Differential cerebral hemometabolic responses to blood transfusions in adults and children with sickle cell anemia.

BACKGROUND: Blood transfusions are administered to children and adults with sickle cell anemia (SCA) for secondary stroke prevention, or as treatment for recurrent pain crises or acute anemia, but transfusion effects on cerebral hemodynamics and metabolism are not well-characterized. PURPOSE: To compare blood transfusion-induced changes in hemometabolic parameters, including oxygen extraction fraction (OEF) and cerebral blood flow (CBF), within and between adults and children with SCA. STUDY TYPE: Prospective, longitudinal study. SUBJECTS: Adults with SCA (n = 16) receiving simple (n = 7) or exchange (n = 9) transfusions and children with SCA (n = 11) receiving exchange transfusions were scanned once when hematocrit was near nadir and again within 7 days of transfusion. Adult controls without SCA or sickle trait (n = 7) were scanned twice on separate days. FIELD STRENGTH/SEQUENCE: 3.0T T1 -weighted, T2 -weighted, and T2 -relaxation-under-spin-tagging (TRUST) imaging, and phase contrast angiography. ASSESSMENT: Global OEF was computed as the relative difference between venous oxygenation (from TRUST) and arterial oxygenation (from pulse oximetry). Global CBF was computed as total blood flow to the brain normalized by intracranial tissue volume. STATISTICAL TESTS: Hemometabolic variables were compared using two-sided Wilcoxon signed-rank tests; associations were analyzed using two-sided Spearman's correlation testing. RESULTS: In adults with SCA, posttransfusion OEF = 0.38 ± 0.05 was lower (P = 0.001) than pretransfusion OEF = 0.45 ± 0.09. A change in OEF was correlated with increases in hematocrit (P = 0.02; rho = -0.62) and with pretransfusion hematocrit (P = 0.02; rho = 0.65). OEF changes after transfusion were greater (P = 0.002) in adults receiving simple versus exchange transfusions. Posttransfusion CBF = 77.7 ± 26.4 ml/100g/min was not different (P = 0.27) from pretransfusion CBF = 82.3 ± 30.2 ml/100g/min. In children with SCA, both posttransfusion OEF = 0.28 ± 0.04 and CBF = 76.4 ± 26.4 were lower than pretransfusion OEF = 0.36 ± 0.06 (P = 0.004) and CBF = 96.4 ± 16.5 (P = 0.004). DATA CONCLUSION: Cerebral OEF reduces following transfusions in adults and children with SCA. CBF reduces following transfusions more often in children compared to adults, indicating that vascular reserve capacity may remain near exhaustion posttransfusion in many adults. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage 5 J. Magn. Reson. Imaging 2019;49:466-477.

Cerebral hemodynamics and pseudo-continuous arterial spin labeling considerations in adults with sickle cell anemia.

Sickle cell anemia (SCA) is a genetic disorder resulting in reduced oxygen carrying capacity and elevated stroke risk. Pseudo-continuous arterial spin labeling (pCASL) measures of cerebral blood flow (CBF) may have relevance for stroke risk assessment; however, the effects of elevated flow velocity and reduced bolus arrival time (BAT) on CBF quantification in SCA patients have not been thoroughly characterized, and pCASL model parameters used in healthy adults are often applied to patients with SCA. Here, cervical arterial flow velocities and pCASL labeling efficiencies were computed in adults with SCA (n = 19) and age- and race-matched controls without sickle trait (n = 7) using pCASL in sequence with phase contrast MR angiography (MRA). Controls (n = 7) and a subgroup of patients (n = 8) also underwent multi-post-labeling-delay pCASL for BAT assessment. Mean flow velocities were elevated in SCA adults (velocity = 28.3 ± 4.1 cm/s) compared with controls (velocity = 24.5 ± 3.8 cm/s), and mean pCASL labeling efficiency (α) was reduced in SCA adults (α = 0.72) relative to controls (α = 0.91). In patients, mean whole-brain CBF from phase contrast MRA was 91.8 ± 18.1 ml/100 g/min, while mean pCASL CBF when assuming a constant labeling efficiency of 0.86 was 75.2 ± 17.3 ml/100 g/min (p < 0.01), resulting in a mean absolute quantification error of 23% when a labeling efficiency appropriate for controls was assumed. This difference cannot be accounted for by BAT (whole-brain BAT: control, 1.13 ± 0.06 s; SCA, 1.02 ± 0.09 s) or tissue T1 variation. In conclusion, BAT variation influences pCASL quantification less than elevated cervical arterial velocity and labeling efficiency variation in SCA adults; thus, a lower labeling efficiency (α = 0.72) or subject-specific labeling efficiency should be incorporated for SCA patients.

Non-invasive imaging of oxygen extraction fraction in adults with sickle cell anaemia.

Sickle cell anaemia is a monogenetic disorder with a high incidence of stroke. While stroke screening procedures exist for children with sickle cell anaemia, no accepted screening procedures exist for assessing stroke risk in adults. The purpose of this study is to use novel magnetic resonance imaging methods to evaluate physiological relationships between oxygen extraction fraction, cerebral blood flow, and clinical markers of cerebrovascular impairment in adults with sickle cell anaemia. The specific goal is to determine to what extent elevated oxygen extraction fraction may be uniquely present in patients with higher levels of clinical impairment and therefore may represent a candidate biomarker of stroke risk. Neurological evaluation, structural imaging, and the non-invasive T2-relaxation-under-spin-tagging magnetic resonance imaging method were applied in sickle cell anaemia (n = 34) and healthy race-matched control (n = 11) volunteers without sickle cell trait to assess whole-brain oxygen extraction fraction, cerebral blood flow, degree of vasculopathy, severity of anaemia, and presence of prior infarct; findings were interpreted in the context of physiological models. Cerebral blood flow and oxygen extraction fraction were elevated (P < 0.05) in participants with sickle cell anaemia (n = 27) not receiving monthly blood transfusions (interquartile range cerebral blood flow = 46.2-56.8 ml/100 g/min; oxygen extraction fraction = 0.39-0.50) relative to controls (interquartile range cerebral blood flow = 40.8-46.3 ml/100 g/min; oxygen extraction fraction = 0.33-0.38). Oxygen extraction fraction (P < 0.0001) but not cerebral blood flow was increased in participants with higher levels of clinical impairment. These data provide support for T2-relaxation-under-spin-tagging being able to quickly and non-invasively detect elevated oxygen extraction fraction in individuals with sickle cell anaemia with higher levels of clinical impairment. Our results support the premise that magnetic resonance imaging-based assessment of elevated oxygen extraction fraction might be a viable screening tool for evaluating stroke risk in adults with sickle cell anaemia.

Cognitive functioning over 2 years after intracerebral hemorrhage in school-aged children.

AIM: Previous research investigating outcomes after pediatric intracerebral hemorrhage (ICH) has generally been limited to global and sensorimotor outcomes. This study examined cognitive outcomes after spontaneous ICH in school-aged children with serial assessments over 2 years after stroke. METHOD: Seven children (age range 6-16y, median 13; six males, one female; 57% white, 43% black) presenting with spontaneous ICH (six arteriovenous malformations) were assessed at 3 months, 12 months, and 24 months after stroke. The Pediatric Stroke Outcome Measure (PSOM) quantified neurological outcome and Wechsler Intelligence Scales measured cognitive outcomes: verbal comprehension, perceptual reasoning, working memory, and processing speed. RESULTS: PSOM scales showed improved neurological function over the first 12 months, with mild to no sensorimotor deficits and moderate overall deficits at 1- and 2-year follow-ups (median 2-year sensorimotor PSOM=0.5, total PSOM=1.5). Changes in cognitive function indicated a different trajectory; verbal comprehension and perceptual reasoning improved over 24 months; low performance was sustained in processing speed and working memory. Age-normed centile scores decreased between 1- and 2-year follow-ups for working memory, suggesting emerging deficits compared with peers. INTERPRETATION: Early and serial cognitive testing in children with ICH is needed to assess cognitive functioning and support children in school as they age and cognitive deficits become more apparent and important for function. WHAT THIS PAPER ADDS: In children with intracerebral hemorrhage (ICH), motor function improved between 3 months and 24 months. Improvements in cognitive function were variable between 3 months and 24 months. Working memory centiles declined, suggesting emerging deficits compared with peers. Processing speed improved but remained significantly below the 50th centile. Cognitive impact of ICH may increase with age in children.

Pediatric Acute Stroke Protocol Activation in a Children's Hospital Emergency Department.

BACKGROUND AND PURPOSE: Pediatric acute stroke teams are a new phenomenon. We sought to characterize the final diagnoses of children with brain attacks in the emergency department where the pediatric acute stroke protocol was activated and to describe the time to neurological evaluation and neuroimaging. METHODS: Clinical and demographic information was obtained from a quality improvement database and medical records for consecutive patients (age, ≤20 years) presenting to a single institution's pediatric emergency department where the acute stroke protocol was activated between April 2011 and October 2014. Stroke protocol activation means that a neurology resident evaluates the child within 15 minutes, and urgent magnetic resonance imaging is available. RESULTS: There were 124 stroke alerts (age, 11.2±5.2 years; 63 boys/61 girls); 30 were confirmed strokes and 2 children had a transient ischemic attack. Forty-six of 124 (37%) cases were healthy children without any significant medical history. Nonstroke neurological emergencies were found in 17 children (14%); the majority were meningitis/encephalitis (n=5) or intracranial neoplasm (n=4). Other common final diagnoses were complex migraine (17%) and seizure (15%). All children except 1 had urgent neuroimaging. Magnetic resonance imaging was the first study in 76%. The median time from emergency department arrival to magnetic resonance imaging was 94 minutes (interquartile range, 49-151 minutes); the median time to computed tomography was 59 minutes (interquartile range, 40-112 minutes). CONCLUSIONS: Of pediatric brain attacks, 24% were stroke, 2% were transient ischemic attack, and 14% were other neurological emergencies. Together, 40% had a stroke or other neurological emergency, underscoring the need for prompt evaluation and management of children with brain attacks.

Pediatric intracerebral hemorrhage score: a simple grading scale for intracerebral hemorrhage in children.

BACKGROUND AND PURPOSE: The intracerebral hemorrhage (ICH) score is the most commonly used clinical grading scale for outcome prediction after adult ICH. We created a similar scale in children to inform clinical care and assist in clinical research. METHODS: Children, full-term newborns to 18 years, with spontaneous ICH were prospectively enrolled from 2007 to 2012 at 3 centers. The pediatric ICH score was created by identifying factors associated with poor outcome. The score's ability to detect moderate disability or worse and severe disability or death was examined with sensitivity, specificity, and area under the receiver operating characteristic curve. RESULTS: The pediatric ICH score components include ICH volume>2% to 3.99% of total brain volume (TBV): 1 point; ICH volume≥4% TBV: 2 points; acute hydrocephalus: 1 point; herniation: 1 point; and infratentorial location: 1 point. The score ranges from 0 to 5. At 3-month follow-up of 60 children, 10 were severely disabled or dead, 30 had moderate disability, and 20 had good recovery. A pediatric ICH score≥1 predicted moderate disability or worse with a sensitivity of 75% (95% confidence interval [CI], 59% to 87%) and a specificity of 70% (95% CI, 46% to 88%). A pediatric ICH score≥2 predicted severe disability or death with a sensitivity and specificity of 90% (95% CI, 55% to 99%) and 68% (95% CI, 53% to 80%), respectively. The area under the receiver operating characteristic curve for classifying outcome as severe disability or death was 0.88 (95% CI, 0.78-0.97). CONCLUSIONS: The pediatric ICH score is a simple clinical grading scale that may ultimately be used for risk stratification, clinical care, and research.

Preliminary evidence for cerebral capillary shunting in adults with sickle cell anemia.

Elevated flow velocities in adults with sickle cell anemia (SCA) may cause rapid erythrocyte transit through capillaries. This phenomenon could present as dural venous sinus hyperintensity on arterial spin labeling (ASL)-MRI and could be indicative of capillary shunting. Here, the prevalence of ASL venous hyperintensities and association with relevant physiology in adults with SCA was investigated. SCA ( n = 46) and age-matched control ( n = 16) volunteers were recruited for 3.0 T MRI. Pseudo-continuous ASL-MRI was acquired for cerebral blood flow (CBF) calculation and venous hyperintensity determination; venous signal intensity and a categorical venous score (three raters; 0 = no hyperintensity, 1 = focal hyperintensity, and 2 = diffuse hyperintensity) were recorded. Flow velocity in cervical internal carotid artery segments was determined from phase contrast data (venc = 40 cm/s) and whole-brain oxygen extraction fraction (OEF) was determined from T2-relaxation-under-spin-tagging MRI. Cerebral metabolic rate of oxygen was calculated as the product of OEF, CBF, and blood oxygen content. ASL venous hyperintensities were significantly ( p < 0.001) more prevalent in SCA (65%) relative to control (6%) participants and were associated with elevated flow velocities ( p = 0.03). CBF ( p < 0.001), but not OEF, increased with increasing hyperintensity score. Prospective trials that evaluate this construct as a possible marker of impaired oxygen delivery and stroke risk may be warranted.

In-Hospital Pediatric Stroke Alert Activation.

BACKGROUND: Pediatric stroke alerts or "code strokes" allow for rapid evaluation, imaging, and treatment of children presenting with stroke-like symptoms. In a previous study of emergency department-initiated pediatric stroke alerts, 24% of children had confirmed strokes. The purpose of this study was to characterize in-hospital pediatric stroke alerts. METHODS: Demographic and clinical information was obtained from a quality improvement database and medical records for children (zero to 20 years) at a single institution for whom a stroke alert was activated after hospital admission between April 2011 and December 2016. Stroke alert activation criteria included a new focal neurological defect occurring within 48 hours. A neurologist evaluated the patient within 15 minutes and rapid magnetic resonance imaging was available. RESULTS: Medical personnel activated in-hospital stroke alerts for 56 children (median age 6.5 years, interquartile range 1 to 13, 52% male). Stroke was the final diagnosis of 25 (45%), 72% ischemic, and 28% hemorrhagic strokes. Other diagnoses included neurological urgencies: seizure (21%), posterior reversible encephalopathy syndrome (7%), transient ischemic attack (5%), and acute disseminated encephalomyelitis (4%). Of the stroke diagnoses, 68% were stroke alerts called in the pediatric intensive care unit or pediatric cardiac intensive care unit. Rapid neuroimaging was completed in 91%; magnetic resonance imaging brain was the first image in 55%. CONCLUSIONS: Of in-hospital pediatric stroke alerts, 45% were stroke while 38% were other neurological conditions requiring urgent evaluation. In-hospital stroke alerts were commonly activated for children with complicated medical histories. Rapid neurological evaluation facilitated care. No child underwent thrombolysis or thrombectomy.

Hemodynamic mechanisms underlying elevated oxygen extraction fraction (OEF) in moyamoya and sickle cell anemia patients.

Moyamoya is a bilateral, complex cerebrovascular condition characterized by progressive non-atherosclerotic intracranial stenosis and collateral vessel formation. Moyamoya treatment focuses on restoring cerebral blood flow (CBF) through surgical revascularization, however stratifying patients for revascularization requires abilities to quantify how well parenchyma is compensating for arterial steno-occlusion. Globally elevated oxygen extraction fraction (OEF) secondary to CBF reduction may serve as a biomarker for tissue health in moyamoya patients, as suggested in patients with sickle cell anemia (SCA) and reduced oxygen carrying capacity. Here, OEF was measured (TRUST-MRI) to test the hypothesis that OEF is globally elevated in patients with moyamoya (n = 18) and SCA (n = 18) relative to age-matched controls (n = 43). Mechanisms underlying the hypothesized OEF increases were evaluated by performing sequential CBF-weighted, cerebrovascular reactivity (CVR)-weighted, and structural MRI. Patients were stratified by treatment and non-parametric tests applied to compare study variables (significance: two-sided P < 0.05). OEF was significantly elevated in moyamoya participants (interquartile range = 0.38-0.45) compared to controls (interquartile range = 0.29-0.38), similar to participants with SCA (interquartile range = 0.37-0.45). CBF was inversely correlated with OEF in moyamoya participants. Elevated OEF was only weakly related to reductions in CVR, consistent with basal CBF level, rather than vascular reserve capacity, being most closely associated with OEF.

Cognitive and attentional functioning in adolescents and young adults with Tetralogy of Fallot and d-transposition of the great arteries.

The objective of this study is to investigate cognitive and attentional function in adolescents and young adults with operated congenital heart disease. Previous research has indicated that children with congenital heart disease have deficits in broad areas of cognitive function. However, less attention has been given to survivors as they grow into adolescence and early adulthood. The participants were 18 non-syndromic adolescents and young adults with tetralogy of Fallot and d-transposition of the great arteries that required cardiac surgery before the age of 5 years, and 18 healthy, unaffected siblings (11-22 years of age for both groups). Cases with congenital heart disease and their siblings were administered Wechsler Intelligence scales and reported attention problems using the Achenbach System of Empirically Based Assessments. Cases were compared to both healthy siblings and established norms. Cases performed significantly lower than siblings on full scale IQ and processing speed, and significantly lower than norms on perceptual reasoning. Cases also reported more attention problems compared to both siblings and norms. Effect sizes varied with medium-to-large effects for processing speed, perceptual reasoning, working memory, and attention problems. Findings suggest that neurocognitive function may continue to be affected for congenital heart disease survivors in adolescence and young adulthood, and that comparisons to established norms may underestimate neurocognitive vulnerabilities.

Association of Blood Pressure, Blood Glucose, and Temperature With Neurological Outcome After Childhood Stroke.

IMPORTANCE: To our knowledge, no evidence-based guidelines are available for the best medical management of blood pressure, blood glucose levels, and temperature in pediatric patients after arterial ischemic stroke. OBJECTIVE: To determine the prevalence of abnormal blood pressure, blood glucose levels, and temperature in pediatric patients with acute arterial ischemic stroke and to explore any association between these measures and neurological outcome. DESIGN, SETTING, AND PARTICIPANTS: We performed a retrospective review of children aged 29 days to 18 years with their first arterial ischemic stroke between January 2009 and December 2013 at a tertiary academic children's hospital. Ninety-eight children with stroke were identified by an International Classification of Diseases, Ninth Revision, code search and medical record review. Blood pressure, blood glucose, and temperature data were collected for 5 days after the stroke. Hypertension was defined as systolic blood pressure at or above the 95th percentile for age, sex, and height for 2 consecutive recordings and 2 consecutive days. Hypotension was defined as systolic and/or diastolic blood pressure below the fifth percentile for age, sex, and height for 2 consecutive recordings. Hyperglycemia was defined as a blood glucose level of 200 mg/dL or greater. Morbidity and mortality at 3 months were documented. Data analyses were performed from July 1, 2014, to December 31, 2015. INTERVENTIONS OR EXPOSURES: Abnormal blood pressure, blood glucose levels, and fever in the setting of arterial ischemic stroke. MAIN OUTCOMES AND MEASURES: The a priori outcome measure was poor clinical outcome, defined as a Pediatric Stroke Outcome Measure score of 1 or greater, which represents a moderate neurological deficit. RESULTS: The median (interquartile range) age of the 98 children was 6.0 (0.6-14.3) years, and 58 (59.2%) were male. Hypertension was present in 64 (65.3%), hypotension in 67 (68.4%), hyperglycemia in 17 (18.1%), and fever in 37 (37.8%). The strongest association with poor neurological outcome was an infarct size of 4% or greater of brain volume (odds ratio, 5.6; 95% CI, 2.0-15.4; P = .001). Hyperglycemia was also independently associated with poor neurological outcome (odds ratio, 3.9; 95% CI, 1.2-12.4; P = .02). Hypertension and fever were not significantly associated with infarct size, poor outcome, or death. Hypertension was not documented in 24 of 87 surviving children (27.6%) at 3-month follow-up and was not associated with poor neurological outcome. CONCLUSIONS AND RELEVANCE: Abnormalities of blood pressure, blood glucose levels, and temperature are prevalent in children with arterial ischemic stroke. Infarct volume and hyperglycemia were associated with poor neurological outcome but hypertension and fever were not. Prospective studies that systematically record blood pressure, blood glucose, and temperature data are required to further assess the associations between these potentially modifiable physiological parameters and pediatric stroke outcome.

Frequency of hematoma expansion after spontaneous intracerebral hemorrhage in children.

IMPORTANCE: Hematoma expansion is the only modifiable predictor of outcome in adult intracerebral hemorrhage; however, the frequency and clinical significance of hematoma expansion after childhood intracerebral hemorrhage are unknown. OBJECTIVE: To assess the frequency and extent of hematoma expansion in children with nontraumatic intracerebral hemorrhage. DESIGN, SETTING, AND PARTICIPANTS: Prospective observational cohort study at 3 tertiary care pediatric hospitals. Children (≥ 37 weeks' gestation to 18 years) with nontraumatic intracerebral hemorrhage were enrolled in a study from 2007 to 2012 focused on predictors of outcome. For this planned substudy of hematoma expansion, neonates 28 days or younger and participants with isolated intraventricular hemorrhage were excluded. Children with 2 head computed tomography (CT) scans within 48 hours were evaluated for hematoma expansion and were compared with children with only 1 head CT scan. Consent for the primary cohort was obtained from 73 of 87 eligible participants (84%); 41 of 73 children enrolled in the primary cohort met all inclusion/exclusion criteria for this substudy, in whom 22 had 2 head CT scans obtained within 48 hours that could be evaluated for hematoma expansion. Within our substudy cohort, 21 of 41 (51%) were male, 25 of 41 (61%) were white, 16 of 41 (39%) were black, and median age was 7.7 years (interquartile range, 2.0-13.4 years). MAIN OUTCOME AND MEASURE: Primary outcome was prevalence of hematoma expansion. RESULTS: Of 73 children, 41 (56%) met inclusion criteria, and 22 (30%) had 2 head CT scans to evaluate expansion. Among these 22 children, median time from symptom onset to first CT was 2 hours (interquartile range, 1.3-6.5 hours). Median baseline hemorrhage volume was 19.5 mL, 1.6% of brain volume. Hematoma expansion occurred in 7 of 22 (32%). Median expansion was 4 mL (interquartile range, 1-11 mL). Three children had significant (>33%) expansion; 2 required urgent hematoma evacuation. Expansion was not associated with poorer outcome. Compared with children with only 1 head CT scan within 48 hours, children with 2 head CT scans had larger baseline hemorrhage volumes (P = .05) and were more likely to receive treatment for elevated intracranial pressure (P < .001). CONCLUSIONS AND RELEVANCE: Hematoma expansion occurs in children with intracerebral hemorrhage and may require urgent treatment. Repeat CT should be considered in children with either large hemorrhage or increased intracranial pressure.

Pediatric intracerebral hemorrhage: acute symptomatic seizures and epilepsy.

IMPORTANCE: Seizures are believed to be common presenting symptoms in neonates and children with spontaneous intracerebral hemorrhage (ICH). However, few data are available on the epidemiology of acute symptomatic seizures or the risk for later epilepsy. OBJECTIVE: To define the incidence of and explore risk factors for seizures and epilepsy in children with spontaneous ICH. Our a priori hypotheses were that younger age at presentation, cortical involvement of ICH, acute symptomatic seizures after presentation, ICH due to vascular malformation, and elevated intracranial pressure requiring urgent intervention would predict remote symptomatic seizures and epilepsy. DESIGN: Prospective cohort study conducted between March 1, 2007, and January 1, 2012. SETTING: Three tertiary care pediatric hospitals. PARTICIPANTS: Seventy-three pediatric subjects with spontaneous ICH including 20 perinatal (≥37 weeks' gestation to 28 days) and 53 childhood subjects (>28 days to <18 years at presentation). MAIN OUTCOME MEASURES: Acute symptomatic seizures (clinically evident and electrographic-only seizures within 7 days), remote symptomatic seizures, and epilepsy. RESULTS: Acute symptomatic seizures occurred in 35 subjects (48%). Acute symptomatic seizures as a presenting symptom of ICH occurred in 12 perinatal (60%) and 19 childhood (36%) subjects (P = .07). Acute symptomatic seizures after presentation occurred in 7 children. Electrographic-only seizures were present in 9 of 32 subjects (28%) with continuous electroencephalogram monitoring. One-year and 2-year remote symptomatic seizure-free survival rates were 82% (95% CI, 68-90) and 67% (95% CI, 46-82), respectively. One-year and 2-year epilepsy-free survival rates were 96% (95% CI, 83-99) and 87% (95% CI, 65-95), respectively. Elevated intracranial pressure requiring acute intervention was a risk factor for seizures after presentation (P = .01; Fisher exact test), remote symptomatic seizures, and epilepsy (P = .03, and P = .04, respectively; log-rank test). CONCLUSIONS AND RELEVANCE: Presenting seizures are common in perinatal and childhood ICH. Continuous electroencephalography may detect electrographic seizures in some subjects. Single remote symptomatic seizures occur in many, and development of epilepsy is estimated to occur in 13% of patients at 2 years. Elevated intracranial pressure requiring acute intervention is a risk factor for acute seizures after presentation, remote symptomatic seizures, and epilepsy.