Ruptured intracranial aneurysm. Clinical series

Chronic circadian misalignment accelerates immune senescence and abbreviates lifespan in mice

Modern society characterized by a 24/7 lifestyle leads to misalignment between environmental cycles and endogenous circadian rhythms. Persisting circadian misalignment leads to deleterious effects on health and healthspan. However, the underlying mechanism remains not fully understood. Here, we subjected adult, wild-type mice to distinct chronic jet-lag paradigms, which showed that long-term circadian misalignment induced significant early mortality. Non-biased RNA sequencing analysis using liver and kidney showed marked activation of gene regulatory pathways associated with the immune system and immune disease in both organs. In accordance, we observed enhanced steatohepatitis with infiltration of inflammatory cells. The investigation of senescence-associated immune cell subsets from the spleens and mesenteric lymph nodes revealed an increase in PD-1⁺CD44^high CD4 T cells as well as CD95⁺GL7⁺ germinal center B cells, indicating that the long-term circadian misalignment exacerbates immune senescence and consequent chronic inflammation. Our results underscore immune homeostasis as a pivotal interventional target against clock-related disorders.

Effects of smoking and hypertension on wall shear stress and oscillatory shear index at the site of intracranial aneurysm formation

OBJECTIVE

The mechanisms by which smoking and hypertension lead to increased incidence of intracranial aneurysm (IA) formation remain poorly understood. The current study investigates the effects of these risk factors on wall shear stress (WSS) and oscillatory shear index (OSI) at the site of IA initiation.

METHODS

Two (n=2) IAs from two patients with history of smoking and hypertension were artificially removed with the help of software @neuFuse (Supercomputing Solutions, Bologna, Italy) and the vessel geometry reconstructed to mimic the condition prior to IA formation. Two computational fluid dynamics (CFD) analyses were performed on each data-set by using in turn the normal physiological values of blood viscosity (BV), and high BV values specific to smoking and hypertension, obtained from literature.

RESULTS

At normal BV, high WSS (>15 Pa) was observed at the site of IA initiation in both patients. When BV values specific to smoking and hypertension were used, both the areas affected by high WSS (>15 Pa) and the maximum WSS were increased whilst the magnitude and distribution of OSI showed no significant change.

CONCLUSIONS

Long-term exposure to high WSS may result in an increased risk of IA development. An incremental increase in areas of high WSS observed secondary to smoking and hypertension may indicate a further increase in the risk of IA initiation. Interestingly, the relationship between BV and the area of increased WSS was not linear, reflecting the need for patient-specific CFD analysis.

Intracranial aneurysms and arterial hypertension: a review and hypothesis

BACKGROUND

Intracranial aneurysms and systemic arterial hypertension coexist in a high percentage of patients. The relationship between intracranial aneurysms and hypertension is poorly defined.

METHODS

Therefore, we reviewed the role of hypertension in the pathogenesis of saccular aneurysms as previously reported in clinical, experimental, and autopsy studies.

RESULTS

Among 24 relevant clinical and/or autopsy studies, the mean incidence of pre-existing hypertension was 43.5% in aneurysm patients compared to 24.4% in the normal population. Although definitive evidence is lacking, data from multiple types of investigations indicate that systemic arterial hypertension creates a greater risk for the development of intracranial aneurysms than previously believed. The underlying pathophysiological mechanism(s) are also poorly defined.

CONCLUSIONS

We propose a unifying hypothesis: Endothelial injury, occlusion of the vasa vasorum, and disruption of the synthesis of collagen and elastin are likely the most important factors in initiating the development of aneurysms. Chronic hypertension potentially affects all of these factors. Consequently, chronic hypertension may cause intimal thickening, necrosis of the tunica media, changes in the compositional matrix, and degeneration of the internal elastic lamina to develop in the arterial wall. These structural changes could cause a focal weakening in the arterial wall with resultant bulging. This theory accounts for the high incidence of intracranial aneurysms in the absence of any known associated hereditary or connective-tissue disease. Nor does it exclude the possibility of other etiological factors. From the perspective of prevention, however, it offers clear opportunities for prophylaxis.

Intracranial aneurysms and cocaine abuse: analysis of prognostic indicators

OBJECTIVE

The outcome of subarachnoid hemorrhage associated with cocaine abuse is reportedly poor. However, no study in the literature has reported the use of a statistical model to analyze the variables that influence outcome.

METHODS

A review of admissions during a 6-year period revealed 14 patients with cocaine-related aneurysms. This group was compared with a control group of 135 patients with ruptured aneurysms and no history of cocaine abuse. Age at presentation, time of ictus after intoxication, Hunt and Hess grade of subarachnoid hemorrhage, size of the aneurysm, location of the aneurysm, and the Glasgow Outcome Scale score were assessed and compared.

RESULTS

The patients in the study group were significantly younger than the patients in the control group (P < 0.002). In patients in the study group, all aneurysms were located in the anterior circulation. The majority of these aneurysms were smaller than those of the control group (8 +/- 6.08 mm versus 11 +/- 5.4 mm; P = 0.05). The differences in mortality and morbidity between the two groups were not significant. Hunt and Hess grade (P < 0.005) and age (P < 0.007) were significant predictors of outcome for the patients with cocaine-related aneurysms.

CONCLUSION

Cocaine use predisposed aneurysmal rupture at a significantly earlier age and in much smaller aneurysms. Contrary to the published literature, this group did reasonably well with aggressive management.

Risk factors in intracranial saccular aneurysms. Aspects on the formation and rupture of aneurysms, and development of cerebral vasospasm

Intracranial saccular aneurysms have been a well-known clinical and pathological entity for over two centuries. The pathophysiological events that lead to aneurysm formation and rupture are, however, poorly understood. Besides an HLA-associated genetic factor, the most widely accepted risk factors are arterial hypertension, female gender, and increasing age. Some aneurysm patients have a deficient formation of Type III collagen. This seems to interfere with the mechanical integrity of the cerebral arterial wall encouraging aneurysm formation. While some of the risk factors may be involved in the process of aneurysm formation, others may be of importance in the actual aneurysm rupture. Medical and surgical developments have only had a slight impact on mortality rates from aneurysm rupture. The principal cause of death and disability is cerebral arterial spasm. Considerable effort has been expended in investigating the etiology of this phenomenon. Previous studies have failed to yield conclusive evidence of the causative agent(s) or the nature of cerebral artery narrowing. The time course of vasospasm after the onset of subarachnoid hemorrhage is consistent with an immune-mediated response, and more recent observations suggest that immunological processes including activation of the complement system may be involved. Missed minor bleeding episodes may thus be a risk factor for aneurysm patients in respect to the development of cerebral vasospasm.

Direct evidence of hypertension and the possible role of post-menopause oestrogen deficiency in the pathogenesis of berry aneurysms

To determine the significance of hypertension in the pathogenesis of berry aneurysms, 113 patients with subarachnoid haemorrhage (SAH) and verified aneurysm and 63 patients with SAH without aneurysm were compared. Of those patients with angiographically verified aneurysms, 61.9% were found to have elevated blood pressure (greater than 160/95 mmHg) and 19.5% showed electrocardiographic signs of left ventricular hypertrophy (SV1 + RV5 (6) greater than 3.5 mV). The percentages for patients without aneurysm were 36.5% and 6.4% respectively. A significant correlation was found between anterior aneurysms and left ventricular hypertrophy (P less than 0.01). The mean Sokolow index values were also significantly elevated in cases of aneurysm (P less than 0.01). There was a complementary relationship between the extent of left ventricular hypertrophy and the percentage of females with regard to localization of an aneurysm and age group. The predominance of females in the total aneurysm population, in the 50- to 59-year-old age group, and among patients with internal carotid aneurysms indicates that a sex-specific hormonal factor may also play a role in the pathogenesis of aneurysms in addition to hypertension. The collagen wasting commonly observed in bone and skin in the post-menopausal period due to decreased oestrogen levels could possibly be responsible for the formation of aneurysms in the proximal segments of the cerebral arteries, as occurs in various connective tissue diseases.

Intracranial aneurysms. Age, sex, blood pressure, and multiplicity in an unselected series of patients

All cases of intracranial aneurysm, arteriovenous malformation, and subarachnoid hemorrhage of undetermined etiology seen at one hospital over a 13-year period were reviewed to assess relationships between age, sex, systolic and diastolic blood pressure, and number of aneurysms. There were 350 patients, of whom 212 had aneurysms. The major findings were as follows: 1) Hypertension was not significantly more prevalent in the aneurysm population than in the age-matched general population, except for females aged 18 to 54 years (systolic pressure elevation of 10 to 15 mm Hg). 2) Under 55 years of age, both male and female hypertensive patients were twice as likely to have multiple aneurysms as normotensive patients. 3) Females were more likely than males to have multiple aneurysms. 4) For females but not males, increasing age, higher systolic pressure, and higher diastolic pressure all correlated with an increasing number of aneurysms. Hypertension appears to be more prevalent in certain subgroups of the total aneurysm population, although the individual relationships between hypertension, atherosclerosis, and aneurysms cannot be determined from either the present or previous studies. The possible role of familial factors, as well as implications for both diagnosis and further research, are briefly noted.

Prognostic factors in ruptured aneurysms of the circle of Willis: the significance of systemic hypertension

The incidence of essential hypertension has been retrospectively studied in a group of sixty-four fatal cases of ruptured berry aneurysm, and compared with a non-fatal group. Hypertension is more frequent in the fatal group, and is associated with a higher incidence of multiple aneurysms, a smaller size of aneurysm at rupture and a poorer survival after two haemorrhages when comparison is made with normotensive patients. The possible role of hypertension in the development and rupture of aneurysms is discussed, and it is concluded that it may contribute to both. Following rupture it carries a poor prognosis with a resulting over emphasis of its significance in autopsy series. Possible mechanisms for this effect include diffuse vascular disease, and an increased liability to oedema or spasm following rupture of an aneurysm.

Cardiac abnormalities in subarachnoid hemorrhage: a resumé

There have been numerous reports demonstrating electrocardiographical changes secondary to subarachnoid hemorrhage, consisting of atrial and ventricular arrhythmias, alterations in QRS configuration, Q-T interval prolongation, T-wave abnormalities, and S-T segment elevation or depression. Abnormalities of cardiac muscle and subendocardial hemorrhage have been seen in patients dying of subarachnoid hemorrhage. Experimental work has shown that electrical impulses in the sympathetic nervous system and hypothalamus produce most of these changes, and the implication is that these changes can be prevented by sympathetic blockade. Pulmonary edema also has been shown to occur frequently after subarachnoid hemorrhage, and again the sympathetic nervous system is implicated in the pathophysiology. Studies done illustrating these points are discussed and conclusions drawn with reference to therapy.

Abnormal U waves in the electrocardiogram in subarachnoid haemorrhage

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