Dear Editor,
we read with great interest the paper by Durst at al. [1], aimed to define
the anatomy of cerebral dural sinus system in the generalized population,
evaluating the prevalence of sinus venous stenosis and hypoplasia. This
condition is considered of pathogenetic relevance in idiopathic
intracranial hypertension (IIH) [2-4] and has been also associated to
chronic and, mostly, to refractory headaches [5-7].
We a...
Dear Editor,
we read with great interest the paper by Durst at al. [1], aimed to define
the anatomy of cerebral dural sinus system in the generalized population,
evaluating the prevalence of sinus venous stenosis and hypoplasia. This
condition is considered of pathogenetic relevance in idiopathic
intracranial hypertension (IIH) [2-4] and has been also associated to
chronic and, mostly, to refractory headaches [5-7].
We appreciate the Authors' efforts in reconstructing the venous system
anatomy by using as source the CT Angiography (CTA) of a large sample of
selected patients. However, we would point that their sample cannot be
easily considered representative of the "generalized population" and that
study results might be appreciably overestimated.
The study has been performed on a large series of cases selected among
patients that, on the basis of their own clinical presentation, underwent
a CTA. At the Author's institution, a CTA was routinely performed in "all
suspected strokes, many trauma patients, and anyone suspected of having a
vascular disorder". In order to make their sample representative of the
general population, out of 600 screened examinations, 245 have been
excluded for technical reasons or because of clinic presentations or
pathologic findings that could "conceivably alter venous outflow".
However, according to the exclusion criteria list, posterior fossa lesions
were excluded, but anterior focal ischemia and head trauma - both
conditions usually running with at least a mild brain edema and consequent
raised intracranial pressure (ICP) - were presumably included. There is
evidence that raised ICP is associated with focal or diffuse narrowing of
sinus venous tree [8].
Moreover, a number of other clinical presentations that could prompt
neurovascular investigations but might result from a cerebral venous
outflow derangement despite a negative CTA, are not listed within the
exclusion criteria. These include: responsive chronic migraine [9-10]
(only refractory chronic headaches were excluded but there is evidence of
> 50% sinus stenosis prevalence in chronic migraine); acute vertigo
(often comorbid with episodic or chronic migraine); cough, exertional and
sexual activity-associated headaches [11], and idiopathic stabbing
headache [12]. Finally, Transient global amnesia may result from a
deranged cerebral venous outflow with jugular valve incompetence [13].
Based on the above considerations, we believe that the design of this
otherwise excellent study implies a not negligible overestimation of the
prevalence of sinus stenosis and hypoplasia in the general population. The
true prevalence of sinus stenosis in healthy subjects remains unknown.
1. Durst CR, Ornan DA, Reardon MA, et al.. Prevalence of dural venous
sinus stenosis and hypoplasia in a generalized population. J Neurointerv
Surg. 2016. [Epub ahead of print]. doi: 10.1136/neurintsurg-2015-012147
2.Farb RI, Vanek I, Scott JN, et al. Idiopathic intracranial
hypertension: the prevalence and morphology of sinovenous stenosis.
Neurology. 2003 May 13; 60(9):1418-24.
3. De Simone R, Ranieri A, Montella S, et al. The role of dural sinus
stenosis in idiopathic intracranial hypertension pathogenesis: the self-
limiting venous collapse feedback-loop model. Panminerva Med. 2014 Sep;
56(3):201-9
4. Puffer RC, Mustafa W, Lanzino G. Venous sinus stenting for
idiopathic intracranial hypertension: a review of the literature. J
Neurointerv Surg. 2013;5(5):483-486
5. Bono F, Salvino D, Tallarico T, et al. Abnormal pressure waves in
headache sufferers with bilateral transverse sinus stenosis. Cephalalgia
2010; 30: 1419-1425
6. De Simone R, Ranieri A, Montella S, et al. Sinus venous stenosis-
associated idiopathic intracranial hypertension without papilledema as a
powerful risk factor for progression and refractoriness of headache. Curr
Pain Headache Rep. 2012 Jun;16(3):261-9.
7. De Simone R, Ranieri A, Montella S, et al. Intracranial pressure
in unresponsive chronic migraine. J Neurol. 2014 Jul;261(7):1365-73.
8. Rohr A, Bindeballe J, Riedel C, et al. The entire dural sinus tree
is compressed in patients with idiopathic intracranial hypertension: a
longitudinal, volumetric magnetic resonance imaging study. Neuroradiology.
2012 Jan;54(1):25-33
9. Bono F, Cristiano D, Mastrandrea C, et al. The upper limit of
normal CSF opening pressure is related to bilateral transverse sinus
stenosis in headache sufferers. Cephalalgia 2010; 30: 145-151.
10. Fofi L, Giugni E, Vadal? R, et al. Cerebral transverse sinus
morphology as detected by MR venography in patients with chronic migraine.
Headache. 2012 Sep;52(8):1254-61.
11. Donnet A, Valade D, Houdart E. Primary cough headache, primary
exertional headache, and primary headache associated with sexual activity:
a clinical and radiological study. Neuroradiology 2013; 55:297-305
12. Montella S, Ranieri A, Marchese M, De Simone R. Primary stabbing
headache: a new dural sinus stenosis-associated primary headache? Neurol
Sci. 2013 May;34 Suppl 1:S157-9.
13. Chung CP, Hsu HY, Chao AC, et al. Transient global amnesia:
cerebral venous outflow impairment-insight from the abnormal flow patterns
of the internal jugular vein. Ultrasound Med Biol. 2007 Nov;33(11):1727-
35. Epub 2007 Jul 16.
Optimal outcome of intra-arterial treatment for Acute ischemic stroke
(AIS) requires the involvement of appropriately trained and qualified
providers from diverse specialties working together in synchrony under
tight time line, communicating effectively to provide evidence-based
clinical care. Hence, we welcome the international multi-society consensus
document on training guidelines for the interventionalists involved in...
Optimal outcome of intra-arterial treatment for Acute ischemic stroke
(AIS) requires the involvement of appropriately trained and qualified
providers from diverse specialties working together in synchrony under
tight time line, communicating effectively to provide evidence-based
clinical care. Hence, we welcome the international multi-society consensus
document on training guidelines for the interventionalists involved in
intra-arterial treatment of AIS.(1) However, we wish to point out the
critical missing link in the consensus document - the role of
anesthesiologists.
We wish to offer a brief outline of the importance of anesthesiology
inputs in stroke care. Given the emergent and complex nature of the
interventional procedures for AIS, frequent association of multiple co-
morbidities, the need for strict hemodynamic management and ensuring
homeostasis, it is recommended to have a qualified and experienced
anesthesiologist to provide monitored anesthesia care (MAC) or general
anesthesia (GA), as deemed suitable based on the patient
characteristics.(2) Providing an optimal milieu for the procedure while
poised to quickly manage complications and concurrently maintaining the
blood pressure in a tight range in patients who often have associated
cardiovascular diseases is challenging. Optimal hemodynamic management of
these patients requires judicious fluid, vasopressor / inotrope selection.
Moreover, oxygenation and ventilation patterns during intra-arterial
therapy can impact cerebral blood flow and contribute to outcome.
Additionally, glycemic management in accordance with current guidelines is
critical. These skill sets are uniquely possessed by anesthesiologists
experienced in the care of stroke patients. Further underscoring the
complexity mandating this expertise is the fact that type of GA including
the choice of anesthetic/sedative agents may impact the ischemic brain and
can affect the outcome of AIS.(3) Not surprisingly, it has been
recommended that acute stroke interventions, even when performed on awake
patients, should be carried out in the presence of experienced anesthesia
providers who can rapidly manage untoward events.(2) Essentially, the
involvement of a qualified and experienced anesthesiologist can have
significant bearing on the outcome. The anesthetic management should
follow the evidence based recommendations made by the Society for
Neuroscience in Anesthesiology and Critical Care (SNACC) consensus
statement.(2)
Although some studies reported that GA, as a generic and
uncharacterized therapy, is associated with poor outcome in patients
undergoing intra-arterial treatment of AIS, these investigators did not
recognize that GA constitutes a continuum of central nervous system
depression, wherein effects on the brain are dose-related, disparate, and
protean in terms of neurochemistry, perfusion, neuroprotection, and
neurotoxicity.(4) This has led to the initiation of clinical trials
randomizing the patients with AIS to GA or MAC. However, these trials
suffer from significant limitations due to lack of anesthetic insight /
involvement and do not reflect the relevant clinical and protean
neuropharmacology of GA.(4) We offer the similar criticism for the
Training Guidelines for Endovascular Ischemic Stroke Intervention.(1)
While this document provides crucial recommendations for not only
physician training and qualification but also essential hospital
requirements like 24/7 access to all relevant expertise such as vascular
neurology, neurosurgery and neurocritical care; it fails to address the
fundamental need of the 24/7 availability of a qualified anesthesiologist.
We encourage the various disciplines involved in stroke care to work
together and we urge the community of stroke providers to actively engage
SNACC and the anesthesiology community in order to effectively enhance the
care of patients with AIS.
References
1. Lavine SD, Cockroft K, Hoh B, et al. Training Guidelines for
Endovascular Ischemic Stroke Intervention: An International Multi-Society
Consensus Document. AJNR Am J Neuroradiol. 2016 Feb 18. [Epub ahead of
print]
2. Talke PO, Sharma D, Heyer EJ, et al. Society for Neuroscience in
Anesthesiology and Critical Care Expert consensus statement: anesthetic
management of endovascular treatment for acute ischemic stroke: endorsed
by the Society of NeuroInterventional Surgery and the Neurocritical Care
Society. J Neurosurg Anesthesiol. 2014 Apr;26(2):95-108.
3. Sivasankar C, Stiefel M, Miano TA, et al. Anesthetic variation and
potential impact of anesthetics used during endovascular management of
acute ischemic stroke. J Neurointerv Surg. 2015 Nov 27. [Epub ahead of
print]
4. Kofke WA, Sharma D. SIESTA trial: Is GA a drug you get from the
hospital pharmacy? International Journal of Stroke. (In Press)
I am glad to see that my letter has piqued the interest of
interventional neuroradiologists like Dr. Jagadeesan. I agree with him
that no one should be running a fellowship that does not have the volume
to expose trainees to enough cases so that they may obtain the necessary
experience to practice safely. However, I think he has misunderstood my
point. As I stated about the original piece, "I have no objection to the
lo...
I am glad to see that my letter has piqued the interest of
interventional neuroradiologists like Dr. Jagadeesan. I agree with him
that no one should be running a fellowship that does not have the volume
to expose trainees to enough cases so that they may obtain the necessary
experience to practice safely. However, I think he has misunderstood my
point. As I stated about the original piece, "I have no objection to the
logic and opinions expressed, and actually have no opinion on the issue
for or against these fellowships." My only request was for the authors of
the original article to disclose the fact (as Dr. Jagadeesan has nicely
done in his own letter) that they may have potential conflicts of interest
by way of already completed and reaping the potential rewards of the very
same fellowship training that they now advocate curtailing, so that the
reader may use this information when making up his or her own mind. I have
no interest in standing between interventional neuroradiologists and their
patients (unless one is trying to run over the other, in which case I hope
I could intervene). As far as taxi drivers, I would applaud their
specialty if one disclosed that he gotten his driver's license from the
black market instead of completing the required training and tests -
indeed, that information might affect my decision to ride in his or
another cab.
We read with interest Dr. Ding's response to our manuscript,
"Angioarchitectural features associated with hemorrhagic presentation in
pediatric cerebral arteriovenous malformations," and we thank him for his
gracious comments. In response to his question regarding whether brain AVM
angioarchitecture influences our particular treatment strategy, we would
point out that the overwhelming majority of our pediatric patients wi...
We read with interest Dr. Ding's response to our manuscript,
"Angioarchitectural features associated with hemorrhagic presentation in
pediatric cerebral arteriovenous malformations," and we thank him for his
gracious comments. In response to his question regarding whether brain AVM
angioarchitecture influences our particular treatment strategy, we would
point out that the overwhelming majority of our pediatric patients with
brain AVM present with hemorrhage or with an AVM-related neurological
symptom. Thus, we are rarely in the position of evaluating an entirely
asymptomatic AVM, in which case particular features of the
angioarchitecture might weigh heavily in assessing whether to proceed. Our
treatment strategy, once the decision has been made to proceed, is
designed to as definitively as possible ensure complete removal of the
AVM, wherever feasible. We thus favor surgical resection, with
preoperative embolization used where this would lower morbidity and
improve surgical outcome. Given the age of our patients, we tend to favor
radiotherapy less than would typically be the case in an adult cohort. We
hope to describe the details of our multidisciplinary approach to
treatment in a future publication.
I have read, with great interest, the paper by Ellis et al. titled
'Angioarchitectural features associated with hemorrhagic presentation in
pediatric cerebral arteriovenous malformations [1]. The authors
retrospectively reviewed the angiographic features of 135 pediatric
patients, mean age 10.1 years (range 0-19 years), who were referred to
Hospital for Sick Children in Toronto, Canada and Boston Children's
Hospital ove...
I have read, with great interest, the paper by Ellis et al. titled
'Angioarchitectural features associated with hemorrhagic presentation in
pediatric cerebral arteriovenous malformations [1]. The authors
retrospectively reviewed the angiographic features of 135 pediatric
patients, mean age 10.1 years (range 0-19 years), who were referred to
Hospital for Sick Children in Toronto, Canada and Boston Children's
Hospital over a period of 11 years from 2000 to 2011. The most common
presenting symptoms were hemorrhage (64%), seizure (13%), and focal
neurological deficits or headache (13%). The authors sought to identify
angiographic features associated with AVM rupture at presentation.
Multivariate logistic regression analysis identified smaller size
(P<0.01), exclusive deep venous drainage (P=0.02), and infratentorial
location (P=0.01) to be independent predictors of hemorrhagic
presentation.
Given the relatively little information available regarding the
natural history of pediatric compared to adult AVMs, this study represents
an important contribution to the pediatric AVM literature. As the authors
note, there is an increased tendency to aggressively treat AVMs,
especially ruptured ones, presenting in children compared to those in
adults due to the higher exposure to hemorrhage risk and hemorrhage-
related morbidity and mortality by children. Given what is currently known
regarding the natural history of AVMs, which is largely derived from adult
patients, this rationale is seems valid [2]. A Randomized Trial of
Unruptured Brain AVMs (ARUBA) is a study of adult patients only [3]. It is
unknown whether the results of ARUBA, which are pending imminent
publication, will alter the management of unruptured pediatric AVMs.
It would be very interesting to know how the patients described in
this study were treated and whether hemorrhagic presentation and AVM
angioarchitectural features influenced the treatment strategies. Although
the method by which AVM obliteration is achieved is biased, at times
significantly, by the treating physician and institution, no single
modality, including endovascular embolization, microsurgical resection,
and radiosurgery, has emerged superior to its counterparts. For example,
AVMs with smaller size and exclusive deep venous drainage, which typically
implies deep location, are ideal radiosurgery targets [4-5]. However, in
the setting of AVM rupture, some may advocate for microsurgical resection
in order to rapidly eliminate future hemorrhage risk. Additionally, the
authors did not distinguish infratentorial location by brainstem versus
cerebellum. Recently, the UCSF cerebrovascular group described cerebellar
AVMs as anatomically distinct lesions from cerebral AVMs with a higher
propensity for hemorrhagic presentation [6]. Not surprisingly, cerebellar
AVMs are significantly more conducive than brainstem AVMs to surgical
resection therefore underscoring the importance of distinguishing the two
locations.
In summary, the authors should be congratulated for identifying
independent predictors of hemorrhagic presentation in a relatively large
cohort of pediatric AVMs combined from two tertiary pediatric referral
centers of international repute. Given the difficulty of obtaining
prospective data regarding the natural history of pediatric AVMs, the
cerebrovascular community will continue to rely on this study and others
like it to guide decision-making for the management of these rare and
complex vascular lesions.
References
1. Ellis, M.J., D. Armstrong, S. Vachhrajani, A.V. Kulkarni, P.B.
Dirks, J.M. Drake, E.R. Smith, R.M. Scott, and D.B. Orbach,
Angioarchitectural features associated with hemorrhagic presentation in
pediatric cerebral arteriovenous malformations. J Neurointerv Surg, 2013.
5(3): p. 191-5.
2. Gross, B.A. and R. Du, Natural history of cerebral arteriovenous
malformations: a meta-analysis. J Neurosurg, 2013. 118(2): p. 437-43.
3. Mohr, J.P., A.J. Moskowitz, C. Stapf, A. Hartmann, K. Lord, S.M.
Marshall, H. Mast, E. Moquete, C.S. Moy, M. Parides, J. Pile-Spellman, R.
Al-Shahi Salman, A. Weinberg, W.L. Young, A. Estevez, I. Kureshi, and J.L.
Brisman, The ARUBA trial: current status, future hopes. Stroke, 2010.
41(8): p. e537-40.
4. Kano, H., D. Kondziolka, J.C. Flickinger, H.C. Yang, T.J. Flannery,
N.R. Awan, A. Niranjan, J. Novotny, and L.D. Lunsford, Stereotactic
radiosurgery for arteriovenous malformations, part 2: management of
pediatric patients. J Neurosurg Pediatr, 2012. 9(1): p. 1-10.
5. Yen, C.P., S.J. Monteith, J.H. Nguyen, J. Rainey, D.J. Schlesinger, and
J.P. Sheehan, Gamma Knife surgery for arteriovenous malformations in
children. J Neurosurg Pediatr, 2010. 6(5): p. 426-34.
6. Rodriguez-Hernandez, A., H. Kim, T. Pourmohamad, W.L. Young, and M.T.
Lawton, Cerebellar arteriovenous malformations: anatomic subtypes,
surgical results, and increased predictive accuracy of the supplementary
grading system. Neurosurgery, 2012. 71(6): p. 1111-24.
I have read, with great interest, the paper by Stemer et al. titled
'Acute embolization of ruptured brain arteriovenous malformations' [1].
The authors describe a cohort of 21 patients with ruptured intracranial
arteriovenous malformations (AVM) who were treated with endovascular Onyx
(ev3, Irvine, California, USA) embolization in the acute phase following
hemorrhage. The median interval from hemorrhagic presentation to...
I have read, with great interest, the paper by Stemer et al. titled
'Acute embolization of ruptured brain arteriovenous malformations' [1].
The authors describe a cohort of 21 patients with ruptured intracranial
arteriovenous malformations (AVM) who were treated with endovascular Onyx
(ev3, Irvine, California, USA) embolization in the acute phase following
hemorrhage. The median interval from hemorrhagic presentation to treatment
was 4 days (range 0-19 days). Thirteen patients received a single
treatment (62%), and eight patients were treated in more than one stage
(38%). Complete occlusion was achieved in 11 patients (52%) including
seven in one stage and four in multiple stages. There were two
asymptomatic intraprocedural complications (10%) as well as two
mortalities unrelated to treatment (10%).
Excluding three patients lost to follow-up and six patients who
underwent post-embolization surgical resection, 12 patients had
angiographic follow-up at a mean interval of 7.5 months. It would be
interesting to know the number of AVMs, if any, which had post-
embolization recanalization at follow-up as this is known to occur at
varying time intervals following endovascular treatment. Despite high
levels of initial enthusiasm for complete AVM cure with standalone
endovascular embolization following the advent and subsequent widespread
therapeutic use of permanent liquid embolic agents, especially Onyx, the
role of embolization in the overall management of AVMs remains largely
adjunctive.
Studies reporting high rates of complete AVM obliteration with
embolization alone, approaching 50%, were subject to significant selection
biases [2]. Total obliteration rates of 10-20% with embolization alone are
more reflective of less selected AVM cohorts [3]. The effect of partial
AVM treatment on the subsequent hemorrhage risk is still controversial
with conflicting studies reporting improved and worsened outcomes of
incompletely obliterated AVMs. With increasing evidence that embolization
reduces AVM obliteration rates following radiosurgery, judicious use of
endovascular therapy for AVMs is crucial to the optimal long-term
management of these complex vascular lesions [4-6].
Early natural history studies of AVMs did not distinguish ruptured
from unruptured lesions. However, several recent studies in the past
decade have repeatedly demonstrated that the hemorrhage risk of ruptured
AVMs is significantly higher than the hemorrhage risk of unruptured ones
[7]. Unlike intracranial aneurysms, for which the risk of acute repeat
hemorrhage following initial rupture is well described, the acute
rehemorrhage rate of ruptured AVMs is poorly defined. In a recent meta-
analysis of over 3900 patients, Gross et al. reported an annual hemorrhage
risk of 4.5% for ruptured AVMs compared to 2.2% for unruptured lesions
[8]. A follow-up duration of less than one year, such as in this study, is
inadequate to compare treatment outcomes to the natural history.
In summary, the authors should be congratulated for demonstrating the
feasibility and safety of endovascular Onyx embolization for the treatment
of acutely ruptured AVMs. As the authors note, the study is significantly
limited by the relatively small number of patients with angiographic
follow-up and the relatively short duration of follow-up. Therefore it
remains to be determined in larger cohorts with longer follow-up whether
the strategy of acute embolization for ruptured AVMs is superior to
current approaches which are largely conservative in the acute post-
hemorrhage phase.
References
1. Stemer, A.B., W.O. Bank, R.A. Armonda, A.H. Liu, D.W. Herzig, and
R.S. Bell, Acute embolization of ruptured brain arteriovenous
malformations. J Neurointerv Surg, 2013. 5(3): p. 196-200.
2. Saatci, I., S. Geyik, K. Yavuz, and H.S. Cekirge, Endovascular
treatment of brain arteriovenous malformations with prolonged intranidal
Onyx injection technique: long-term results in 350 consecutive patients
with completed endovascular treatment course. J Neurosurg, 2011. 115(1):
p. 78-88.
3. van Rooij, W.J., M. Sluzewski, and G.N. Beute, Brain AVM embolization
with Onyx. AJNR Am J Neuroradiol, 2007. 28(1): p. 172-7; discussion 178.
4. Schwyzer, L., C.P. Yen, A. Evans, S. Zavoian, and L. Steiner, Long-term
Results of Gamma Knife Surgery for Partially Embolized Arteriovenous
Malformations. Neurosurgery, 2012. 71(6): p. 1139-48.
5. Ding, D., C.P. Yen, Z. Xu, R.M. Starke, and J.P. Sheehan, Radiosurgery
for patients with unruptured intracranial arteriovenous malformations. J
Neurosurg, 2013.
6. Andrade-Souza, Y.M., M. Ramani, D. Scora, M.N. Tsao, K. terBrugge, and
M.L. Schwartz, Embolization before radiosurgery reduces the obliteration
rate of arteriovenous malformations. Neurosurgery, 2007. 60(3): p. 443-51;
discussion 451-2.
7. Stapf, C., H. Mast, R.R. Sciacca, J.H. Choi, A.V. Khaw, E.S. Connolly,
J. Pile-Spellman, and J.P. Mohr, Predictors of hemorrhage in patients with
untreated brain arteriovenous malformation. Neurology, 2006. 66(9): p.
1350-5.
8. Gross, B.A. and R. Du, Natural history of cerebral arteriovenous
malformations: a meta-analysis. J Neurosurg, 2013. 118(2): p. 437-43.
We read with great interest the article by Turk et al[1] assessing
the safety and efficacy of endovascular stroke intervention based on CT
perfusion (CTP) criteria. The authors are to be congratulated for this
excellent report and for achieving remarkably high rates of favorable
outcomes (42%) in stroke patients with poor neurological sta...
We read with great interest the article by Turk et al[1] assessing
the safety and efficacy of endovascular stroke intervention based on CT
perfusion (CTP) criteria. The authors are to be congratulated for this
excellent report and for achieving remarkably high rates of favorable
outcomes (42%) in stroke patients with poor neurological status (mean
NIHSS, 18.2). They further categorize their patient population based on
time from symptom onset and clearly show that patients treated after 8 h
had no difference in outcomes or mortality than those treated before 8 h.
The fact that time from symptom onset to intervention was as long as 16.4
h in the late group (>8h) lends further credence to their findings
because the extent of salvageable brain tissue and the prospect of
improvement significantly decrease with delayed recanalization.[2-4] This
report adds substantially to the growing body of literature supporting the
use of CTP in stroke patients and reinforces what we have always believed;
specifically, CTP can optimize and guide patient selection for
intraarterial therapy based on an individual's physiological parameters
namely the extent of salvageable ischemic penumbra.
Although we agree with the authors about the merits of CTP and stress
the importance of their results, we would like to bring to their attention
that their conclusion may not be totally supported by the presented data.
The authors have compared functional outcomes in patients treated <8 h
and >8 h after symptom onset. Although all patients were selected for
endovascular stroke intervention based on CTP criteria, they conclude that
"physiologic imaging-guided patient selection rather than time for
endovascular reperfusion in ischemic stroke may be effective and safe". We
believe the only way to reach such a conclusion is to compare two groups
of patients, one selected based on CTP criteria and the other based on
time from symptom onset. Indeed, the authors do not discuss the study by
Hassan et al[5] published in 2010 that retrospectively compared 69
patients undergoing CTP-guided and 127 patients undergoing time-guided
endovascular treatment. The authors of this study found no incremental
benefit with the use of CTP, with similar rates of recanalization,
intracranial hemorrhage, favorable outcomes, and in-hospital mortality in
both groups. It should be noted, however, that only 40% of patients in
their study underwent mechanical thrombectomy and that CTP-guided
treatment at the primary author's institution was compared to time-guided
treatment at a different institution, which could have influenced their
results. Still, this is to our knowledge the only study that has compared
time-guided to CTP-guide patient selection for acute stroke intervention.
Randomized controlled trials comparing the 2 strategies are needed
especially that many prominent centers still have not adopted CTP as a
screening tool in this setting.
We would also like to highlight some of the potential shortcomings
associated with CTP that were not discussed in this study. The inter-
observer variability remains a great concern with CTP.[6] Additionally,
the optimal post-processing algorithm for defining penumbra and core
infarct have yet to be determined, and thresholds for guiding therapy are
still under investigation.[7] The variation in reconstruction of CTP
images and qualitative interpretation of salvageable tissue may lead to
selection of a relatively heterogeneous population, leading to the
inclusion of patients with limited salvageable tissue. False negatives and
non interpretable imaging can occur with CTP due to low cardiac output,
inappropriate slow rate of bolus administration, contrast extravasation in
the subcutaneous tissue, patient movement, and operator inexperience.
Finally, despite the potential caveats of CTP imaging , Turk et al[1]
have clearly demonstrated that CTP allows effective treatment of many
patients who otherwise would be destined for supportive management or end
of life care due to presentation outside of the therapeutic window. We
commend the authors for their rigorous work and await similar
contributions that will help us determine the best approach for patient
selection for acute stroke intervention.
References
1. Turk AS, Magarick JA, Frei D, et al. CT perfusion-guided patient
selection for endovascular recanalization in acute ischemic stroke: a
multicenter study. J Neurointerv Surg 2012 doi: neurintsurg-2012-010491
[pii]
10.1136/neurintsurg-2012-010491[published Online First: Epub Date]|.
2. Wardlaw JM, Murray V, Berge E, et al. Recombinant tissue plasminogen
activator for acute ischaemic stroke: an updated systematic review and
meta-analysis. Lancet 2012;379(9834):2364-72 doi: S0140-6736(12)60738-7
[pii]
10.1016/S0140-6736(12)60738-7[published Online First: Epub Date]|.
3. Hesselmann V, Niederstadt T, Dziewas R, et al. Reperfusion by combined
thrombolysis and mechanical thrombectomy in acute stroke: effect of
collateralization, mismatch, and time to and grade of recanalization on
clinical and tissue outcome. AJNR Am J Neuroradiol 2012;33(2):336-42 doi:
ajnr.A2746 [pii]
10.3174/ajnr.A2746[published Online First: Epub Date]|.
4. Vergouwen MD, Algra A, Pfefferkorn T, et al. Time Is Brain(stem) in
Basilar Artery Occlusion. Stroke 2012 doi: STROKEAHA.112.666867 [pii]
10.1161/STROKEAHA.112.666867[published Online First: Epub Date]|.
5. Hassan AE, Zacharatos H, Rodriguez GJ, et al. A comparison of Computed
Tomography perfusion-guided and time-guided endovascular treatments for
patients with acute ischemic stroke. Stroke 2010;41(8):1673-8 doi:
STROKEAHA.110.586685 [pii]
10.1161/STROKEAHA.110.586685[published Online First: Epub Date]|.
6. Hassan AE, Zacharatos H, Chaudhry SA, et al. Agreement in endovascular
thrombolysis patient selection based on interpretation of presenting CT
and CT-P changes in ischemic stroke patients. Neurocrit Care 2012;16(1):88
-94 doi: 10.1007/s12028-011-9577-9[published Online First: Epub Date]|.
7. Amenta PS, Ali MS, Dumont AS, et al. Computed tomography perfusion-
based selection of patients for endovascular recanalization. Neurosurg
Focus 2011;30(6):E6 doi: 10.3171/2011.4.FOCUS10296[published Online First:
Epub Date]|.
The reply from Perez et al to my letter of March 2012 is misleading
and wrong in two important regards.1 First, they state that their report
of the use of the solitaire stent for thrombectomy was just a case report,
"nothing else". 2 This is not true. In fact, they explicitly use this
report, both in the abstract and conclusion to lay claim for developing
the stentreiever concept for thrombectomy: "This was the first...
The reply from Perez et al to my letter of March 2012 is misleading
and wrong in two important regards.1 First, they state that their report
of the use of the solitaire stent for thrombectomy was just a case report,
"nothing else". 2 This is not true. In fact, they explicitly use this
report, both in the abstract and conclusion to lay claim for developing
the stentreiever concept for thrombectomy: "This was the first .. use of
the Solitaire stent for this purpose and the ignition spark for the
development of a whole new generation of devices". In addition, this
report was titled a "Historical Vignette". This report was written to
take credit for the development of stentreivers for acute stroke. To
state, as they do in their response to my letter, that their paper makes
no claims is clearly disingenuous.
Second, they dismiss the idea that the prior publication by Kelly et
al -- reporting the use of an Enterprise stent (Codman Neurovascular,
Rayhnam, MA) as a temporary endovascular bypass to achieve successful
revascularization in a patient with an acute ischemic stroke and large
vessel occlusion -- had any influence on their work. This claim is
disingenuous as well. In their response, they state that " ... temporary
bypass might have been a local and ephemeral phenomenon; however it did
not cause to much commotion, at least in Europe." However, the technique
of stent-retrieval, or any kind of temporary stenting for acute stroke is,
in fact, part and parcel of "temporary endovascular bypass". The best
evidence of this is that the authors presented their own original
experience with the Solitaire at the 2010 International Stroke Conference
in an abstract entitled "Temporary Endovascular Bypass for the treatment
of ischemic stroke: Experience After 50 Patients". Clearly their work
with the Solitaire stent in acute stroke was influenced by this prior
report.
In summary, despite their claims, the concept of temporary stenting
for acute stroke treatment preceded the authors' 2008 case. In their
Historical Vignette and subsequent response to my prior letter, the
authors are attempting to rewrite history. They do deserve credit for
taking this concept and rapidly moving it forward in clinical practice,
however.
References:
1. Re: Perez et al 'Intracranial thrombectomy using the Solitaire stent: a
historical vignette'. Derdeyn CP. J Neurointerv Surg. 2012 Mar;4(2):153-4;
Author Response 154
2. Intracranial thrombectomy using the Solitaire stent: a historical
vignette. P?rez MA, Miloslavski E, Fischer S, B?zner H, Henkes H. J
Neurointerv Surg. 2011 Dec 14.
3. Kelly ME, Furlan AJ, Fiorella D. Recanalization of an acute middle
cerebral artery occlusion using a self-expanding, reconstrainable,
intracranial microstent as a temporary endovascular bypass. Stroke
2008;39:1770-3.
4. Liebig T, Lockau H, Stehle S, Dorn F, Prothmann S, Henkes HH. Temporary
Endovascular Bypass in Acute Stroke: Experience After 50 Patients. Stroke
2010 Vol 41,1:e259-260.
As a participant in the creation of the original ACGME ESNR
fellowship training standards, I read the article concerning fellowship
suspension with great interest (1). The paper is timely and thorough. It
is unfortunate that the Neurointerventional world is dealing with so many
unknowns. We do not seem to know how many we are, where we work, what we
do, or where we were trained. The problem is very well summarized at...
As a participant in the creation of the original ACGME ESNR
fellowship training standards, I read the article concerning fellowship
suspension with great interest (1). The paper is timely and thorough. It
is unfortunate that the Neurointerventional world is dealing with so many
unknowns. We do not seem to know how many we are, where we work, what we
do, or where we were trained. The problem is very well summarized at the
end of the paper. We seem to be spreading our patient population among
too many practitioners, which subsequently restricts the number of
patients available to each practitioner to stay in practice, make a
living, and be proficient.
The first line states: "The purpose of any training program is to
provide a supply of skilled workers to address an unmet demand for their
services." The authors discuss numbers of procedures and extrapolate
implications but do not discuss what the training was that got these
people out into the world. Further, there is no clear statement as to
what these unmet needs are. These workers might perhaps be skilled in
certain areas, but not know anything about other subjects.
Adequacy of numbers is the primary thrust of the article. One
endovascular neurosurgeon can possibly cover 5 different hospitals by
themselves for aneurysms, AVMs etc., and could do 300 aneurysms per year
easily. Most, but not all, neurointerventional fellowships provide an
adequate number of aneurysms for training. But as correctly pointed out,
the numerous auxiliary procedures that are necessary to be proficient in
this profession, such as skull base tumor embolization, epistaxis,
vertebroplasty, nerve root block or ablation, are not routinely performed
at all institutions. AVMs might be completely ignored at many places.
Endovascular spinal procedures are rare.
The gaping hole in fellowship training is acute ischemic stroke.
Consistently complete training for all fellows continues to be a void in
our profession and a gap in the entire premise of this statement. It is
perfectly acceptable to produce specialists in aneurysm intervention as
well as vertebroplasty, but we should not count them all in the same
bucket and presume we have enough people to cover the nation for stroke.
Everyone does not do everything nor do they want to. Many fellowship
programs have inadequate caseload and resultant inadequate or poor
training in acute stroke treatment. We should not just expect this
specialized training to magically appear in fellowships where there is
inadequate case volume to begin with. Therefore, what is the true number
of interventionists that are available, trained, able, and willing to
treat strokes?
The need for trained physicians to treat stroke is not based upon the
number of strokes (as might be the case for aneurysms), but rather on the
number of hospitals that need stroke coverage. The issue with stroke
coverage is that there needs to be a minimal number of practitioners at
each hospital to take call 24/7/365, no matter the number of cases: 1 per
month or 1 per day. Another paper describes the necessity of stroke
coverage as 2-3 interventionists per center for 24/7/365 coverage (2),
contradicting the official SNIS stated position as well as EMTALA
(Emergency Medical Treatment and Active Labor Act) that states that no
requirement can be made for 24/7 coverage with less than 4 persons. If
there is a need for 200 hospitals to have 24/7/365 coverage, then there
needs to be at least 800 interventionists just at those hospitals alone.
The official SNIS position on stroke coverage is as follows: "Current
staffing levels at Comprehensive Stroke Centers will rarely allow
continuous immediate coverage for IA stroke therapy at all times, 365 days
a year. Instantly available coverage on a continuous basis 24/7/365
should not be expected with fewer than 4 persons. Until adequate staffing
levels are achieved, continuously available catheter-directed intra-
arterial emergency stroke therapy is considered the "ideal", but is not
mandatory in order to be classified as Comprehensive Stroke Center.
Therefore, in agreement with federal regulations, IA stroke therapy might
be available only a portion of the time as determined by local hospital
conditions and staffing levels of qualified and appropriately trained
personnel, and the institution still qualify as a Comprehensive Stroke
Center." (SNIS executive committee, John Barr president, 2005). As we all
know, there are very few hospitals that have 4 neurointerventionists.
There are probably fewer than 20 fellowships in the US that treat by
endovascular techniques more than 50 strokes per year. Maybe 10. Even
with 50 cases, a "fellow" can only "maybe" attain the SNIS mandated 10
cases as "primary operator" in his last few months. Thus, in the
remaining 60-70 fellowships (90%?), the trainees will not get the required
experience. There are numerous examples of fellowships that provide a
certificate of competency for everything "neurointerventional" where the
number of endovascular stroke cases can be counted on one hand... or one
finger. How will these fellows get sufficient training, experience, and
knowledge to have good outcomes when treating strokes when they are in
private practice?
Foremost, I hope that this call for a moratorium in fellowships will
be accompanied by an equally vigorous call for augmented and improved
stroke training for fellows and our members. A recent SNIS webinar
bemoaned the poor operator performance for intracranial stenting during
SAMMPRIS. A recent article has documented "death and destruction" in
endovascular stroke therapy (3). The failure of SAMMPRIS and the stoppage
of IMS 3 only highlights the fact that we are not doing very well at this.
As we all used to believe, IMS 3 should have been a slam-dunk. SNIS/SVIN
should offer specialized intensive training courses that are, in actual
fact, a responsibility of our professional organizations. Our societies
need a plan for improved training and continuing education for our fellows
and members in addition to a moratorium.
References
1) Fiorella D, Hirsch JA, Woo HH, et al. Should neurointerventional
fellowship training be suspended indefinitely? J NeuroIntervent Surg
2012;4:315-318
2) Zaidat OO, Lazzaro M, McGinley E, et al. Demand-supply of
neurointerventionalists for endovascular ischemic stroke therapy.
Neurology 2012;79 (Suppl 1):S35-S41.
3) Cloft HJ. Death and Destruction in the Intra-Arterial Battle with
Acute Ischemic
Stroke. AJNR Am J Neuroradiol 32:1767-70.
Hirsh and Meyers espouse that same party line of the many private non
-governmental agencies (and academics who will personally benefit from
this program) who wish to impose private interest group-unproven corporate
interests upon practicing physicians. They continue to state MOC is
"voluntary" and then describe the many ways these "non-profit"
corporations (who earn handsomely and have over $400 million in assets and
as g...
Hirsh and Meyers espouse that same party line of the many private non
-governmental agencies (and academics who will personally benefit from
this program) who wish to impose private interest group-unproven corporate
interests upon practicing physicians. They continue to state MOC is
"voluntary" and then describe the many ways these "non-profit"
corporations (who earn handsomely and have over $400 million in assets and
as great yearly gross receipts!) will see this product forced on
physicians. HOWEVER, Working physicians do not want or even see any value
in this unproven imposition:
The American Medical Association (AMA) developed the Physician's
Recognition Award (PRA) in the late 1960's as the validation program for
Continuing Medical Education (CME), embraced by most, but not all states,
to validate physician "lifelong learning" as the educational component of
re-licensure. Recently, the Federation of State Medical Boards (FSMB),
Inc., a multimillion dollar, non-profit and non-governmental corporation,
targeted the State of Ohio as the first of 11 pilot states to implement
their corporate brand of MOL (Ohio., Calif., Colo., Del., Iowa, Mass.,
Mississippi, Okla., Ore., Va., Wis.).
On May 19, 2012, the Ohio State Medical Association, as the first Ohio
physician organization, formally resolved at the state meeting to oppose
the FSMB MOL program. (1) OSMA recognized early that FSMB MOL was the
unwarranted regulatory capture of physician licensure: the act of securing
corporate income through legislation. (2) An intense battle over FSMB MOL
ensued within the State Medical Board of Ohio (SMBO), zealously led by two
FSMB board members, who also occupied the SMBO Executive Director and one
senior Board member positions. On October 5, 2012, the OSMA drafted with
10 other state medical associations, representing over 15,000 physicians,
a formal resolution of opposition directed to the SMBO. (3) The defeat of
the FSMB MOL proposal by SMBO vote followed on October 11, 2012.
In the aftermath, the two FSMB board members serving on the SMBO were
formally reviewed. The Executive Director of the SMBO was ousted October
12th and formal investigations regarding violations of conflict of
interests continue regarding the senior SMBO member. (4) Subsequent
communications with legal offices of the SMBO and OSMA concluded that: 1)
FSMB MOL was not advocated by any other corporate, government or consumer
groups, no deficiency of AMA PRA CME programs or physician competency
issues were identified in Ohio and 2) FSMB MOL initiative appeared solely
promulgated by the FSMB as a corporate mandate. It continues to be
actively advocated by FSMB in 9 states and must be either fought or
approved in each state. FSMB MOL serves primarily corporate coffers and
false reassurance through testing vs CME. Effective physician opposition
is primarily possible via grass-roots resolutions at state level. We must
inform and support all state organizations at this time regarding FSMB
MOL, using this "Ohio experience" as evidence and instruction in opposing
this regulatory capture of physicians, solely for corporate profits. (5)
The assertions by the Certification industrial complex including the ABMS
that MOC and MOL are "Done deals" is simple propaganda-nothing more!
References:
1) Ohio State Medical Association Statement on MOL. Available at:
http://www.osma.org/files/pdf/facts-maintenance-of-licensure-final-.pdf
Accessed 10/27/12
2)Kempen PM: Maintenance of Certification (MOC), Maintenance of
Licensure (MOL), and Continuing Medical Education (CME):the Regulatory
Capture of Medicine. Journal of American Physicians and Surgeons 2012;
17:72-5. Available at: http://www.jpands.org/vol17no3/kempen.pdf Accessed
10/27/12
3) Kumar D et al: Joint letter from 11 medical societies to the SMBO.
Available at:
http://www.itraumaohio.org/aws/OACEP/asset_manager/get_file/54757/2012.10.5_joint_mol_letter_to_medical_board.pdf
Accessed 10/27/12
4) Alan Johnson In The Columbus Dispatch Thursday October 18, 2012 6:07
AM: State medical board ousts chief Available at:
http://www.dispatch.com/content/stories/local/2012/10/18/state-medical-
board-ousts-chief.html Accessed 10/27/12
5)Kempen PM: What to do about MOC and MOL? Available at:
http://www.youtube.com/watch?v=WRS15Dmsk7E Accessed Nov 1, 2012
Dear Editor, we read with great interest the paper by Durst at al. [1], aimed to define the anatomy of cerebral dural sinus system in the generalized population, evaluating the prevalence of sinus venous stenosis and hypoplasia. This condition is considered of pathogenetic relevance in idiopathic intracranial hypertension (IIH) [2-4] and has been also associated to chronic and, mostly, to refractory headaches [5-7]. We a...
Optimal outcome of intra-arterial treatment for Acute ischemic stroke (AIS) requires the involvement of appropriately trained and qualified providers from diverse specialties working together in synchrony under tight time line, communicating effectively to provide evidence-based clinical care. Hence, we welcome the international multi-society consensus document on training guidelines for the interventionalists involved in...
I am glad to see that my letter has piqued the interest of interventional neuroradiologists like Dr. Jagadeesan. I agree with him that no one should be running a fellowship that does not have the volume to expose trainees to enough cases so that they may obtain the necessary experience to practice safely. However, I think he has misunderstood my point. As I stated about the original piece, "I have no objection to the lo...
We read with interest Dr. Ding's response to our manuscript, "Angioarchitectural features associated with hemorrhagic presentation in pediatric cerebral arteriovenous malformations," and we thank him for his gracious comments. In response to his question regarding whether brain AVM angioarchitecture influences our particular treatment strategy, we would point out that the overwhelming majority of our pediatric patients wi...
I have read, with great interest, the paper by Ellis et al. titled 'Angioarchitectural features associated with hemorrhagic presentation in pediatric cerebral arteriovenous malformations [1]. The authors retrospectively reviewed the angiographic features of 135 pediatric patients, mean age 10.1 years (range 0-19 years), who were referred to Hospital for Sick Children in Toronto, Canada and Boston Children's Hospital ove...
I have read, with great interest, the paper by Stemer et al. titled 'Acute embolization of ruptured brain arteriovenous malformations' [1]. The authors describe a cohort of 21 patients with ruptured intracranial arteriovenous malformations (AVM) who were treated with endovascular Onyx (ev3, Irvine, California, USA) embolization in the acute phase following hemorrhage. The median interval from hemorrhagic presentation to...
Nohra Chalouhi M.D., Stavropoula Tjoumakaris M.D.,and Pascal Jabbour M.D.
We read with great interest the article by Turk et al[1] assessing the safety and efficacy of endovascular stroke intervention based on CT perfusion (CTP) criteria. The authors are to be congratulated for this excellent report and for achieving remarkably high rates of favorable outcomes (42%) in stroke patients with poor neurological sta...
The reply from Perez et al to my letter of March 2012 is misleading and wrong in two important regards.1 First, they state that their report of the use of the solitaire stent for thrombectomy was just a case report, "nothing else". 2 This is not true. In fact, they explicitly use this report, both in the abstract and conclusion to lay claim for developing the stentreiever concept for thrombectomy: "This was the first...
As a participant in the creation of the original ACGME ESNR fellowship training standards, I read the article concerning fellowship suspension with great interest (1). The paper is timely and thorough. It is unfortunate that the Neurointerventional world is dealing with so many unknowns. We do not seem to know how many we are, where we work, what we do, or where we were trained. The problem is very well summarized at...
Hirsh and Meyers espouse that same party line of the many private non -governmental agencies (and academics who will personally benefit from this program) who wish to impose private interest group-unproven corporate interests upon practicing physicians. They continue to state MOC is "voluntary" and then describe the many ways these "non-profit" corporations (who earn handsomely and have over $400 million in assets and as g...
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