Transient ischemic attack and minor stroke as "surgeons affairs": a narrative review

OBJECTIVE

The scope of this paper is to review the subtypes of transient ischemic attack (TIA) and minor stroke (mS) in which a surgical treatment is needed, discussing the importance and the timing of a multidisciplinary approach, in order to achieve an optimized management and prevent major strokes or other critical complications.

MATERIALS AND METHODS

The keywords "transient ischemic attack," "minor stroke," "surgical treatment," "vascular surgery," "heart surgery," "neurosurgery," and "multidisciplinary" were searched using MEDLINE, EMBASE, and Scopus. Relevant search results were discussed by the authors for references inclusion.

RESULTS

Notwithstanding that best medical therapy is usually the first choice for the most part of cases, there are specific but recurrent etiologies that must be properly recognized because of a potential surgical approach, even in urgency. In fact, symptomatic carotid stenosis, or particular cases of hemodynamic cerebrovascular events, should be promptly referred to vascular surgeon, since increasing evidences highlighted a benefit from an early artery revascularization. In addition, beyond arrhythmic causes, cardioembolic events due to bacterial endocarditis and atrial myxoma should be quickly diagnosed, possibly in emergency department, because they are a presumptive urgency for heart surgery. In addition to the above-mentioned conditions, in patients suffering from vertebrobasilar TIA or mS, clinicians should keep in mind the Bow Hunter disease, because surgical artery decompression can represent the only suitable treatment in selected cases.

CONCLUSIONS

TIA and mS require a multidisciplinary in order to discuss therapeutic options, comparing risks and benefits and determining the best timing for an optimized management.

MRI of unruptured infectious intracranial aneurysms in infective endocarditis. A case-control study

PURPOSE

To evaluate the usefulness of T2* and FLAIR sequences in the detection of unruptured infectious intracranial aneurysms (UIIAs) in infective endocarditis (IE) including the relationships between the lesion patterns within subarachnoid spaces and the presence of UIIA.

METHODS

Retrospective review of 15 consecutive patients with definite IE undergoing MR imaging (FLAIR, T2*, DWI, CE-MRA, 3D-T1, CE-3DT1 sequences), in whom DSA detected infectious intracranial aneurysms (IIA). Aneurysmal features (diameter, location, morphology on DSA) and signal patterns onT2*, FLAIR and conventional MR sequences at the site of the UIIA, follow-up MRI and IE background, were analyzed. A control-group of 15 IE-patients without IIA at DSA served for comparison.

RESULTS

Among 17 UIIAs studied, T2* sequence displayed a susceptibility vessel sign in 15/17 (88.2%), both distal and proximal, which matched with the IIA visualized on DSA. Three patterns of hyposignal areas were identified: (a) signet-ring or target-sign appearance (n = 7), (b) homogeneous, round-, oval- or pear-shaped area (n = 4), and (c) heterogeneous area (n = 4). A FLAIR hyperintensity of the lumen and of the adjacent cortex was present in 6 (35.3%) and 9 (53%) UIIAs, respectively. On T1 (12 UIIAs) a rounded hyposignal (n = 2), within the UIIA lumen matched with the FLAIR hypersignal. Using both T2* and FLAIR had an incremental value with 100% sensitivity and specificity.

CONCLUSION

The susceptibility vessel sign is an MR imaging pattern frequently observed at the site of UIIAs in IE-patients. Both T2* and FLAIR may have the potential to depict UIIAs, regardless of their location and shape.

Ruptured intracranial infectious aneurysms: Single Canadian center experience

Background:

Ruptured intracranial infected aneurysms (IIAs) are relatively rare, but they portend high mortality. To the best of our knowledge, there is no Canadian case series on IIA, as well there is a relative paucity of international published experiences. Our purpose is to share the experience of a single Canadian tertiary center in managing ruptured IIA and to conduct a systematic review.

Methods:

We did a retrospective case review series of adult patients with ruptured IIA treated at our institution. Second, we conducted a systematic review of the literature on ruptured IIA between 2011 and 2021 inclusive.

Results:

At our institution, of a total eight cases with ruptured IIA, four were treated endovascularly and two by surgical bypass. For the systematic review, we included nine noncomparative studies with a total of 509 patients (318 males) and at least 437 ruptured IIA aneurysms. Favorable outcome was specified for 63.3% of patients (n = 57). Regarding ruptured IIA, favorable clinical outcome was described in 59.3% (n = 16).

Conclusion:

This study highlights a single Canadian tertiary center experience in the management of IIA and compares it to the global trends of the past 10 years in a systematic review.

Infectious Causes of Stroke

Stroke is one of the primary causes of mortality and morbidity worldwide. It can be ischemic or hemorrhagic, and the former can be due to an in-situ thrombus or a distant embolus. Despite being a rare cause, stroke can also be caused in the setting of infection. Bacterial agents are the most common cause of stroke, among other infectious agents. Until the antibiotic era, rheumatic heart disease was a predisposing risk factor of infective endocarditis. VZV is the most common cause of strokes in pediatric and adult populations. Cryptococcus and Candida spp are the most common yeasts involved in CNS infections, especially in immunocompromised patients. In COVID-19 patients, ischemic strokes are more common than hemorrhagic strokes. In this review, we will discuss the most common infectious agents, with particular emphasis on COVID-19.

How Are We Monitoring Brain Injuries in Patients With Left Ventricular Assist Device? A Systematic Review of Literature

Despite the common occurrence of brain injury in patients with left ventricular assist device (LVAD), optimal neuromonitoring methods are unknown. A systematic review of PubMed and six electronic databases from inception was conducted until June 5, 2019. Studies reporting methods of neuromonitoring while on LVAD were extracted. Of 5,190 records screened, 37 studies met the inclusion criteria. The neuromonitoring methods include Transcranial Doppler ultrasound for emboli monitoring (TCD-e) (n = 13) and cerebral autoregulation (n = 3), computed tomography and magnetic resonance imaging (n = 9), serum biomarkers (n = 7), carotid ultrasound (n = 3), and near-infrared spectroscopy (n = 2). Of 421 patients with TCD-e, thromboembolic events (TEs) were reported in 79 patients (20%) and microembolic signals (MES) were detected in 105 patients (27%). Ischemic stroke was more prevalent in patients with MES compared to patients without MES (43% vs.13%, p < 0.001). Carotid ultrasound for assessing carotid stenosis was unreliable after LVAD implantation. Elevated lactate dehydrogenase (LDH) levels were associated with TEs. Significant heterogeneity exists in timing, frequency, and types of neuromonitoring tools. TCD-e and serial LDH levels appeared to have potential for assessing the risk of ischemic stroke. Future prospective research incorporating protocolized TCD-e and LDH may assist in monitoring adverse events in patients with LVAD.

Cerebrovascular Complication and Valve Surgery in Infective Endocarditis

Infective endocarditis (IE) with neurologic complications is common in patients with active IE. The most common and feared neurological complication of left-sided IE is cerebrovascular, from septic emboli causing ischemic stroke, intracranial hemorrhage (ICH), or an infectious intracranial aneurysm with or without rupture. In patients with cerebrovascular complications, valve replacement surgery is often delayed for concern of further neurological worsening. However, in circumstances when an indication for valve surgery to treat IE is present, the benefits of early surgical treatment may outweigh the potential neurologic deterioration. Furthermore, valve surgery has been associated with lower in-hospital mortality than medical therapy with intravenous antibiotics alone. Early valve surgery can be performed within 7 days of transient ischemic attack or asymptomatic stroke when medically indicated. Timing of valve surgery for IE after symptomatic medium or large symptomatic ischemic stroke or ICH remains challenging, and current data in the literature are conflicting about the risks and benefits. A delay of 2 to 4 weeks from the time of the cerebrovascular event is often recommended, balancing the risks and benefits of surgery. The range of timing of valve surgery varies depending on the clinical scenario, and is best determined by a multidisciplinary decision between cardiothoracic surgeons, cardiologists, infectious disease experts, and vascular neurologists in an experienced referral center.

Brain Injury in Extracorporeal Membrane Oxygenation: A Multidisciplinary Approach

Extracorporeal membrane oxygenation (ECMO) represents an established technique to provide temporary cardiac and/or pulmonary support. ECMO, in veno-venous, veno-arterial or in extracorporeal carbon dioxide removal modality, is associated with a high rate of brain injuries. These complications have been reported in 7 to 15% of adults and 20% of neonates, and are associated with poor survival. Thromboembolic events, loss of cerebral autoregulation, alteration of the blood-brain barrier, and hemorrhage related to anticoagulation represent the main causes of severe brain injury during ECMO. The most frequent forms of acute neurological injuries in ECMO patients are intracranial hemorrhage (2-21%), ischemic stroke (2-10%), seizures (2-6%), and hypoxic-ischemic brain injury; brain death may also occur in this population. Other frequent complications are infarction (1-8%) and cerebral edema (2-10%), as well as neuropsychological and psychiatric sequelae, including posttraumatic stress disorder.

Utility of Susceptibility-Weighted Angiography Sequence in the Diagnosis of Ruptured Infectious Aneurysms

In a patient with infective endocarditis (IE), susceptibility-weighted angiography (SWAN) sequence revealed 2 intracranial infectious aneurysms (IIAs) as bright signal lesion, related to the high-velocity arterial flow within the IIAs. In addition, SWAN revealed a convexal subarachnoid hemorrhage-related to distal IIA rupture-as a dark signal. The risk of IIA rupture emphasizes the need for serial imaging follow-up in patients with IE receiving antibiotic therapy after endovascular treatment and after valve surgery. Considering its specific risks, particularly in patients with IE who may be on anticoagulation, digital subtraction angiography is not used routinely in this context. Therefore, SWAN might be an alternative method for selecting patients with IE who need conventional angiography and might be useful for serial follow-up and monitoring after treatment. Future studies should investigate the role of SWAN for the detection of IIAs.

Simultaneous feedback control for joint field and motion correction in brain MRI

T2*-weighted gradient-echo sequences count among the most widely used techniques in neuroimaging and offer rich magnitude and phase contrast. The susceptibility effects underlying this contrast scale with B₀, making T2*-weighted imaging particularly interesting at high field. High field also benefits baseline sensitivity and thus facilitates high-resolution studies. However, enhanced susceptibility effects and high target resolution come with inherent challenges. Relying on long echo times, T2*-weighted imaging not only benefits from enhanced local susceptibility effects but also suffers from increased field fluctuations due to moving body parts and breathing. High resolution, in turn, renders neuroimaging particularly vulnerable to motion of the head. This work reports the implementation and characterization of a system that aims to jointly address these issues. It is based on the simultaneous operation of two control loops, one for field stabilization and one for motion correction. The key challenge with this approach is that the two loops both operate on the magnetic field in the imaging volume and are thus prone to mutual interference and potential instability. This issue is addressed at the levels of sensing, timing, and control parameters. Performance assessment shows the resulting system to be stable and exhibit adequate loop decoupling, precision, and bandwidth. Simultaneous field and motion control is then demonstrated in examples of T2*-weighted in vivo imaging at 7T.

Infectious causes of stroke

PURPOSE OF REVIEW

Stroke continues to be a leading cause of debility in the world. Infections have been associated with stroke, but are not considered as directly causal, and so they are not often included in the traditional stroke workup and management. They are especially important in patients with stroke of undetermined etiology, and in certain patient populations, such as young patients without traditional risk factors, and immunocompromised patients.

RECENT FINDINGS

There has been strong evidence for infectious conditions, such as endocarditis, and pathogens, such as varicella zoster in stroke causation, and more supportive evidence is surfacing in recent years of several organisms increasing the stroke risk or being directly causal in stroke. The evidence also seems to be pointing to the role of inflammation in increasing the risk of stroke via accelerated atherosclerosis, vasculitis and vasculopathy.

SUMMARY

Infectious causes should be considered in the differential and work up of stroke in certain patient populations and appropriate treatments need to be initiated to minimize adverse stroke-related outcomes.

Stroke Risk Following Infection in Patients with Continuous-Flow Left Ventricular Assist Device

BACKGROUND

Infection has been associated with stroke in patients with left ventricular assist devices (LVAD); however, little data exist on the timing, type and mortality impact of infection-related stroke.

METHODS

Prospectively collected data of HeartMate II (N = 332) and HeartWare (N = 70) LVAD patients from a single center were reviewed. Only strokes (ischemic or hemorrhagic) that occurred within 6 weeks following a LVAD infection were considered in analyses. The association between LVAD infections (wound, pump pocket, driveline and/or bloodstream infection [BSI]), specific pathogens and ischemic and hemorrhagic strokes was evaluated using multivariable logistic regression analysis. The impact of infection-related stroke on cumulative survival was assessed using Kaplan-Meier analysis.

RESULTS

Of 402 patients, LVAD infection occurred in 158 (39%) including BSI in 107 (27%), driveline infection in 67 (17%), wound infection in 31 (8%) and pump pocket infection in 24 (6%). LVAD infection-related stroke occurred in 20/158 (13%) patients in a median of 4 days (0-36 days) from documented infection. In multivariable analysis, ischemic stroke was associated with wound infection (aOR 9.0, 95% CI 2.4-34.0, P = 0.001) and BSI (aOR 7.7, 95% CI 0.9-66.0, P = 0.064), and hemorrhagic stroke was associated with BSI in 100% of cases (P = 0.01). There was no association with driveline or pump pocket infection. The cumulative survival rate among patients with infection-related stroke was significantly lower compared to those with LVAD infection but no stroke (log-rank P < 0.001). There was a trend toward shorter stroke-free survival among patients with LVAD infection.

CONCLUSIONS

LVAD infections, particularly BSI, are significantly associated with stroke, and infection-related stroke conferred significantly lower cumulative survival.

MRI Presentation of Infectious Intracranial Aneurysms in Infective Endocarditis

BACKGROUND

The radiographic appearance of infectious intracranial aneurysms (IIAs) of infective endocarditis (IE) on magnetic resonance imaging (MRI) of brain is varied. We aimed to describe the IIA-specific MRI features in a series of patients with IIAs.

METHODS

Records of patients with active IE who had digital subtraction angiography (DSA) at a tertiary medical center from January 2011 to December 2016 were reviewed. MRIs performed prior to IIA treatment were reviewed for findings on susceptibility-weighted imaging (SWI), diffusion-weighted imaging, and T1 with and without contrast.

RESULTS

Of the 732 patients with IE, 53 (7%) had IIAs. Of these, 28 patients had an evaluable pre-treatment MRI, in whom 33 IIAs were imaged. MRI to DSA median time was 1 day (interquartile range = 1-5). On MRI, 12 (36%) IIAs had SWI lesion with contrast enhancement, 7 (21%) had cerebral microbleeds, 3 (11%) had sulcal SWI lesion, 2 (6%) IIAs had abscesses, 3 (9%) had intraparenchymal hemorrhage, 3 (9%) had subarachnoid hemorrhage, and 6 (18%) had ischemic stroke at the anatomical locations of IIAs. Four IIAs (12%) had no correlating MRI findings, though those patients had MRI without contrast.

CONCLUSION

The MRI features such as SWI lesion and contrast enhancement were the commonest MRI presentations associated with the presence of IIA.

Clinical course of infectious intracranial aneurysm undergoing antibiotic treatment

INTRODUCTION

Infectious intracranial aneurysm (IIA, or mycotic aneurysm) is a cerebrovascular complication of infective endocarditis. We aimed to describe the clinical course of IIAs during antibiotic treatment.

METHODS

We reviewed medical records of persons with infective endocarditis who underwent cerebral angiography at a single tertiary referral center from 2011 to 2016. Aneurysms were followed with subsequent angiography for unfavorable outcome (growth, rupture, no change, or new IIA formation) or favorable outcome (regression or resolution) until endovascular therapy, aneurysm resolution, or end of observation.

RESULTS

Of 618 patients included, 40 (6.5%) had 43 IIAs. Eighteen (42%) aneurysms underwent initial endovascular treatment. Twenty-five unruptured aneurysms were followed for a median 18 antibiotic days after IIA discovery (interquartile range [IQR] 4-32). Eleven (44%) aneurysms had unfavorable outcome (1 rupture, 2 new IIA formation, 6 enlargement, and 2 no change) at median 21 days (IQR 5-32). Favorable angiographic outcome was seen in 7 (28%) patients (6 resolution, 1 regression) at median 36 days (IQR 24-41). Seven aneurysms had no angiographic reevaluations but showed no evidence of rupture during clinical follow-up for median 4 days (IQR 3-12) until hospital discharge. Saccular morphology was associated with unfavorable aneurysmal outcome (p = 0.013). Longer duration of antibiotic exposure prior to IIA discovery was associated with favorable aneurysmal outcome (p = 0.046).

CONCLUSION

IIAs represent a dynamic disease. Only a quarter of IIAs resolve with antibiotics alone. Saccular aneurysmal morphology might predict unfavorable aneurysmal outcome. IIA found after longer antibiotic therapy has higher likelihood of resolution or regression on antibiotic treatment.

Neurological Complications of Infective Endocarditis

PURPOSE OF REVIEW

The purpose of this narrative review and update is to summarize the current knowledge and provide recent advances on the neurologic complications of infective endocarditis.

RECENT FINDINGS

Neurological complications occur in about one-fourth of patients with infective endocarditis. Brain MRI represents a major tool for the identification of asymptomatic lesions, which occur in most of the patients with infective endocarditis. The usefulness of systematic brain imaging and the preferred treatment of patients with infective endocarditis and silent brain lesions remains uncertain. The basis of treatment of infective endocarditis is early antimicrobial therapy. In stroke due to infective endocarditis, anticoagulation and thrombolysis should be avoided. Endovascular treatment can be useful for both acute septic emboli and mycotic aneurysms, but evidence is still limited. In patients with neurological complications, cardiac surgery can be safely performed early, if indicated. The optimal management of a patients with neurological complications of infective endocarditis needs an individualized case discussion and the participation of a multidisciplinary team including neurologists, cardiologists, cardiothoracic surgeons, neuroradiologists, neurosurgeons, and infectious disease specialists.

Cerebral microbleeds predict infectious intracranial aneurysm in infective endocarditis

BACKGROUND AND PURPOSE

Magnetic resonance imaging (MRI) features such as cerebral microbleeds and sulcal susceptibility-weighted imaging (SWI) or gradient-echo T2* lesions in infective endocarditis (IE) have been associated with the presence of infectious intracranial aneurysm (IIA). Our aim was to validate these MRI predictors for IIA in order to better assist in assessing the appropriate indications for digital subtraction angiography (DSA).

METHODS

The derivation cohort comprised IE patients with neurological evaluation, MRI and DSA at a single tertiary referral center from January 2015 to July 2016. Validation was performed in a cohort of IE patients who underwent MRI and DSA at the same center from 2010 to 2014.

RESULTS

Of 62 patients in the derivation cohort, 10 (16%) had IIAs. Of 129 in the validation cohort, 19 (15%) IIAs were identified. The MRI predictors for IIA consist of (i) contrast enhancement with microbleeds, (ii) cerebral microbleeds >5 mm or sulcal SWI lesions and (iii) any MRI hemorrhages. The sensitivity for the presence of IIA in each group of the derivation cohort was 90%, 80% and 100%, respectively. The sensitivity in the validation cohort was 47%, 68% and 94% respectively. The specificity in the derivation cohort was 87%, 85% and 18%. In the validation cohort, the specificity was similar at 87%, 75% and 27%.

CONCLUSIONS

The absence of MRI hemorrhages may not necessitate the need for DSA.