Finbar J. O'Callaghan

The United Kingdom Infantile Spasms Study (UKISS) comparing hormone treatment with vigabatrin on developmental and epilepsy outcomes to age 14 months: a multicentre randomised trial

BACKGROUND Infantile spasms is a severe infantile seizure disorder that is difficult to treat and has a high morbidity. Absence of spasms on days 13 and 14 after randomisation is more common in infants allocated hormone treatments than in those allocated vigabatrin. We sought to assess whether early control of spasms is associated with improved developmental or epilepsy outcomes. METHODS Infants enrolled in the United Kingdom Infantile Spasms Study (UKISS) were randomly assigned hormone treatment (n=55) or vigabatrin (n=52) and were followed up until clinical assessment at 12-14 months of age. We assessed neurodevelopment with the Vineland adaptive behaviour scales (VABS) at 14 months of age on an intention to treat basis. FINDINGS Of 107 infants enrolled, five died and 101 survivors reached both follow-up assessments. Absence of spasms at final clinical assessment (hormone 41/55 [75%] vs vigabatrin 39/51 [76%]) was similar in each treatment group (difference 1.9%, 95% CI -18.3% to 14.4%; chi(2)=0.05; p=0.82). Mean VABS score did not differ significantly (hormone 78.6 [SD 16.8] vs vigabatrin 77.5 [SD 12.7]; difference 1.0, 95% CI -4.9 to 7.0; t(99)=0.35, p=0.73). In infants with no identified underlying aetiology, the mean VABS score was higher in those allocated hormone treatment than in those allocated vigabatrin (88.2 [17.3] vs 78.9 [14.3]; difference 9.3, 95% CI 1.2 to 17.3; t(95)=2.28, p=0.025). INTERPRETATION Hormone treatment controls spasms better than does vigabatrin initially, but not at 12-14 months of age. Better initial control of spasms by hormone treatment in those with no identified underlying aetiology may lead to improved developmental outcome.

The United Kingdom Infantile Spasms Study comparing vigabatrin with prednisolone or tetracosactide at 14 days: a multicentre, randomised controlled trial

BACKGROUND Infantile spasms, which comprise a severe infantile seizure disorder, have a high morbidity and are difficult to treat. Hormonal treatments (adrenocorticotropic hormone and prednisolone) have been the main therapy for decades, although little evidence supports their use. Vigabatrin has been recorded to have a beneficial effect in this disorder. We aimed to compare the effects of vigabatrin with those of prednisolone and tetracosactide in the treatment of infantile spasms. METHODS The United Kingdom Infantile Spasms Study assessed these treatments in a multicentre, randomised controlled trial in 150 hospitals in the UK. The primary outcome was cessation of spasms on days 13 and 14. Minimum doses were vigabatrin 100 mg/kg per day, oral prednisolone 40 mg per day, or intramuscular tetracosactide depot 0.5 mg (40 IU) on alternate days. Analysis was by intention to treat. FINDINGS Of 208 infants screened and assessed, 107 were randomly assigned to vigabatrin (n=52) or hormonal treatments (prednisolone n=30, tetracosactide n=25). None was lost to follow-up. Proportions with no spasms on days 13 and 14 were: 40 (73%) of 55 infants assigned hormonal treatments (prednisolone 21/30 [70%], tetracosactide 19/25 [76%]) and 28 (54%) of 52 infants assigned vigabatrin (difference 19%, 95% CI 1%-36%, p=0.043). Two infants allocated tetracosactide and one allocated vigabatrin received prednisolone. Adverse events were reported in 30 (55%) of 55 infants on hormonal treatments and 28 (54%) of 52 infants on vigabatrin. No deaths were recorded. INTERPRETATION Cessation of spasms was more likely in infants given hormonal treatments than those given vigabatrin. Adverse events were common with both treatments.

The influence of head growth in fetal life, infancy, and childhood on intelligence at the ages of 4 and 8 years

OBJECTIVE. We investigated the effects of head growth prenatally, during infancy, and during later periods of development on cognitive function at the ages of 4 and 8 years. METHODS. We studied 633 term-born children from the Avon Longitudinal Study of Parents and Children cohort whose head circumference was measured at birth and at regular intervals thereafter. Their cognitive function was assessed with the Wechsler Preschool and Primary Scale of Intelligence at the age of 4 years and with the Wechsler Intelligence Scale for Children at the age of 8 years. Linear regression analysis was used to calculate postnatal head growth between successive time points, conditional on previous size, and to examine the relationship between head growth during different periods of development and later IQ. RESULTS. When the influence of head growth was distinguished for different periods, only prenatal growth and growth during infancy were associated with subsequent IQ. At 4 years, after adjustment for parental characteristics, full-scale IQ increased an average of 2.41 points for each 1-SD increase in head circumference at birth and 1.97 points for each 1-SD increase in head growth during infancy, conditional on head size at birth. At 8 years, head circumference at birth was no longer associated with IQ, but head growth during infancy remained a significant predictor, with full-scale IQ increasing an average of 1.56 points for each 1-SD increase in growth. CONCLUSION. The brain volume a child achieves by the age of 1 year helps determine later intelligence. Growth in brain volume after infancy may not compensate for poorer earlier growth.

Prevalence of tuberous sclerosis estimated by capture-recapture analysis.

time. Unfortunately, in human populations these assumptions are frequently violated. The problem can be minimised by the use of techniques such as log-linear modelling but a high degree of accuracy in the estimate of numbers of missing cases should not be expected. We carried out a capture-recapture analysis of data collected in the survey of prevalence of tuberous sclerosis in Wessex. Cases had been identified from a large number of different sources. Data from these individual sources were pooled to construct three summary sources: cases identified by paediatricians; cases identified by other medical practitioners; and cases identified from other sources (for example, the Tuberous Sclerosis Association or Hospital Activity Analysis). We used the method described by Hook and Regal to first derive estimates for the total number of cases from each of the three possible two-source models and finally from all three sources. The figure shows the number of cases identified from each source and the overlap between sources. No cases were identified from all three sources. Maximum likelihood estimates are given for the total number of people with tuberous sclerosis in this population derived from each of the two-source models and from the three-source model. Dependency between sources was investigated by including terms for interaction between sources in the loglinear model; none of these terms was statistically significant. The Wessex survey originally identified 131 cases of tuberous sclerosis in a population of 3·4 million. The results of the capture-recapture analysis suggest that, despite the efforts of the investigators to locate all cases, more than half remained undetected. A revised estimate of prevalence, taking account of unascertained cases, is 8·8 per 100 000 population (95% CI 6·8–12·4). One implication is that many people with tuberous sclerosis do not receive either genetic counselling or specialist medical supervision.

CDKL5 mutations cause infantile spasms, early onset seizures, and severe mental retardation in female patients

Objective: To determine the frequency of mutations in CDKL5 in both male and female patients with infantile spasms or early onset epilepsy of unknown cause, and to consider whether the breadth of the reported phenotype would be extended by studying a different patient group. Methods: Two groups of patients were investigated for CDKL5 mutations. Group 1 comprised 73 patients (57 female, 16 male) referred to Cardiff for CDKL5 analysis, of whom 49 (42 female, 7 male) had epileptic seizure onset in the first six months of life. Group 2 comprised 26 patients (11 female, 15 male) with infantile spasms previously recruited to a clinical trial, the UK Infantile Spasms Study. Where a likely pathogenic mutation was identified, further clinical data were reviewed. Results: Seven likely pathogenic mutations were found among female patients from group 1 with epileptic seizure onset in the first six months of life, accounting for seven of the 42 in this group (17%). No mutations other than the already published mutation were found in female patients from group 2, or in any male patient from either study group. All patients with mutations had early signs of developmental delay and most had made little developmental progress. Further clinical information was available for six patients: autistic features and tactile hypersensitivity were common but only one had suggestive Rett-like features. All had a severe epileptic seizure disorder, all but one of whom had myoclonic jerks. The EEG showed focal or generalised changes and in those with infantile spasms, hypsarrhythmia. Slow frequencies were seen frequently with a frontal or fronto-temporal predominance and high amplitudes. Conclusions: The spectrum of the epileptic seizure disorder, and associated EEG changes, in those with CDKL5 mutations is broader than previously reported. CDKL5 mutations are a significant cause of infantile spasms and early epileptic seizures in female patients, and of a later intractable seizure disorder, irrespective of whether they have suspected Rett syndrome. Analysis should be considered in these patients in the clinical setting.

The underlying etiology of infantile spasms (West syndrome): Information from the United Kingdom Infantile Spasms Study (UKISS) on contemporary causes and their classification

Purpose:  To examine the underlying etiology of infantile spasms from the United Kingdom Infantile Spasms Study (UKISS), using the pediatric adaptation of ICD 10.

Childhood arterial ischaemic stroke incidence, presenting features, and risk factors: a prospective population-based study

BACKGROUND Arterial ischaemic stroke is an important cause of acquired brain injury in children. Few prospective population-based studies of childhood arterial ischaemic stroke have been undertaken. We aimed to investigate the epidemiology and clinical features of childhood arterial ischaemic stroke in a population-based cohort. METHODS Children aged 29 days to less than 16 years with radiologically confirmed arterial ischaemic stroke occurring over a 1-year period (July 1, 2008, to June 30, 2009) residing in southern England (population denominator 5·99 million children) were eligible for inclusion. Cases were identified using several sources (paediatric neurologists and trainees, the British Paediatric Neurology Surveillance Unit, paediatricians, radiologists, physiotherapists, neurosurgeons, parents, and the Paediatric Intensive Care Audit Network). Cases were confirmed by personal examination of cases and case notes. Details of presenting features, risk factors, and investigations for risk factors were recorded by analysis of case notes. Capture-recapture analysis was used to estimate completeness of ascertainment. FINDINGS We identified 96 cases of arterial ischaemic stroke. The crude incidence of childhood arterial ischaemic stroke was 1·60 per 100 000 per year (95% CI 1·30-1·96). Capture-recapture analysis suggested that case ascertainment was 89% (95% CI 77-97) complete. The incidence of arterial ischaemic stroke was highest in children aged under 1 year (4·14 per 100 000 per year, 95% CI 2·36-6·72). There was no difference in the risk of arterial ischaemic stroke between sexes (crude incidence 1·60 per 100 000 per year [95% CI 1·18-2·12] for boys and 1·61 per 100 000 per year [1·18-2·14] for girls). Asian (relative risk 2·14, 95% CI 1·11-3·85; p=0·017) and black (2·28, 1·00-4·60; p=0·034) children were at higher risk of arterial ischaemic stroke than were white children. 82 (85%) children had focal features (most commonly hemiparesis) at presentation. Seizures were more common in younger children (≤1 year) and headache was more common in older children (>5 years; p<0·0001). At least one risk factor for childhood arterial ischaemic stroke was identified in 80 (83%) cases. INTERPRETATION Age and racial group, but not sex, affected the risk of arterial ischaemic stroke in children. Investigation of such differences might provide causative insights. FUNDING The Stroke Association, UK.

Clinical and molecular characterisation of hereditary dopamine transporter deficiency syndrome: an observational cohort and experimental study

Summary Background Dopamine transporter deficiency syndrome is the first identified parkinsonian disorder caused by genetic alterations of the dopamine transporter. We describe a cohort of children with mutations in the gene encoding the dopamine transporter (SLC6A3) with the aim to improve clinical and molecular characterisation, reduce diagnostic delay and misdiagnosis, and provide insights into the pathophysiological mechanisms. Methods 11 children with a biochemical profile suggestive of dopamine transporter deficiency syndrome were enrolled from seven paediatric neurology centres in the UK, Germany, and the USA from February, 2009, and studied until June, 2010. The syndrome was characterised by detailed clinical phenotyping, biochemical and neuroradiological studies, and SLC6A3 mutation analysis. Mutant constructs of human dopamine transporter were used for in-vitro functional analysis of dopamine uptake and cocaine-analogue binding. Findings Children presented in infancy (median age 2·5 months, range 0·5–7) with either hyperkinesia (n=5), parkinsonism (n=4), or a mixed hyperkinetic and hypokinetic movement disorder (n=2). Seven children had been initially misdiagnosed with cerebral palsy. During childhood, patients developed severe parkinsonism-dystonia associated with an eye movement disorder and pyramidal tract features. All children had raised ratios of homovanillic acid to 5-hydroxyindoleacetic acid in cerebrospinal fluid, of range 5·0–13·2 (normal range 1·3–4·0). Homozygous or compound heterozygous SLC6A3 mutations were detected in all cases. Loss of function in all missense variants was recorded from in-vitro functional studies, and was supported by the findings of single photon emission CT DaTSCAN imaging in one patient, which showed complete loss of dopamine transporter activity in the basal nuclei. Interpretation Dopamine transporter deficiency syndrome is a newly recognised, autosomal recessive disorder related to impaired dopamine transporter function. Careful characterisation of patients with this disorder should provide novel insights into the complex role of dopamine homoeostasis in human disease, and understanding of the pathophysiology could help to drive drug development. Funding Birmingham Childrens Hospital Research Foundation, Birth Defects Foundation Newlife, Action Medical Research, US National Institutes of Health, Wellchild, and the Wellcome Trust.

Developmental and epilepsy outcomes at age 4 years in the UKISS trial comparing hormonal treatments to vigabatrin for infantile spasms: a multi-centre randomised trial

Background Infantile spasms is the name given to a difficult to treat, severe infantile epilepsy with high morbidity. The United Kingdom Infantile Spasms Study (UKISS) showed that absence of spasms on days 13 and 14 after randomisation was more common in infants allocated hormonal treatments than vigabatrin. At 12–14 months, those with no identified aetiology allocated hormonal treatment had better development. However, epilepsy outcome was not affected by treatment allocated. It is not known if the difference in development persists as the infants grow. Methods Infants in UKISS were followed up blind to treatment allocation by telephone at a mean age of 4 years using the Vineland Adaptive Behaviour Scales (VABS) and an epilepsy questionnaire. Findings 9 of 107 enrolled infants had died. 77 were traced and consented to take part. The median (quartile) VABS scores were 60 (42, 97) for the 39 allocated hormonal treatment and 50 (36, 67) for the 38 allocated vigabatrin (Mann–Whitney U=575; p=0.091; median difference (95% CI): 8 (−1 to 19)). For those with no identified aetiology, VABS scores were 96 (52, 102) for the 21 allocated hormonal treatment and 63 (37, 92) for the 16 allocated vigabatrin (U=98.5; p=0.033; median difference (95% CI): 14 (1 to 42)).The proportions in each treatment group with epilepsy were similar. Interpretation For all 77 infants, development and epilepsy outcomes were not significantly different between the two treatment groups. The better development seen at 14 months in those with no identified aetiology allocated hormonal treatment was seen again at 4 years in this study.

Phospholipase C beta 1 deficiency is associated with early-onset epileptic encephalopathy

The epileptic encephalopathies of infancy and childhood are a collection of epilepsy disorders characterized by refractory, severe seizures and poor neurological outcome, in which the mechanism of disease is poorly understood. We report the clinical presentation and evolution of epileptic encephalopathy in a patient, associated with a loss-of-function mutation in the phospholipase C-β 1 gene. We ascertained a consanguineous family containing a male infant who presented with early-onset epileptic encephalopathy for detailed clinical phenotyping and molecular genetic investigation. In addition, a cohort of 12 consanguineous families of children with infantile spasms were analysed for linkage to the phospholipase C-β 1 gene locus. The male infant presented with tonic seizures in early infancy and subsequently developed infantile spasms. Over time, he developed drug-resistant epilepsy associated with severe neurological regression and failure to thrive. Molecular genetic investigation revealed a homozygous loss-of-function 0.5-Mb deletion, encompassing the promoter element and exons 1, 2 and 3 of phospholipase C-β 1 in the index case. Linkage to the phospholipase C-β 1 locus was excluded in the 12 other consanguineous families, consistent with genetic heterogeneity in this disorder. Although phospholipase C-β 1 deficiency has not previously been reported in humans, the Plcb1 homozygote knockout mouse displays early-onset severe tonic seizures and growth retardation, thus recapitulating the human phenotype. Phospholipase C-β 1 has important functions in both hippocampal muscarinic acetylcholine receptor signalling and in cortical development. Thus, the discovery of a phospholipase C-β 1 mutation allows us to propose a novel potential underlying mechanism in early-onset epileptic encephalopathy.