Sickle cell disease: ischemia and seizures

Incident Breakthrough Seizures, Serum Matrix Metalloproteinase-9 and Perfusion Magnetic Resonance Imaging Parameters in a Cohort of Children and Adolescents With Neurocysticercosis: A Longitudinal Observational Study

BACKGROUND

The current study estimated incident breakthrough seizures, serum matrix metalloproteinase-9 (MMP-9), and perfusion magnetic resonance imaging (MRI) parameters in five- to 18-year-olds with neurocysticercosis (NCC) from colloidal or vesicular through calcified stages over at least 24 months' follow-up.

METHODS

Single, colloidal, or vesicular parenchymal NCC cases were treated with albendazole and steroids and followed at a tertiary care north Indian hospital. Serum MMP-9 was estimated in colloidal or vesicular treatment-naive state and in a subset of calcified cases at six-month follow-up. The same subset of calcified cases also underwent perfusion MRI of the brain at six-month follow-up.

RESULTS

Among 70 cases, 70% calcified at six-month follow-up. Over a median follow-up of 30 months, the incidence of breakthrough seizures was 48.6% (61.2% in calcified and 19.2% in resolved, P = 0.001; 32.9% early [within six months] and 15.7% late [beyond six months], P = 0.02). Serum MMP-9 levels were higher in colloidal and vesicular compared with calcified stage (242.5 vs 159.8 ng/mL, P = 0.007); however, there was no significant association with breakthrough seizures and/or calcification in follow-up. In a subgroup of calcified cases (n = 31), the median relative cerebral blood volume on perfusion MRI in and around the lesion was lower in those with seizures (n = 12) than in those without (n = 19) (10.7 vs 25.2 mL/100 g, P = 0.05).

CONCLUSIONS

In post-treatment colloidal or vesicular NCC, incident breakthrough seizures decrease beyond six months. In calcified NCC with remote breakthrough seizures, significant perilesional hypoperfusion is seen compared with those without seizures.

Cerebrovascular disease in sickle cell disease

Sickle cell disease (SCD) is the most common type of hereditary anaemia and genetic disorder worldwide. Cerebrovascular disease is one of its most devastating complications, with consequent increased morbidity and mortality. Current guidelines suggest that children and adults with SCD who develop acute ischaemic stroke should be transfused without delay. Those with acute ischaemic stroke aged over 18 years who present within 4.5 hours of symptom onset should be considered for intravenous thrombolysis; older patients with conventional vascular risk factors are the most likely to benefit. Endovascular thrombectomy should be considered carefully in adults with SCD as there are few data to guide how the prevalence of cerebral vasculopathy may confound the expected benefits or risks of intervention. We present a practical approach to cerebrovascular disease in sickle cell patients based on the available evidence and our experience.

Association of Anemia With Epilepsy and Antiepileptic Drugs

Epilepsy is a disorder that causes unprovoked seizures regularly. It affects between 1% and 3% of the population. After the first seizure, the chances of having another one are almost 40%-52%. The etiology of febrile seizures in children with sickle cell disease is still unknown. In some groups, iron deficiency anemia has been linked to an increased risk of seizures. Although the reason and process are uncertain, some people believe that taking iron supplements can help prevent seizures. This literature covers haptene, non-haptene immune-related hemolysis, and oxidative processes activated by anti-seizure medications (ASMs). In epileptic patients, ASMs can cause anemia. Folic acid can be given to carbamazepine-treated anemic patients. There is growing evidence that it improves hemoglobin and leukocytes in individuals who take it. Therefore, one of the most efficient strategies to avoid future seizures is to take ASMs daily to maintain an even level of anticonvulsant in the body. To prevent further seizures, lifestyle changes are essential. Further studies and clinical trials are warranted to prove a clear association between epilepsy and hematologic disease, which will improve quality of life in the future.

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

Seizures risk factors in sickle cell disease. The cooperative study of sickle cell disease

INTRODUCTION

Although evidence suggests that neurological complications, including seizures and epilepsy, are more common among sickle cell disease (SCD) patients, few studies have assessed the risk factors of developing seizures among SCD patients METHODS: We used a nested case-control study design to compare pediatric and adult SCD patients who experienced seizures with patients who did not experience any seizure regarding clinical and laboratory parameters. We conducted a secondary analysis using the data from the Cooperative Study of Sickle Cell Disease in this study RESULTS: There were 153 out of 2804 (5.5%) pediatric patients who had seizures with a median age of 8.5 (Interquartile range [IQR] = 10.1) years at first seizure and 115 out of 1281 (9.0%) adult patients who had seizures with a median age of 28.0 (IQR = 10.6) years at first seizure. Cerebrovascular accident ([CVA], OR = 5.7, 95% CI = 2.9-11.0), meningitis (OR = 3.6, 95% CI = 1.8-7.2), and eye disease (OR = 3.4, 95% CI = 1.5-8.0) were associated with increased risk of developing seizures among pediatric patients. While CVA (OR = 7.5, 95% CI = 3.5-16.0), meningitis (OR = 5.6, 95% CI = 1.5-20.0), nephrotic syndrome (OR = 3.0, 95% CI = 1.2-7.9), spleen sequestration (OR = 2.7, 95% CI = 1.1-6.3), and pneumonia (OR = 2.1, 95% CI = 1.0-4.4) were associated with increased risk of developing seizures among adult patients CONCLUSION: These findings suggest the need for treatment optimization and regular neurological follow up for SCD patients with these identified risk factors to prevent the development of seizures.

Acute Ischemic Stroke in Sickle Cell Disease Challenges for Thrombolysis

Sickle cell disease (SCD) is a hemoglobinopathy disorder that was recognized in 1949. Stroke is one of the most devastating complications of this disorder. The risk of stroke in SCD patients varies with the genotype; the highest rate has been reported with hemoglobin S. Tissue type plasminogen activator (t PA) is class I recommended therapy for acute ischemic stroke (AIS) since 1996. Although it is unclear if SCD patients were included in the t PA trail, SCD has never been identified as contraindication. The debate of offering t PA for adult SCD patient presenting with AIS continued for at least 2 decades. It is not up and until 2 years ago when the American Heart Association and American stroke association (AHA/ASA) announced that intravenous (IV) t PA can be offered to adult SCD patients presenting with AIS. Here, we report a case where successful IV thrombolytic therapy was offered to an adult SCD patient presenting with AIS with excellent outcome.

Blood Cell Disorders and the Nervous System

PURPOSE OF REVIEW

This article discusses the epidemiology, diagnosis, treatment, and prevention of neurologic complications of common and rare blood cell disorders.

RECENT FINDINGS

A growing number of preventive treatment options are available for stroke in sickle cell disease. Paroxysmal nocturnal hemoglobinuria and immune thrombocytopenia can lead to stroke. Thrombotic thrombocytopenic purpura frequently causes neurologic symptoms and should be considered in the differential diagnosis of a patient with neurologic symptoms, thrombocytopenia, and hemolytic anemia. Polycythemia vera and essential thrombocythemia are rare causes of stroke.

SUMMARY

This article discusses sickle cell disease and the most recent advances in stroke preventive therapy as well as neurologic complications of paroxysmal nocturnal hemoglobinuria, immune thrombocytopenia, thrombotic thrombocytopenic purpura, polycythemia vera, and essential thrombocythemia.

Transcranial Doppler and Magnetic Resonance in Tanzanian Children With Sickle Cell Disease

Supplemental Digital Content is available in the text.

Background and Purpose—

We determined prevalences of neurological complications, vascular abnormality, and infarction in Tanzanian children with sickle cell disease.

Methods—

Children with sickle cell disease were consecutively enrolled for transcranial Doppler; those with slightly elevated (>150 cm/s), low (<50 cm/s) or absent cerebral blood flow velocity (CBFv) were invited for brain magnetic resonance imaging and magnetic resonance angiography.

Results—

Of 200 children (median age 9; range 6–13 years; 105 [2.5%] boys), 21 (11%) and 15 (8%) had previous seizures and unilateral weakness, respectively. Twenty-eight (14%) had elevated and 39 (20%) had low/absent CBFv, all associated with lower hemoglobin level, but not higher indirect bilirubin level. On multivariable analysis, CBFv>150 cm/s was associated with frequent painful crises and low hemoglobin level. Absent/low CBFv was associated with low hemoglobin level and history of unilateral weakness. In 49 out of 67 children with low/absent/elevated transcranial Doppler undergoing magnetic resonance imaging, 43% had infarction, whereas 24 out of 48 (50%) magnetic resonance angiographies were abnormal. One had hemorrhagic infarction; none had microbleeds. Posterior circulation infarcts occurred in 14%. Of 11 children with previous seizure undergoing magnetic resonance imaging, 10 (91%) had infarction (5 silent) compared with 11 out of 38 (29%) of the remainder (P=0.003). Of 7 children with clinical stroke, 2 had recurrent stroke and 3 died; 4 out of 5 had absent CBFv. Of 193 without stroke, 1 died and 1 had a stroke; both had absent CBFv.

Conclusions—

In one-third of Tanzanian children with sickle cell disease, CBFv is outside the normal range, associated with frequent painful crises and low hemoglobin level, but not hemolysis. Half have abnormal magnetic resonance angiography. African children with sickle cell disease should be evaluated with transcranial Doppler; those with low/absent/elevated CBFv should undergo magnetic resonance imaging/magnetic resonance angiography.

Children with sickle cell anemia with normal transcranial Doppler ultrasounds and without silent infarcts have a low incidence of new strokes

In a prospective cohort study, we tested the hypothesis that children with sickle cell anemia (SCA) with normal transcranial Doppler ultrasound (TCD) velocities and without silent cerebral infarcts (SCIs) would have a lower incidence rate of new neurological events (strokes, seizures or transient ischemic attacks) compared to children with normal TCD measurements and SCIs, not receiving regular blood transfusions. Nonrandomized participants from the silent cerebral infarct transfusion (SIT) Trial who had screening magnetic resonance imaging (MRI) of the brain and normal TCD measurements were included. Follow-up ended at the time of first neurological event (stroke, seizure or transient ischemic attack), start of regular blood transfusion, or loss to follow-up, whichever came first. The primary endpoint was a new neurological event. Of 421 participants included, 68 had suspected SCIs. Mean follow-up was 3.6 years. Incidence rates of new neurological events in nontransfused participants with normal TCD values with SCIs and without SCIs were 1.71 and 0.47 neurological events per 100 patient-years, respectively, P = .065. The absence of SCI(s) at baseline was associated with a decreased risk of a new neurological event (hazard ratio 0.231, 95% CI 0.062-0.858; P = .029). Local pediatric neurologists examined 67 of 68 participants with suspected SCIs and identified 2 with overt strokes classified as SCIs by local hematologists; subsequently one had a seizure and the other an ischemic stroke. Children with SCA, without SCIs, and normal TCD measurements have a significantly lower rate of new neurological events when compared to those with SCIs and normal TCD measurements. Pediatric neurology assessment may assist risk stratification.

Central nervous system complications and management in sickle cell disease

With advances in brain imaging and completion of randomized clinical trials (RCTs) for primary and secondary stroke prevention, the natural history of central nervous system (CNS) complications in sickle cell disease (SCD) is evolving. In order of current prevalence, the primary CNS complications include silent cerebral infarcts (39% by 18 years), headache (both acute and chronic: 36% in children with sickle cell anemia [SCA]), ischemic stroke (as low as 1% in children with SCA with effective screening and prophylaxis, but ∼11% in children with SCA without screening), and hemorrhagic stroke in children and adults with SCA (3% and 10%, respectively). In high-income countries, RCTs (Stroke Prevention in Sickle Cell Anemia [STOP], STOP II) have demonstrated that regular blood transfusion therapy (typically monthly) achieves primary stroke prevention in children with SCA and high transcranial Doppler (TCD) velocities; after at least a year, hydroxycarbamide may be substituted (TCD With Transfusions Changing to Hydroxyurea [TWiTCH]). Also in high-income countries, RCTs have demonstrated that regular blood transfusion is the optimal current therapy for secondary prevention of infarcts for children with SCA and strokes (Stroke With Transfusions Changing to Hydroxyurea [SWiTCH]) or silent cerebral infarcts (Silent Infarct Transfusion [SIT] Trial). For adults with SCD, CNS complications continue to be a major cause of morbidity and mortality, with no evidence-based strategy for prevention.

How I treat and manage strokes in sickle cell disease

Neurologic complications are a major cause of morbidity and mortality in sickle cell disease (SCD). In children with sickle cell anemia, routine use of transcranial Doppler screening, coupled with regular blood transfusion therapy, has decreased the prevalence of overt stroke from ∼11% to 1%. Limited evidence is available to guide acute and chronic management of individuals with SCD and strokes. Current management strategies are based primarily on single arm clinical trials and observational studies, coupled with principles of neurology and hematology. Initial management of a focal neurologic deficit includes evaluation by a multidisciplinary team (a hematologist, neurologist, neuroradiologist, and transfusion medicine specialist); prompt neuro-imaging and an initial blood transfusion (simple followed immediately by an exchange transfusion or only exchange transfusion) is recommended if the hemoglobin is >4 gm/dL and <10 gm/dL. Standard therapy for secondary prevention of strokes and silent cerebral infarcts includes regular blood transfusion therapy and in selected cases, hematopoietic stem cell transplantation. A critical component of the medical care following an infarct is cognitive and physical rehabilitation. We will discuss our strategy of acute and long-term management of strokes in SCD.

Proteomic and biomarker studies and neurological complications of pediatric sickle cell disease

Biomarker analysis and proteomic discovery in pediatric sickle cell disease has the potential to lead to important discoveries and improve care. The aim of this review article is to describe proteomic and biomarker articles involving neurological and developmental complications in this population. A systematic review was conducted to identify relevant research publications. Articles were selected for children under the age of 21 years with the most common subtypes of sickle cell disease. Included articles focused on growth factors (platelet-derived growth factor), intra and extracellular brain proteins (glial fibrillary acidic protein, brain-derived neurotrophic factor), and inflammatory and coagulation markers (interleukin-1β, l-selectin, thrombospondin-1, erythrocyte, and platelet-derived microparticles). Positive findings include increases in plasma brain-derived neurotrophic factor and platelet-derived growth factor with elevated transcranial Dopplers velocities, increases in platelet-derived growth factor isoform AA with overt stroke, and increases in glial fibrillary acidic protein with acute brain injury. These promising potential neuro-biomarkers provide insight into pathophysiologic processes and clinical events, but their clinical utility is yet to be established. Additional proteomics research is needed, including broad-based proteomic discovery of plasma constituents and blood cell proteins, as well as urine and cerebrospinal fluid components, before, during and after neurological and developmental complications.

Sickle-cell disease stroke throughout life: a retrospective study in an adult referral center

Strokes are one of the most severe complications of sickle-cell disease. Most studies have been restricted to children with sickle-cell disease. To better understand the characteristics and follow-up of strokes occurring from childhood to adulthood, we undertook a retrospective cohort study of 69 stroke patients among the 2,875 patients consulting at the French Adult Sickle-Cell Disease Referral Center. Between 1970 and 2008, they had experienced 104 strokes: 80 ischemic, 22 hemorrhagic, and 2 intracranial sinus thromboses. Coma and/or fatal outcomes underscored the severity of strokes in sickle-cell disease patients.Hemorrhagic strokes occurred mostly in adults and carried a higher risk of death than ischemic stroke. The mechanisms underlying sickle-cell disease associated strokes were reevaluated and etiologies were determined for first stroke and recurrences, in childhood and adulthood. Sickle-cell disease vasculopathy concerned only SS patients and remains their most frequent stroke etiology. Cardioembolism, vaso-occlusive crisis and triggering factors were other etiologies identified in adults. Recurrences occurred in 19 SS patients only after a first ischemic stroke. SC patients' strokes occurred in adulthood and were associated with cardiovascular risk factors. Our findings provide novel information about cerebrovascular pathologies throughout the lives of sickle-cell disease patients and suggest the need for different diagnostic and therapeutic management approaches in those different settings.

Haptoglobin, alpha-thalassaemia and glucose-6-phosphate dehydrogenase polymorphisms and risk of abnormal transcranial Doppler among patients with sickle cell anaemia in Tanzania

Transcranial Doppler ultrasonography measures cerebral blood flow velocity (CBFv) of basal intracranial vessels and is used clinically to detect stroke risk in children with sickle cell anaemia (SCA). Co‐inheritance in SCA of alpha‐thalassaemia and glucose‐6‐phosphate dehydrogenase (G6PD) polymorphisms is reported to associate with high CBFv and/or risk of stroke. The effect of a common functional polymorphism of haptoglobin (HP) is unknown. We investigated the effect of co‐inheritance of these polymorphisms on CBFv in 601 stroke‐free Tanzanian SCA patients aged <24 years. Homozygosity for alpha‐thalassaemia 3·7 deletion was significantly associated with reduced mean CBFv compared to wild‐type (β‐coefficient −16·1 cm/s, P = 0·002) adjusted for age and survey year. Inheritance of 1 or 2 alpha‐thalassaemia deletions was associated with decreased risk of abnormally high CBFv, compared to published data from Kenyan healthy control children (Relative risk ratio [RRR] = 0·53 [95% confidence interval (CI):0·35–0·8] & RRR = 0·43 [95% CI:0·23–0·78]), and reduced risk of abnormally low CBFv for 1 deletion only (RRR = 0·38 [95% CI:0·17–0·83]). No effects were observed for G6PD or HP polymorphisms. This is the first report of the effects of co‐inheritance of common polymorphisms, including the HP polymorphism, on CBFv in SCA patients resident in Africa and confirms the importance of alpha‐thalassaemia in reducing risk of abnormal CBFv.

Extent of silent cerebral infarcts in adult sickle-cell disease patients on magnetic resonance imaging: is there a correlation with the clinical severity of disease?

The aim of this paper is to correlate the extent of silent cerebral infarcts (SCIs) on magnetic resonance imaging (MRI) with the clinical severity of sickle cell disease (SCD) in adult patients. Twenty-four consecutive adult asymptomatic SCD patients (11 male and 13 female) with a mean age of 38.4 years (range 20-59) were submitted to brain MRI on a 1 Tesla Gyroscan Intera, Philips MR scanner with a dedicated head coil. The protocol consisted of TSE T2-weighted and FLAIR images on the axial and coronal planes. MRI readings were undertaken by two radiologists and consensus readings. Patients were compound heterozygotes (HbS/β-thal). The extent of SCIs was classified from 0-2 with 0 designating no lesions. Clinical severity was graded as 0-2 by the hematologist, according to the frequency and severity of vaso-occlusive crises. There was no statistically significant correlation between the severity of clinical disease and the extent of SCIs on MR imaging. The extent of SCI lesions did not differ statistically between younger and older patients. Patients receiving hydroxyurea had no statistically significant difference in the extent of SCI lesions. The extent of SCIs in heterozygous (HbS/β-thal) SCD patients is not age related and may be quite severe even in younger (<38.4 years) patients. However the extent of SCIs is not correlated with the severity of clinical disease.

Adverse neurological outcomes in Nigerian children with sickle cell disease

Sickle cell disease (SCD) is reported to be the most common genetic disorder affecting Nigerians. Children with SCD are at a high risk of neurological morbidity. The main objective of this study was to determine the pattern of adverse neurological outcomes among a cohort of Nigerian children with SCD. All children with SCD seen in the Department of Paediatrics, University College Hospital, Ibadan, Nigeria, over a period of 2 years were carefully evaluated for symptoms and signs of neurological complications, defined as clinical outcomes referable to the central nervous system. Of the 214 children evaluated, 187 were diagnosed with Hb SS disease and 27 with Hb SC disease. Neurological complications were identified in 78 (36.4 %) of the cases. The most common complications were headache (17.8 %), seizure (9.3 %) and stroke (8.4 %). Other less frequent complications included bacterial meningitis (2.8 %), spontaneous visual loss (1.4 %), paraplegia (0.9 %) and transient ischaemic attacks (0.9 %). Neurological complications occurred more frequently in children with sickle cell anaemia than in those with Hb SC disease (P = 0.002, 95 % CI 1.450-82.870). Adverse neurological events are common in Nigerian children with SCD, with a significantly higher risk in Hb SS than Hb SC disease. Stroke represents a major underlying cause of symptomatic epilepsy in SCD. Institution of primary preventive measures for stroke in SCD will significantly reduce the burden of stroke and epilepsy associated with SCD in Nigeria.

Neurologic complications of hemoglobinopathies

The hemoglobinopathies, including sickle cell disease and its variants, are genetic abnormalities of hemoglobin. Hemoglobin SS (sickle cell disease) is the most common form of hemoglobin mutation in North America. Complications of hemoglobinopathies are numerous and involve many organ systems, including the nervous system. This article is intended to introduce the reader to the epidemiology, diagnosis, treatment, and prevention of neurologic complications of hemoglobinopathies, focusing specifically on sickle cell disease because of its prevalence.

Neuroimaging in assessment of risk of stroke in children with sickle cell disease

PURPOSE

Stroke and subclinical "silent infarcts" are major causes of morbidity in children with Sickle Cell Disease (SCD). Ischemic strokes are more common in younger children while hemorrhagic strokes are more frequent in adults. The goal of neuroimaging in acute stroke is to document whether the stroke is ischemic or hemorrhagic, to assess the extent of parenchymal abnormalities and to determine the presence of other cerebrovascular lesions. Computed Tomography (CT) is the primary modality for the assessment of acute stroke patients because of its 24/7 availability and ability to exclude hemorrhagic causes. Magnetic resonance imaging (MRI) and MR angiography (MRA) are recommended to determine precisely extent of infarction and detect cerebrovascular abnormalities. The goal of neuroimaging in patients with hemorrhagic stroke is to identify an arteriovenous malformation or aneurysm(s) amenable to surgery or catheter intervention.The risk of first stroke is very high in asymptomatic children with intracranial arterial mean velocities over 200 cm/s on transcranial Doppler (TCD) examination. The risk can be substantially reduced if chronic blood transfusions are timely implemented. Large cerebral vessel disease detected by TCD can be confirmed or excluded by MRI/MRA. Those with evidence of parenchymal and/or cerebrovascular lesions should be followed by preventive therapy. In patients with neurologic symptoms and negative MRI/MRA findings Positron Emission Tomography or single photon emission CT is recommended. There are no specific neuroimaging findings that suggest that blood transfusions can be safely halted in children with SCD.

MRI abnormalities of the brain in one-year-old children with sickle cell anemia

BACKGROUND

Sickle cell anemia (SCA) frequently results in damage to the central nervous system (CNS), but the age of onset of these effects is uncertain. We performed MRI examinations of the brain in infants with SCA, who were evaluated as part of the multicenter randomized double-blinded Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG).

METHODS

Determination of eligibility for enrollment in the trial originally required baseline MRI and magnetic resonance angiography (MRA) of the brain. A standardized imaging protocol was utilized across eight clinical centers. MRI/MRA exams were reviewed by a panel of three neurology/neuroradiology readers and interpretations reported to the coordinating center. Results were correlated with patient age, gender, history, WBC count, platelet count, hemoglobin (Hb), HbF level, score on the Bayley Scales of Infant Development, and velocity on transcranial Doppler ultrasonography (TCD).

RESULTS

Twenty-three subjects with HbSS were examined at average age 13.7 months (range 10-18 months); 13 were male. Three (13%, CI: 3-34%) had silent infarcts on MRI, two in the right frontal area and one bilaterally. None had MRA abnormalities. The lesions were correlated with increased right-sided TCD velocity and low HbF level, but not with age, history, Hb level, developmental score, or left-sided velocity.

CONCLUSIONS

Silent brain infarcts occur in a small but significant number of infants with SCA as early as a year of age. This finding indicates a need for thorough evaluation of the CNS very early in life in children with SCA in order to develop timely intervention strategies.

Neurological complications of sickle cell anemia in Nigerian Africans--a case-control study

PURPOSE

To determine the neurological complications associated with sickle cell anaemia (SCA) in Nigerians and evaluate the relative frequencies.

METHODOLOGY

Six-hundred-thirteen patients with SCA attending outpatient clinics of Lagos University Teaching Hospital and 616 control subjects were evaluated using a uniform structured questionnaire to determine the occurrence of neurological complications. The relative frequencies of neurological abnormalities in patients and controls were compared.

RESULTS

Neurological abnormalities occurred in a significantly higher percentage of patients (76%) compared to controls (32.1%). Among children, these abnormalities included stroke, febrile seizures and headache. Among adolescents and adults, the abnormalities included paraplegia, epileptic seizures and localized sensory neuropathy. Headache occurred in a significantly higher percentage in children and adolescents compared to controls, but not in adults.

CONCLUSIONS

We conclude that SCA is associated with neurological complications: stroke and febrile seizures in children, epileptic seizures, paraplegia and localized sensory neuropathy in adolescents and adults, headache in children and adolescents. Detailed studies of each of these complications would be required to provide further insight into their significance.

Pediatric stroke: current developments

PURPOSE OF REVIEW

Pediatric arterial ischemic stroke is relatively rare but carries a considerable impact and high risk of recurrence--especially in patients with sickle cell disease and various forms of vasculopathy. We will discuss risk factors, vascular physiology, and primary/secondary/rehabilitative therapies. Goals for future investigation and treatment are suggested.

RECENT FINDINGS

Risk factors include chronic disease, vasculopathy, acute illness, cardiac disease, head and neck trauma, infection, and prothrombic disorders. Research has begun to implicate genetic risk factors--initially in sickle cell disease and more recently in prothrombotic disorders, moyamoya, and nitric oxide regulation. The vascular physiology of pediatric arterial ischemic stroke, especially sickle cell disease stroke, is currently undergoing study in animal models and in humans. No primary prevention therapy for pediatric arterial ischemic stroke is known. Various primary and secondary prevention therapies are used, however, in at-risk sickle cell disease patients. Aspirin, coumadin, and heparin are often initiated as secondary prevention therapies for non-sickle cell disease-associated arterial ischemic stroke, but no studies have assessed efficacy.

SUMMARY

Pediatric arterial ischemic stroke is under-recognized and under-studied. Investigation into the hemodynamic aspects of arterial ischemic stroke, although best studied thus far in sickle cell disease, has been neglected. It is likely that enhanced study of hemodynamics and autoregulation will elucidate both new prevention opportunities and novel treatments.

Therapy Insight: stroke risk and its management in patients with sickle cell disease

Children with sickle cell disease, a chronic hemolytic anemia, present with a wide variety of neurological syndromes, including ischemic and hemorrhagic stroke, transient ischemic attacks, 'soft neurological signs', seizures, headache, coma, visual loss, altered mental status, cognitive difficulties, and covert or 'silent' infarction. Those with ischemic stroke usually have stenosis or occlusion of the distal internal carotid and proximal middle cerebral arteries. Indefinite transfusion prevents recurrence in most patients who have had a stroke, and can prevent first stroke in those with high transcranial Doppler velocities. High white cell count, low hemoglobin and oxyhemoglobin desaturation predict neurological complications. Other risk factors for overt ischemic stroke include hypertension, previous transient ischemic attack, covert infarction and chest crisis. For hemorrhagic stroke, aneurysms are common in adults but not children, who often present with hypertension after transfusion or corticosteroids. Seizures are particularly common in patients with cerebrovascular disease and covert infarction; the latter is also associated with hyposplenism and infrequent pain. Factors associated with cognitive difficulties include thrombocytosis, infarction, large-vessel disease, and perfusion abnormality on neuroimaging. As well as investigating the role of genes and the possibility that hydroxyurea or blood pressure control reduce neurological complications, we should explore the modifiable effects of poor nutrition, chronic infection, hemolysis and oxyhemoglobin desaturation on stroke risk.

Central Nervous System Complications of Sickle Cell Disease in Children: An Overview

Complications involving the central nervous system are among the most devastating manifestations of sickle cell disease. Although overt stroke occurs in 1 in 10 children with Hemoglobin SS, "silent cerebral infarcts" are even more frequent. Both are associated with significant neuropsychological deficits. The end result of these effects on the CNS often is diminished school performance. The use of transcranial Doppler ultrasonography screening allows the identification of patients at high risk for clinical stroke as well as stroke prevention by chronic transfusion. However, definitive prophylaxis and treatment for most CNS complications of sickle cell disease have yet to be determined.

Cerebral malaria and sequelar epilepsy: first matched case-control study in Gabon

PURPOSE

Cerebral malaria (CM) is suspected to be a potential cause of epilepsy in tropical areas. The purpose of this article was to evaluate the relationship between CM and epilepsy in Gabon.

METHODS

A matched case-control study was carried out on a sample of subjects aged six months to 25 years and hospitalized between 1990 and 2004 in three hospitals in Libreville, Gabon. Cases were defined as patients suffering from epilepsy and confirmed by a neurologist. Controls were defined as patients without epilepsy. The exposure of interest was CM according to WHO criteria.

RESULTS

In total, 296 cases and 296 controls were included. Of these, 36 (26 cases and 10 controls) had a CM history. The adjusted odds ratio (aOR) to develop epilepsy after CM was 3.9 [95% CI: 1.7-8.9], p<0.001. Additional risk factors were identified: family history of epilepsy: aOR=6.0 [95% CI: 2.6-14.1], p<0.0001, and febrile convulsions: aOR=9.2 [95% CI 4.0-21.1], p<0.0001.

CONCLUSIONS

This first case-control study on that issue suggests that epilepsy-related CM is an underrecognized problem. It emphasizes the need for further studies to better evaluate the role of convulsions during CM.

Hypoxic adaptation during development: relation to pattern of neurological presentation and cognitive disability

Children with acute hypoxic-ischaemic events (e.g. stroke) and chronic neurological conditions associated with hypoxia frequently present to paediatric neurologists. Failure to adapt to hypoxia may be a common pathophysiological pathway linking a number of other conditions of childhood with cognitive deficit. There is evidence that congenital cardiac disease, asthma and sleep disordered breathing, for example, are associated with cognitive deficit, but little is known about the mechanism and whether there is any structural change. This review describes what is known about how the brain reacts and adapts to hypoxia, focusing on epilepsy and sickle cell disease (SCD). We prospectively recorded overnight oxyhaemoglobin saturation (SpO2) in 18 children with intractable epilepsy, six of whom were currently or recently in minor status (MS). Children with MS were more likely to have an abnormal sleep study defined as either mean baseline SpO2 <94% or >4 dips of >4% in SpO2/hour (p = .04). In our series of prospectively followed patients with SCD who subsequently developed acute neurological symptoms and signs, mean overnight SpO2 was lower in those with cerebrovascular disease on magnetic resonance angiography (Mann-Whitney, p = .01). Acute, intermittent and chronic hypoxia may have detrimental effects on the brain, the clinical manifestations perhaps depending on rapidity of presentation and prior exposure.

Electroencephalography hyperventilation and stroke in children with sickle cell disease

A recent study and report in which hyperventilation was used during electroencephalography (EEG) in 6 children with sickle cell disease (SCD) and seizures, without serious complication, prompted a cautionary response regarding the potential risks attending the practice of EEG hyperventilation in SCD patients. Earlier reports of neurological impairment and stroke precipitated by the routine use of hyperventilation in children with SCD are reviewed, the mechanism and management of vascular infarction following hyperventilation are discussed, and readers are reminded of the AEEGS guidelines and contraindications to routine hyperventilation, which include SCD and trait and cerebrovascular disorders. The frequent nonobservance of these guideline recommendations among neurologists, and the need to more widely inform practitioners of the risks of hyperventilation in SCD are discussed.

Neurodevelopment and chronic illness: Mechanisms of disease and treatment

Successful treatment of many childhood diseases once considered terminal has resulted in the emergence of long-term effects of the disease or consequences of treatment that were previously unrecognized. Many of these long-term effects involve the central nervous system (CNS) and are developmental in the way that they emerge over time. Because we are now able to observe the natural history of childhood diseases such as sickle cell anemia or HIV, or the consequences of treatment of disease such as leukemia, brain tumors, or kidney disease, we are also able to study a number of biological mechanisms that result in long-term neurocognitive impairment. While some of the neurodevelopmental outcomes can be directly linked to structural damage of the CNS, other systems (e.g., hematologic, immunologic, pulmonary) appear to play crucial indirect roles in the development of the CNS and neurocognitive abilities because of the way that they affect the course of brain development and activity of the brain across time. Important interactions between acute disease factors, biological mechanisms, age at the time of disease or treatment effect, and disruptions in patterns of development after successful treatment or management all provide support for a neurodevelopmental model of childhood chronic illness. Testing this model may make it possible to more accurately predict the timing and degree of severity of long-term neurodevelopmental consequences, provide guidance for improved treatment and prevention, and offer better understanding of neurodevelopmental disruptions that occur in other non-chronic illness related disabilities.