Pediatric patients with sickle cell disease (SCD) have decreased oxygen-carrying capacity in the blood and reduced or restricted cerebral blood flow resulting in neurocognitive deficits and cerebral infarcts. The standard treatment for children with SCD is hydroxyurea; however, the treatment-related neurocognitive effects are unclear. A key area of impairment in SCD is working memory, which is implicated in other cognitive and academic skills. N-back tasks are commonly used to investigate neural correlates of working memory. We analyzed functional magnetic resonance imaging (fMRI) of patients with SCD while they performed n-back tasks by assessing the blood-oxygenation level-dependent (BOLD) signals during working memory processing. Twenty hydroxyurea-treated and 11 control pediatric patients with SCD (7-18 years old) performed 0-, 1-, and 2-back tasks at 2 time points, once before hydroxyurea treatment (baseline) and ~1 year after treatment (follow-up). Neurocognitive measures (e.g., verbal comprehension, processing speed, full-scale intelligence quotient, etc.) were assessed at both time points. Although no significant changes in behavior performance of n-back tasks and neurocognitive measures were observed in the treated group, we observed a treatment-by-time interaction in the right cuneus and angular gyrus for the 2- > 0-back contrast. Through searchlight-pattern classifications in the treated and control groups to identify changes in brain activation between time points during the 2-back task, we found more brain areas, especially the posterior region, with changes in the pattern and magnitude of BOLD signals in the control group compared to the treated group. In the control group, increases in 2-back BOLD signals were observed in the right crus I cerebellum, right inferior parietal lobe, right inferior temporal lobe, right angular gyrus, left cuneus and left middle frontal gyrus at 1-year follow-up. Moreover, BOLD signals elevated as the working memory load increased from 0- to 1-back but did not increase further from 1- to 2-back in the right inferior temporal lobe, right angular gyrus, and right superior frontal gyrus. These observations may result from increased cognitive effort during working memory processing with no hydroxyurea treatment. In contrast, we found fewer changes in the pattern and magnitude of BOLD signals across time points in the treated group. Furthermore, BOLD signals in the left crus I cerebellum, right angular gyrus, left cuneus and right superior frontal gyrus of the treated group increased continuously with increasing working memory load from 0- to 2-back, potentially related to a broader dynamic range in response to task difficulty and cognitive effort. Collectively, these findings suggest that hydroxyurea treatment helped maintain working memory function in SCD.

Supplementary Figures 1-7 from p18Ink4c and p53 Act as Tumor Suppressors in Cyclin D1–Driven Primitive Neuroectodermal Tumor

AbstractThe retinoblastoma (RB) tumor suppressor pathway is likely important in primitive neuroectodermal tumors (PNET) of the brain. In fact, 10% to 15% of children born with RB mutations develop brain PNETs, commonly in the pineal gland. Cyclin D1, which in association with cyclin-dependent kinase (Cdk) 4 and Cdk6 phosphorylates and inactivates the RB protein, is expressed in 40% of sporadic medulloblastoma, a PNET of the cerebellum. To understand tumorigenic events cooperating with RB pathway disruption in brain PNET, we generated a transgenic mouse where cyclin D1 was expressed in pineal cells. Cyclin D1 enhanced pinealocyte proliferation, causing pineal gland enlargement. However, proliferation ceased beyond 2 weeks of age with reversal of Cdk4-mediated Rb phosphorylation despite continued expression of the transgene, and the pineal cells showed heterochromatin foci suggestive of a senescent-like state. In the absence of the p53 tumor suppressor, cell proliferation continued, resulting in pineal PNET that limited mouse survival to ∼4 months. Interestingly, the Cdk inhibitor p18Ink4c was induced in the transgenic pineal glands independently of p53, and transgenic mice that lacked Ink4c developed invasive PNET, although at an older age than those lacking p53. Analogous to our mouse model, we found that children with heritable RB often had asymptomatic pineal gland enlargement that only rarely progressed to PNET. Our finding that the Cdk4 inhibitor p18Ink4c is a tumor suppressor in cyclin D1–driven PNET suggests that pharmacologic interventions to inhibit Cdk4 activity may be a useful chemoprevention or therapeutic strategy in cancer driven by primary RB pathway disruption. [Cancer Res 2009;69(2):440–8]

Introduction: Allogeneic hematopoietic cell transplantation (HCT) is potentially curative for patients with sickle cell disease (SCD). It is often recommended for patients with severe SCD, including those at risk of, or with a history of stroke. There has been limited investigation into the direct impact of HCT on cerebral hemodynamics. Quantitative biomarkers of cerebral hemodynamics, including oxygen extraction fraction (OEF) and cerebral blood flow (CBF), can provide an objective assessment of therapeutic efficacy of HCT as well as other emerging therapies. We have previously shown that CBF improves after HCT in patients with SCD (Sharma A, et al. Suppl 1, Blood 2021). Here, we performed a prospective evaluation using magnetic resonance imaging (MRI) to measure the OEF of the whole brain and the superior sagittal sinus (SSS), to compare cerebral oxygen metabolism in SCD patients before and after HCT. Methods: We performed anatomical and hemodynamic MRI of the brain prior to, and at 6 months after HCT in children with SCD undergoing a reduced intensity conditioning based HCT on a clinical trial (NCT04362293). Patients were receiving either hydroxyurea (HU) or chronic transfusion therapy (CTT) before HCT. MRI brain scanning was performed for all patients in a 3 Tesla MRI imaging system (Siemens MAGNETOM Prisma, Erlangen, Germany) with a 16-channel phased-array coil. Quantitative susceptibility map (QSM) imaging was performed through a 3D multi-echo gradient echo sequence with flow compensation and reconstructed with the morphology-enabled dipole inversion (MEDI) method (Liu T, et al. MRM 2013). The oxygen extraction fraction was calculated utilizing the established formula incorporating clinically measured hematocrit, tissue susceptibility, and hemoglobin susceptibility values quantified through quantitative susceptibility mapping (QSM), as previously delineated (Fan A, et al. JCBFM 2020) for the segmented vessels from the whole brain and the SSS. Results: The median age at HCT was 15.6 years (N=11). Hematocrit as well as global and regional (SSS) OEF of the patients were quantified and compared between baseline and at 6 months after HCT (Fig 1). All patients experienced a decrease in OEF after HCT. We then stratified the patients into those who were receiving HU or CTT prior to HCT. In patients receiving HU prior to HCT (n=7), there was a small decrease in OEF for the whole brain (42.4% vs. 39.9%, P = 0.40) and SSS (33.1% vs. 31.3%, P =0.12) at 6 months after HCT compared to baseline. However, in patients receiving CTT prior to HCT (n=4) both the global OEF (50.0% vs. 34.4 %, P < 0.01) and regional OEF (31.8% vs. 26.7 %, P < 0.05) decreased significantly at 6 months after HCT. All patients exhibited an increased hematocrit following HCT (Fig 2). Specifically, the HU cohort improved from a mean of 27.4% to 37.5% ( P<0.01), while the CTT cohort increased from 26.2% to 39.6% ( P<0.01) after HCT. Conclusions: Our results demonstrate the feasibility of global and regional OEF quantification using MRI in patients undergoing HCT for SCD. We observed that the OEF of the whole brain and SSS exhibited a similar downward trend after HCT in patients receiving either HU or CTT. This indicates an overall improvement in oxygen delivery after HCT. OEF decrease was marked after HCT in the CTT group, suggesting that HCT provided better cerebral hemodynamic outcomes than at baseline for this group. In contrast, the cohort of patients receiving HU showed a subtle decrease in OEF after HCT, perhaps implying that these patients had milder cerebral hemodynamic compromise than the CTT group. Both pretreatment groups demonstrated significantly higher hemoglobin concentrations after HCT compared to before treatment which may have contributed to the improvement in OEF. Our study presents objective physiologic comparisons of different clinical therapies on cerebral hemodynamics, providing early data on the effects of cerebral oxygen delivery in pediatric patients with SCD. Further studies with larger patient numbers are warranted to confirm the trends observed in oxygen metabolism and understand the mechanisms underlying differential responses to HCT and other disease-modifying therapies. These imaging biomarkers may also help assess different genetic therapies currently in development.

To investigate the developmental changes of cerebral blood flow (CBF) and hemodynamic responses to changing neural activity, we used the arterial spin label (ASL) technique to measure resting CBF and simultaneous CBF / blood-oxygen-level dependent (BOLD) signal changes during visual stimulation in 97 typically developing children and young adults (age 13.35 [6.02, 25.25] (median [min, max]) years old at the first time point). The longitudinal study protocol included three MRIs (2.7 ± 0.06 obtained), one year apart, for each participant. Mixed-effect linear and non-linear statistical models were used to analyze age effects on CBF and BOLD signals. Resting CBF decreased exponentially with age (p = 0.0001) throughout the brain, and developmental trajectories differed across brain lobes. The absolute CBF increase in visual cortex during stimulation was constant over the age range, but the fractional CBF change increased with age (p = 0.0001) and the fractional BOLD signal increased with age (p = 0.0001) correspondingly. These findings suggest that the apparent neural hemodynamic coupling in visual cortex does not change after age six years, but age-related BOLD signal changes continue through adolescence primarily due to the changes with age in resting CBF.

Introduction: Sickle cell anemia (SCA) results in numerous adverse effects on the brain, including ischemic lesions and neurocognitive dysfunction. Hydroxyurea has been utilized extensively for management of SCA, but its effects on brain function have not been established. Methods: We examined prospectively the effects of one year of treatment with hydroxyurea on brain function in a cohort of children with SCA (HbSS/HbSβ0-thalassemia) by baseline and exit evaluations, including comprehensive neurocognitive testing, transcranial Doppler ultrasound (TCD), and brain MRI [silent cerebral infarcts (SCI), gray matter cerebral blood flow (GM-CBF), and blood oxygen level dependent (BOLD) signal from visual stimulation]. Results: Nineteen patients with SCA, mean age 12.4 years (range 7.2-17.8), were evaluated. At baseline, subjects had these mean values: full scale IQ (FSIQ) 81.9, TCD velocity 133 cm/sec, GM-CBF 64.4 ml/100g/min, BOLD signal 2.34% increase, and frequency of SCI 47%. After one year of hydroxyurea, there were significant increases in FSIQ (+2.8, p=0.036) and reading comprehension (+4.8, p=0.016), a significant decrease in TCD velocity (-11.4 cm/sec, p=0.007), and no significant changes in GM-CBF, BOLD, or SCI frequency. Furthermore, FSIQ was associated with higher hemoglobin F (HbF) and lower GM-CBF, but not with hemoglobin level. Discussion: Significant improvement of neurocognition and decreased TCD velocity following one year of treatment support the use of hydroxyurea for improving neurocognitive outcomes in SCA. Understanding the mechanisms of benefit, as indicated by relationships of neurocognitive function with HbF, hemoglobin, and CBF, requires further evaluation.

Supplemental material, sj-pdf-1-jcb-10.1177_0271678X20925303 for Developmental patterns of CBF and BOLD responses to visual stimulus by Ping Zou, Matthew A Scoggins, Yimei Li, Melissa Jones, Kathleen J Helton and Robert J Ogg in Journal of Cerebral Blood Flow & Metabolism

Multiple etiologies should be considered in the differential diagnosis of immunocompromised patients with non–central nervous system cancer and viral infections who develop mutism. Acute cerebellitis, caused by infections or by neurotoxicity resulting from chemotherapy; paraneoplastic cerebellar degeneration; atypical posterior reversible encephalopathy syndrome; and acute disseminated encephalomyelitis may all cause mutism in such patients. This condition warrants prompt recognition and may require treatment with immunotherapy, as it may be an immune-mediated process. We present 2 patients with leukemia and viral illness who developed cerebellar mutism in the setting of acute cerebellitis and responded to immunotherapy, suggesting that the condition involved a parainfectious immune-mediated response.

Viral infections involving the central nervous system (CNS) may result from a wide variety of agents and have clinically overlapping manifestations. The diagnosis is often made based on a combination of the clinical exam, local epidemiology, imaging, and biochemical findings. Despite the advances in medicine and imaging, the diagnosis often remains elusive. Imaging, however, still plays a vital role in suggesting the diagnosis in typical cases, excluding potential mimics, and in evaluating changes with therapy. Herein, the authors present a review of various common and rare viral encephalitides with emphasis on the imaging literature.

Purpose To evaluate a new postprocessing framework that eliminates arterial vessel signal contributions in the quantification of normalized visible venous volume (NVVV, a ratio between venous and brain volume) in susceptibility-weighted imaging (SWI) exams in patients with sickle cell disease (SCD). Materials and Methods We conducted a retrospective study and qualitatively reviewed for hypointense arterial vessel contamination in SWI exams from 21 children with SCD. We developed a postprocessing framework using magnetic resonance angiography in combination with SWI to provide a more accurate quantification of NVVV. NVVV was calculated before and after removing arterial vessel contributions to determine the error from hypointense arterial vessels in quantifying NVVV. Results Hypointense arterial vessel contamination was observed in 86% SWI exams and was successfully corrected by the proposed method. The contributions of hypointense arterial vessels in the original SWI were significant and accounted for approximately 33% of the NVVV [uncorrected NVVV = 0.012 ± 0.005 versus corrected NVVV = 0.008 ± 0.003 (mean ± SD), P < 0.01]. Conclusion Hypointense arterial vessel contamination occurred in the majority of SWI exams and led to a sizeable overestimation of the visible venous volume. A prospective longitudinal study is needed to evaluate if quantitation of NVVV was improved and to assess the role of NVVV as a biomarker of SCD severity or stroke risk.

The phase III multicenter clinical trial TWiTCH (NCT See Appendix for list of investigators) enrolled children with sickle cell anemia (SCA), who had previous abnormal transcranial Doppler ultrasound velocities (TCD V) and were receiving chronic transfusions for primary stroke prevention.1 Because the impact of chronic transfusions on sickle cell nephropathy is unknown in children, we investigated baseline kidney function of this transfused cohort and compared it to the prevalence of albuminuria and glomerular hyperfiltration in two age-matched non-chronically transfused cohorts at St. Jude (HUSTLE, NCT00305175) and University of Miami (UM). Entry renal function evaluation in TWiTCH included serum creatinine and cystatin C; spot urine for albumin/creatinine ratio (ACR) and specific gravity; abdominal ultrasound with measurement of kidney length and volume; and abdominal MRI R2* that measured liver, kidney, and pancreas iron content. Glomerular filtration rate (GFR) was estimated by bedside Schwartz and Schwartz CKiD equations. Glomerular hyperfiltration was defined as estimated GFR > 1 standard deviation above the mean for age. Albuminuria was present when ACR ≥ 30 mg/g creatinine and was reported as microalbuminuria if ACR was 30–300 mg/g creatinine. Macroalbuminuria was defined as ACR > 300 mg/g creatinine. UM and HUSTLE data for aged-matched (4–15 years) children with hemoglobin (Hb) SS or HbS/β0-thalassemia, not receiving chronic erythrocyte transfusions or hydroxyurea, were analyzed for comparable kidney parameters. None of the children had an abnormal TCD when the renal parameters were assessed. Both cohorts have been partially published.2, 3 Descriptive analyses (independent sample t-tests and contingency tables) were performed on baseline demographic, clinical, and kidney function parameters. Predictors of albuminuria were assessed using stepwise multivariate logistic regression. Assessment of associations with CKiD Schwartz was performed using stepwise linear regression. Baseline covariates included age at screening and at start of transfusions, Hb concentration, %HbS level, reticulocyte count, LDH, presence or absence of hyperfiltration (logistic only), months of chelation therapy, serum ferritin, kidney R2* and liver R2* measurements, maximum time-averaged TCD V, magnetic resonance angiography (MRA) vasculopathy staging 1–3,4 and brain MRI evidence of silent infarction or other parenchymal abnormalities. Two-sided t-tests and contingency tables compared age at baseline, estimated GFR and ACR among TWiTCH, UM, and HUSTLE cohorts. P-values ≤.05 were considered statistically significant, with no adjustment for multiple comparisons. There were a total of 121 randomized TWiTCH participants, mean age 9.5 ± 3.0 years, and 73 (60%) were females. Children had a normal body mass index (mean 17.7 ± 3.6) and were not hypertensive (mean systolic and diastolic pressures were 109 ± 10 and 61 ± 8 mm Hg, respectively). TWiTCH participants had started transfusions at a mean age of 5.5 ± 2.0 years, and were transfused for an average of 4.4 years (range 1.0–10.8 years) at enrollment. Study participants had mean baseline Hb = 9.2 ± 0.8 g/dL, mean %HbS = 27 ± 10%, and elevated ferritin = 2895 ± 2275 μg/L. The vast majority (107, 88%) of the children had iron overload and were prescribed chelation for 34 ± 24 months preceding study enrollment. Participants had received iron chelation with deferasirox only (N = 92), deferoxamine only (N = 1), or both (N = 14). TWiTCH participants had an average bedside Schwartz GFR = 140.1 ± 66.7mL/min/1.73 m2 (27.0% with hyperfiltration) and CKiD Schwartz GFR = 122.2 ± 29.8 mL/min/1.73 m2 (13.3% with hyperfiltration). There were 31 (27.9%) and 23 (20.7%) with bilateral and unilateral kidney enlargement, respectively (combined prevalence of 48.7%). Mean renal R2* was elevated (≥35 Hz), indicating increased iron content. Twelve children (10.3%) had microalbuminuria (mean urine ACR 60.2 ± 25.5 mg/g creatinine, range 34.5–121.3 mg/g creatinine) and none had macroalbuminuria. Children with albuminuria had significantly higher estimated GFR by bedside Schwartz (199.80 ± 153.0 vs. 132.94 ± 45.0 mL/min/1.73 m2, P = .001) and CKiD Schwartz (140.58 ± 44.9 vs. 119.96 ± 26.5 mL/min/1.73 m2, P = .025), and lower renal R2* compared to children without albuminuria (39.02 ± 18.3 vs. 74.81 ± 49.7 Hz, P = .035). GFR significantly correlated with renal R2* and absolute reticulocyte count in univariate analysis, but only with renal R2* in multivariate analysis. The correlation between renal R2* and LDH was 0.48 (P < .0001), indicating that renal R2* was associated with endothelial inflammation and/or hemolysis. Albuminuria was significantly associated with MRA cerebral vasculopathy, with an odds ratio of 7.17 (95% CI 1.50–34.23, P = .013), and a 3% reduction in risk of albuminuria was observed for each renal R2* unit increase. The maximum mean TCD V at baseline and iron chelation were not independently associated with albuminuria. Table 1 shows the comparison between TWiTCH and the two non-transfused cohorts. TWiTCH participants had lower prevalence of albuminuria (10%) compared to non-transfused cohorts with 14%-22% prevalence (P = 0.049). The mean GFR in TWiTCH was significantly lower than the mean GFR in HUSTLE, but not significantly different than the UM cohort. This is the first description of kidney function parameters in large age-matched cohorts of school-age children with SCA, analyzed by the presence of chronic transfusions. In TWiTCH, we did not detect associations with albuminuria and hemolytic laboratory parameters, which could reflect treatment effect by chronic transfusions, the relatively small number of children with albuminuria, or lack of a pathophysiological correlation between intravascular hemolysis and albuminuria. Despite the known risk of developing proteinuria with the use of the iron chelator deferasirox, we also did not find an association between iron chelation and albuminuria. Albuminuria was associated with cerebral vasculopathy on MRA, but not with baseline TCD V. This association suggests that sickled-related endothelial damage and dysfunction may contribute to the development of both cerebral vasculopathy and albuminuria. Microalbuminuria was an independent predictor of future stroke (Cox proportional hazard ratio 4.9) in a general population of adults.5 Our finding establishes that such association also exists in children with SCA and mild (stages 1–3) cerebral vasculopathy. We found that the prevalence of baseline albuminuria was lower in TWiTCH than the non-transfused and non-chelated cohorts, and within the range of that encountered (up to 12%) in screening healthy children aged 8–18 years (Third National Health and Nutrition Examination Survey (NHANES III).6 Because albuminuria was associated with cerebral vasculopathy, the fact that fewer children had albuminuria in TWITCH than in the non-transfused cohorts suggests a therapeutic or protective effect of transfusions on renal function. This work was supported by the National Heart Lung and Blood Institute (NHLBI), through grants R01 HL-095647 (REW) and R01 HL-095511 (BRD). Dr. Ofelia Alvarez participated in an advisory board for Novartis. Dr. Kerri Nottage has been employed by Janssen Research & Development, LLC. Dr. John Wood served as a consultant for Vifor, Apopharma, and Ionis. Dr. Sharada Sarnaik is an advisory board member for AstraZeneca. Dr. Russell Ware is a consultant for Global Blood Therapeutics and Nova Laboratories. Drs. Simpson, Davis, Fuh, Aygun, and Helton have nothing to disclose. Ofelia Alvarez http://orcid.org/0000-0003-4811-267X Principal Investigator: Russell E. Ware, MD, PhD, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio. Clinical Site Investigators: Texas Children's Hospital, Houston, Texas: Alex George, MD, PhD, Brigitta U. Mueller, MD, MHCM; Children's Hospital, Boston, Massachusetts: Matthew M. Heeney, MD; Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio: Theodosia A. Kalfa, MD, PhD; Children's Hospitals and Clinics of Minnesota, Minneapolis, Minnesota: Stephen Nelson, MD; Emory/CHOA, Atlanta, Georgia: R. Clark Brown, MD PhD; Co-Investigator: Beatrice Gee, MD; Children's Hospital of Philadelphia, Philadelphia, Pennsylvania: Clinical Investigator: Janet L. Kwiatkowski, MD, MSCE; Co-Investigator: Kim Smith-Whitley, MD; The Hospital for Sick Children, Toronto, Ontario, Canada: Isaac Odame, MB ChB, FRCPath, FRCPC; Children's National Medical Center, Washington, DC: Lori Luchtman Jones MD; Jennifer Webb, MD; Co-Investigators: Brenda Martin, MSN CPNP, and Elizabeth Yang, MD PhD; Columbia University, New York, New York: Margaret T. Lee, MD; Rainbow Babies & Children's Hospital, Case Western Reserve University, Cleveland, Ohio: Connie Piccone, MD; University of South Alabama (USA), Mobile, Alabama: Hamayun Imran, MD, MSc; Medical University of South Carolina, Charleston, South Carolina: Sherron M. Jackson, MD; Children's Medical Center of New York, New Hyde Park, New York: Banu Aygun, MD, Sharon Singh, MD; St. Jude Children's Research Hospital, Memphis, Tennessee: Kerri Nottage, MD, MPH, Jane S. Hankins, MD, MS; State University of New York- Downstate Medical Center, Brooklyn, New York: Scott T. Miller, MD; University of Alabama at Birmingham (UAB) Birmingham, Alabama: Lee Hilliard, MD; University of Miami Miller School of Medicine, Miami, Florida: Ofelia Alvarez, MD; University of Mississippi Medical Center (UMMC), Jackson, Mississippi: Melissa Rhodes, MD, Rathi Iyer, MD; UT Southwestern, Dallas, Texas: Zora R. Rogers, MD; Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit, Michigan: Sharada A. Sarnaik, MD; Anna and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois: Alexis A. Thompson, MD, MPH; Children's Hospital of The King's Daughters, Norfolk, Virginia: William C. Owen, MD; Nemours Children's Clinic, Jacksonville, Florida: Cynthia Gauger, MD; University of South Carolina/Palmetto Health, Columbia, South Carolina: Carla Roberts, MD; Duke University Medical Center, Durham, North Carolina: Jennifer A. Rothman, MD; Brody School of Medicine at East Carolina University, Greenville, North Carolina: Beng Fuh, MD, Charles Daeschner, MD Medical Coordinating Center Cincinnati Children's Hospital, Cincinnati, Ohio- Principal Investigator: Russell E. Ware, MD, PhD; Clinical Coordinator and Medical Monitor: William H. Schultz, MHS, PA-C; Project Manager: Susan Stuber MA, CCRP, RAC Data Coordinating Center UT School of Public Health, Houston, Texas- Principal Investigator: Barry R. Davis, MD, PhD; Co-Investigator: Sara Pressel, MS, Peng Wei, PhD, Seoun Kim, PhD; Project Manager: Cecilia Lara, BS; Safety: Linda Piller, MD, MPH, Lara Simpson, PhD, Aliza Matusevich Neurology and TCD Core MUSC Stroke Center, Charleston, South Carolina- Principal Investigator: Robert J. Adams, MD, PhD Central Laboratory, Georgia Health Sciences University, Augusta, Georgia: Abdullah Kutlar, MD and Niren Patel, MBBS Consultants: Abdominal MRI: John C. Wood, MD PhD; Neuroradiology: Kathleen J. Helton, MD and Donna Roberts, MD; Ultrasound: Jamie Coleman, MD; Neurocognitive: Melanie J. Bonner, PhD; Hematology: Nicole Mortier, MHS, PA-C; Transfusions: Naomi Luban, MD; Iron/Chelation: Alan R. Cohen, MD

Background: Sickle cell anemia is associated with progressive compromise of neurocognitive function exacerbated by stroke or silent cerebral infarction. Despite decades of experience with chronic transfusion, hematopoietic stem cell transplantation, and HU, improvement in neurocognitive performance from these interventions has not been clearly demonstrated; only one study has reported improvement in global cognitive index from HU (Puffer, Child Neuropsychology, 2007). As part of a comprehensive prospective evaluation of the effects of HU treatment on the central nervous system, we evaluated neuropsychological performance in school-age children with sickle cell anemia.

Silent cerebral infarction (SCI) is the most common neurological abnormality among children with sickle cell anaemia (SCA). The effect of hydroxycarbamide (also termed hydroxyurea) on the development and progression of SCI is unclear. We evaluated brain magnetic resonance imaging/angiography (MRI/MRA) in children with SCA receiving long-term hydroxycarbamide therapy. Fifty participants (median 9·4 years, range 1·1-17·3) enrolled in the Hydroxyurea Study of Long-Term Effects (HUSTLE; NCT00305175) underwent brain MRI/MRA and laboratory evaluations before hydroxycarbamide initiation and after 3 and 6 years of treatment to maximum tolerated dose. SCI and vascular stenosis were evaluated. At baseline, 3 and 6 years, SCI were present in 19/50 (38%), 20/49 (41%), and 7/17 (41%), respectively. At 3 years, one child developed a SCI lesion, and another progressed (single lesion to multiple). Lower haemoglobin (Hb) (80 g/l vs. 86 g/l, P = 0·049), fetal Hb (5·0% vs. 10·4%, P < 0·001) and oxygen saturation (97% vs. 98%, P = 0·027) before hydroxycarbamide initiation were associated with SCI. No patients had vascular stenosis identified on MRA, transient ischaemic attack or stroke. Our data indicate that children receiving hydroxycarbamide over a 3- to 6-year period have a low rate of new or worsening cerebrovascular disease. Further studies are needed to confirm that hydroxycarbamide can prevent the onset and progression of SCI.

Unusual magnetic resonance imaging presentation of post-BMT cerebral toxoplasmosis masquerading as meningoencephalitis and ventriculitis

Transcranial Doppler (TCD) screening in children with sickle cell anemia (SCA) identifies abnormally elevated cerebral artery flow velocities that confer an elevated risk for primary stroke. Chronic transfusions offer effective stroke prophylaxis in this setting, but must be continued indefinitely and lead to transfusional iron overload. An alternative treatment strategy that offers similar effective protection against primary stroke, and provides control of iron overload, is needed. TCD With Transfusions Changing to Hydroxyurea (TWiTCH, NCT01425307) was an NHLBI-funded Phase III multicenter randomized clinical trial comparing 24-months of standard treatment (transfusions) to alternative treatment (hydroxyurea) in children with SCA and abnormal TCD velocities. All eligible children had received at least 12 months of transfusions. TWiTCH had a non-inferiority trial design; the primary study endpoint was the 24-month TCD velocity obtained from a linear mixed model, controlling for baseline (enrollment) values, with a non-inferiority margin of 15 cm/sec. The transfusion arm maintained children at HbS <30%; an elevated liver iron concentration (LIC) identified by R2 MRI FerriScan® was managed with chelation. The hydroxyurea arm included an overlap period with transfusions until a stable maximum tolerated dose (MTD) of hydroxyurea was reached; transfusions were then replaced by serial phlebotomy to reduce iron overload. In both arms, TCD velocities were obtained every 12 weeks and reviewed centrally, with local investigators masked to the results. A centralized TCD alert algorithm monitored changes from enrollment velocities. A total of 159 children were enrolled but 38 failed screening due primarily to severe vasculopathy on brain MRA or inadequate TCD exams; 121 children were randomized (61 to transfusions, 60 to hydroxyurea) with balanced characteristics including enrollment maximum TCD velocities (145 ± 21 versus 145 ± 26 cm/sec), age, duration of transfusions, serum ferritin, and LIC. Study participants randomized to transfusions maintained an average HbS <30% throughout the study, while those on hydroxyurea reached MTD after 7 ± 2 months at an average dose of 27 mg/kg/day, with expected hematological changes including HbF ~25% throughout the treatment period. After 37% of the participants exited the study, a scheduled interim analysis suggested the primary study endpoint was likely to be achieved. NHLBI allowed the study to continue until 50% of the children exited, at which time the statistical analysis was confirmed and the study was terminated; all remaining participants moved to the exit phase. The final analysis included 42 on the transfusion arm who completed all treatment, 11 with truncated treatment, and 8 withdrawn; the hydroxyurea arm included 41 who completed all treatment, 13 with truncated treatment, and 6 withdrawn. The final calculated TCD velocities (mean ± standard error) in the transfusion and hydroxyurea arms were 143 ± 1.6 and 138 ± 1.6 cm/sec, respectively; by intention-to-treat analysis, the p-value for non-inferiority = 8.82 x 10-16 and by post-hoc analysis the p-value for superiority = 0.046. Among 29 new neurological events, all centrally adjudicated by masked reviewers, there were no strokes but 6 transient ischemic attacks (3 in each arm). One child (transfusion arm) was withdrawn per the TCD alert algorithm after developing on-study TCD velocities >240 cm/sec. Exit brain MRI/MRA exams documented no new parenchymal abnormalities but one child (transfusion arm) developed new vasculopathy. Sickle cell related serious adverse events were more common in the hydroxyurea arm than the transfusion arm (23 to 15), but none was related to study treatment or study procedures. Iron overload improved more in the hydroxyurea arm than in the transfusion arm, with a greater average change in serum ferritin (-1085 compared to -38 ng/mL, p<0.001) and LIC (average -1.9 compared to +2.4 mg/g dry weight liver, p=0.001). In the multicenter Phase III TWiTCH trial, which treated children with SCA and abnormal TCD velocities but without severe MRA vasculopathy, hydroxyurea at MTD was non-inferior and possibly superior to chronic transfusions for maintaining TCD velocities. Serial phlebotomy effectively managed iron overload. Hydroxyurea may represent an effective alternative to indefinite transfusions for the prevention of primary stroke in this high risk population.

Silent cerebral infarctions (SCI) are the most common neurological injury in children with sickle cell anaemia (SCA), but their incidence/prognosis in early childhood has not been well described. We report clinical, neuroradiological, psychometric and academic follow-up over an average period of 14 years in 37 children with SCA who had magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the brain between ages 7 and 48 months. Ten patients (27%) younger than age 5 years (Group I) had SCI, as did 12 (32%) older than 5 years (Group II). Fifteen (41%) had no lesions (Group III). Overt stroke or transient ischaemic attack occurred in 5/9 (56%) in Group I. Most Group I patients had progressive MRI abnormalities, concurrent stenosis, decreased cognitive ability, attention/executive function deficits and hindered academic attainment. The proportions of subjects in Group I with subsequent neurological events (P ≤ 0·006), progressive ischaemia (P ≤ 0·001) and vascular stenosis (P ≤ 0·006) were greater than in Groups II and III. Thus, SCI in young children with SCA may predict overt central nervous system events, progressive MRI abnormalities, stenosis, cognitive dysfunction and poor academic performance. Children younger than 5 years may benefit from MRI/MRA testing and should be considered for aggressive intervention when SCI are detected.

Background For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions.Methods TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD fl ow velocities (>= 200 cm/s) but no severe vasculopathy. After screening, eligible participants were randomly assigned 1: 1 to continue standard transfusions (standard group) or hydroxycarbamide (alternative group). Randomisation was done at a central site, stratified by site with a block size of four, and an adaptive randomisation scheme was used to balance the covariates of baseline age and TCD velocity. The study was open-label, but TCD examinations were read centrally by observers masked to treatment assignment and previous TCD results. Participants assigned to standard treatment continued to receive monthly transfusions to maintain 30% sickle haemoglobin or lower, while those assigned to the alternative treatment started oral hydroxycarbamide at 20 mg/kg per day, which was escalated to each participant's maximum tolerated dose. The treatment period lasted 24 months from randomisation. The primary study endpoint was the 24 month TCD velocity calculated from a general linear mixed model, with the non-inferiority margin set at 15 cm/s. The primary analysis was done in the intention-totreat population and safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, number NCT01425307.Findings Between Sept 20, 2011, and April 17, 2013, 159 patients consented and enrolled in TWiTCH. 121 participants passed screening and were then randomly assigned to treatment (61 to transfusions and 60 to hydroxycarbamide). At the first scheduled interim analysis, non-inferiority was shown and the sponsor terminated the study. Final model-based TCD velocities were 143 cm/s (95% CI 140-146) in children who received standard transfusions and 138 cm/s (135-142) in those who received hydroxycarbamide, with a difference of 4.54 (0.10-8.98). Non-inferiority (p= 8.82 x 10(-16)) and post-hoc superiority (p= 0.023) were met. Of 29 new neurological events adjudicated centrally by masked reviewers, no strokes were identified, but three transient ischaemic attacks occurred in each group. Magnetic resonance brain imaging and angiography (MRI and MRA) at exit showed no new cerebral infarcts in either treatment group, but worsened vasculopathy in one participant who received standard transfusions. 23 severe adverse events in nine (15%) patients were reported for hydroxycarbamide and ten serious adverse events in six (10%) patients were reported for standard transfusions. The most common serious adverse event in both groups was vaso-occlusive pain (11 events in five [8%] patients with hydroxycarbamide and three events in one [2%] patient for transfusions).Interpretation For high-risk children with sickle cell anaemia and abnormal TCD velocities who have received at least 1 year of transfusions, and have no MRA-defined severe vasculopathy, hydroxycarbamide treatment can substitute for chronic transfusions to maintain TCD velocities and help to prevent primary stroke.

Background: Up to 40% of children with sickle cell anemia (SCA) will have abnormalities on brain imaging due to their hematologic disorder, much of which is subclinical. Common abnormalities on brain magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) include leukoencephalopathy from microvascular ischemic insult and vascular stenosis from endothelial damage. Silent cerebral ischemic insults are progressive; further neurologic abnormalities, including overt stroke, are more common among children with ischemic findings on MRI compared to children without them. Furthermore, poor performance on neuropsychological testing, lower IQ, and higher rates of grade retention are common in children with SCA and cerebral ischemic disease. The effect of hydroxyurea treatment on the development and progression of vascular stenosis and leukoencephalopathy is unclear. This study aimed to longitudinally evaluate the development of intracerebral abnormalities through serial MRI/MRA in children with SCA (HbSS and HbSβ0-thalassemia) who receive long-term therapy with hydroxyurea.

The Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial compared standard (transfusions/chelation) to alternative (hydroxyurea/phlebotomy) treatment to prevent recurrent stroke and manage iron overload in children chronically transfused over 7 years before enrollment. Standardized brain magnetic resonance imaging/magnetic resonance angiography (MRA) and transcranial Doppler (TCD) exams were performed at entry and exit, with a central blinded review. A novel MRA vasculopathy grading scale demonstrated frequent severe baseline left/right vessel stenosis (53%/41% ≥Grade 4); 31% had no vessel stenosis on either side. Baseline parenchymal injury was prevalent (85%/79% subcortical, 53%/37% cortical, 50%/35% subcortical and cortical). Most children had low or uninterpretable baseline middle cerebral artery TCD velocities, which were associated with worse stenoses (incidence risk ratio [IRR] = 5.1, P ≤ .0001 and IRR = 4.1, P < .0001) than normal velocities; only 2% to 12% had any conditional/abnormal velocity. Patients with adjudicated stroke (7) and transient ischemic attacks (19 in 11 standard/8 alternative arm subjects) had substantial parenchymal injury/vessel stenosis. At exit, 1 child (alternative arm) had a new silent infarct, and another had worse stenosis. SWiTCH neuroimaging data document severe parenchymal and vascular abnormalities in children with SCA and stroke and support concerns about chronic transfusions lacking effectiveness for preventing progressive cerebrovascular injury. The novel SWiTCH vasculopathy grading scale warrants validation testing and consideration for use in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00122980.

Journal of Pediatric Hematology/Oncology 36(6):p 501, August 2014. | DOI: 10.1097/MPH.0000000000000139