Brain swelling and death in children with cerebral malaria.

BACKGROUND: Case fatality rates among African children with cerebral malaria remain in the range of 15 to 25%. The key pathogenetic processes and causes of death are unknown, but a combination of clinical observations and pathological findings suggests that increased brain volume leading to raised intracranial pressure may play a role. Magnetic resonance imaging (MRI) became available in Malawi in 2009, and we used it to investigate the role of brain swelling in the pathogenesis of fatal cerebral malaria in African children. METHODS: We enrolled children who met a stringent definition of cerebral malaria (one that included the presence of retinopathy), characterized them in detail clinically, and obtained MRI scans on admission and daily thereafter while coma persisted. RESULTS: Of 348 children admitted with cerebral malaria (as defined by the World Health Organization), 168 met the inclusion criteria, underwent all investigations, and were included in the analysis. A total of 25 children (15%) died, 21 of whom (84%) had evidence of severe brain swelling on MRI at admission. In contrast, evidence of severe brain swelling was seen on MRI in 39 of 143 survivors (27%). Serial MRI scans showed evidence of decreasing brain volume in the survivors who had had brain swelling initially. CONCLUSIONS: Increased brain volume was seen in children who died from cerebral malaria but was uncommon in those who did not die from the disease, a finding that suggests that raised intracranial pressure may contribute to a fatal outcome. The natural history indicates that increased intracranial pressure is transient in survivors. (Funded by the National Institutes of Health and Wellcome Trust U.K.).

Histidine-rich protein 2 plasma levels predict progression to cerebral malaria in Malawian children with Plasmodium falciparum infection.

Some children with uncomplicated malaria progress to cerebral malaria despite appropriate treatment; identifying them in advance might improve their care. The objective of this study was to determine if plasma concentrations of a malaria protein, HRP2 (histidine-rich protein 2) would serve this purpose. Cases and controls were children presenting with uncomplicated malaria; the cases (n = 25) developed cerebral malaria, and the controls (n = 125) did not. Mean plasma HRP2 concentrations were significantly higher in the cases, and an HRP2 cutoff was identified that could predict disease progression (sensitivity and specificity, 88% for each). Quantitative measurements of HRP2 may be a useful screening tool.

Plasma concentrations of parasite histidine-rich protein 2 distinguish between retinopathy-positive and retinopathy-negative cerebral malaria in Malawian children.

BACKGROUND: Brain histology and ophthalmoscopy suggest that approximately 25% of children with World Health Organization-defined cerebral malaria (CM) have a nonmalarial cause of death. Misclassification complicates clinical care, confounds studies of association, and may obfuscate successes in malaria control. Retinopathy predicts intracerebral parasite sequestration with >90% sensitivity and specificity, but detecting retinopathy requires well-trained personnel and expensive equipment. METHODS: We investigated the utility of plasma concentrations of parasite histidine-rich protein 2 (pHRP2), a Plasmodium-specific protein, as a predictor of intracerebral parasite sequestration at autopsy and of malaria retinopathy on clinical examination in patients with clinically defined CM. RESULTS: In 64 autopsy cases, 47 of whom had histological evidence of sequestration, the sensitivity and specificity of a plasma pHRP2 level of >1700 ng/mL were 98% and 94%, respectively, and the area under the receiver operating characteristic (AUROC) curve was 0.98. In a separate, prospectively studied group of 101 children with clinically defined CM, of whom 71 had retinopathy, the same pHRP2 cutoff predicted retinopathy-positivity with a sensitivity of 90% and specificity of 87% (AUROC, 0.90). CONCLUSIONS: Elevated plasma pHRP2 concentrations can identify Malawian children with histologically confirmed or retinopathy-positive CM and is a more field-friendly approach to confirming the diagnosis than post mortem sampling or ophthalmoscopy.

Angiopoietin-2 levels are associated with retinopathy and predict mortality in Malawian children with cerebral malaria: a retrospective case-control study*.

OBJECTIVE: To investigate the relationship among the angiopoietin-Tie-2 system, retinopathy, and mortality in children with cerebral malaria. DESIGN: A case-control study of retinopathy-positive vs. retinopathy-negative children with clinically defined cerebral malaria. SETTING: Queen Elizabeth Central Hospital in Blantyre, Malawi. SUBJECTS: One hundred fifty-five children presenting with severe malaria and meeting a strict definition of clinical cerebral malaria (Blantyre Coma Score ≤ 2, Plasmodium falciparum parasitemia, no other identifiable cause for coma) were included in the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical and laboratory parameters were recorded at admission and funduscopic examinations were performed. Admission levels of angiopoietin-1, angiopoietin-2, and a soluble version of their cognate receptor were measured by enzyme-linked immunosorbent assay. We show that angiopoietin-1 levels are decreased and angiopoietin-2 and soluble Tie-2 levels are increased in children with cerebral malaria who had retinopathy compared with those who did not. Angiopoietin-2 and soluble Tie-2 were independent predictors of retinopathy (adjusted odds ratio [95% CI], angiopoietin-2, 4.3 [1.3-14.6], p = .019; soluble Tie-2, 9.7 [2.1-45.8], p = .004). Angiopoietin-2 and soluble Tie-2 were positively correlated with the number of hemorrhages, the severity or retinal whitening, and the extent of capillary whitening observed on funduscopic examination (p < .05 after adjustment for multiple comparisons). Angiopoietin-2 and soluble Tie-2 levels were elevated in children with cerebral malaria who subsequently died and angiopoetin-2 was an independent predictor of death (adjusted odds ratio: 3.9 [1.2-12.7], p = .024). When combined with clinical parameters, angiopoetin-2 improved prediction of mortality using logistic regression models and classification trees. CONCLUSIONS: These results provide insights into mechanisms of endothelial activation in cerebral malaria and indicate that the angiopoietin-Tie-2 axis is associated with retinopathy and mortality in pediatric cerebral malaria.

Human cerebral malaria and Plasmodium falciparum genotypes in Malawi.

BACKGROUND: Cerebral malaria, a severe form of Plasmodium falciparum infection, is an important cause of mortality in sub-Saharan African children. A Taqman 24 Single Nucleotide Polymorphisms (SNP) molecular barcode assay was developed for use in laboratory parasites which estimates genotype number and identifies the predominant genotype. METHODS: The 24 SNP assay was used to determine predominant genotypes in blood and tissues from autopsy and clinical patients with cerebral malaria. RESULTS: Single genotypes were shared between the peripheral blood, the brain, and other tissues of cerebral malaria patients, while malaria-infected patients who died of non-malarial causes had mixed genetic signatures in tissues examined. Children with retinopathy-positive cerebral malaria had significantly less complex infections than those without retinopathy (OR = 3.7, 95% CI [1.51-9.10]).The complexity of infections significantly decreased over the malaria season in retinopathy-positive patients compared to retinopathy-negative patients. CONCLUSIONS: Cerebral malaria patients harbour a single or small set of predominant parasites; patients with incidental parasitaemia sustain infections involving diverse genotypes. Limited diversity in the peripheral blood of cerebral malaria patients and correlation with tissues supports peripheral blood samples as appropriate for genome-wide association studies of parasite determinants of pathogenicity.

Detection of raised intracranial pressure by ultrasound measurement of optic nerve sheath diameter in African children.

OBJECTIVE: To evaluate optic nerve sheath (ONS) ultrasound as a non-invasive method of detecting raised intracranial pressure (ICP) and to establish normal ONS diameter data for African children. METHOD: Children with acute neurological disease admitted to the Paediatric Department of Queen Elizabeth Central Hospital, Malawi had ultrasound measurements of ONS diameter. Controls were children admitted to the same department with non-neurological disease. The mean of three measurements of the ONS diameter was used for analysis. Children were assessed for clinical signs of raised ICP. Patients had CT brain scans if required for their normal clinical care. RESULTS: In 14 children with neurological disease and clinical signs suggestive of raised ICP, the mean ONS diameter was 5.4 mm (range 4.3-6.2 mm). Radiological signs on CT scans substantiated the presence of raised ICP in eight (all those scanned). In seven children with neurological disease but no specific signs of raised ICP the mean ONS diameter was 3.6 mm (range 2.8-4.4 mm). None of four of these patients examined by CT scan had signs of elevated ICP. The mean ONS diameter in 30 controls without neurological disease was 3.5 mm (range 2.5-4.1 mm). If 4.2 mm is taken as the upper limit of normal the sensitivity and specificity of this test for elevated ICP is 100% and 86%, respectively. CONCLUSION: ONS ultrasound is an accurate method for detecting raised ICP that can be applied in a broad range of settings. It has the advantages of being a non-invasive, bedside test, which can be repeated multiple times for re-evaluation.

Noninvasive measures of brain edema predict outcome in pediatric cerebral malaria.

BACKGROUND: Increased brain volume (BV) and subsequent herniation are strongly associated with death in pediatric cerebral malaria (PCM), a leading killer of children in developing countries. Accurate noninvasive measures of BV are needed for optimal clinical trial design. Our objectives were to examine the performance of six different magnetic resonance imaging (MRI) BV quantification measures for predicting mortality in PCM and to review the advantages and disadvantages of each method. METHODS: Receiver operator characteristics were generated from BV measures of MRIs of children admitted to an ongoing research project with PCM between 2009 and 2014. Fatal cases were matched to the next available survivor. A total of 78 MRIs of children aged 5 months to 13 years (mean 4.0 years), of which 45% were males, were included. RESULTS: Areas under the curve (AUC) with 95% confidence interval on measures from the initial MRIs were: Radiologist-derived score = 0.69 (0.58-0.79; P = 0.0037); prepontine cistern anteroposterior (AP) dimension = 0.70 (0.56-0.78; P = 0.0133); SamKam ratio [Rt. parietal lobe height/(prepontine AP dimension + fourth ventricle AP dimension)] = 0.74 (0.63-0.83; P = 0.0002); and global cerebrospinal fluid (CSF) space ascertained by ClearCanvas = 0.67 (0.55-0.77; P = 0.0137). For patients with serial MRIs (n = 37), the day 2 global CSF space AUC was 0.87 (0.71-0.96; P < 0.001) and the recovery factor (CSF volume day 2/CSF volume day 1) was 0.91 (0.76-0.98; P < 0.0001). Poor prognosis is associated with radiologist score of ≥7; prepontine cistern dimension ≤3 mm; cisternal CSF volume ≤7.5 ml; SamKam ratio ≥6.5; and recovery factor ≤0.75. CONCLUSION: All noninvasive measures of BV performed well in predicting death and providing a proxy measure for brain volume. Initial MRI assessment may inform future clinical trials for subject selection, risk adjustment, or stratification. Measures of temporal change may be used to stage PCM.

1.5 Tesla Magnetic Resonance Imaging to Investigate Potential Etiologies of Brain Swelling in Pediatric Cerebral Malaria.

The hallmark of pediatric cerebral malaria (CM) is sequestration of parasitized red blood cells in the cerebral microvasculature. Malawi-based research using 0.35 Tesla (T) magnetic resonance imaging (MRI) established that severe brain swelling is associated with fatal CM, but swelling etiology remains unclear. Autopsy and clinical studies suggest several potential etiologies, but limitations of 0.35 T MRI precluded optimal investigations into swelling pathophysiology. A 1.5 T MRI in Zambia allowed for further investigations including susceptibility-weighted imaging (SWI). SWI is an ideal sequence for identifying regions of sequestration and microhemorrhages given the ferromagnetic properties of hemozoin and blood. Using 1.5 T MRI, Zambian children with retinopathy-confirmed CM underwent imaging with SWI, T2, T1 pre- and post-gadolinium, diffusion-weighted imaging (DWI) with apparent diffusion coefficients and T2/fluid attenuated inversion recovery sequences. Sixteen children including two with moderate/severe edema were imaged; all survived. Gadolinium extravasation was not seen. DWI abnormalities spared the gray matter suggesting vasogenic edema with viable tissue rather than cytotoxic edema. SWI findings consistent with microhemorrhages and parasite sequestration co-occurred in white matter regions where DWI changes consistent with vascular congestion were seen. Imaging findings consistent with posterior reversible encephalopathy syndrome were seen in children who subsequently had a rapid clinical recovery. High field MRI indicates that vascular congestion associated with parasite sequestration, local inflammation from microhemorrhages and autoregulatory dysfunction likely contribute to brain swelling in CM. No gross radiological blood brain barrier breakdown or focal cortical DWI abnormalities were evident in these children with nonfatal CM.

Safety of lumbar puncture in comatose children with clinical features of cerebral malaria.

OBJECTIVE: We assessed the independent association of lumbar puncture (LP) and death in Malawian children admitted to the hospital with the clinical features of cerebral malaria (CM). METHODS: This was a retrospective cohort study in Malawian children with clinical features of CM. Allocation to LP was nonrandom and was associated with severity of illness. Propensity score-based analyses were used to adjust for this bias and assess the independent association between LP and mortality. RESULTS: Data were available for 1,075 children: 866 (80.6%) underwent LP and 209 (19.4%) did not. Unadjusted mortality rates were lower in children who underwent LP (15.3% vs 26.7% in the no-LP group) but differences in covariates between the 2 groups suggested bias in LP allocation. After propensity score matching, all covariates were balanced. Propensity score-based analyses showed no change in mortality rate associated with LP: by inverse probability weighting, the average risk reduction was 2.0% at 12 hours (95% confidence interval -1.5% to 5.5%, p = 0.27) and 1.7% during hospital admission (95% confidence interval -4.5% to 7.9%, p = 0.60). Undergoing LP did not change the risk of mortality in subanalyses of children with severe brain swelling on MRI or in those with papilledema. CONCLUSION: In comatose children with suspected CM who were clinically stable, we found no evidence that LP increases mortality, even in children with objective signs of raised intracranial pressure.

Brain MRI of children with retinopathy-negative cerebral malaria.

Our goals were to understand the brain magnetic resonance imaging (MRI) findings in children with retinopathy-negative cerebral malaria (CM) and investigate whether any findings on acute MRI were associated with adverse outcomes. We performed MRI scans on children admitted to the hospital in Blantyre, Malawi with clinically defined CM. Two hundred and seventeen children were imaged during the study period; 44 patients were malarial retinopathy-negative; and 173 patients were retinopathy-positive. We compared MRI findings in children with retinopathy-negative and retinopathy-positive CM. In children who were retinopathy-negative, we identified MRI variables that were associated with death and adverse neurologic outcomes. On multivariate analysis, cortical diffusion weighted imaging (DWI) abnormality and increased brain volume were strongly associated with neurologic morbidity in survivors. Investigations to explore the underlying pathophysiologic processes responsible for these MRI changes are warranted.

MRI findings in a cohort of brain injured survivors of pediatric cerebral malaria.

Abstract. A prospective cohort study of retinopathy-confirmed cerebral malaria (CM) survivors identified 42 of 132 with neurologic sequelae. The 38 survivors with sequelae who were alive when magnetic resonance imaging (MRI) technology became available underwent brain MRIs. Common MRI abnormalities included periventricular T2 signal changes (53%), atrophy (47%), subcortical T2 signal changes (18%), and focal cortical defects (16%). The χ(2) tests assessed the relationship between chronic MRI findings, acute clinical and demographic data, and outcomes. Children who were older at the time of CM infection (P = 0.01) and those with isolated behavioral problems (P = 0.02) were more likely to have a normal MRI. Acute focal seizures were associated with atrophy (P = 0.05). Acute papilledema was associated with subcortical T2 signal changes (P = 0.02). Peripheral retinal whitening (P = 0.007) and a higher admission white blood cell count (P = 0.02) were associated with periventricular T2 signal changes. Chronic MRI findings suggest seizures, increased intracranial pressure, and microvascular ischemia contribute to clinically relevant structural brain injury in CM.

Prevalence of diabetic retinopathy, cataract and visual impairment in patients with diabetes in sub-Saharan Africa.

BACKGROUND/AIMS: There are few published data on the prevalence of diabetic retinopathy in sub-Saharan Africa. We report the prevalence of all grades of retinopathy and associations with systemic parameters in patients attending a secondary care diabetes clinic in Blantyre, Malawi. METHODS: Cross-sectional study of all patients attending for diabetes care in a hospital setting. Clinical examination and biochemical testing was performed to assess visual acuity (VA), grade of retinopathy (slit lamp biomicroscopy), microvascular complications, glycaemic control, hypertension and HIV status. Sight-threatening diabetic retinopathy (STDR) was defined as moderate preproliferative retinopathy or worse, circinate maculopathy or exudates within one disc diameter of the foveal centre or clinically significant macular oedema. RESULTS: In patients with type 2 diabetes (n=249) the prevalence (95% CI) of any retinopathy, STDR and proliferative diabetic retinopathy (PDR) was 32.5% (26.7 to 38.3%), 19.7% (14.7 to 24.6%) and 4.8% (2.2 to 7.5%), respectively. The presence of STDR was associated with albuminuria (OR 2.6; p=0.02), the presence of neuropathy (OR 3.4; p=0.005) and insulin use (OR 5.3; p=0.0004), but not with HIV status. In patients with type 1 diabetes (n= 32), the prevalence of any retinopathy, STDR and PDR was 28.1% (12.5 to 43.7%), 18.8% (5.2 to 32.2%) and 12.5% (1.0 to 24.0%), respectively. 12.1% of study subjects had VA worse than 6/18 (20/60). CONCLUSION: This study provides baseline information on prevalence of all grades of retinopathy and STDR in consecutive cases attending an urban/semi-urban diabetes clinic in sub-Saharan Africa. Prevalence of STDR was high and in type 2 diabetes was associated with albuminuria, neuropathy and insulin use.

Prevalence of raised intracranial pressure in cerebral malaria detected by optic nerve sheath ultrasound.

We aimed to use optic nerve sheath (ONS) ultrasound to determine the prevalence of raised intracranial pressure (ICP) in African children with cerebral malaria (CM); and if increased ONS diameter is associated with poor outcome. We measured ONS diameter in 101 children with CM and 11 children with malaria and impaired consciousness in Malawi. The prevalence of raised ICP detected by increased ONS diameter was 49%. Case fatality was similar in children with increased ONS diameter on admission (9/55) and those children without increased ONS diameter (11/57). Neurological sequelae were more common in those children with increased ONS diameter (7/46 versus 2/46, P < 0.05). Lumbar puncture (LP) opening pressure was elevated in 95% of 46 children who underwent LP. In Malawian children with CM, raised ICP is less commonly detected by ONS ultrasound than LP. This study suggests that raised ICP is not universal in CM and that other mechanisms may account for coma.

Elevated plasma von Willebrand factor and propeptide levels in Malawian children with malaria.

BACKGROUND: In spite of the significant mortality associated with Plasmodium falciparum infection, the mechanisms underlying severe disease remain poorly understood. We have previously shown evidence of endothelial activation in Ghanaian children with malaria, indicated by elevated plasma levels of both von Willebrand factor (VWF) and its propeptide. In the current prospective study of children in Malawi with retinopathy confirmed cerebral malaria, we compared these markers with uncomplicated malaria, non malarial febrile illness and controls. METHODS AND FINDINGS: Children with cerebral malaria, mild malaria and controls without malaria were recruited into the study. All comatose patients were examined by direct and indirect ophthalmoscopy. Plasma VWF and propeptide levels were measured by ELISA. Median VWF and propeptide levels were significantly higher in patients with uncomplicated malaria than in children with non-malarial febrile illness of comparable severity, in whom levels were higher than in non-febrile controls. Median concentrations of both markers were higher in cerebral malaria than in uncomplicated malaria, and were similar in patients with and without retinopathy. Levels of both VWF and propeptide fell significantly 48 hours after commencing therapy and were normal one month later. CONCLUSIONS: In children with malaria plasma VWF and propeptide levels are markedly elevated in both cerebral and mild paediatric malaria, with levels matching disease severity, and these normalize upon recovery. High levels of both markers also occur in retinopathy-negative 'cerebral malaria' cases, many of whom are thought to be suffering from diseases other than malaria, indicating that further studies of these markers will be required to determine their sensitivity and specificity.

Identification of malaria retinopathy improves the specificity of the clinical diagnosis of cerebral malaria: findings from a prospective cohort study.

The diagnosis of cerebral malaria (CM) is difficult to confirm in endemic regions with limited neurodiagnostics. Accurate diagnoses are critical for trials and outcomes studies. Findings from an autopsy-based study suggest that identifying malaria retinopathy in children satisfying the standard clinical case definition of CM improves our ability to accurately diagnose CM in vivo. In a post hoc analysis of a prospective exposure-control study to evaluate CM as a risk factor for epilepsy, we stratified children meeting the standard case definition by their retinopathy status (presence versus absence) and compared these groups for pre-existing risk factors for epilepsy. We also compared them to the concurrently enrolled, non-comatose controls. Children meeting the standard case definition of CM who lacked malaria retinopathy had a higher prevalence of pre-existing developmental problems and family history of epilepsy. This subset of patients may represent children with a pre-existing propensity to adverse neurologic symptoms and outcomes.