent brain volume change seems promising as an adjunct outcome measure in future interventional trials.