Pediatric Moyamoya Revascularization Perioperative Care: A Modified Delphi Study

BACKGROUND

Surgical revascularization decreases the long-term risk of stroke in children with moyamoya arteriopathy but can be associated with an increased risk of stroke during the perioperative period. Evidence-based approaches to optimize perioperative management are limited and practice varies widely. Using a modified Delphi process, we sought to establish expert consensus on key components of the perioperative care of children with moyamoya undergoing indirect revascularization surgery and identify areas of equipoise to define future research priorities.

METHODS

Thirty neurologists, neurosurgeons, and intensivists practicing in North America with expertise in the management of pediatric moyamoya were invited to participate in a three-round, modified Delphi process consisting of a 138-item practice patterns survey, anonymous electronic evaluation of 88 consensus statements on a 5-point Likert scale, and a virtual group meeting during which statements were discussed, revised, and reassessed. Consensus was defined as ≥ 80% agreement or disagreement.

RESULTS

Thirty-nine statements regarding perioperative pediatric moyamoya care for indirect revascularization surgery reached consensus. Salient areas of consensus included the following: (1) children at a high risk for stroke and those with sickle cell disease should be preadmitted prior to indirect revascularization; (2) intravenous isotonic fluids should be administered in all patients for at least 4 h before and 24 h after surgery; (3) aspirin should not be discontinued in the immediate preoperative and postoperative periods; (4) arterial lines for blood pressure monitoring should be continued for at least 24 h after surgery and until active interventions to achieve blood pressure goals are not needed; (5) postoperative care should include hourly vital signs for at least 24 h, hourly neurologic assessments for at least 12 h, adequate pain control, maintaining normoxia and normothermia, and avoiding hypotension; and (6) intravenous fluid bolus administration should be considered the first-line intervention for new focal neurologic deficits following indirect revascularization surgery.

CONCLUSIONS

In the absence of data supporting specific care practices before and after indirect revascularization surgery in children with moyamoya, this Delphi process defined areas of consensus among neurosurgeons, neurologists, and intensivists with moyamoya expertise. Research priorities identified include determining the role of continuous electroencephalography in postoperative moyamoya care, optimal perioperative blood pressure and hemoglobin targets, and the role of supplemental oxygen for treatment of suspected postoperative ischemia.

Yield of genetic evaluation in non-syndromic pediatric moyamoya patients

PURPOSE

Few guidelines exist for genetic testing of patients with moyamoya arteriopathy. This study aims to characterize the yield of genetic testing of non-syndromic moyamoya patients given the current pre-test probability.

METHODS

All pediatric moyamoya patients who received revascularization surgery at one institution between 2018 and 2022 were retrospectively reviewed. Patients with previously diagnosed moyamoya syndromes or therapeutic cranial radiation were excluded.

RESULTS

Of 117 patients with moyamoya, 74 non-syndromic patients (44 females, 59%) were eligible. The median age at surgery was 8.1 years. Neurosurgeons referred 18 (24%) patients for neurogenetic evaluation. Eleven (61%) patients subsequently underwent genetic testing. Eight (73%) patients had available testing results. Five (62.5%) of these patients had developmental delay compared to 16 (22%) of the entire cohort. Six (75%) patients who underwent genetic testing were found to have at least one genetic variant. These results led to diagnosis of a new genetic disorder for 1 (12.5%) patient and screening recommendations for 2 (25%) patients. An RNF213 variant in one patient led to recommendations for family member screening and pulmonary hypertension screening. Another patient was diagnosed with CBL disorder and referred for cancer screening. The median age at surgery in patients with clinically actionable findings was 4.6 years compared to 9.2 years in those who were referred for genetic testing. All 3 patients who had an actionable finding had developmental delay.

CONCLUSION

It may be beneficial to refer moyamoya patients under 5 for genetic screening given the high likelihood of discovering actionable mutations.

Prevention of postoperative stroke in pediatric moyamoya patients: a standardized perioperative care protocol

OBJECTIVE

Perioperative stroke is a major complication of revascularization surgery in patients with moyamoya. Vomiting is common after neurosurgical procedures and may result in acute changes in intracranial pressure and cerebral blood flow. The authors instituted a standardized perioperative nausea and vomiting protocol for children with moyamoya undergoing indirect bypass surgery at their institution and analyzed its association with perioperative stroke. They hypothesized that instituting a standardized perioperative nausea and vomiting protocol would be associated with reduction in the number of perioperative strokes in children with moyamoya undergoing indirect bypass surgery.

METHODS

The authors retrospectively reviewed consecutive cases of children and young adults with moyamoya who underwent indirect bypass surgery before and after implementation of a new perioperative nausea and vomiting protocol at a single institution. They compared the rate of strokes in the perioperative period (postoperative days 0 and 1) in the 31 months following implementation to 31 months prior to implementation using Fisher's exact test.

RESULTS

The median ages pre- and postimplementation were 8.5 (IQR 4-12) years and 8.3 (IQR 5-15) years, respectively. There were no significant differences between the cohorts in disease severity or other potentially confounding factors. In the 31 months prior to initiation of the perioperative nausea and vomiting protocol, there were 5 strokes in 137 surgically treated hemispheres (3.6%). After initiation of the protocol, there were no strokes in 114 surgically treated hemispheres (p = 0.065).

CONCLUSIONS

Instituting a standardized perioperative nausea and vomiting protocol was associated with reduction in perioperative strokes in children with moyamoya treated with indirect bypass surgery.

Cerebral Vasculopathy in Children with Neurofibromatosis Type 1

Cerebrovascular abnormalities are a severe and often underrecognized complication of childhood neurofibromatosis type 1 (NF1). There are no prospective studies of cerebral vasculopathy in NF1; thus, the estimated frequency of vasculopathy varies between studies. The data is difficult to interpret due to the retrospective data collection and variability in whether imaging is done based on screening/surveillance or due to acute neurologic symptoms. The prevalent NF1-associated cerebral vasculopathy is moyamoya syndrome (MMS). Vascular changes can present without symptoms or with acute TIA or stroke-like symptoms or a range of progressive neurologic deficits. Advanced imaging may enhance sensitivity of neuroimaging in children. Medical and/or surgical interventions may prevent short- and long-term complications. Challenges for establishment of a screening protocol for cerebral vasculopathy in children with NF1 include the relatively large number of patients with NF1, the potential need for sedation to achieve quality imaging and the broad age range at time of detection for cerebral vascular changes. The goal of this review is to present the epidemiology, clinical presentation, imaging features and medical/surgical management of cerebral arteriopathies in children with NF1.

Autism Spectrum Disorder in Children With Perinatal Ischemic Stroke Varies by Stroke Type

Background and Objectives: Perinatal stroke leads to significant morbidity over a child's lifetime, including diagnosis of various neurodevelopmental disorders. Specific studies examining the prevalence of autism spectrum disorder in children with perinatal stroke are scarce. Following the clinical observation of autism spectrum disorder in a pediatric referral stroke center, we evaluated the rate of autism spectrum disorder diagnosis after perinatal ischemic stroke, including analysis by subtypes of perinatal ischemic stroke. Methods: We retrospectively examined all children diagnosed with perinatal ischemic stroke, who were ≥18 months old at the time of last follow-up at a single institution from 2008 through 2021. We classified patients as having autism spectrum disorder if they were diagnosed by a neurologist, neuropsychologist, clinical psychologist, or developmental pediatrician. Multivariable logistic regression was performed to examine the association between ischemic stroke subtype and autism spectrum disorder. Results: Among 260 children with perinatal stroke, 19 children (7.3%) also had autism spectrum disorder. Children with perinatal venous stroke had 3-fold higher odds of autism spectrum disorder compared to those with perinatal arterial ischemic stroke (adjusted odds ratio: 3.01, 95% confidence interval: 1.07-8.47). Conclusion: In our perinatal ischemic stroke population, children with venous stroke had higher odds of autism spectrum disorder compared to those with arterial ischemic stroke alone. Prospective studies are needed to further investigate the role of perinatal stroke in autism spectrum disorder development.

Neurosurgical outcomes of pediatric cerebral venous sinus thrombosis following acute mastoiditis: a systematic review and meta-analysis

OBJECTIVE

Neurosurgical outcomes are not well defined in the management of pediatric patients with cerebral venous sinus thrombosis (CVST) following acute mastoiditis. Specific notable sequelae are otogenic (otitic) hydrocephalus and CVST management. Correspondingly, the aim of this study was to integrate the currently published metadata to summarize these outcomes.

METHODS

Electronic searches were performed using the Ovid Embase, PubMed, Scopus, and Cochrane databases from inception to November 2022 following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Cohort-level data were then abstracted for analysis for appropriate pediatric patients. Outcomes were pooled by random-effects meta-analyses of proportions where possible.

RESULTS

Twenty-three study cohorts describing 312 pediatric patients with otogenic CVST were included. At a cohort level, the median patient age was 6 years among 181 boys (58%) and 131 girls (42%). Modeling indicated papilledema at presentation in 46% of cases (95% CI 30%-62%). Regarding management, antibiotics were applied universally in all cases, mastoidectomy or other otologic surgery was performed in 91% (95% CI 82%-98%), and prophylactic anticoagulation was administered in 86% (95% CI 75%-95%). There was only 1 case (0.3%) of postprocedural intracranial hemorrhage, and there were no deaths reported among all studies. Although diagnostic lumbar puncture was performed in 14% (95% CI 3%-28%) at presentation, clinical otogenic hydrocephalus was ultimately suspected in 31% (95% CI 14%-49%), and acetazolamide was given in 65% (95% CI 35%-91%) overall. There were 10 cases (3%) that proceeded to permanent CSF diversion in the form of ventricular shunting. At a median follow-up of 8 months among all studies, the venous sinus was completely recanalized in 67% (95% CI 53%-79%).

CONCLUSIONS

Most CVSTs following acute mastoiditis will recanalize with the standard use of antibiotics, otologic surgery, and anticoagulation, with minimal symptomatic hemorrhage risk. However, an appreciable proportion of these patients will develop symptomatic otogenic hydrocephalus, and it is imperative that the appropriate surveillance and workup is performed to fully optimize patient outcomes long-term. The possible need for permanent CSF diversion should be recognized.

Diffusion-Weighted Magnetic Resonance Imaging Demonstrates White Matter Alterations in Watershed Regions in Children With Moyamoya Without Stroke or Silent Infarct

BACKGROUND

Moyamoya is a disease with progressive cerebral arterial stenosis leading to stroke and silent infarct. Diffusion-weighted magnetic resonance imaging (dMRI) studies show that adults with moyamoya have significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) compared with controls, which raises concern for unrecognized white matter injury. Children with moyamoya have significantly lower FA and higher MD in their white matter compared with controls. However, it is unknown which white matter tracts are affected in children with moyamoya.

METHODS

We present a cohort of 15 children with moyamoya with 24 affected hemispheres without stroke or silent infarct compared with 25 controls. We analyzed dMRI data using unscented Kalman filter tractography and extracted major white matter pathways with a fiber clustering method. We compared the FA, MD, AD, and RD in each segmented white matter tract and combined white matter tracts found within the watershed region using analysis of variance.

RESULTS

Age and sex were not significantly different between children with moyamoya and controls. Specific white matter tracts affected included inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus, thalamofrontal, uncinate fasciculus, and arcuate fasciculus. Combined watershed region white matter tracts in children with moyamoya had significantly lower FA (-7.7% ± 3.2%, P = 0.02) and higher MD (4.8% ± 1.9%, P = 0.01) and RD (8.7% ± 2.8%, P = 0.002).

CONCLUSIONS

Lower FA with higher MD and RD is concerning for unrecognized white matter injury. Affected tracts were located in watershed regions suggesting that the findings may be due to chronic hypoperfusion. These findings support the concern that children with moyamoya without overt stroke or silent infarction are sustaining ongoing injury to their white matter microstructure and provide practitioners with a noninvasive method of more accurately assessing disease burden in children with moyamoya.

Abstract 66: Diffusion Imaging Demonstrates White Matter Alterations In Children With Moyamoya In Watershed Tracts

Introduction: Moyamoya is a progressive cerebrovascular disease leading to stenosis of arteries located in the circle of Willis which increases risk of hypoperfusion in specific areas of the brain called watershed regions. Using diffusion weighted magnetic resonance imaging (dMRI), adults with moyamoya have significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) and radial diffusivity (RD) in their white matter compared to controls. These areas of white matter alterations have been associated with cognitive deficits as well. To our knowledge the examination of combined white matter tracts in the watershed regions of the brain in children with moyamoya has not been previously examined.

Hypothesis: We hypothesize that children with moyamoya will have higher FA and lower MD and RD in the combined white matter tracts that are in the watershed region compared to control children.

Methods: We compared a cohort of 15 children with moyamoya with 24 affected hemispheres without stroke to 25 children controls. We analyzed dMRI data using an unscented Kalman filter (UKF) tractography method and extracted major white matter pathways with a fiber clustering method. We compared the FA, MD, axial diffusivity (AD), and RD of the combined watershed white matter tracts using co-variate adjusted ANOVA.

Results: Age and sex were not significantly different between children with moyamoya and controls. For the combined watershed white matter tracts, children with moyamoya had significantly lower FA and higher MD and RD. AD was also higher but not significant compared to control children (Table 1).

Conclusion: Lower FA with higher MD and RD is consistent with alterations in white matter tracts concerning for unrecognized white matter injury from hypoperfusion. These dMRI findings could be used as a biomarker for children with moyamoya at risk for cognitive deficits due to hypoperfusion.

Pediatric Moyamoya Syndrome Secondary to Tuberculous Meningitis: A Case Report

Objectives

Tuberculosis is uncommon in the United States and a rare cause of meningitis in children with severe neurologic consequences. Tuberculous meningitis (TBM) is an even rarer cause of moyamoya syndrome with only a handful of cases previously reported.

Methods

We report the case of a female patient who initially presented at 6 years of age with TBM and developed moyamoya syndrome requiring revascularization surgery.

Results

She was found to have basilar meningeal enhancement and right basal ganglia infarcts. She was treated with 12 months of antituberculosis therapy and 12 months of enoxaparin and maintained on daily aspirin indefinitely. However, she developed recurrent headaches and transient ischemic attacks and was found to have progressive bilateral moyamoya arteriopathy. At age 11 years, she underwent bilateral pial synangiosis for the treatment of her moyamoya syndrome.

Discussion

Moyamoya syndrome is a rare but serious sequalae of TBM and may be more common in pediatric patients. The risk of stroke may be mitigated by pial synangiosis or other revascularization surgeries in carefully selected patients.

Abstract TMP21: Association Of A Perioperative Nausea And Vomiting Treatment Protocol With Reduction In Perioperative Strokes In Children And Young Adults With Moyamoya

Introduction: Perioperative stroke is a major complication of revascularization surgery in patients with moyamoya. Vomiting is common after neurosurgical procedures and may result in acute changes in intracranial pressure and cerebral blood flow. We instituted a standardized perioperative nausea and vomiting protocol for children and young adults with moyamoya undergoing indirect bypass surgery at our institution.

Hypothesis: Instituting a standardized perioperative nausea and vomiting protocol will be associated with reduction in the number of perioperative strokes in children with moyamoya undergoing indirect bypass surgery.

Methods: We retrospectively reviewed consecutive cases of children and young adults with moyamoya who underwent indirect bypass surgery before and after implementation of a new perioperative nausea and vomiting protocol. We compared the rate of strokes in the perioperative period (post-operative day 0 and 1) in the 41 months following implementation (155 surgically treated hemispheres) to 155 surgically treated hemispheres (over 30 months) prior to implementation using Fisher’s Exact test.

Results: The mean age prior to implementation was 8.7 years (SD 5.5 years) and 9.9 years (SD 6.2 years) post implementation which was not significantly different (p=0.17). In the 30 months prior to initiation of the perioperative nausea and vomiting protocol there were 5 strokes in 155 surgically treated hemispheres (3.2%). After initiation of the protocol, there were no strokes in 155 surgically treated hemispheres (p = 0.03).

Conclusions: Instituting a standardized perioperative nausea and vomiting protocol was associated with reduction in perioperative strokes in children with moyamoya treated with indirect bypass surgery.

Pediatric Moyamoya Biomarkers: Narrowing the Knowledge Gap

Moyamoya is a progressive cerebrovascular disorder that leads to stenosis of the arteries in the distal internal carotid, proximal middle cerebral and proximal anterior cerebral arteries of the circle of Willis. Typically a network of collaterals form to bypass the stenosis and maintain cerebral blood flow. As moyamoya progresses it affects the anterior circulation more commonly than posterior circulation, and cerebral blood flow becomes increasingly reliant on external carotid supply. Children with moyamoya are at increased risk for ischemic symptoms including stroke and transient ischemic attacks (TIA). In addition, cognitive decline may occur over time, even in the absence of clinical stroke. Standard of care for stroke prevention in children with symptomatic moyamoya is revascularization surgery. Treatment of children with asymptomatic moyamoya with revascularization surgery however remains more controversial. Therefore, biomarkers are needed to assist with not only diagnosis but also with determining ischemic risk and identifying best surgical candidates. In this review we will discuss the current knowledge as well as gaps in research in relation to pediatric moyamoya biomarkers including neurologic presentation, cognitive, neuroimaging, genetic and biologic biomarkers of disease severity and ischemic risk.

Closing the Gap in Pediatric Hemorrhagic Stroke: A Systematic Review

Pediatric hemorrhagic stroke (HS) accounts for a large proportion of childhood strokes, 1 of the top 10 causes of pediatric deaths. Morbidity and mortality lead to significant socio-economic and psychosocial burdens. To understand published data on recognizing and managing children with HS, we conducted a systematic review of the literature presented here. We searched PubMed, Embase, CINAHL and the Cochrane Library databases limited to English language and included 174 studies, most conducted in the USA (52%). Terminology used interchangeably for HS included intraparenchymal/intracranial hemorrhage, spontaneous ICH, and cerebrovascular accident (CVA). Key assessments informing prognosis and management included clinical scoring (Glasgow coma scale), and neuroimaging. HS etiologies reported were systemic coagulopathy (genetic, acquired pathologic, or iatrogenic), or focal cerebrovascular lesions (brain arteriovenous malformations, cavernous malformations, aneurysms, or tumor vascularity). Several scales were used to measure outcome: Glasgow outcome score (GOS), Kings outcome score for head injury (KOSCHI), modified Rankin scale (mRS) and pediatric stroke outcome measure (PSOM). Most studies described treatments of at-risk lesions. Few studies described neurocritical care management including raised ICP, seizures, vasospasm, or blood pressure. Predictors of poor outcome included ethnicity, comorbidity, location of bleed, and hematoma >2% of total brain volume. Motor and cognitive outcomes followed independent patterns. Few studies reported on cognitive outcomes, rehabilitation, and transition of care models. Interdisciplinary approach to managing HS is urgently needed, informed by larger cohort studies targeting key clinical question (eg development of a field-guide for the clinician managing patients with HS that is reproducible internationally).

Racial and Ethnic Disparities in Incidence and Prognosis of Perioperative Stroke Among Pediatric Cardiac Transplant Recipients

Background

In the general population, Black children have a higher incidence of stroke and all‐cause mortality after stroke than White children. Beginning 6 months following cardiac transplantation, Black children have higher mortality than White children. However, whether there are racial and ethnic disparities in incidence and all‐cause mortality following perioperative stroke among pediatric cardiac transplant recipients is unknown.

Methods and Results

Using the Scientific Registry of Transplant Recipients, we studied children who underwent their first heart transplant in the United States between January 1994 and September 2019. Using multivariable logistic regression, we assessed the association between race and ethnicity and perioperative stroke. We used multivariable piecewise Cox regression to examine the association between race and ethnicity and mortality among survivors of perioperative stroke. Among 8224 children who had a first cardiac transplant, 255 (3%) had a perioperative stroke. Black children had 32% lower odds of perioperative stroke compared with White children (adjusted odds ratio, 0.68 [95% CI, 0.46–0.996]). Following perioperative stroke, mortality rates were similar for Black and White children in the first 6 months (adjusted hazard ratio [HR], 0.99 [95% CI, 0.44–2.26]). However, Black children had a higher mortality rate than White children beyond 6 months (adjusted HR, 3.36 [95% CI, 1.22–9.22]).

Conclusions

Among pediatric cardiac transplant recipients, Black children have a lower incidence of perioperative stroke than White children. Among survivors of perioperative stroke, mortality is initially similar by race and ethnicity, but beyond 6 months, Black children have over a 3‐fold higher mortality rate than White children. Identifying and intervening on potential differences in care is essential to addressing these disparities.

Abstract WP176: Compared To Catheter Angiogram MRA Is A Moderate Predictor Of Suzuki Grade In Children With Moyamoya

Introduction: Moyamoya is a progressive cerebral arteriopathy affecting the arteries in the circle of Willis. Suzuki grade for moyamoya using catheter angiogram has been gold standard for the evaluation of moyamoya both in children and adults. Suzuki grade evaluates the amount of stenosis and collateral formation in the cerebral arteries. Magnetic resonance angiography (MRA) non-luminal imaging can overestimate stenosis and underestimate collaterals. With greater use of MRA for diagnosis and follow-up, it is important to understand MRA staging is truly comparable to catheter angiogram.

Methods: Study neurologist and interventional radiologist reviewed both catheter angiograms and MRAs without clinical information. The modified Suzuki stage was used to evaluate the MRA. Median time from MRA to catheter angiogram was calculated. Cohen’s Kappa was used to compare modalities of Suzuki grade based on catheter angiogram to modified Suzuki grade by MRA on the same patients.

Results: A total of 29 patients with moyamoya were reviewed. Median time between MRA and catheter angiogram was 2.4 months with interquartile range from 0.6-5.3 months. Unweighted Cohen’s Kappa was 0.34 (p<0.0001) which is considered fair correlation. When we calculated a weighted Cohen’s Kappa it improved but only to 0.49 (p<0.0001) which is moderate correlation.

Conclusion: Using Cohen’s kappa to compare two methods of evaluating cerebral artery stenosis in children with moyamoya, we demonstrated that there is only moderate correlation between catheter angiogram Suzuki staging compared to modified Suzuki staging with MRA. In conclusion, we suggest caution in the reliance of MRA for diagnosis and follow-up of children with moyamoya. We recommend consideration catheter angiograms at time of diagnosis and with surgical planning.

Abstract WP212: Racial Disparities In Perioperative Stroke And Mortality Following Stroke In Adult Cardiac Transplant Recipients

Introduction: In the general US population, Black adults have a higher stroke incidence and mortality rate after stroke compared to white adults. Among heart transplant recipients, Black adults also have a higher mortality rate beginning 6-12 months post-transplant. Whether there are racial disparities in perioperative stroke incidence and all-cause mortality following perioperative stroke among cardiac transplant recipients is unknown.

Methods: Using the Scientific Registry of Transplant Recipients, we examined all adults in the United States who received their first heart transplant between January 2008 - December 2018. We used multivariable conditional logistic regression to assess the association between race and perioperative stroke. We used multivariable Cox proportional hazard regression to examine the association between race and mortality among adults who survived a perioperative stroke. In both models, we included age, sex, hospitalization status, prior ventricular assist device (VAD) implantation, extracorporeal membrane oxygenation (ECMO), calendar year, etiology of heart disease, bilirubin, and functional status as covariates.

Results: Among 20,912 adults, 428 (2.7%) white recipients and 126 (2.4%) Black recipients had a perioperative stroke. In a multivariable model, there was 11% lower odds of perioperative stroke in Black recipients compared to white recipients (OR = 0.89, 95% CI: 0.71, 1.12). Among perioperative stroke survivors, mortality rates were similar between Black and white recipients within 6 months (HR = 1.02, 95% CI: 0.70, 1.49) and in long-term follow up (HR = 0.95, 95% CI: 0.52, 1.73). However, our regression results were imprecise. Further adjustment for health behaviors and socioeconomic position did not alter the results.

Conclusion: Black recipients experienced a lower incidence of perioperative stroke; however, mortality rates were similar between Black and white recipients following perioperative stroke. These unexpected findings warrant further research.

Abstract TMP87: Higher Prevalence Of Autism Spectrum Disorder In Children With Perinatal Ischemic Stroke

Introduction: Perinatal stroke leads to significant morbidity over a child’s lifetime. Following perinatal stroke, children are more likely to be diagnosed with attention-deficit/hyperactivity disorder, intellectual disability, and language disorders. However, to our knowledge, studies examining the prevalence of autism spectrum disorder (ASD) in children with perinatal stroke do not exist.

Methods: We retrospectively examined all children seen in the Stroke and Cerebrovascular Center at Boston Children’s Hospital from August 2008 through April 2021. All children with a history of perinatal ischemic stroke, either arterial or venous, aged ≥15 months old at the time of last follow-up were considered for inclusion. We classified patients as having ASD if their medical record included an ASD diagnosis by a neurologist, neuropsychologist, clinical psychologist, or developmental pediatrician. Multivariable logistic regression was performed to examine association between stroke type and ASD.

Results: Among 285 children with perinatal stroke, 22 children (7.71%) also had ASD. Males had 8 times higher odds of ASD compared to females (OR= 8.07, p=0.007). Children with perinatal venous stroke had 2.5 times higher odds of ASD compared to those with arterial stroke (OR=2.58, p=0.05), which approached significance. There was not a significant difference in odds of autism in children diagnosed with presumed perinatal stroke compared to neonatal stroke.

Conclusion: In our perinatal stroke population, the prevalence of ASD is 4 times higher than the prevalence of ASD in the general U.S. population (1.85%) as per the CDC in 2020. Boys had higher odds of autism, similar to what has been found in the general population. Interestingly, patients with venous stroke had higher odds of autism compared to those with arterial stroke. In conclusion, prospective studies are needed to further investigate the role of perinatal stroke in ASD development.

Pediatric Ischemic Stroke: An Infrequent Complication of SARS-CoV-2

OBJECTIVE

Severe complications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) include arterial ischemic stroke (AIS) in adults and multisystem inflammatory syndrome in children. Whether stroke is a frequent complication of pediatric SARS-CoV-2 is unknown. This study aimed to determine the proportion of pediatric SARS-CoV-2 cases with ischemic stroke and the proportion of incident pediatric strokes with SARS-CoV-2 in the first 3 months of the pandemic in an international cohort.

METHODS

We surveyed 61 international sites with pediatric stroke expertise. Survey questions included: numbers of hospitalized pediatric (≤ 18 years) patients with SARS-CoV-2; numbers of incident neonatal and childhood ischemic strokes; frequency of SARS-CoV-2 testing for pediatric patients with stroke; and numbers of stroke cases positive for SARS-CoV-2 from March 1 to May 31, 2020.

RESULTS

Of 42 centers with SARS-CoV-2 hospitalization numbers, 8 of 971 (0.82%) pediatric patients with SARS-CoV-2 had ischemic strokes. Proportions of stroke cases positive for SARS-CoV-2 from March to May 2020 were: 1 of 108 with neonatal AIS (0.9%), 0 of 33 with neonatal cerebral sinovenous thrombosis (CSVT; 0%), 6 of 166 with childhood AIS (3.6%), and 1 of 54 with childhood CSVT (1.9%). However, only 30.5% of neonates and 60% of children with strokes were tested for SARS-CoV-2. Therefore, these proportions represent 2.9, 0, 6.1, and 3.0% of stroke cases tested for SARS-CoV-2. Seven of 8 patients with SARS-CoV-2 had additional established stroke risk factors.

INTERPRETATION

As in adults, pediatric stroke is an infrequent complication of SARS-CoV-2, and SARS-CoV-2 was detected in only 4.6% of pediatric patients with ischemic stroke tested for the virus. However, < 50% of strokes were tested. To understand the role of SARS-CoV-2 in pediatric stroke better, SARS-CoV-2 testing should be considered in pediatric patients with stroke as the pandemic continues. ANN NEUROL 2021;89:657-665.

Adverse effects of erenumab on cerebral proliferative angiopathy: A case report

BACKGROUND

Cerebral proliferative angiopathy is a vascular malformation associated with compromised blood-brain barrier and with migraine-like headache. Treating blood-brain barrier-compromised patients with erenumab, an anti-calcitonin gene-related peptide receptor monoclonal antibody, may be risky.

CASE

We describe a case of a 22-year-old chronic migraine patient with cerebral proliferative angiopathy who presented to our hospital in status epilepticus 2 d after his first dose of erenumab. Serial magnetic resonance imaging (MRI) studies demonstrated progressive areas of diffusion restriction including the brain tissue adjacent to the cerebral proliferative angiopathy, bilateral white matter and hippocampi. His 6-month post-presentation magnetic resonance imaging was notable for white matter injury, encephalomalacia surrounding cerebral proliferative angiopathy and bilateral hippocampal sclerosis. He remains clinically affected with residual symptoms, including refractory epilepsy and cognitive deficits.

CONCLUSION

The evidence presented in this case supports further investigation into potential deleterious side effects of erenumab in patients with compromised blood-brain barrier, such as individuals with intracranial vascular malformations.

Prevalence of Symptoms of Anxiety, Depression, and Post-traumatic Stress Disorder in Parents and Children Following Pediatric Stroke

Post-traumatic stress disorder (PTSD), anxiety, and depression are seen in parents and children following critical illness. Whether this exists in parents and children following pediatric stroke has not been thoroughly studied. We examined emotional outcomes in 54 mothers, 27 fathers, and 17 children with stroke. Parents of children 0-18 years and children 7-18 years who were within 2 years of stroke occurrence were asked to complete questionnaires to determine their emotional outcomes. Of participating mothers, 28% reported PTSD, 26% depression, and 4% anxiety; in fathers, 15% reported PTSD, 24% depression, and none reported anxiety. Further, children reported significant emotional difficulty, with 24% having depression, 14% anxiety, and 6% PTSD by self-report ratings. Maternal PTSD, anxiety and depression, and paternal anxiety were all negatively associated with the child's functional outcome. Clinically significant anxiety (based on clinical thresholds) was not found in fathers; however, continuous scores were still analyzed for association between subclinical anxiety and functional outcome, which revealed a statistically significant association between more reported symptoms and higher Recovery and Recurrence Questionnaire scores. Prevalence of PTSD and depression are greater in parents compared to the general population in this preliminary study.

Characteristics and Outcome in Children With Craniectomy Following Acute Ischemic Stroke in the International Pediatric Stroke Study

The outcome of children with acute ischemic stroke treated with craniectomy has not been thoroughly examined. In adults, hemicraniectomy after middle cerebral artery territory stroke and posterior decompression after posterior circulation stroke has been shown to improve outcome. Pediatric cases of hemicraniectomy for middle cerebral artery stroke and posterior decompression following posterior circulation stroke suggest relatively good outcome. There are no published data in adults or children with craniectomy after cerebral sinovenous thrombosis. Our aim was to determine the outcome of children with acute ischemic stroke treated with craniectomy in the International Pediatric Stroke Study (IPSS). We included children enrolled who had a craniectomy following stroke presentation. Of 4294 patients in IPSS, 38 children (1%) were found to have craniectomy following an ischemic stroke. Of 38 craniectomy cases, 29 had anterior circulation strokes, 5 had posterior circulation strokes, and 4 had cerebral sinovenous thromboses. The mortality rate was 8%. Overall, children who have craniectomies have significant neurologic deficits. Prospective studies are needed to examine long-term morbidity following craniectomy.

Pediatric Stroke Rates Over 17 Years: Report From a Population-Based Study

We previously published rates of pediatric stroke using our population-based Greater Cincinnati Northern Kentucky Stroke Study (GCNK) for periods July 1993-June 1994 and 1999. We report population-based rates from 2 additional study periods: 2005 and 2010. We identified all pediatric strokes for residents of the GCNK region that occurred in July 1, 1993-June 30, 1994, and calendar years 1999, 2005, and 2010. Stroke cases were ascertained by screening discharge ICD-9 codes, and verified by a physician. Pediatric stroke was defined as stroke in those <20 years of age. Stroke rates by study period, overall, by age and by race, were calculated. Eleven children died within 30 days, yielding an all-cause case fatality rate of 15.7% (95% confidence interval 1.1%, 26.4%) with 3 (27.3%) ischemic, 6 (54.5%) hemorrhagic, and 2 (18.2%) unknown stroke type. The pediatric stroke rate of 4.4 per 100 000 in the GCNK study region has not changed over 17 years.

Placental Pathology in Neonatal Stroke: A Retrospective Case-Control Study

OBJECTIVE

To assess the association of placental abnormalities with neonatal stroke.

STUDY DESIGN

This retrospective case-control study at 3 academic medical centers examined placental specimens for 46 children with neonatal arterial or venous ischemic stroke and 99 control children without stroke, using a standard protocol. Between-group comparisons used χ² and Fisher exact t test. Correlations used Spearman correlation coefficient.

RESULTS

Case placentas were more likely than controls to meet criteria for ≥1 of 5 major categories of pathologic abnormality (89% vs 62%; OR, 5.1; 95% CI, 1.9-14.0; P = .0007) and for ≥2 categories (38% vs 8%; OR, 7.3; 95% CI, 2.9-19.0; P < .0001). Fetal vascular malperfusion occurred in 50% of cases and 17% of controls (OR, 4.8; 95% CI, 2.2-10.5; P = .0001). Amniotic fluid inflammation occurred in 46% of cases with arterial ischemic stroke vs 25% of controls (OR, 2.6; 95% CI, 1.1-6.1; P = .037). There was evidence of a "stress response" (meconium plus elevated nucleated red blood cells) in 24% of cases compared with 1% of controls (OR, 31; 95% CI, 3.8-247.0; P < .0001).

CONCLUSIONS

Placental abnormality was more common in children with neonatal stroke compared with controls. All placental findings represent subacute-to-chronic intrauterine stressors. Placental thrombotic processes were associated with both arterial and venous stroke. Our findings provide evidence for specific mechanisms that may predispose to acute perinatal stroke. Amniotic fluid inflammation associated with neonatal arterial ischemic stroke deserves further investigation.

Transient Focal Neurologic Symptoms Correspond to Regional Cerebral Hypoperfusion by MRI: A Stroke Mimic in Children

Children who present with acute transient focal neurologic symptoms raise concern for stroke or transient ischemic attack. We present a series of 16 children who presented with transient focal neurologic symptoms that raised concern for acute stroke but who had no evidence of infarction and had unilateral, potentially reversible imaging features on vascular and perfusion-sensitive brain MR imaging. Patients were examined with routine brain MR imaging, MRA, perfusion-sensitive sequences, and DWI. Fourteen (88%) children had lateralized MRA evidence of arterial tree pruning without occlusion, all had negative DWI findings, and all showed evidence of hemispheric hypoperfusion by susceptibility-weighted imaging or arterial spin-labeling perfusion imaging at presentation. These findings normalized following resolution of symptoms in all children who had follow-up imaging (6/16, 38%). The use of MR imaging with perfusion-sensitive sequences, DWI, and MRA can help to rapidly distinguish children with conditions mimicking stroke from those with acute stroke.

Abstract TP399: Hemodynamic Imaging in Children with Transient Neurologic Symptoms

Children who present with transient neurologic symptoms raise concern for stroke as the underlying etiology. The rapid differentiation of stroke mimic from stroke in order to determine eligibility for hyperacute stroke treatment constitutes a unique and important diagnostic challenge in children. We used perfusion, diffusion, and magnetic resonance angiography (MRA) imaging to identify key imaging findings that together indicated a stroke mimic. We present a case series of 17 children who had transient neurologic symptoms and had MRA, perfusion, and diffusion weighted imaging in the acute period. The children ranged in age from 2 to 17 years of age. Among 17 children, 13 (76%) had headache at presentation. Thirteen (76%) children had focal MRA evidence of arterial pruning without occlusion, all had negative diffusion weighted imaging, and all showed evidence of hemispheric decreased perfusion by susceptibility-weighted imaging and/or arterial spin label perfusion imaging. Thirteen of 17 had left sided imaging findings. In all children who had repeat imaging (6/17;35%) these findings had reversed. No patient met clinical criteria for familial hemiplegic migraine. Only 6 (35%) had recurrence of transient neurologic symptoms since initial presentation; none had stroke. Use of combined MR imaging to include perfusion, diffusion and angiography can help to distinguish rapidly children who present with stroke mimics whose symptoms are likely to be transient and who do not require hyperacute stroke treatment.

Predictors of Stroke After Transient Ischemic Attack in Children

BACKGROUND AND PURPOSE

Transient ischemic attack (TIA) in children has received far less attention compared with TIA in adults. The risk factors of stroke after TIA in children are relatively unknown. We aimed to determine the percentage of children who have stroke after TIA and the risk factors associated with stroke after TIA.

METHODS

We searched the medical records at Boston Children's Hospital for the year 2010 to find children who were evaluated for TIA to determine associated risk factors of stroke after TIA. We included children who were evaluated in 2009 through 2010 for TIA and had magnetic resonance imaging. We examined follow-up imaging through August 2014 for subsequent stroke. Logistic regression was used to calculate odds ratios for factors in our cohort who are associated with stroke after presentation with TIA.

RESULTS

We identified 63 children who experienced a TIA. The mean time of imaging follow-up was 4.5 years after TIA presentation. Of the 63 children, 10 (16%) developed radiological evidence of ischemic cerebral injury within the follow-up period. Four of the 10 (6%) demonstrated diffusion abnormalities on magnetic resonance imaging at TIA presentation, whereas 8 (13%) had a stroke after their TIA. Arteriopathy, female sex, and autoimmune disorders were significantly associated with stroke after TIA.

CONCLUSIONS

In our cohort of children, stroke occurred after TIA at a rate similar to that seen in adults, but the risk factors for stroke after TIA in children are different.

Abstract T P363: A Pilot Study: Parents Show Evidence of PTSD while Children Display Anxiety following Childhood Stroke

Objectives: Post-traumatic stress disorder (PTSD) is commonly found in parents and child following life-threatening pediatric illness or injury including cancer, organ transplant, traumatic brain injury, and admission to the pediatric intensive care unit. It can be diagnosed months to years after the event. The prevalence and significance of PTSD in parents and children following a childhood stroke are unknown. We examine the emotional outcomes of a cohort of 33 parents and 10 children following recent stroke in the child.

Methods: We prospectively enrolled children with stroke of ages 7-18 years and parents of children with stroke ages 0-18 years whose stroke occurred in 2013 or 2014. Parents were screened for PTSD using the PTSD checklist and children with stroke ≥ 7 years of age were screened with the University of California Los Angeles PTSD Reaction Index. Emotional outcome of the child was examined with the Behavior Assessment System for Children (BASC-2). Parents were surveyed on their child’s stroke outcome with the Recurrence and Recovery Questionnaire (RRQ).

Results: Of the 33 parents (10 fathers, 23 mothers) 18 (55%) met one or more of the 3 PTSD criteria and 8 (24%) met all criteria for PTSD. Although not yet reaching significance, RRQ is higher in the group of parents with PTSD (RRQ M= 1.2, SD=1.4) compared to parents without PTSD (M=0.6, SD=1.0). The subsample of children enrolled ranged in age from 7 to 17 years old at time of stroke. Although preliminary, of the children who were surveyed none met criteria for PTSD while 2 of the 9 (22%) had clinically significant levels of anxiety.

Conclusion: Preliminary findings reveal a rate of PTSD in parents of children with childhood stroke similar to that found in parents of other critically ill children. We did not yet detect PTSD in our small sample of children. However, emotional ratings revealed that over 20% experience anxiety. The children of parents with PTSD had higher RRQ scores reflecting increased disability which may be related to the parent’s PTSD. PTSD in parents of a child with stroke and children with anxiety following stroke could impede compliance with therapeutic interventions and, consequently, lead to poorer functional outcome in the child.

Perinatal arterial ischemic stroke: presentation, risk factors, evaluation, and outcome

BACKGROUND

Perinatal arterial ischemic stroke is as common as large vessel arterial ischemic stroke in adults and leads to significant morbidity. Perinatal arterial ischemic stroke is the most common identifiable cause of cerebral palsy and can lead to cognitive and behavioral difficulties that are amortized over a lifetime.

METHODS

The literature on perinatal arterial ischemic stroke was reviewed and analyzed.

RESULTS

Risk factors for perinatal arterial ischemic stroke include those that are maternal, neonatal, and placental. The most common clinical signs at presentation are seizures and hemiparesis. Evaluation should begin with thorough history acquisition and physical examination followed by magnetic resonance imaging of the brain, with consideration of magnetic resonance angiography of the head and neck, echocardiogram, and thrombophilia evaluation. Treatment beginning early to include physical, speech, and occupational therapies including constraint-induced movement therapy and close cognitive and developmental follow-up may be beneficial. Future treatments may include transcranial magnetic stimulation, hypothermia, and erythropoietin.

CONCLUSIONS

Perinatal arterial ischemic stroke comprises a group of arterial ischemic injuries that can occur in the prenatal, perinatal, and postnatal periods in term and preterm infants with different types of perinatal arterial ischemic stroke having different clinical presentations, risk factors, and long-term outcomes.

Changing ethnic disparity in ischemic stroke mortality in US children after the STOP trial

IMPORTANCE

A prior report showed higher stroke mortality in US black children compared with white children (1979-1998), a disparity likely due in part to sickle cell disease, which leads to a high risk of childhood ischemic stroke. We hypothesized that this disparity has diminished since the publication of the Stroke Prevention Trial in Sickle Cell Anemia (STOP trial) in 1998 demonstrating the efficacy of long-term blood transfusions for primary stroke prevention.

OBJECTIVE

To evaluate the demographics and secular trends in mortality from ischemic and hemorrhagic stroke (as a primary cause of death) in US children (<20 years) and determine if there has been a decrease in the disparity between white and black children since the publication of the STOP trial in 1998.

DESIGN

We used death certificate data from the National Center for Health Statistics, 1988 through 2007.

SETTING

United States.

PARTICIPANTS

Children who died in 1988 through 2007 in the United States.

INTERVENTION

Publication of the STOP trial.

MAIN OUTCOME MEASURES

Incidence rate ratios were calculated as the measure of relative risk.

RESULTS

Among 1.6 billion person-years of US children (1988-2007), there were 4425 deaths attributed to stroke, yielding an average of 221 deaths per year; 20% were ischemic; 67%, hemorrhagic; and 12%, unspecified. The relative risk of ischemic stroke mortality for black vs white children dropped from 1.74 from 1988 through 1997 to 1.27 from 1998 through 2007. The ethnic disparity in hemorrhagic stroke mortality, however, remained relatively stable between these 2 periods: black vs white relative risk, 1.90 (1988-1997) and 1.97 (1998-2007).

CONCLUSIONS AND RELEVANCE

The excess risk of death from ischemic, but not hemorrhagic, stroke in US black children has decreased over the past decade. This may be related to the implementation of an effective ischemic stroke prevention strategy for children with sickle cell disease.

Abstract TMP98: Transient Ischemic Attack in Children and Its Relationship to Cerebral Infarction Identified by MRI

Objectives: Recent definition of transient ischemic attack (TIA) in adults includes negative neuroimaging for ischemic injury. Among children, TIA has not been well characterized. Further, the extent to which TIA symptoms are associated with MRI evidence of new cerebral injury has not been investigated. We present a cohort of 68 children with TIA symptoms and associated neuroimaging (MRI).

Methods: We searched the patient medical record database at Boston Children’s Hospital using the search terms “transient ischemic attack” or “TIA” in the year 2010. We examined cases of TIAs in children 18 years of age or younger whose TIA occurred between 2009 to 2011. TIA was defined as a focal neurologic deficit that resolved completely. We only included children who had an MRI done close to the time of the event. A blinded neuroradiologist evaluated all MRIs.

Results: Diffusion weighted imaging was done in 82% of cases in the cohort. Time from TIA to MRI varied from the day of TIA to 122 days after TIA with 68% scanned within 10 days of TIA presentation. Following TIA, nine of the 68 patients (13%) sustained a stroke verified by evidence of new ischemic injury in a vascular territory on neuroimaging. Time from initial TIA to stroke occurrence varied from hours to 3 years. Acute stroke was documented within one week of TIA in 56% of children who developed stroke following TIA. Further, 67% of the children who had a stroke after TIA demonstrated neuroimaging evidence of arteriopathy as compared to only 10% of children who did not have a stroke. Recurrent TIA was more common in children who eventually had a stroke (78%) than in children who did not have a stroke (59%).

Conclusion: In our cohort of 68 children who presented with TIA symptoms, 13% subsequently demonstrated evidence of acute cerebral infarction by neuroimaging, some as early as the first week following TIA. Like adults, TIA symptoms may herald stroke in children. Clinical evidence of cerebral arteriopathy and multiple TIAs may identify children at high risk for stroke after presentation with TIA symptoms. Additional inquiry to identify features of TIAs in children that impart high risk for stroke and their treatment is warranted.

Leukoaraiosis and sex predict the hyperacute ischemic core volume

BACKGROUND AND PURPOSE

Leukoaraiosis (LA) and male sex have been associated with decreased cerebrovascular reactivity, which potentially adversely affects tissue viability in acute stroke. Therefore, we aimed to elucidate the contribution of LA-severity and sex to the extent of the hyperacute ischemic core volume after intracranial large artery occlusion.

METHODS

We analyzed data from 87 patients with acute intracranial large artery occlusion who had acute multimodal computed tomography-imaging. LA-severity was assessed using the van Swieten scale on noncontrast computed tomography. Computed tomography perfusion data were analyzed using automatic calculation of the mean transit time and hyperacute cerebral blood volume defects. Multivariate linear and logistic regression analyses were used to identify independent predictors of the hyperacute infarct-volume.

RESULTS

Severe LA (van Swieten Scale, 3-4; odds ratio, 43.22; 95% CI, 6.26-298.42; P<0.001) and male sex (odds ratio, 7.52; 95% CI, 1.38-40.86; P=0.020) were independently associated with a hyperacute cerebral blood volume-lesion >25 mL on multivariate logistic regression analysis. Multivariate linear regression analysis confirmed the association between severe LA (P<0.001) and male sex (P=0.01) with larger cerebral blood volume-lesions. There was no significant difference in the absolute or relative mean transit time-lesion volumes when stratified by LA-severity or sex. Women had significantly smaller cerebral blood volume-lesion volumes compared with men (P=0.036).

CONCLUSIONS

Severe LA and male sex are associated with larger infarct cores, which adds to the notion that sex and LA alter the brain's intrinsic susceptibility to acute cerebral ischemia. Future, larger studies are needed to confirm our observation that women have smaller core volumes and its significance.

Abstract 2602: Changing Ethnic Disparity in Ischemic Stroke Mortality in US Children after the STOP Trial

Objective: A prior report showed higher stroke mortality in U.S. black children compared to white children (1979-1998), a disparity likely due in part to sickle cell disease. We hypothesized that this disparity has diminished since the publication of the Stroke Prevention Trial in Sickle Cell Anemia (STOP) trial in 1998 demonstrating the efficacy of chronic blood transfusions for primary stroke prevention. Because most childhood strokes in the setting of sickle cell disease are ischemic, we would expect a greater impact on ethnic disparities in ischemic than hemorrhagic stroke.

Methods: We evaluated the demographics and secular trends in mortality from ischemic and hemorrhagic stroke in U.S. children <20 years of age, using death certificate data from the National Center of Health Statistics (NCHS) from 1988 to 2007.

Results: A total of 1,555,045,537 person-years were included in the study. There were 4,425 deaths attributed to childhood stroke (as primary cause of death) within this cohort, yielding an average of 221 deaths per year. Ischemic strokes accounted for 20% of deaths; hemorrhagic strokes accounted for 67% (12% were unspecified). The relative risk of ischemic stroke mortality for black versus white children from 1988 to 1998 was 1.74 (95% CI 1.42-2.13, p<0.001) while the relative risk from 1999 to 2007 was 1.27 (95%CI 0.99-1.64, p= 0.063). While ischemic stroke mortality rates in black versus white children appear to be converging, the ethnic disparity in hemorrhagic stroke mortality has remained relatively stable ( Figure 1 ).

Conclusion: The excess risk of death from ischemic, but not hemorrhagic, stroke in U.S. black children has decreased over the past decade. This may be related to the implementation of an effective primary stroke prevention strategy for children with sickle cell disease.

Potential eligibility for recombinant tissue plasminogen activator therapy in children: a population-based study

Intravenous recombinant tissue plasminogen activator is an established therapy for adults with ischemic stroke. In this Greater Cincinnati/Northern Kentucky population-based study, 8% were eligible. However, no established therapy exists for children with acute ischemic stroke. Accordingly, investigators assessed rates of eligibility for recombinant tissue plasminogen activator therapy among children (<18 years of age) in the same population to aid planning of future clinical trials. The investigators identified 29 pediatric ischemic strokes during 3 separate study periods (1993-1994, 1999, and 2005) and determined potential eligibility for recombinant tissue plasminogen activator therapy based on 2007 American Heart Association guidelines for adults. Depending on how relative contraindications were considered, 1 to 3 cases (3%-10%) met eligibility criteria. On the basis of national pediatric stroke incidence rates extrapolated from our population, it is estimated that up to 178 children might be eligible for intravenous recombinant tissue plasminogen activator therapy annually in the United States. Thus, recruitment for clinical studies is likely to be challenging and requires a concerted multicenter effort.