S.R. Mordekar

Homozygous loss-of-function mutations in the gene encoding the dopamine transporter are associated with infantile parkinsonism-dystonia

Genetic variants of the SLC6A3 gene that encodes the human dopamine transporter (DAT) have been linked to a variety of neuropsychiatric disorders, particularly attention deficit hyperactivity disorder. In addition, the homozygous Slc6a3 knockout mouse displays a hyperactivity phenotype. Here, we analyzed 2 unrelated consanguineous families with infantile parkinsonism-dystonia (IPD) syndrome and identified homozygous missense SLC6A3 mutations (p.L368Q and p.P395L) in both families. Functional studies demonstrated that both mutations were loss-of-function mutations that severely reduced levels of mature (85-kDa) DAT while having a differential effect on the apparent binding affinity of dopamine. Thus, in humans, loss-of-function SLC6A3 mutations that impair DAT-mediated dopamine transport activity are associated with an early-onset complex movement disorder. Identification of the molecular basis of IPD suggests SLC6A3 as a candidate susceptibility gene for other movement disorders associated with parkinsonism and/or dystonic features.

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.

Role of imaging in the diagnosis of acute bacterial meningitis and its complications.

Acute bacterial meningitis is a common neurological emergency and a leading cause of death and neurological disability worldwide. Diagnosis is based on clinical and microbiological findings with neuroimaging in the form of CT reserved for those with specific adverse clinical features or when an underlying cause such as mastoiditis is suspected. MRI is extremely useful for detecting and monitoring the complications of meningitis. These can be remembered by the mnemonic HACTIVE (hydrocephalus, abscess, cerebritis/cranial nerve lesion, thrombosis, infarct, ventriculitis/vasculopathy and extra-axial collection). Diffusion weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) are useful to distinguish abscess from other ring enhancing lesions.

Retention rate of Levetiracetam in children with intractable epilepsy at 1 year

UNLABELLED Levetiracetam (LEV) is a novel antiepileptic drug (AED) that has recently obtained marketing authorisation for use in children. The purpose of this study was to assess the efficacy, tolerability and retention rate of LEV in children with refractory epilepsies. It is a retrospective multicentre observational study reporting the use of LEV in 200 children, aged 0.3-19 years (median 9-years-old) over a 4-year period. All of the patients included in the study had refractory epilepsy with a median age of onset of epilepsy of 3 years (range 0-13 years). The 38% had failed and withdrawn 3 or more AEDs previously and 24% were taking at least 2 other AEDs in addition to LEV. The 47% had focal, and 58% had symptomatic epilepsies. The LEV dose ranged from 8 to 100 mg/kg/day (mean 39 mg/kg). The study comprised 215 person years of LEV exposure. RESULTS LEV was well tolerated with a retention rate of 49% at 1 year. No serious adverse events were reported with possibly related adverse events reported in only 24% of patients (mainly emotional or behavioural changes). At more than 2, 6 and 12 months, worthwhile improvement (>50% seizure reduction) was noted in 60, 40 and 32%, including seizure freedom in 14, 14 and 5%, respectively. CONCLUSION Our results confirm the efficacy and tolerability of LEV in children with refractory epilepsies and demonstrate good response and retention rates at 12 months. It represents the largest cohort of paediatric patients published so far on LEV with a 1-year follow-up.

An investigation into the relationship between vigabatrin, movement disorders, and brain magnetic resonance imaging abnormalities in children with infantile spasms

We aimed to investigate the relationship between movement disorders, changes on brain magnetic resonance imaging (MRI), and vigabatrin therapy in children with infantile spasms.

Movement disorders associated with complex regional pain syndrome in children.

The aim of the present study was to review the history, clinical course, treatment, and outcome of movement disorders in children and young people with complex regional pain syndrome (CRPS). Case notes were reviewed retrospectively of children and young people who presented with movement disorders in CRPS to our tertiary paediatric pain service over a period of 13 years. Ten children with CRPS presented with movement disorders (eight females, two males). The age at first presentation with symptoms of CRPS ranged from 8 to 15 years (mean 11y 2mo, median 13y). The most common movement disorder was dystonia (n=8), followed by tremors (n=3) and myoclonus (n=3); two patients had all three movement disorders. The movement disorder affected mainly the lower limb (n=9) with a predilection for the foot (n=7) and was frequently initiated by minor trauma (n=7). Follow‐up ranged from 6 months to 14 years. The outcome was variable, with good prognosis in nearly half of the cases: four children experienced complete resolution of symptoms. Two children showed a slight improvement. Four children showed no improvement. Movement disorders in CRPS are under‐recognized in children. The management has to be multidisciplinary with an expertize in paediatric pain.

The value of long term EEG monitoring in children: A comparison of ambulatory EEG and video telemetry

PURPOSE Outpatient ambulatory EEG may be followed by inpatient video telemetry EEG when investigating children for possible seizures and for classification of epilepsy. We investigated the value of ambulatory EEG and subsequent video telemetry recording in our centre. METHOD The departmental EEG database was interrogated retrospectively for children undergoing ambulatory recording followed by inpatient video telemetry within an 18-month period. RESULTS 30 patients fitted these criteria, 21 females, 9 males, age range 3-16 years. The mean interval between studies was 9 months. For ambulatory recordings 93% of studies were undertaken to ascertain if behaviours were epileptic. 66% of ambulatory recordings studies captured an event of interest and 63% were able to answer the question asked of the test. In video telemetry recording 80% of studies were aimed at ascertaining if events were epileptic or not, 20% were undertaken for classification of seizure type. 70% of recordings captured an ictus and were considered helpful in addressing the clinical question. Pooled together 90% of patients had a paroxysmal event captured and the clinical question answered by the recording techniques. In patients for whom ambulatory recording failed to capture an attack or answer the clinical question, 70% went on to have a successful video telemetry recording. CONCLUSION Both ambulatory EEG and inpatient video telemetry are effective tools for diagnosis of seizures. The majority of patients with failed ambulatory recordings go on to have successful video telemetry. Combining the two resources provides useful clinical information in nearly all instances.

The use of MR imaging and spectroscopy of the brain in children investigated for developmental delay: What is the most appropriate imaging strategy?

ObjectivesDevelopmental delay is a common problem in paediatric practice and many children with developmental delay are referred for MR imaging. Our study was performed as part of a continuing audit process to optimise our MR protocol and case selection.Materials and methodsWe performed MR imaging and spectroscopy protocol on 157 children with developmental delay. We analysed the effect of these interventions by looking at the overall detection rate of relevant pathology and in particular subgroups of the children.Results71% of the children had normal MR imaging, 10% had non-specific findings and 19% had specific abnormalities on MR imaging. The overall risk of having a specific structural abnormality with isolated developmental was 7.5% but if other neurological symptoms/signs were present the risk was 28%. Two children had abnormal spectroscopic findings, one with tuberous sclerosis and the other with absent brain creatine.ConclusionCase selection for MR imaging is important in children with developmental delay. The best strategies for selecting children for MR are either; not performing MR with developmental delay in one domain only or performing MR with developmental delay in three or four domains or if there are other neurological features.

Stroke in a child with neurofibromatosis type 2.

Neurofibromatosis types 1 (NF1) and 2 (NF2) are genetically distinct conditions caused by mutations in tumour suppressor genes that share a number of phenotypic features. Childhood stroke and vasculopathy have been associated with NF1, but not with NF2. We describe a case of brainstem stroke in a child with NF2.

Corticosteroid treatment of behaviour, language and motor regression in childhood disintegrative disorder

Childhood disintegrative disorder (CDD) (ICD-10 F84.3) is defined by a period of normal development before onset followed by gradual loss of previously acquired skills with the development of characteristic abnormalities of social, communicative and behavioural functioning. We report two children with apparent CDD, who showed amelioration of behaviour, language and motor regression after corticosteroid treatment.