Impairment of anti-platelet-aggregating activity of endothelial cells after experimental subarachnoid hemorrhage

Prevention of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage-Summary of Existing Clinical Evidence

The 2023 International Subarachnoid Hemorrhage Conference identified a need to provide an up-to-date review on prevention methods for delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage and highlight areas for future research. A PubMed search was conducted for key factors contributing to development of delayed cerebral ischemia: anesthetics, antithrombotics, cerebrospinal fluid (CSF) diversion, hemodynamic, endovascular, and medical management. It was found that there is still a need for prospective studies analyzing the best methods for anesthetics and antithrombotics, though inhaled anesthetics and antiplatelets were found to have some advantages. Lumbar drains should increasingly be considered the first line of CSF diversion when applicable. Finally, maintaining euvolemia before and during vasospasm is recommended as there is no evidence supporting prophylactic spasmolysis or angioplasty. There is accumulating observational evidence, however, that intra-arterial spasmolysis with refractory DCI might be beneficial in patients not responding to induced hypertension. Nimodipine remains the medical therapy with the most support for prevention.

The management of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a rare event affecting relatively young patients therefore leading to a high social impact. The management of SAH follows a biphasic course with early brain injuries in the first 72 hours followed by a phase at risk of secondary deterioration due to delayed cerebral ischemia (DCI) in 20 to 30% patients. Cerebral infarction from DCI is the most preventable cause of mortality and morbidity after SAH. DCI prevention, early detection and treatment is therefore advocated. Formerly limited to the occurrence of vasospasm, DCI is now associated with multiple pathophysiological processes involving for instance the macrocirculation, the microcirculation, neurovascular units, and inflammation. Therefore, the therapeutic targets and management strategies are also evolving and are not only focused on proximal vasospasm. In this review, we describe the current knowledge of DCI pathophysiology. We then discuss the diagnosis strategies that may guide physicians at the bedside with a multimodal approach in the unconscious patient. We will present the prevention strategies that have proven efficient as well as future targets and present the therapeutic approach that is currently being developed when a DCI occurs.

Role of platelets in the pathogenesis of delayed injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) patients develop delayed cerebral ischemia and delayed deficits (DCI) within 2 weeks of aneurysm rupture at a rate of approximately 30%. DCI is a major contributor to morbidity and mortality after SAH. The cause of DCI is multi-factorial with contributions from microthrombi, blood vessel constriction, inflammation, and cortical spreading depolarizations. Platelets play central roles in hemostasis, inflammation, and vascular function. Within this review, we examine the potential roles of platelets in microthrombi formation, large artery vasospasm, microvessel constriction, inflammation, and cortical spreading depolarization. Evidence from experimental and clinical studies is provided to support the role(s) of platelets in each pathophysiology which contributes to DCI. The review concludes with a suggestion for future therapeutic targets to prevent DCI after aSAH.

Follow-Up DSA at Day 9 ± 2 after Subarachnoid Hemorrhage Predicts Long-Term Recurrence of Ruptured Cerebral Aneurysm after Coiling

Objective

The recurrence rate of coiled ruptured cerebral aneurysms is greater than that of clipped aneurysms. The aim of this study is to determine the factors that relate to the recurrence of embolized, ruptured cerebral aneurysms, and the evidence thereto.

Methods

From April 2007 through July 2017, we treated 134 ruptured cerebral aneurysm cases by coiling. DSA and/or MRI were done in 98 saccular aneurysm cases one year after the coiling. Recurrence was defined as enlargement of the aneurysm neck or contrast opacification along the aneurysm wall. A chi-square test and a logistic regression analysis were done to analyze the relationship between aneurysm recurrence and clinical factors.

Results

The median follow-up period was 58 months (interquartile range [IQR]: 33-107). Ten cases (10.2%) were subjected to aneurysm recurrence. Internal carotid artery (ICA) aneurysms proximal to the posterior communicating artery, incomplete obliteration of an aneurysm at initial embolization and postoperative DSA during day 9 ± 2, and increased contrast medium in the aneurysm at postoperative DSA during day 9 ± 2 were all statistically related to the recurrence of the aneurysm. Logistic regression analysis showed that the increased contrast medium in the aneurysm at day 9 ± 2 was statistically related to aneurysm recurrence (p <0.0001). Recurrence or retreatment of the aneurysm did not influence the outcome.

Conclusion

Complete obliteration of the aneurysm at the first session is important. Recurrence of an embolized ruptured aneurysm can be estimated by postoperative DSA at day 9 ± 2 days.

Endovascular Treatment Strategy and Clinical Outcomes for Ruptured Blood Blister-Like Aneurysms of the Internal Carotid Artery Using Low-Profile Visualized Intraluminal Support Stent

OBJECTIVE

It is challenging to safely treat blood blister-like aneurysms (BBAs) of the internal carotid artery. Endovascular surgery has been reported, but the optimal strategy is yet to be established. We report our endovascular treatment strategy using the Low-profile Visualized Intraluminal Support (LVIS) stent.

METHODS

Twelve patients with ruptured BBAs including 1 patient with 2 separate aneurysmal bulges were treated from December 2017 to January 2020. Single LVIS stent-assisted coil embolization was performed as the initial treatment. If the coil could not be placed in the aneurysm, or follow-up angiography showed persistent filling or regrowth of the aneurysm, a second LVIS stent was deployed as an overlapping stent. Clinical characteristics, treatment details, and clinical outcomes were retrospectively examined.

RESULTS

Single stent-assisted coiling was performed in 8 patients (69%), 2 overlapping stents with coiling in 1 (8%), a single stent in 2 (15%), and 2 overlapping stents in 2 (15%). Three patients with persistent filling or regrowth of the aneurysm were re-treated with overlapping stents. Follow-up angiography confirmed complete occlusion in 12 aneurysms (92%). No re-rupture occurred. Postoperative symptomatic ischemia was confirmed in 4 patients (33%), and all 4 patients suffered severe subarachnoid hemorrhage. Modified Rankin scale was 0-2 in 8 patients (67%).

CONCLUSIONS

LVIS stent-assisted coil embolization is effective in preventing re-rupture of BBAs. However, the morphology of the aneurysm may change within a short period, so careful angiographic follow-up is needed. Appropriate preoperative antiplatelet administration and optimal timing of the treatment may reduce the risk of postoperative ischemic complication.

Effects of post-interventional antiplatelet therapy on angiographic vasospasm, delayed cerebral ischemia, and clinical outcome after aneurysmal subarachnoid hemorrhage: a single-center experience

Platelet activation has been postulated to be involved in the pathogenesis of delayed cerebral ischemia (DCI) and cerebral vasospasm (CVS) after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to investigate potentially beneficial effects of antiplatelet therapy (APT) on angiographic CVS, DCI-related infarction and functional outcome in endovascularly treated aSAH patients. Retrospective single-center analysis of aSAH patients treated by endovascular aneurysm obliteration. Based on the post-interventional medical regime, patients were assigned to either an APT group or a control group not receiving APT. A subgroup analysis separately investigated those APT patients with aspirin monotherapy (MAPT) and those receiving dual treatment (aspirin plus clopidogrel, DAPT). Clinical and radiological characteristics were compared between groups. Possible predictors for angiographic CVS, DCI-related infarction, and an unfavorable functional outcome (modified Rankin scale ≥ 3) were analyzed. Of 160 patients, 85 (53%) had received APT (n = 29 MAPT, n = 56 DAPT). APT was independently associated with a lower incidence of an unfavorable functional outcome (OR 0.40 [0.19-0.87], P = 0.021) after 3 months. APT did not reduce the incidence of angiographic CVS or DCI-related infarction. The pattern of angiographic CVS or DCI-related infarction as well as the rate of intracranial hemorrhage did not differ between groups. However, the lesion volume of DCI-related infarctions was significantly reduced in the DAPT subgroup (P = 0.011). Post-interventional APT in endovascularly treated aSAH patients is associated with better functional outcome at 3 months. The beneficial effect of APT might be mediated by reduction of the size of DCI-related infarctions.

Post-treatment Antiplatelet Therapy Reduces Risk for Delayed Cerebral Ischemia due to Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) has a strong impact on outcome of patients with aneurysmal subarachnoid hemorrhage (SAH). Positive effect of antiplatelet therapy on DCI rates has been supposed upon smaller SAH series.

OBJECTIVE

To analyze the benefit/risk profile of antiplatelet use in SAH patients.

METHODS

This retrospective case-control study was based on institutional observational cohort with 994 SAH patients treated between January 2003 and June 2016. The individuals with postcoiling antiplatelet therapy (aspirin with/without clopidogrel) were compared to a control group without antiplatelet therapy. Occurrence of DCI, major/minor bleeding events in the follow-up computed tomography scans, and favorable outcome at 6 mo after SAH (modified Rankin scale < 3) were compared in both groups.

RESULTS

Of 580 patients in the final analysis, 329 patients received post-treatment antiplatelet medication. There were no significant differences between the compared groups with regard to basic outcome confounders. Aspirin use was independently associated with reduced DCI risk (P < .001, adjusted odds ratio = 0.41, 95% confidence interval 0.24-0.65) and favorable outcome (P = .02, adjusted odds ratio = 1.78, 95% confidence interval 1.06-2.98). Regarding bleeding complications, aspirin was associated only with minor bleeding events (P = .02 vs P = .51 for major bleeding events).

CONCLUSION

Regular administration of aspirin might have a positive impact on DCI risk and outcome of SAH patients, without increasing the risk for clinically relevant bleeding events. In our SAH cohort, dual antiplatelet therapy showed no additional benefit on DCI risk, but increased the likelihood of major bleeding events.

Vascular endothelial growth factor A promotes platelet adhesion to collagen IV and causes early brain injury after subarachnoid hemorrhage

The role of vascular endothelial growth factor A in platelet adhesion in cerebral microvessels in the early stage of subarachnoid hemorrhage remains unclear. In this study, the endovascular puncture method was used to produce a rat model of subarachnoid hemorrhage. Then, 30 minutes later, vascular endothelial growth factor A antagonist anti-vascular endothelial growth factor receptor 2 antibody, 10 μg, was injected into the right ventricle. Immunohistochemistry and western blot assay were used to assess expression of vascular endothelial growth factor A, occludin and claudin-5. Immunohistochemical double labeling was conducted to examine co-expression of GP Ia-II integrin and type IV collagen. TUNEL was used to detect apoptosis in the hippocampus. Neurological score was used to assess behavioral performance. After subarachnoid hemorrhage, the expression of vascular endothelial growth factor A increased in the hippocampus, while occludin and claudin-5 expression levels decreased. Co-expression of GP Ia-II integrin and type IV collagen and the number of apoptotic cells increased, whereas behavioral performance was markedly impaired. After treatment with anti-vascular endothelial growth factor receptor 2 antibody, occludin and claudin-5 expression recovered, while co-expression of GP Ia-II integrin and type IV collagen and the number of apoptotic cells decreased. Furthermore, behavioral performance improved notably. Our findings suggest that increased vascular endothelial growth factor A levels promote platelet adhesion and contribute to early brain injury after subarachnoid hemorrhage. This study was approved by the Biomedical Ethics Committee, Medical College of Xi’an Jiaotong University, China in December 2015.

Platelet activation and aggregation after aneurysmal subarachnoid hemorrhage

Background

Endovascular techniques have proven beneficial in the treatment of aneurysmal subarachnoid hemorrhage (aSAH), but with high risk of arterial clotting, emboli and dissection. Platelet activation and alterations in hemostasis may contribute to these complications. We investigated platelet activation and aggregation pathways in aSAH patients who underwent endovascular treatment.

Methods

Two blood samples were taken, in the early days after bleeding and during the period at risk of vasospasm. We studied platelet activation through the expression of GpIIbIIIa and P-selectin as well as aggregation rate in the presence of agonists. Platelets from aSAH patients were compared with those from orthopedic postoperative patients (POSTOP).

Results

Platelets in aSAH were initially spontaneously activated and remained so over time. aSAH platelets were further activated with rapid aggregation in the presence of agonists, particularly ADP, with behavior comparable to POSTOP platelets.

Conclusions

aSAH platelets showed prolonged increases in activation and aggregation. Therapies targeting the ADP pathway might reduce the risk of clotting and ischemic events in this context among patients requiring multiple endovascular procedures.

Trial registration

Not applicable.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1062-z) contains supplementary material, which is available to authorized users.

Embolic signals during routine transcranial Doppler ultrasonography in aneurysmal subarachnoid hemorrhage

INTRODUCTION

Cerebral emboli may occur in subarachnoid hemorrhage (SAH) and intracranial aneurysm surgery. Although embolic signs (ES) have been reported in SAH, their origin remains unclear. The aim of this study was to report the detection of ES during routine TCD monitoring in patients with aneurysmal SAH.

METHODS

A total of 105 patients with aneurysmal SAH were submitted to TCD evaluation. Patients were monitored almost daily (5 times per week). In each monitoring session, one experienced operator performed TCD to detect or assess vasospasm and ES in arteries of the Willis polygon.

RESULTS

Four patients out of a total of 105 patients with aneurysmal SAH were found to present spontaneous cerebral embolization during routine TCD monitoring. The average age of the 4 patients (mean ± standard deviation) was 59.5 ± 8.34 years (range 49-68 ys); female patients predominated representing 75% (3/4) of subjects.

CONCLUSION

Although detection of ES was relatively rare in this study, rates of emboli occurrence may be higher under systematic monitoring. The detection of ES after SAH surgery reinforces the need to study the role of embolus in this condition and may be an indicator for prophylactic antithrombotic treatment.

Platelets in inflammation and infection

Although platelets are traditionally recognized for their central role in hemostasis, many lines of research clearly demonstrate these rather ubiquitous blood components are potent immune modulators and effectors. Platelets have been shown to directly recognize, sequester and kill pathogens, to activated and recruit leukocytes to sites of infection and inflammation, and to modulate leukocyte behavior, enhancing their ability to phagocytose and kill pathogens and inducing unique effector functions, such as the production of Neutrophil Extracellular Traps (NETs). This multifaceted response to infection and inflammation is due, in part, to the huge array of soluble mediators and cell surface molecules expressed by platelets. From their earliest origins as primordial hemocytes in invertebrates to their current form as megakaryocyte-derived cytoplasts, platelets have evolved to be one of the key regulators of host intravascular immunity and inflammation. In this review, we present the diverse roles platelets play in immunity and inflammation associated with autoimmune diseases and infection. Additionally, we highlight recent advances in our understanding of platelet behavior made possible through the use of advanced imaging techniques that allow us to visualize platelets and their interactions, in real-time, within the intact blood vessels of a living host.

Safety of preprocedural antiplatelet medication in coil embolization of ruptured cerebral aneurysms at the acute stage

Preoperative antiplatelet medication for aneurysm coil embolization during acute subarachnoid hemorrhage (SAH) is not common. However, recent advances in neurointerventional devices make antiplatelet medication necessary for SAH surgery. We tested the hypothesis that preprocedural antiplatelet therapy in the acute stage of SAH prevents complications due to ischemia or induced bleeding. We retrospectively reviewed 35 consecutive ruptured cerebral saccular aneurysms that underwent coiling at our institute. Two hundred milligrams of aspirin and 150 mg of clopidogrel were administered to the patients at least two hours before coiling. Systemic heparinization was given after sheath insertion. Procedure-related thrombus formation on digital subtraction angiography, and clinical evidence of ischemia and procedure-related stroke on CT were reviewed. The median patient age was 69 years. Five males and 30 females were included. Seventy-seven percent of patients were Hunt-Hess grades 1 to 3. Assist techniques were used in 20 cases (57%). We inserted one extracranial internal carotid artery stent, but no intracranial stent. Intraoperative thrombosis occurred in one case (2.9%), with no clinical symptoms. Postoperative cerebrospinal fluid drainage was done in three cases, but we experienced no bleeding complications. Preoperative antiplatelet therapy leads to a low rate of thromboembolic events in coiling during acute stage SAH, and this strategy had no adverse influence on bleeding complications.

The role of arterioles and the microcirculation in the development of vasospasm after aneurysmal SAH

Cerebral vasospasm of the major cerebral arteries, which is characterized by angiographic narrowing of those vessels, had been recognized as a main contributor to delayed cerebral ischemia (DCI) in subarachnoid hemorrhage (SAH) patients. However, the CONSCIOUS-1 trial revealed that clazosentan could not improve mortality or clinical outcome in spite of successful reduction of relative risk in angiographic vasospasm. This result indicates that the pathophysiology underlying DCI is multifactorial and that other pathophysiological factors, which are independent of angiographic vasospasm, can contribute to the outcome. Recent studies have focused on microcirculatory disturbance, such as microthrombosis and arteriolar constriction, as a factor affecting cerebral ischemia after SAH. Reports detecting microthrombosis and arteriolar constriction will be reviewed, and the role of the microcirculation on cerebral ischemia during vasospasm after SAH will be discussed.

Microembolic signals in subarachnoid hemorrhage

Microembolic signals (MES) detected by transcranial Doppler (TCD) have been reported in subarachnoid hemorrhage (SAH), although their origin and contribution to brain ischemia remain uncertain. We conducted a prospective study to evaluate the frequency of MES among patients with SAH and to determine their origin. Twenty-seven patients with SAH, comprising 15 aneurysmal and 12 non-aneurysmal patients, participated in the study. TCD evaluation was performed using a 2 MHz probe. Patients were studied three times per week during their in-patient stay to detect vasospasm, and then each middle cerebral artery (MCA) was monitored for 30 min using the Monolateral Multigate mode to detect MES. Using this method, MES were detected in 7 out of 15 patients (47%) with aneurysmal SAH and were not seen in non-aneurysmal patients (p=0.007). Vasospasm occurred in 52% (14/27) of cases. However, clinical signs and symptoms of vasospasm were identified in only 18.5% (5/27). There was no significant relationship between MES and vasospasm (p=0.224). Also, no relationship was found between MES and the location of the aneurysm (p=0.685). Thus, in this study MES were only detected in aneurysmal SAH. However, we did not find a relationship between the location of the aneurysm and MES, or the presence of vasospasm and MES. Therefore, MES in patients with SAH may also originate from vascular pathology other than the aneurysm sac or vascular spasm.

Antiplatelet therapy for aneurysmal subarachnoid haemorrhage

BACKGROUND

Secondary ischaemia is a frequent cause of poor outcome in patients with aneurysmal subarachnoid haemorrhage (SAH). Besides vasospasm, platelet aggregation seems to play a role in the pathogenesis of secondary ischaemia. Experimental studies have suggested that antiplatelet agents can prevent secondary ischaemia.

OBJECTIVES

To determine whether antiplatelet agents change outcome in patients with aneurysmal SAH.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched August 2006), MEDLINE (1966 to August 2006) and EMBASE databases (1980 to August 2006). We also searched reference lists of identified trials.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing any antiplatelet agent with control in patients with aneurysmal SAH.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed trial quality. Relative risks (RR) were calculated with regard to poor outcome, case fatality, secondary ischaemia, haemorrhagic intracranial complications and aneurysmal rebleeding according to the intention-to-treat principle. In case of a statistically significant primary analysis, a worst case analysis was performed.

MAIN RESULTS

Seven RCTs were included in the review, totalling 1385 patients. Four of these trials met the criteria for good quality studies. For any antiplatelet agent there were reductions of a poor outcome (RR 0.79, 95% confidence interval (CI) 0.62 to 1.01) and secondary brain ischaemia (RR 0.79, 95% CI 0.56 to 1.22) and more intracranial haemorrhagic complications (RR 1.36, 95% CI 0.59 to 3.12), but none of these differences were statistically significant. There was no effect on case fatality (RR 1.01, 95% CI 0.74 to 1.37) or aneurysmal rebleeding (RR 0.98, 95% CI 0.78 to 1.38). For individual antiplatelet agents, only ticlopidine was associated with statistically significant fewer occurrences of a poor outcome (RR 0.37, 95% CI 95% CI 0.14 to 0.98) but this estimate was based on only one small RCT.

AUTHORS' CONCLUSIONS

This review shows a trend towards better outcome in patients treated with antiplatelet agents, possibly due to a reduction in secondary ischaemia. However, results were not statistically significant, thus no definite conclusions can be drawn. Also, antiplatelet agents could increase the risk of haemorrhagic complications. On the basis of the current evidence treatment with antiplatelet agents in order to prevent secondary ischaemia or poor outcome cannot be recommended.

Effects of common medications on cerebral vasospasm after subarachnoid haemorrhage

Cerebral vasospasm is a common and serious complication of aneurysmal subarachnoid haemorrhage (SAH). At present, no consistently effective preventative and therapeutic measures are available, perhaps because of incomplete understanding of the pathogenesis of vasospasm. Experimental studies provide evidence that the incidence and severity of vasospasm after SAH can be modulated by drugs that affect neurotransmitter levels, intracellular signalling mechanisms, vascular smooth muscle function, inflammation and cellular proliferation, and the concentration of 'spasmogenic' factors. Preliminary clinical studies indicate that some illicit drugs and common prescription medications can have similar effects in humans. Recognition of these pharmacological effects is important because medications that can worsen or alleviate vasospasm are frequently administered to SAH patients to treat coincident medical problems.

Cerebral vasospasm: a consideration of the various cellular mechanisms involved in the pathophysiology

The cellular mechanisms responsible for cerebral vasospasm (CVS) occurring after subarachnoid hemorrhage (SAH) have been of major interest over the past 50 years. The present review describes how each of the discrete anatomic components that comprise the cerebral artery may contribute to the pathology of CVS. The blood extravasated after SAH is hemolyzed and undergoes degradation with resultant production of free radicals, known to be powerful initiators of vascular damage. An inflammatory response is generated activating both leukocytes and platelets with subsequent release of inflammatory agents. The cerebral artery affected by CVS undergoes phenotypic change involving both the endothelial and smooth muscle cells. In the endothelium the production of nitric oxide and prostacyclin is affected. In the smooth muscle cells signal transduction pathways that enhance the function of the contractile proteins and induce the upregulation of contractile receptors are activated. In parallel, there is evidence that nervous reflex pathways involving the trigeminal ganglion and the hypothalamus are activated. However, the relative contributions of each of the systems are speculative. Therapy may be directed at disrupting the cascade leading from the SAH insult to CVS or at overcoming the dysfunction incurred by CVS; possible therapeutical interventions are considered.

Cerebrovascular inflammation following subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage frequently results in complications including intracranial hypertension, rebleeding and vasospasm. The extravasated blood is responsible for a cascade of reactions involving release of various vasoactive and pro-inflammatory factors (several of which are purported to induce vasospasm) from blood and vascular components in the subarachnoid space. The authors review the available evidence linking these factors to the development of inflammatory lesions of the cerebral vasculature, emphasizing: 1) neurogenic inflammation due to massive release of sensory nerve neuropeptides; 2) hemoglobin from lysed erythrocytes, which creates functional lesions of endothelial and smooth muscle cells; 3) activity, expression and metabolites of lipoxygenases cyclooxygenases and nitric oxide synthases; 4) the possible role of endothelin-1 as a pro-inflammatory agent; 5) serotonin, histamine and bradykinin which are especially involved in blood-brain barrier disruption; 6) the prothrombotic and pro-inflammatory action of complement and thrombin towards endothelium; 7) the multiple actions of activated platelets, including platelet-derived growth factor production; 8) the presence of perivascular and intramural macrophages and granulocytes and their interaction with adhesion molecules; 9) the evolution, origins, and effects of pro-inflammatory cytokines, especially IL-1, TNF-alpha and IL-6. Human and animal studies on the use of anti-inflammatory agents in subarachnoid hemorrhage include superoxide and other radical scavengers, lipid peroxidation inhibitors, iron chelators, NSAIDs, glucocorticoids, and serine protease inhibitors. Many animal studies claim reduced vasospasm, but these effects are not always confirmed in human trials, where symptomatic vasospasm and outcome are the major endpoints. Despite recent work on penetrating vessel constriction, there is a paucity of studies on inflammatory markers in the microcirculation.

Morphological changes of intraparenchymal arterioles after experimental subarachnoid hemorrhage in dogs

OBJECTIVE

Morphological and microcirculatory changes in intraparenchymal vessels after subarachnoid hemorrhage (SAH) have not yet been fully clarified. We conducted this experimental study to investigate the serial morphological changes of intraparenchymal arterioles after SAH.

METHODS

SAH was produced by injecting autologous arterial blood into the cisterna magna twice at 48-hour intervals in 30 dogs. The dogs were killed 3, 7, or 14 days after SAH, and then perfusion-fixed specimens of both anterior sylvian giri were obtained by using two methods. Microvascular corrosion casts produced by arterial injection of polyester resin were examined using scanning electron microscopy, and the widths of 40 arterioles of each animal were measured. Sectioned slices from the brain surface to 500 microns deep were examined by light microscopy, and external diameter, internal diameters, and wall thickness of the arterioles at depths of 50, 200, and 500 microns from the brain surface were morphometrically evaluated in 40 arterioles of each animal. In control animals receiving cisternal injections of mock cerebrospinal fluid (n = 10) and in healthy control animals (n = 10), the same examination and evaluation were performed.

RESULTS

Corrosion casts of arterioles showed tapered narrowing with folding after SAH, and the width of the arterioles significantly decreased 3 and 7 days after SAH (P < 0.01). Morphometric examination by light microscopy showed a significant decrease of internal diameter of arterioles associated with a significant increase of wall thickness at any depth from the brain surface 3 and 7 days after SAH (P < 0.05 or P < 0.01). These findings improved 14 days after SAH. Control animals receiving cisternal injections of mock cerebrospinal fluid showed no significant differences compared with healthy control animals.

CONCLUSION

These results suggest that constriction of intraparenchymal arterioles occurs after SAH and may contribute to delayed cerebral ischemia.

Anticoagulation for prevention of cerebral infarcts following subarachnoid hemorrhage

BACKGROUND

Late neurologic deterioration following subarachnoid hemorrhage is often due to vasospasm and rebleeding. Although the sudden onset of a focal neurologic deficit can actually be the result of thromboembolism, anticoagulation has rarely been used in such cases.

METHODS

We report a case of a 55-year-old woman who developed recurrent transient focal neurologic deficits 13 days after having a subarachnoid hemorrhage, with multiple cerebral infarcts by CT. Two cerebral angiograms showed no aneurysm. Her symptoms and clinical temporal profile were consistent with thromboembolic phenomenon. We elected to treat her with systemic anticoagulation.

RESULTS

The patient had no recurrent events after systemic anticoagulation, but had episodic sensory changes and a new infarct on MRI once the anticoagulation was discontinued.

CONCLUSIONS

Anticoagulant was safely administered after subarachnoid hemorrhage (SAH) in this patient and may have been effective in preventing further cerebral ischemic infarction following her SAH. Our patient's clinical profile of sudden (rather than gradual) onset of a transient focal neurologic deficit and resolution of blood on CT indicates one setting in which the use of heparin may be considered.