CSF neopterin, quinolinic acid and kynurenine/tryptophan ratio are biomarkers of active neuroinflammation.

BACKGROUND: Defining the presence of acute and chronic brain inflammation remains a challenge to clinicians due to the heterogeneity of clinical presentations and aetiologies. However, defining the presence of neuroinflammation, and monitoring the effects of therapy is important given its reversible and potentially damaging nature. We investigated the utility of CSF metabolites in the diagnosis of primary neuroinflammatory disorders such as encephalitis and explored the potential pathogenic role of inflammation in epilepsy. METHODS: Cerebrospinal fluid (CSF) collected from 341 paediatric patients (169 males, median age 5.8 years, range 0.1-17.1) were examined. The patients were separated into a primary inflammatory disorder group (n = 90) and epilepsy group (n = 80), who were compared with three control groups including neurogenetic and structural (n = 76), neurodevelopmental disorders, psychiatric and functional neurological disorders (n = 63), and headache (n = 32). FINDINGS: There were statistically significant increases of CSF neopterin, kynurenine, quinolinic acid and kynurenine/tryptophan ratio (KYN/TRP) in the inflammation group compared to all control groups (all p < 0.0003). As biomarkers, at thresholds with 95% specificity, CSF neopterin had the best sensitivity for defining neuroinflammation (82%, CI 73-89), then quinolinic acid (57%, CI 47-67), KYN/TRP ratio (47%, CI 36-56) and kynurenine (37%, CI 28-48). CSF pleocytosis had sensitivity of 53%, CI 42-64). The area under the receiver operating characteristic curve (ROC AUC) of CSF neopterin (94.4% CI 91.0-97.7%) was superior to that of CSF pleocytosis (84.9% CI 79.5-90.4%) (p = 0.005). CSF kynurenic acid/kynurenine ratio (KYNA/KYN) was statistically decreased in the epilepsy group compared to all control groups (all p ≤ 0.0003), which was evident in most epilepsy subgroups. INTERPRETATION: Here we show that CSF neopterin, kynurenine, quinolinic acid and KYN/TRP are useful diagnostic and monitoring biomarkers of neuroinflammation. These findings provide biological insights into the role of inflammatory metabolism in neurological disorders and provide diagnostic and therapeutic opportunities for improved management of neurological diseases. FUNDING: Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, University of Sydney, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead. Prof Guillemin is funded by NHMRC Investigator grant APP 1176660 and Macquarie University.

Treatment of severe acute necrotizing encephalopathy of childhood with interleukin-6 receptor blockade in the first 24 h as add-on immunotherapy shows favorable long-term outcome at 2 years.

BACKGROUND: Acute necrotizing encephalopathy (ANE) of childhood is a rare and devastating infection-associated acute encephalopathy. While there are no consensus treatments for ANE, recent case reports suggest a beneficial role for the use of tocilizumab, a recombinant humanized monoclonal antibody against the interleukin-6 (IL-6) receptor. The correlation of the timing of add-on tocilizumab in relation to long-term outcome has not been reported. METHODS: We report on the timing of administration of tocilizumab in two patients classified as high-risk using the ANE severity score (ANE-SS) with respect to the long-term outcome at 2 years. RESULTS: Case 1 was a 19-month-old previously well boy who presented to a tertiary children's hospital with seizures, evolving status dystonicus and shock. Case 2 was a three-year-old boy who presented to a peripheral hospital with fever, sepsis and encephalopathy. The patients were transferred to the tertiary intensive care unit and MRI confirmed ANE with extensive brainstem involvement. Case 1 received intravenous immunoglobulin (IVIg), methylprednisolone and tocilizumab at 21, 39 and 53 h respectively. His modified Rankin scale (mRS) at discharge and two years was unchanged at 5. The functional independence measure - for children (WeeFIM) at two years was very low (19/126). Case 2 received dexamethasone at 1 h, methylprednisolone at 21 h and IVIg and tocilizumab at 22 h. The mRS at discharge and two years was 4 and 3 respectively. The WeeFIM score at two years showed substantial improvement (96/126). CONCLUSION: The very early use of interleukin-6 blockade as 'add-on' immunotherapy in the first 24 h demonstrates potential for improving the long-term outcome in patients classified as high-risk using the ANE-SS.

Urgent computed tomography angiography in paediatric stroke.

AIM: To improve delivery of acute therapies for acute ischaemic stroke (AIS). METHOD: We identified factors influencing the speed of diagnosis and delivery of acute therapies in a prospective cohort of 21 children with suspected AIS (eight with AIS, 13 stroke mimics) and explored them in a retrospective cohort with confirmed AIS. RESULTS: Approximately half of the prospective and total AIS cohorts presented with acute, sustained hemiparesis, and were diagnosed relatively quickly. AIS was suspected and diagnosed more slowly in the half presenting with symptoms other than sustained hemiparesis. Thirty-one out of 51 patients with AIS (19 females, 32 males, mean age 8 years 6 months, SD 5 years 4 months) had arterial abnormalities identified by computed tomography angiography (CTA) or magnetic resonance angiography (MRA): 11 with large vessel occlusion, six with dissection, five with moyamoya disease, nine with other arteriopathies. Among these patients, those initially imaged with CTA were diagnosed more quickly than those with initial magnetic resonance imaging/angiography, which facilitated thrombectomy and thrombolytic therapy. Twenty out of 51 had AIS without arterial abnormalities on CTA or MRA: eight with lenticulostriate vasculopathy and 12 with other small-vessel AIS. Among these patients, 80% were ineligible for thrombolysis for reasons beyond delay to diagnosis, and all showed good outcomes with supportive treatments alone. INTERPRETATION: Clinical features at presentation influence rapidity with which childhood AIS is suspected and diagnosed. Readily available CTA can direct thrombectomy in patients with large vessel occlusion and thrombolysis in most, but not all, eligible patients. WHAT THIS PAPER ADDS: Children with acute ischaemic stroke (AIS) commonly present with symptoms other than sustained hemiparesis. Stroke is more slowly recognized in these patients, which limits potential therapies. Computed tomography angiography (CTA) accurately identifies AIS with large vessel occlusion, enabling timely endovascular thrombectomy. CTA is sufficient to direct thrombolytic therapy in most eligible children. Most childhood AIS without arterial abnormalities identified by CTA had good outcomes.

CSF neopterin, a useful biomarker in children presenting with influenza associated encephalopathy?

PURPOSE: Neurological complications of influenza cause significant disease in children. Central nervous system inflammation, the presumed mechanism of influenza-associated encephalopathy, is difficult to detect. Characteristics of children presenting with severe neurological complications of influenza, and potential biomarkers of influenza-associated encephalopathy are described. METHODS: A multi-center, retrospective case-series of children with influenza and neurological complications during 2017 was performed. Enrolled cases met criteria for influenza-associated encephalopathy or had status epilepticus. Functional outcome at discharge was compared between groups using the Modified Rankin Scale (mRS). RESULTS: There were 22 children with influenza studied of whom 11/22 had encephalopathy and 11/22 had status epilepticus. Only one child had a documented influenza immunization. The biomarker CSF neopterin was tested in 10/11 children with encephalopathy and was elevated in 8/10. MRI was performed in all children with encephalopathy and was abnormal in 8 (73%). Treatment of children with encephalopathy was with corticosteroids or intravenous immunoglobulin in 9/11 (82%). In all cases oseltamivir use was low (59%) while admission to the intensive care unit was frequent (14/22, 66%). Clinical outcome at discharge was moderate to severe disability (mRS score > 2) in the majority of children with encephalopathy (7/11, 64%), including one child who died. Children with status epilepticus recovered to near-baseline function in all cases. CONCLUSION: Raised CSF neopterin was present in most cases of encephalopathy, and along with diffusion restriction on MRI, is a useful diagnostic biomarker. Lack of seasonal influenza vaccination represents a missed opportunity to prevent illness in children, including severe neurological disease.

High sensitivity and specificity in proposed clinical diagnostic criteria for anti-N-methyl-D-aspartate receptor encephalitis.

AIM: To determine the validity of the proposed clinical diagnostic criteria for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis in paediatric patients. METHOD: The diagnostic criteria for anti-NMDAR encephalitis proposed by Graus et al. (2016) use clinical features and conventional investigations to facilitate early immunotherapy before antibody status is available. The criteria are satisfied if patients develop four out of six symptom groups within 3 months, together with at least one abnormal investigation (electroencephalography/cerebrospinal fluid) and reasonable exclusion of other disorders. We evaluated the validity of the criteria using a retrospective cohort of paediatric patients with encephalitis. Twenty-nine patients with anti-NMDAR encephalitis and 74 comparison children with encephalitis were included. RESULTS: As expected, the percentage of patients with anti-NMDAR encephalitis who fulfilled the clinical criteria increased over time. During the hospital inpatient admission, most patients (26/29, 90%) with anti-NMDAR encephalitis fulfilled the criteria, significantly more than the comparison group (3/74, 4%) (p<0.001). The median time of fulfilling the criteria in patients with anti-NMDAR encephalitis was 2 weeks from first symptom onset (range 1-6). The sensitivity of the criteria was 90% (95% confidence interval 73-98) and the specificity was 96% (95% confidence interval 89-99). INTERPRETATION: The proposed diagnostic criteria for anti-NMDAR encephalitis have good sensitivity and specificity. Incomplete criteria do not exclude the diagnosis. WHAT THIS PAPER ADDS: The proposed clinical diagnostic criteria for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis by Graus et al. (2016) have high sensitivity and specificity in paediatric patients. The median time of fulfilling the criteria in patients with anti-NMDAR was 2 weeks from first symptom onset.

Utility of CSF Cytokine/Chemokines as Markers of Active Intrathecal Inflammation: Comparison of Demyelinating, Anti-NMDAR and Enteroviral Encephalitis.

BACKGROUND: Despite the discovery of CSF and serum diagnostic autoantibodies in autoimmune encephalitis, there are still very limited CSF biomarkers for diagnostic and monitoring purposes in children with inflammatory or autoimmune brain disease. The cause of encephalitis is unknown in up to a third of encephalitis cohorts, and it is important to differentiate infective from autoimmune encephalitis given the therapeutic implications. AIM: To study CSF cytokines and chemokines as diagnostic biomarkers of active neuroinflammation, and assess their role in differentiating demyelinating, autoimmune, and viral encephalitis. METHODS: We measured and compared 32 cytokine/chemokines using multiplex immunoassay and APRIL and BAFF using ELISA in CSF collected prior to commencing treatment from paediatric patients with confirmed acute disseminated encephalomyelitis (ADEM, n = 16), anti-NMDAR encephalitis (anti-NMDAR E, n = 11), and enteroviral encephalitis (EVE, n = 16). We generated normative data using CSF from 20 non-inflammatory neurological controls. The sensitivity of CSF cytokine/chemokines to diagnose encephalitis cases was calculated using 95th centile of control values as cut off. We correlated CSF cytokine/chemokines with disease severity and follow up outcome based on modified Rankin scale. One-way hierarchical correlational cluster analysis of molecules was performed in different encephalitis and outcome groups. RESULTS: In descending order, CSF TNF-α, IL-10, IFN-α, IL-6, CXCL13 and CXCL10 had the best sensitivity (>79.1%) when all encephalitis patients were included. The combination of IL-6 and IFN-α was most predictive of inflammation on multiple logistic regression with area under the ROC curve 0.99 (CI 0.97-1.00). There were no differences in CSF cytokine concentrations between EVE and anti-NMDAR E, whereas ADEM showed more pronounced elevation of Th17 related (IL-17, IL-21) and Th2 (IL-4, CCL17) related cytokine/chemokines. Unlike EVE, heat map analysis showed similar clustering of cytokine/chemokine molecules in immune mediated encephalitis (ADEM and anti-NMDAR E). Th1 and B cell (CXCL13 and CXCL10) molecules clustered together in patients with severe encephalopathy at admission and worse disability at follow up in all encephalitis. There was no correlation between CSF neopterin and IFN-γ or IFN-α. CONCLUSION: A combination panel of cytokine/chemokines consisting of CSF TNF-α, IL-10, IFN-α, IL-6, CXCL13 and CXCL10 measured using multiplex immunoassay may be used to diagnose and monitor intrathecal inflammation in the brain. Given their association with worse outcome, certain key chemokines (CXCL13, CXCL10) could represent potential therapeutic targets in encephalitis.

Etiological associations and outcome predictors of acute electroencephalography in childhood encephalitis.

OBJECTIVES: To examine EEG features in a retrospective 13-year cohort of children with encephalitis. METHODS: 354 EEGs from 119 patients during their admission were rated blind using a proforma with demonstrated inter-rater reliability (mean k=0.78). Patients belonged to 12 etiological groups that could be grouped into infectious and infection-associated (n=47), immune-mediated (n=36) and unknown (n=33). EEG features were analyzed between groups and for risk of abnormal Liverpool Outcome Score and drug resistant epilepsy (DRE) at last follow up. RESULTS: 86% children had an abnormal first EEG and 89% had at least one abnormal EEG. 55% had an abnormal outcome, and 13% had DRE after median follow-up of 7.3years (2.0-15.8years). Reactive background on first EEGs (9/11, p=0.04) and extreme spindles (4/11, p<0.001) distinguished patients with anti-N-Methyl-d-Aspartate Receptor encephalitis. Non-reactive EEG background (48% first EEGs) predicted abnormal outcome (OR 3.8, p<0.001). A shifting focal seizure pattern, seen in FIRES (4/5), anti-voltage gated potassium channel (2/3), Mycoplasma (1/10), other viral (1/10) and other unknown (1/28) encephalitis, was most predictive of DRE after multivariable analysis (OR 11.9, p<0.001). CONCLUSIONS: Non-reactive EEG background and the presence of shifting focal seizures resembling migrating partial seizures of infancy are predictors of abnormal outcome and DRE respectively in childhood encephalitis. SIGNIFICANCE: EEG is a sensitive but non-discriminatory marker of childhood encephalitis. We highlight the EEG features that predict abnormal outcome and DRE.

Postencephalitic epilepsy and drug-resistant epilepsy after infectious and antibody-associated encephalitis in childhood: Clinical and etiologic risk factors.

To define the risk factors for postencephalitic epilepsy (PE) and drug-resistant epilepsy (DRE) in childhood following infectious and autoimmune encephalitis, we included 147 acute encephalitis patients with a median follow-up of 7.3 years (range 2-15.8 years). PE was defined as the use of antiepileptic drugs (AEDs) for ≥24 months, and DRE was defined as the persistence of seizures despite ≥2 appropriate AEDs at final follow-up. PE and DRE were diagnosed in 31 (21%) and 15 (10%) of patients, respectively. The features during acute encephalitis predictive of DRE (presented as odds ratio [OR] with confidence intervals [CIs]) were status epilepticus (OR 10.8, CI 3.4-34.3), visual disturbance (6.4, 1.4-29.9), focal seizures (6.2, 1.9-20.6), magnetic resonance imaging (MRI) hippocampal/amygdala involvement (5.0, 1.7-15.4), intensive care admission (4.7, 1.4-15.4), use of >3 AEDs (4.5, 1.2-16.1), MRI gadolinium enhancement (4.1, 1.2-14.2), any seizure (3.9, 1.1-14.4), and electroencephalography (EEG) epileptiform discharges (3.9, 1.3-12.0). On multivariable regression analysis, only status epilepticus remained predictive of DRE in all models. DRE was common in herpes simplex virus (3/9, 33%) and unknown (8/40, 20%) encephalitis, but absent in acute disseminated encephalomyelitis (ADEM) (0/32, 0%), enterovirus (0/18), and anti-N-methyl-d-aspartate receptor-NMDAR encephalitis (0/9). We have identified risk factors for DRE and demonstrated "high-risk," and "low-risk" etiologies.

Symptomatic treatment of children with anti-NMDAR encephalitis.

AIM: We performed the first study on the perceived benefit and adverse effects of symptomatic management in children with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. METHOD: A retrospective chart review was undertaken at two tertiary paediatric hospitals in Australia and New Zealand. We included 27 children (12 males, 15 females; mean age at admission 7y 1mo) with anti-NMDAR antibodies in serum or cerebrospinal fluid with a typical clinical syndrome. RESULTS: Only two out of 27 patients were white, whereas 16 out of 27 patients were from the Pacific Islands/New Zealand Maori. The mean duration of admission was 69 days (10-224d) and 48% of patients (13/27) needed treatment in an intensive care setting. A mean of eight medications per patient was used for symptomatic management. Symptoms treated were agitation (n=25), seizures (n=24), movement disorders (n=23), sleep disruption (n=17), psychiatric symptoms (n=10), and dysautonomia (n=four). The medications used included five different benzodiazepines (n=25), seven anticonvulsants (n=25), eight sedatives and sleep medications (n=23), five antipsychotics (n=12), and five medications for movement disorders (n=10). Sedative and sleep medications other than benzodiazepines were the most effective, with a mean benefit of 67.4% per medication and a mean adverse effect-benefit ratio of 0.04 per medication. Antipsychotic drugs were used for a short duration (median 9d), and had the poorest mean benefit per medication of 35.4% and an adverse effect-benefit ratio of 2.0 per medication. INTERPRETATION: Long-acting benzodiazepines, anticonvulsants, and clonidine can treat multiple symptoms. Patients with anti-NMDAR encephalitis appear vulnerable to antipsychotic-related adverse effects. Pacific Islanders appear to have a vulnerability to anti-NMDAR encephalitis in our region.

Infectious and autoantibody-associated encephalitis: clinical features and long-term outcome.

BACKGROUND AND OBJECTIVES: Pediatric encephalitis has a wide range of etiologies, clinical presentations, and outcomes. This study seeks to classify and characterize infectious, immune-mediated/autoantibody-associated and unknown forms of encephalitis, including relative frequencies, clinical and radiologic phenotypes, and long-term outcome. METHODS: By using consensus definitions and a retrospective single-center cohort of 164 Australian children, we performed clinical and radiologic phenotyping blinded to etiology and outcomes, and we tested archived acute sera for autoantibodies to N-methyl-D-aspartate receptor, voltage-gated potassium channel complex, and other neuronal antigens. Through telephone interviews, we defined outcomes by using the Liverpool Outcome Score (for encephalitis). RESULTS: An infectious encephalitis occurred in 30%, infection-associated encephalopathy in 8%, immune-mediated/autoantibody-associated encephalitis in 34%, and unknown encephalitis in 28%. In descending order of frequency, the larger subgroups were acute disseminated encephalomyelitis (21%), enterovirus (12%), Mycoplasma pneumoniae (7%), N-methyl-D-aspartate receptor antibody (6%), herpes simplex virus (5%), and voltage-gated potassium channel complex antibody (4%). Movement disorders, psychiatric symptoms, agitation, speech dysfunction, cerebrospinal fluid oligoclonal bands, MRI limbic encephalitis, and clinical relapse were more common in patients with autoantibodies. An abnormal outcome occurred in 49% of patients after a median follow-up of 5.8 years. Herpes simplex virus and unknown forms had the worst outcomes. According to our multivariate analysis, an abnormal outcome was more common in patients with status epilepticus, magnetic resonance diffusion restriction, and ICU admission. CONCLUSIONS: We have defined clinical and radiologic phenotypes of infectious and immune-mediated/autoantibody-associated encephalitis. In this resource-rich cohort, immune-mediated/autoantibody-associated etiologies are common, and the recognition and treatment of these entities should be a clinical priority.

Confirmed enterovirus encephalitis with associated steroid-responsive acute disseminated encephalomyelitis: an overlapping infection and inflammation syndrome.

BACKGROUND: Inflammatory disorders of the central nervous system have generally been separated into infectious or immune-mediated aetiologies. However, there are emerging examples of confirmed infectious viral infection of the brain followed by secondary inflammation or autoimmunity that is amenable to immune suppressive therapies. METHODS: We report four children with confirmed enterovirus encephalitis (CSF enterovirus PCR positivity), who had MRI evidence of inflammatory demyelination compatible with ADEM. RESULTS: Two patients had a monophasic course, whereas two had a biphasic course. Serum myelin oligodendrocyte glycoprotein antibodies were negative in two tested patients, although all patients had mirrored CSF and serum oligoclonal bands. All four patients only improved with introduction of immune therapy (corticosteroids in three, corticosteroid and intravenous immunoglobulin in one). CONCLUSION: These cases provide a further example of the overlap between CNS infection and immune mediated CNS disease. Randomised controlled trials investigating immune therapies in encephalitis are required.

Movement disorders in children with anti-NMDAR encephalitis and other autoimmune encephalopathies.

Accurate recognition of movement disorder phenomenology may differentiate children with anti-N-methyl D-aspartate receptor (NMDAR) encephalitis, autoimmune basal ganglia encephalitis (BGE), and Sydenham's chorea (SC). Three neurologists blinded to the diagnoses recorded dominant and associated movement disorders seen on videos of 31 patients with anti-NMDAR encephalitis (n = 10), BGE (n = 12), and SC (n = 9). Stereotypy was only seen in anti-NMDAR encephalitis (8/10) and not in BGE and SC (P < 0.001). Perseveration was only seen in anti-NMDAR encephalitis (5/10) and not in BGE and SC (P < 0.001). Akinesia was more commonly seen in BGE (5/12) than in anti-NMDAR encephalitis (1/10, P = 0.097). Tremor was more commonly seen in BGE (5/12) than in anti-NMDAR encephalitis (1/10, P = 0.097). Chorea was seen in all groups: anti-NMDAR encephalitis (4/10), BGE (3/12), and SC (9/9). Likewise, dystonia was seen in all groups: anti-NMDAR encephalitis (6/10), BGE (7/12), and SC (2/9). Stereotypies or perseveration are suggestive of anti-NMDAR encephalitis, whereas their absence and the presence of akinesia and tremor is more suggestive of BGE. Chorea and dystonia are least discriminating.

Herpes simplex encephalitis relapse with chorea is associated with autoantibodies to N-Methyl-D-aspartate receptor or dopamine-2 receptor.

BACKGROUND: Movement disorder relapses after herpes simplex virus 1 (HSV1) encephalitis have been hypothesized to be secondary to postviral autoimmunity. Recently, a proportion of patients with HSV1 encephalitis (HSE) were shown to produce autoantibodies against N-methyl-D-aspartate receptor (NMDAR). METHODS: We measured autoantibodies against NMDAR and dopamine-2 receptor (D2R) expressed at the cell surface in the stored acute serum of 9 children with HSE, 3 of whom had a relapsing course with chorea. RESULTS: The 3 patients with chorea had elevated autoantibodies against NMDAR (n = 1), D2R (n = 1), or both (n = 1), whereas patients without chorea were negative (n = 6). The prospectively identified patient with chorea and NMDAR autoantibodies improved after early treatment with steroids, intravenous immunoglobulin, and cyclophosphamide, with reduction in serum NMDAR antibody titers. CONCLUSIONS: These autoantibody findings lend support to the autoimmune hypothesis and the early use of immune suppression in post-HSE chorea.

Cerebrospinal fluid CD19(+) B-cell expansion in N-methyl-D-aspartate receptor encephalitis.

There is increasing interest in the role of autoantibodies in acquired autoimmune central nervous system disorders. N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis defined by the presence of autoantibodies that bind to the NMDAR. Although there is evidence of NMDAR antibody pathogenicity, it is unclear which treatment results in the best outcome. We measured the proportion of B-cells in the cerebrospinal fluid of two children with NMDAR encephalitis (a 6-year-old male and a 4-year-old female), one in the acute phase and one in the relapsing phase. The proportion of CD19(+) B-cells in both children was greater than 10%, significantly higher than seen in non-inflammatory neurological disorders (<1%). This finding supports the use of drugs, such as rituximab, that deplete B-cells in severe or refractory cases of NMDAR encephalitis, and lends further support to the humoral autoimmune hypothesis in NMDAR encephalitis.

Antibodies to surface dopamine-2 receptor in autoimmune movement and psychiatric disorders.

Recent reports of autoantibodies that bind to neuronal surface receptors or synaptic proteins have defined treatable forms of autoimmune encephalitis. Despite these developments, many cases of encephalitis remain unexplained. We have previously described a basal ganglia encephalitis with dominant movement and psychiatric disease, and proposed an autoimmune aetiology. Given the role of dopamine and dopamine receptors in the control of movement and behaviour, we hypothesized that patients with basal ganglia encephalitis and other putative autoimmune basal ganglia disorders harboured serum autoantibodies against important dopamine surface proteins. Basal ganglia encephalitis sera immunolabelled live surface cultured neurons that have high expression of dopamine surface proteins. To detect autoantibodies, we performed flow cytometry cell-based assays using human embryonic kidney cells to express surface antigens. Twelve of 17 children (aged 0.4-15 years, nine males) with basal ganglia encephalitis had elevated immunoglobulin G to extracellular dopamine-2 receptor, compared with 0/67 controls. Immunofluorescence on wild-type mouse brain showed that basal ganglia encephalitis sera immunolabelled microtubule-associated protein 2-positive neurons in striatum and also in cultured striatal neurons, whereas the immunolabelling was significantly decreased in dopamine-2 receptor knock-out brains. Immunocytochemistry confirmed that immunoreactivity localized to the surface of dopamine-2 receptor-transfected cells. Immunoabsorption of basal ganglia encephalitis sera on dopamine-2 receptor-transfected human embryonic kidney cells decreased immunolabelling of dopamine-2 receptor-transfected human embryonic kidney cells, neurons and wild-type mouse brain. Using a similar flow cytometry cell-based assay, we found no elevated immunoglobulin G binding to dopamine 1, 3 or 5 receptor, dopamine transporter or N-methyl-d-aspartate receptor. The 12 dopamine-2 receptor antibody-positive patients with encephalitis had movement disorders characterized by parkinsonism, dystonia and chorea. In addition, the patients had psychiatric disturbance with emotional lability, attention deficit and psychosis. Brain magnetic resonance imaging showed lesions localized to the basal ganglia in 50% of the patients. Elevated dopamine-2 receptor immunoglobulin G was also found in 10/30 patients with Sydenham's chorea, 0/22 patients with paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection and 4/44 patients with Tourette's syndrome. No dopamine-1 receptor immunoglobulin G was detected in any disease or control groups. We conclude that assessment of dopamine-2 receptor antibodies can help define autoimmune movement and psychiatric disorders.

Cortical hypometabolism demonstrated by PET in relapsing NMDA receptor encephalitis.

N-methyl-d-aspartate (NMDA) receptor encephalitis is a newly defined type of autoimmune encephalitis. Two girls (age 3 years, case 1, and 7 years, case 2) with relapsing NMDA receptor encephalitis each had the classic clinical features of encephalopathy, movement disorders, psychiatric symptoms, seizures, insomnia, and mild autonomic dysfunction. Both patients had persistent neuropsychiatric disability, despite immune therapies. Positron emission tomography (PET) scans were performed during clinical relapse at 6 weeks (case 1) and 5 months (case 2). In both cases, the scans demonstrated reduced fluorodeoxyglucose metabolism in the cerebral cortex, with the temporal regions being most affected. PET imaging was more sensitive than magnetic resonance imaging in these patients. In contrast, the one previous report of acute NMDA receptor encephalitis indicated cortical hypermetabolism. Thus, NMDA receptor encephalitis may be associated with variable PET findings, possibly dependent upon the timing of the study, or other factors. Future studies should investigate whether cortical hypometabolism is associated with a relapsing course, and whether it is predictive of a poorer outcome in NMDA receptor encephalitis.

A prospective study of acute movement disorders in children.

AIM: The purpose of this study was to report a prospective cohort of children with acute-onset movement disorders. METHOD: We report on 52 individuals (31 females, 21 males; mean age 6y 5mo, range 2mo-15y) with acute-onset movement disorders managed at a busy tertiary paediatric referral hospital over a 40-month period. RESULTS: In descending order of frequency, the movement disorders reported were chorea, dystonia, tremor, myoclonus, and parkinsonism. It was possible to divide the participants into three groups: (1) those with inflammatory or autoimmune disorders (n=22), (2) those with non-inflammatory disorders (n=18), and (3) those with psychogenic disorders (n=12). The inflammatory or autoimmune aetiologies included N-methyl-D-aspartate receptor encephalitis (n=5), opsoclonus-myoclonus syndrome (n=4), Sydenham chorea (n=3), systemic lupus erythematosus (n=3), acute necrotizing encephalopathy (n=3), and other types of encephalitis (n=4). Other important non-inflammatory movement disorder aetiologies included drug-induced movement disorder (n=6), post-pump chorea (n=5), metabolic (n=3) and vascular (n=2) disease. The participants with psychogenic movement disorders (n=12) were all over 10 years of age and were more likely to be female. Tremor and myoclonus were significantly over-represented in the psychogenic movement disorder subgroup. The outcomes of the total cohort were variable, and included full recovery, severe morbidity, and death. INTERPRETATION: Acute-onset movement disorders in children are important and may be treatable. Management should focus upon identifying the cause and treating the underlying disease process, as symptomatic treatment of the abnormal movements is variably effective.

N-methyl-D-aspartate receptor antibodies in pediatric dyskinetic encephalitis lethargica.

Encephalitis lethargica (EL) describes an encephalitis with psychiatric, sleep, and extrapyramidal movement disorders. Dyskinetic and parkinsonian forms have been described. EL shares clinical features with the anti-N-methyl-D-aspartate receptor (NMDAR-Ab) encephalitis. We studied 20 sera from pediatric patients with contemporary EL. Ten sera (from 2 males and 8 females, aged 1.3-13 years) and 6/6 cerebrospinal fluid samples were positive for NMDAR-Ab. NMDAR-Ab-positive patients had dyskinesias, agitation, seizures, and insomnia, whereas parkinsonism and somnolence dominated in the NMDAR-Ab-negative children. We were unable to identify any tumors. The dyskinetic form of EL is an NMDAR-Ab encephalitis and can affect very young children.

Early relapse risk after a first CNS inflammatory demyelination episode: examining international consensus definitions.

The International Pediatric Multiple Sclerosis Study Group (IPMS) has recently proposed consensus definitions for paediatric multiple sclerosis (MS) and related disorders. The term 'acute disseminated encephalomyelitis' (ADEM) has been used previously to describe any monophasic episode of disseminated demyelination. The study group now propose that ADEM must be multifocal, polysymptomatic, and include encephalopathy (as an essential requirement). An alternative diagnosis for a first acute inflammatory event is 'clinically isolated syndrome' (CIS). A CIS event may be either monofocal (such as isolated optic neuritis) or multifocal, but cannot include encephalopathy. As with adults, children with two or more discrete demyelinating events separated in time and space meet criteria for MS. In children with MS, the demyelination events must not meet ADEM criteria. To test the usefulness of these new criteria, a new cohort of 40 patients (18 males, 22 females; mean age 8 y [SD 4 y 4 mo]) with central nervous system (CNS) demyelination were studied. Using IPMS definitions, the presenting diagnosis was ADEM in 12 patients and CIS in 28 patients. At presentation, patients with CIS were more likely to have intrathecal synthesis of oligoclonal bands and fulfil KIDMUS MS magnetic resonance imaging criteria, compared with patients with ADEM (p<0.025). Patients were followed-up for a mean of 2 years 2 months. Only one of 12 patients with ADEM went on to develop MS during the study period, whereas 13 of 28 patients with CIS relapsed and fulfilled a diagnosis of MS (p<0.025). The new diagnostic criteria for ADEM may be criticized for being overly restrictive (particularly with encephalopathy being an essential criterion), and it is suspected that many practising physicians will be of the opinion that these new criteria will underdiagnose ADEM, and overdiagnose MS at the expense of multiphasic ADEM. However, it is hoped that these new criteria may improve prognostic specificity and provide uniformity to future paediatric CNS demyelination research.