Microbleeds after Carotid Artery Stenting: Small Embolism May Induce Cerebral Microbleeds

Post-Carotid Artery Stenting Hyperperfusion Syndrome in a Hypotensive Patient: Case Report and Systematic Review of Literature

Cerebral hyperperfusion syndrome (CHS) is a serious post-procedural complication of carotid artery stenting (CAS). The pathophysiological mechanisms of CHS in the absence of arterial hypertension (AH) remain only partially understood. We performed a systematic literature search of the PubMed database using the terms »cerebral hyperperfusion syndrome«, »hypotension«, »hyperperfusion«, »stroke«, »intracranial hemorrhages«, »risk factors«, »carotid revascularization«, »carotid stenting«, »carotid endarterectomy«, »blood-brain barrier«, »endothelium«, »contrast encephalopathy«, and combinations. We present a case of a normotensive female patient who developed CHS post-CAS for symptomatic carotid stenosis while being hypotensive with complete recovery. We identified 393 papers, among which 65 were deemed relevant to the topic. The weighted average prevalence of CHS after CAS is 1.2% [0.0-37.7%] with that of intracranial hemorrhage (ICH) being 0.51% [0-9.3%]. Recently symptomatic carotid stenosis or contralateral carotid revascularization, urgent intervention, acute carotid occlusion, contralateral ≥70% stenosis, and the presence of leptomeningeal collaterals were associated with CHS. A prolonged hemodynamic instability after CAS conveys a higher risk for CHS. However, none of the articles mentioned isolated hypotension as a risk factor for CHS. Whereas mortality after ICH post-CAS ranges from 40 to 75%, in the absence of ICH, CHS generally carries a good prognosis. AH is not obligatory in CHS development. Even though impaired cerebral autoregulation and post-revascularization changes in cerebral hemodynamics seem to play a pivotal role in CHS pathophysiology, our case highlights the complexity of CHS, involving factors like endothelial dysfunction and sudden reperfusion. Further research is needed to refine diagnostic and management approaches for this condition.

Number of cerebral microbleeds after intracranial/extracranial stenting and dual antiplatelet therapy

BACKGROUND

Cerebral microbleeds (CMBs) are small (<1 cm) perivascular hemosiderin depositions. They may be visible in T2* or susceptibility-weighted magnetic resonance imaging (MRI) sequences. CMBs may indicate an increased risk of intracerebral hemorrhage (ICH) or vascular disease. Cerebral white matter changes indicate small vessel disease (SVD), which is also related to CMBs. In cerebral vascular treatment, dual antiplatelet therapy (DAPT) is routinely used after stenting. We surveyed our cerebral stenting case series for changes in the number of CMBs.

METHODS

Patients receiving extracranial or intracranial stenting between 2018 and 2020 were included. All patients received DAPT after stenting. Changes in CMBs, SVD degree, and other findings from pretreatment to follow-up MRI were recorded. Differences between stented artery supplying territory and other territories were compared.

RESULTS

The average age of the 75 enrolled patients was 65.37 years ± 11.53 (50 male and 25 female patients); 84 extracranial or intracranial stentings were performed. The average Fazekas scale score was 1.32 ± 0.77. Significantly more CMBs developed in the initial ≥6 CMB group than in the initial 0 and 1-5 CMB groups (7 ± 3.6 vs 0.56 ± 1.06, 1.45 ± 3.32, p < 0.001). No significant difference in increased CMBs was observed between the initial 0 and 1-5 CMB groups. Significantly more CMBs developed in the stented artery supplying territory than elsewhere (0.6 ± 0.13 vs 0.44 ± 0.17, p < 0.05). No ICH was noted in our case series.

CONCLUSION

Preexisting CMB was a risk factor for the onset of new CMBs after stenting and DAPT. Poststenting and DAPT statistically increased CMBs in stented artery supplying territories at short-term follow-up.

Cerebral Microbleeds With Atrial Fibrillation After Ablation Therapy

Background

The prevalence of cerebral microbleeds (CMBs) is significantly higher in patients with atrial fibrillation (AF) than in those without AF. CMBs in patients with AF have been reported to be primarily of the lobar type, but the exact cause of this remains unknown. We investigated the possibility that hemorrhagic transformation of embolic microinfarction can account for de novo lobar CMBs.

Methods

A total of 101 patients who underwent ablation therapy for AF were prospectively registered, and 72 patients completed the assessment with MRI 6 months after catheter ablation. Brain MRI, including diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI), were examined at 1–3 days (baseline) and 6 months after catheter ablation. We quantitatively evaluated the spatial and temporal distribution of embolic microinfarctions and de novo CMBs.

Results

Of the 101 patients, 68 were enrolled in this study. Fifty-nine patients (86.8%) showed embolic microinfarctions on baseline DWI immediately after catheter ablation. There were 137 CMBs in SWI, and 96 CMBs were of the lobar type. Six months later, there were 208 CMBs, including 71 de novo CMBs, and 60 of 71 (84.5%) were of the lobar type. Of the 71 de novo CMBs, 56 (78.9%) corresponded to the location of previous embolic microinfarctions found on baseline DWI. The platelet count was significantly lower and hematocrit/hemoglobin and Fazekas score were higher in the group with de novo CMBs than in the group without de novo CMBs.

Conclusion

De novo CMBs frequently appeared after catheter ablation therapy. Our results suggest that embolic microinfarction can cause lobar CMBs.

Relationship of pharmacotherapy and the incidence of embolic complications of carotid reconstructive surgery

Aim. To evaluate the relationship between lipid-lowering and antiplatelet therapy and the incidence of cerebral microembolism and related complications in open and endovascular revascularization of the carotid arteries (CA).

Material and methods. This single-center study involved patients with internal CA stenosis. The patients were divided into 2 groups depending on the surgery type performed: carotid endarterectomy (CEA)  — 163 patients; CA stenting (CAS)  — 71 patients. All patients underwent intraoperative transcranial Doppler monitoring to register cerebral embolism during CAS and CE.

Results. In CAS, microembolism episodes were observed in 66,2% vs 22,1% of patients in the CEA group (p=0,04), the largest number of which was recorded during catheterization of the internal CA and embolic filter installation (p=0,000). There were no significant differences between the groups in terms of the stroke incidence. In 8 patients in the CAS group and 1 patient in the CEA group, a transient ischemic attack was observed within 30 days after surgery (p=4x10-4 ). Intraoperative embolism was a predictor of a neurological event in the early postoperative period (odds ratio (OR), 33,08; 95% confidence interval (CI): 3,49-56,37 (p6 months before surgery reduces the likelihood of embolism by 4 times (OR 0,25; 95% CI: 0,11-0,58 (p=0,001), while lipid-lowering and antiplatelet therapy combination — by 12,5 times (OR, 0,08; 95% CI: 0,01-0,40 (p=0,001)).

Conclusion. Preoperative antiplatelet and statin therapy reduces the likelihood of embolism during the CA revascularization procedure.

Micro-MRI improves the accuracy of clinical diagnosis in cerebral small vessel disease

Even with postmortem pathological examination, only limited information is provided of the foci of in vivo clinical information. Cerebral small vessel disease, which is associated with ageing, dementia and stroke, highlights the difficulty in arriving at a definitive diagnosis of the lesions detected on in vivo radiological examination. We performed a radiological−pathological comparative study using ex vivo MRI to examine small cerebral lesions. Four patients with small vessel disease lesions detected on in vivo MRI were studied. Exact pathological findings of in vivo MRI-detected lesions were revealed. The ischaemic lesion after 17 days from onset showed positivity for peroxiredoxin, cluster of differentiation 204 and glial fibrillary acidic protein, indicating sterile inflammation and neuroprotective reaction. Cortical microinfarcts beneath the cortical superficial siderosis were associated with inflammation from the superficial layer in a patient with cerebral amyloid angiopathy; in this patient, a bilinear track-like appearance of the cortical superficial siderosis on the ex vivo MRI was compatible with iron deposition on the pia matter and within cortical layers II–III. An in vivo MRI-detected cerebral microbleed was revealed to be heterogeneous. An in vivo MRI-detected cerebral microbleed was revealed to be a venous angioma. Furthermore, a neuropathologically confirmed embolic cerebral microbleed was firstly detected using this method. Our results suggest that in vivo MRI-detected lobar cerebral microbleeds can be caused by non-cerebral amyloid angiopathy aetiologies, such as microembolism and venous angioma. Venous angioma and embolic microbleeds may mimic cerebral amyloid angiopathy markers on in vivo MRI. To clarify the clinical importance of these lesions, we should investigate their rate and frequency in a large cohort of healthy individuals and patients with cardiac risk factors. Thus, we provide evidence that ex vivo micro-MRI improves the clinical diagnosis of small vessel diseases.

Factors associated with the new appearance of cerebral microbleeds after endovascular treatment for unruptured intracranial aneurysms

PURPOSE

Endovascular treatment of unruptured intracranial aneurysms may increase cerebral microbleeds (CMBs) in postprocedural T2*-weighted MRIs, which may be a risk for future intracerebral hemorrhage. This study examined the characteristics of postprocedural CMBs and the factors that cause their increase.

METHODS

The patients who underwent endovascular treatment for unruptured intracranial aneurysms from April 2016 to February 2018 were retrospectively analyzed. Treatment techniques for endovascular treatment included simple coiling, balloon-assisted coiling, stent-assisted coiling, or flow diverter placement. To evaluate the increase in CMBs, a head MRI including diffusion-weighted imaging and T2*-weighted MRIs was performed on the preprocedural day; the first postprocedural day; and at 1, 3, and 6 months after the procedure.

RESULTS

Among the 101 aneurysms that were analyzed, 38 (37.6%) showed the appearance of new CMBs. In the multivariate analysis examining the causes of the CMB increases, chronic kidney disease, a higher number of preprocedural CMBs, and a higher number of diffusion-weighted imaging-positive lesions on the first postprocedural day were independent risk factors. Furthermore, a greater portion of the increased CMBs was found in cortical and subcortical lesions of the treated vascular perfusion area within 1 month after the procedure.

CONCLUSION

In endovascular treatment for unruptured intracranial aneurysms, CMBs tended to increase in patients with small vessel disease before the procedure, and it was also implicated in hemorrhagic changes after periprocedural microinfarction.

Clinical Features and Experimental Models of Cerebral Small Vessel Disease

Cerebral small vessel disease (SVD) refers to a group of disease conditions affecting the cerebral small vessels, which include the small arteries, arterioles, capillaries, and postcapillary venules in the brain. SVD is the primary cause of vascular cognitive impairment and gait disturbances in aged people. There are several types of SVD, though arteriolosclerosis, which is mainly associated with hypertension, aging, and diabetes mellitus, and cerebral amyloid angiopathy (CAA) comprise most SVD cases. The pathology of arteriolosclerosis-induced SVD is characterized by fibrinoid necrosis and lipohyalinosis, while CAA-associated SVD is characterized by progressive deposition of amyloid beta (Aβ) protein in the cerebral vessels. Brain magnetic resonance imaging (MRI) has been used for examination of SVD lesions; typical lesions are characterized by white matter hyperintensity, lacunar infarcts, enlargement of perivascular spaces (EPVS), microbleeds, cortical superficial siderosis (cSS), and cortical microinfarcts. The microvascular changes that occur in the small vessels are difficult to identify clearly; however, these consequent image findings can represent the SVD. There are two main strategies for prevention and treatment of SVD, i.e., pharmacotherapy and lifestyle modification. In this review, we discuss clinical features of SVD, experimental models replicating SVD, and treatments to further understand the pathological and clinical features of SVD.