29 e-Letters

published between 2015 and 2018

  • Response to “Impact of balloon guiding catheter on technical and clinical outcomes: a systematic review and meta-analysis”

    I read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
    First, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
    In this letter, we made a funnel plot for successful recanalization based on the revised number of events we h...

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  • Reduction of ghost infarct core with TMax/CBF mismatch in CT perfusion

    TO THE EDITOR: We read with interest the recent paper by Boned and colleagues.1 The authors conclude that “CT perfusion may overestimate final infarct core, especially in the early time window. Selecting patients for reperfusion therapies based on the CTP mismatch concept may deny treatment to patients who might still benefit from reperfusion”. We completely agree with this consideration, mainly when, as in this article, the core volume is assessed according to the classical CT perfusion (CTP) mismatch mean transit time (MTT)/cerebral blood volume (CBV)2 by measuring the lesion on CBV maps generated with a one-phase CT perfusion (CTP) acquisition protocol. In fact, it is well-known that a short CTP scan duration often produces a truncation of the perfusion curves resulting in an overestimation of CBV lesion that can frequently reverse.3 In addition, it has recently been demonstrated that relative cerebral blood flow (CBF) < 30% and time to peak of the residual function (Tmax) > 6 seconds is more reliable than CBV < 2.0 ml/100gr and relative MTT > 145% in identifying infarct core and ischemic penumbra at admission, respectively.4,5 As a consequence, the new CTP mismatch model Tmax/CBF was successfully used to include acute ischemic stroke (AIS) patients in the last trials showing the efficacy of endovascular treatment.6-9 We recently treated with combined intravenous thrombolysis and with mechanical thrombectomy patients imaged within 1.5 hour from symptom onset...

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  • Comments on Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis

    We read with interest the meta-analysis conducted by our colleague Dr Waleed Brinjikji (1). In the text (section "Limitations", he stated: "Data from the Interest of Direct Aspiration First Pass Technique (ADAPT) for Thrombectomy Revascularization of Large Vessel Occlusion in Acute Ischemic Stroke (ASTER) trial suggest that there were no statistically significant differences in revascularization rates when performing the ADAPT technique compared with using a stent retriever. However, it is unclear at this time whether BGCs were used in this trial."
    Nevertheless in our publication of the ASTER trial results (2), we clearly stated in the Results section that a balloon-guide catheter was used to allow proximal flow arrest during stent retriever removal in 92% of patients treated with the stent retriever technique.
    1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis. J Neurointerv Surg 2018;10:335–339.
    2. Lapergue B, Blanc R, Gory B, et al. JAMA. 2017;318:443-452.

  • Letter to the Editor

    We read with interest the editorial by Darsaut and colleagues entitled, “PHASES and the natural history of unruptured aneurysms: science or pseudoscience?”[1]. Beginning with references to Aristotle and Pliny the Elder (always impressive), the authors launch a critique of studies of the natural history of unruptured aneurysms. With attention to ISUIA and the PHASES system, the contributors from Quebec call attention to limitations in both prospective and retrospective studies of the risk of rupture and associated risk factors for rupture of intracranial aneurysms. In their view, these imperfect studies are so deeply flawed that they are essentially useless as tools to inform decision-making with patients with unruptured intracranial aneurysms. Ending with the umpteenth call for a randomized trial, the authors create the impression that, for all patients with all kinds, sizes and locations of intracranial aneurysms, clinicians are powerless to use data from the available studies, condensed in the PHASES Score, to guide decision-making.

    The PHASES score, developed from a pooled analysis of six prospective cohort studies of patients with unruptured intracranial aneurysms, was designed to use existing natural history data (limited though that may be), to provide some estimate of future rupture risk and to aid in identifying risk factors for rupture that may push clinician and patient past the treatment threshold. Several lines of evidence support the use of PHASES...

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  • Prediction of hyperperfusion phenomenon after carotid artery stenting and carotid angioplasty using quantitative DSA with cerebral circulation time imaging; methodological issues

    I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and c...

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  • Venous Sinus Pressure Measurement Technique

    We read with interest the recent paper looking at venous sinus pressure gradients prior to stenting (1), and commend the authors for their work on this interesting topic. We also share an interest in the subject, and recently published our experience looking at venous stenting in a similar patient population (2). The authors of the current paper documented significant differences in trans-stenotic venous pressure-gradients measured under general anaesthesia (GA), and suggested that pressure measurements should be performed with patients awake to counteract this. Another paper published in this issue of JNIS also documented the disparities between pressure measurements performed under GA versus those performed under conscious sedation (CS) (3). The pressure differences in our paper were significantly more marked in those patients who underwent measurements under local anaesthesia alone versus under CS. We can therefore hypothesise that even the use of CS can result in changes in the measured venous pressures in these patients, and indeed in the current paper the authors noted that the use of midazolam in their awake patients had a statistically significant effect on the pressures obtained. Since the decision to treat often hinges on this all-important measurement, we thus propose that venous sinus pressure measurements should be always performed using local anaesthesia alone, in an effort to minimise this variability.

    1: Fargen KM, Spiotta AM, Hyer M, et al, Comparis...

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  • The Authors' response to "Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage"

    We appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.

    The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
    (5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.

    The second suggestion by Drs. Yao and You was to perform a regression ana...

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  • Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage

    With great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
    Firstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
    Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
    Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs w...

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  • Re:Comment on “Delayed enhancing lesions after coil embolization of aneurysms: clinical experience and benchtop analyses”

    We would like to thank Dr. Shotar and colleagues for their interest in our article. As highlighted by Dr. Shotar, delayed enhancing lesions (DEL) after coil embolization of aneurysm are suspected as a result of foreign body reaction 1-5. We agree with their opinion that the catheter coating of the inner wall of guiding catheter and/or the outer wall of microcatheter may be the source of foreign body. However, according to our experiences and analysis, it is our opinion that the coating material of the inner wall of microcatheter may also be the source.
    Dr Shotar suggests that the distribution of the MR lesions in the territory of the parent artery (i.e.: ICA) in our series suggests the guiding catheter as the culprit. However, in all our cases 6, the aneurysms were located at the distal ICA (Ophthalmic artery, IC-anterior choroidal artery, superior hypophyseal artery). Thus, we believe that the distribution of the DELs on MR is not in conflict with our claim that the inner wall of the microcatheter is the source. Foreign body fragments from the microcatheter probably migrated into the aneurysmal sac during multiple coil introduction attempts under unusual friction and were swept downstream. Our benchtop analyses also support this finding.
    Regarding Dr Shotar’s suggestion that "the patient treated with the microcatheter that showed coating fragments at the location of the friction on bench tests did not have DELs", this microcatheter was withdrawn imme...

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  • ‘Continuous’ vs. continuous

    To the Editor:

    We read with great interest the article by McTaggart et al. on the new embolectomy technique called Continuous Aspiration Prior To Intracranial Vascular Embolectomy (CAPTIVE).(1) The paper adds information on the supporting evidence that a combined approach of stentretriever and aspiration-catheter utilization may be the optimal path in achieving higher rates of complete reperfusion in patients with large vessel occlusions.(2, 3) While the idea of starting aspiration with the intermediate catheter prior to and during the stentretriever placement is intriguing, attention has to be paid on the effect of prolonged aspiration on collateral flow, as reported in a recent JNIS publication.(4) Additionally, the ‘continuous’ part of the title may be misleading, as the authors state that they advance the aspiration-catheter towards the face of the clot until the drip rate has stopped. As seen in Fig 1E of the CAPTIVE publication, the tip of the aspiration-catheter becomes clogged with clot as ‘a portion is held captive within the distal aspiration catheter.’ This probably results in vacuum within the aspiration-catheter and non-existent aspiration in the vicinity of the aspiration-catheter tip during immobilization of the stentretriever/clot/aspiration-catheter unit. At last, the authors describe thoroughly a ‘De-CAPTIVE shear’ on Fig 2 but neglect to acknowledge that the same danger of clot-shearing applies to the moments of stentretriever/clot/aspiration-cath...

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