Genetic mapping of a major susceptibility locus for juvenile myoclonic epilepsy on chromosome 15q

The epilepsies are a group of disorders characterised by recurrent seizures caused by episodes of abnormal neuronal hyperexcitability involving the brain. Up to 60 million people are affected worldwide and genetic factors may contribute to the aetiology in up to 40% of patients. The most common human genetic epilepsies display a complex pattern of inheritance. These are categorised as idiopathic in the absence of detectable structural or metabolic abnormalities. Juvenile myoclonic epilepsy (JME) is a distinctive and common variety of familial idiopathic generalised epilepsy (IGE) with a prevalence of 0.5-1.0 per 1000 and a ratio of sibling risk to population prevalence (lambda(s)) of 42. The molecular genetic basis of these familial idiopathic epilepsies is entirely unknown, but a mutation in the gene CHRNA4, encoding the alpha4 subunit of the neuronal nicotinic acetylcholine receptor (nAChR), was recently identified in a rare Mendelian variety of idiopathic epilepsy. Chromosomal regions harbouring genes for nAChR subunits were therefore tested for linkage to the JME trait in 34 pedigrees. Significant evidence for linkage with heterogeneity was found to polymorphic loci encompassing the region in which the gene encoding the alpha7 subunit of nAChR (CHRNA7) maps on chromosome 15q14 (HLOD = 4.4 at alpha = 0.65; Z(all) = 2.94, P = 0.0005). This major locus contributes to genetic susceptibility to JME in a majority of the families studied.

Severe myoclonic epilepsy of infancy: extended spectrum of GEFS+?

PURPOSE

Severe myoclonic epilepsy of infancy (SMEI) is an intractable epilepsy of early childhood of unknown etiology. It is often associated with a family history of seizure disorders, but epilepsy phenotypes have not been well described. We sought to characterize the seizure phenotypes of relatives to better understand to the genetic basis of SMEI.

METHODS

Probands with SMEI were identified, and systematic family studies were performed. Epilepsy syndromes were characterized in affected family members.

RESULTS

Twelve probands with SMEI were identified. Eleven of the 12 probands with SMEI had a family history of seizures, and the twelfth was the result of a consanguineous marriage. We found that 16.7% of full siblings and 8.3% of parents had definite seizures. A total of 39 affected family members was identified. The most common phenotype was febrile seizures in 14, febrile seizures plus in seven, partial epilepsy in two, and there were single individuals with SMEI, myoclonic-astatic epilepsy, Lennox-Gastaut syndrome, and 13 cases with unclassified or unconfirmed seizures.

CONCLUSIONS

The family history of seizures in SMEI is in keeping with the spectrum of seizure phenotypes seen in generalized epilepsy with febrile seizures plus (GEFS+). Our findings suggest that SMEI is the most severe phenotype in the GEFS+ spectrum.

Melatonin for sleep problems in children with neurodevelopmental disorders: randomised double masked placebo controlled trial

OBJECTIVE

To assess the effectiveness and safety of melatonin in treating severe sleep problems in children with neurodevelopmental disorders.

DESIGN

12 week double masked randomised placebo controlled phase III trial.

SETTING

19 hospitals across England and Wales.

PARTICIPANTS

146 children aged 3 years to 15 years 8 months were randomised. They had a range of neurological and developmental disorders and a severe sleep problem that had not responded to a standardised sleep behaviour advice booklet provided to parents four to six weeks before randomisation. A sleep problem was defined as the child not falling asleep within one hour of lights out or having less than six hours' continuous sleep.

INTERVENTIONS

Immediate release melatonin or matching placebo capsules administered 45 minutes before the child's bedtime for a period of 12 weeks. All children started with a 0.5 mg capsule, which was increased through 2 mg, 6 mg, and 12 mg depending on their response to treatment.

MAIN OUTCOME MEASURES

Total sleep time at night after 12 weeks adjusted for baseline recorded in sleep diaries completed by the parent. Secondary outcomes included sleep onset latency, assessments of child behaviour, family functioning, and adverse events. Sleep was measured with diaries and actigraphy.

RESULTS

Melatonin increased total sleep time by 22.4 minutes (95% confidence interval 0.5 to 44.3 minutes) measured by sleep diaries (n=110) and 13.3 (-15.5 to 42.2) measured by actigraphy (n=59). Melatonin reduced sleep onset latency measured by sleep diaries (-37.5 minutes, -55.3 to -19.7 minutes) and actigraphy (-45.3 minutes, -68.8 to -21.9 minutes) and was most effective for children with the longest sleep latency (P=0.009). Melatonin was associated with earlier waking times than placebo (29.9 minutes, 13.6 to 46.3 minutes). Child behaviour and family functioning outcomes showed some improvement and favoured use of melatonin. Adverse events were mild and similar between the two groups.

CONCLUSIONS

Children gained little additional sleep on melatonin; though they fell asleep significantly faster, waking times became earlier. Child behaviour and family functioning outcomes did not significantly improve. Melatonin was tolerable over this three month period. Comparisons with slow release melatonin preparations or melatonin analogues are required.

TRIAL REGISTRATION

ISRCT No 05534585.

Acute disseminated encephalomyelitis: a review of 18 cases in childhood

OBJECTIVE

Acute disseminated encephalomyelitis (ADEM) is a treatable inflammatory demyelinating disorder seen more commonly in children than in adults. It typically presents to general paediatricians, often, like encephalitis, with non-specific cerebrospinal fluid findings. The brain computerized tomography scan is usually normal, so is falsely reassuring and delays the diagnosis, which might result in considerable morbidity. The present study was initiated to report on the various modes of presentation and raise the awareness of the diagnosis of ADEM among general paediatricians.

METHODS

A retrospective review of the case notes of 18 children with a diagnosis of ADEM established in a tertiary referral centre from 1995 to 2000 was undertaken with particular reference to clinical features, investigations and treatment.

RESULTS

The most common presenting features were ataxia (10 cases), followed by headache (eight cases) and weakness (five cases). Magnetic resonance imaging (MRI) of the brain was needed to confirm the diagnosis in all 18 children. Treatment usually included a course of intravenous methylprednisolone followed by a tapering dose of oral prednisolone over several weeks. Although the outcome for most of the children was generally good, two relapsed after cessation of steroids and five children had ongoing disabilities.

CONCLUSIONS

The investigation of choice for establishing the diagnosis of ADEM was MRI of the brain. Other investigations were seldom helpful in reaching the diagnosis. Early diagnosis and prompt treatment of ADEM will probably reduce morbidity.

Acute disseminated encephalomyelitis: recognition in the hands of general paediatricians

Acute disseminated encephalomyelitis will often present to the general paediatrician as an acute polysymptomatic encephalopathy, and initially the diagnosis may not be clear. A brain MRI scan is essential in establishing the diagnosis and so enabling appropriate advice and treatment to be given. Multicentre clinical audit of outcome and controlled therapeutic trials are needed to secure an evidence base for current practice.

Melatonin is useful for recording sleep EEGs: a prospective audit of outcome

The study aimed to determine if melatonin could reliably induce sleep in children undergoing sleep EEG without affecting the usefulness of the EEG itself. One hundred and sixty three children (112 males, 51 females; mean age 8 years, range 1 to 16 years) referred for sleep EEG were studied. The children were given 2 to 10 mg of melatonin, depending on age, just before EEG recording. Measurements included sleep-onset latency, adverse effects, and acceptability of the EEG. Usefulness and acceptability of melatonin-induced sleep EEG were compared with the standard technique of sleep EEG following sleep deprivation in 30 children (matched for sex and age). Sleep was obtained in 79% of the 163 children who received melatonin after an average of 33 minutes. Yield of epileptiform abnormalities demonstrated in the melatonin sleep EEG was similar to that reported in the literature for sleep-deprived EEGs. There was no significant adverse effect. When compared, a melatonin-induced sleep EEG was as useful as a sleep-deprived EEG. However, the children's behaviour on the day of the melatonin-induced sleep EEG recording was more acceptable to parents.

Pyruvate dehydrogenase E3 binding protein (protein X) deficiency

Pyruvate dehydrogenase (PDH) deficiency is a major cause of neurological dysfunction and lactic acidosis in infancy and early childhood. The great majority of cases (>80%) result from mutations in the X-linked gene for the E1alpha subunit of the complex (PDHA1). Mutations in the genes for the other subunits have all been described, but only dihydrolipoamide dehydrogenase (E3) and E3 binding protein (E3BP) defects contribute significantly to the total number of patients with PDH deficiency. Although previously considered rare, with only 13 reported cases, we have found that mutations in PDX1, the gene for the E3 binding protein, are in fact relatively common. Clinical, biochemical, and genetic features of six new patients (four males, two females; age range 15mo-6y) with mutations in this gene are compared with previously reported cases. All patients with E3BP deficiency identified to date have mutations which completely prevent synthesis of the protein product. However, they are generally less severely affected than patients with PDHA1 mutations, although there is considerable overlap in clinical and neuroradiological features.

Comparative audit of intravenous lorazepam and diazepam in the emergency treatment of convulsive status epilepticus in children

There is little evidence on which to judge the optimal treatment for convulsive status epilepticus (CSE) in children. This study compares the effect of intravenous (iv) lorazepam with iv diazepam as the first line of treatment of CSE. We studied all children with prolonged seizures arriving in the Accident and Emergency (A&E) Department in two separate periods. In the first 6-month period iv diazepam was used as standard treatment, in the second 1-year period iv lorazepam was used. We measured latency to stopping of seizure and any adverse events. A successful treatment was defined as one in which the seizure clinically ceased within 15 minutes after siting the iv cannula, requiring no further treatment.Intravenous diazepam (0.32 mg kg (-1)) was used in 17 of 26 patients, whilst iv lorazepam (0.13 mg kg (-1)) was used in 31 of 59. There were no differences between the two groups regarding age, sex and seizure type.The seizure was successfully controlled 15 minutes after siting the iv cannula in 11 (65%) patients treated with diazepam (median time of 3 minutes) and in 20 (65%) patients treated with lorazepam (median time of 5 minutes). These preliminary results suggest that iv lorazepam may be as effective as iv diazepam.

A case of Ohtahara syndrome with cytochrome oxidase deficiency

Ohtahara syndrome is a rare cause of epileptic seizures during the neonatal period. This is believed to be the first report of this syndrome with a specific metabolic defect. Defects in respiratory chain function may be more common than previously assumed in patients with this epilepsy syndrome.

Benign childhood epilepsy with centrotemporal spikes and the focal sharp wave trait is not linked to the fragile X region

Benign childhood epilepsy with centrotemporal spikes (BCECS, benign rolandic epilepsy) is a common form of genetically determined localisation-related epilepsy of childhood. The characteristic age-dependent focal sharp wave (fsw) found on the EEG in this disorder segregates as a dominant trait in families with probands with BCECS. Seizures occur in a significant proportion of individuals with the fragile X syndrome in association with EEG abnormalities comparable to those found in BCECS. The possibility of a common genetic basis for these disorders was investigated by linkage analysis. Six pedigrees with probands with BCECS were analysed using a marker locus DXS548, close to the fragile X site, fra (X). Obligate recombinants between DXS548 and the fsw trait were observed in all six families. Assuming X-linked dominant inheritance and penetrance values of 0.4 (male) and 0.1 (female) a negative lod score of -6.823 was obtained at zero recombination and lod scores of -2.0 at 10cM either side of the fra (X) locus. These results exclude an important candidate gene for this common childhood disorder.

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

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.

Epilepsy and associated mortality in patients with multiple sclerosis

BACKGROUND AND PURPOSE

We aimed to determine the prevalence of epilepsy in patients with multiple sclerosis (MS) at diagnosis, the risk of developing epilepsy after the diagnosis of MS and the relative risk of mortality associated with epilepsy.

METHODS

We used the UK Clinical Practice Research Data-link to identify 2526 patients with incident MS and 9980 age-, sex- and index year-matched non-MS controls from 1997 to 2006. Logistic regression was used to estimate odds ratios [95% confidence interval (CI)] for epilepsy and Cox regression was used to estimate hazard ratios (HRs) (95% CI) for epilepsy and mortality.

RESULTS

Patients with incident MS were on average 45 years old and 70.9% were female. At diagnosis, the prevalence of epilepsy in patients with MS was 1.30% compared with 0.57% in non-MS controls. At diagnosis, MS was associated with an adjusted odds ratio (95% CI) of 2.11 (1.36-3.27) for pre-existing epilepsy. Among epilepsy-free patients, the cumulative probabilities of developing epilepsy, first recorded within 10 years of the index date, were 2.77% for patients with MS and 0.90% for controls. MS was associated with an adjusted HR (95% CI) of 6.01 (2.94-12.29) for epilepsy. Among patients with MS, epilepsy was associated with an HR (95% CI) of 2.23 (1.02-4.84) for all-cause mortality.

CONCLUSIONS

This population-based study found an increased prevalence of epilepsy in patients with MS at diagnosis when compared with non-MS controls and the risk of developing epilepsy was also higher following the MS diagnosis. Patients with MS with epilepsy had a higher risk of mortality compared with those without.

Personal resuscitation plans and end of life planning for children with disability and life-limiting/life-threatening conditions

This article discusses the need for person-specific planning for the increasing numbers of disabled children with life-limiting and life-threatening conditions. It describes the system developed in Nottingham for this client group to have a family-held personal resuscitation plan, (PRP) which is developed with the child and family by their lead paediatrician. The PRP is an emergency medical care plan which supports the provision of the most appropriate level of intervention for the child whether they are at home, school, short break unit or hospital. The PRP template is presented with advice on implementation and case examples. Feedback from families, medical and nursing staff is that PRPs are useful and empowering. The system supports timely discussions about appropriate care in an emergency and the communication of decisionsmade jointly by the child, family and medical team to all concerned. A flexible and person-specific PRP stating what interventions to do such as airway clearance, facial oxygen, trial of bag and mask ventilation is preferable to a do not attempt resuscitation form which is an 'all or nothing system' and can seem very negative to families. A PRP in the home can support appropriate action from local rapid response teams set up to review unexpected child deaths.

When to image neurologically normal children with headaches: development of a decision rule

AIMS

The aim of this study was to develop and refine a decision rule on when to undertake brain imaging (BI) in neurologically normal children with headaches.

METHODS

From the literature and a questionnaire study, a list of red flags (RFs) was drawn-up. During the prospective 4-year period, consecutive children with headache were classified according to RFs and the headache diagnosis.

RESULT

Three of 709 (0.4%) neurologically normal children had significant brain abnormalities. BI was carried out in 389 of 498 (78%) children with RFs. Significant abnormalities were found in three of 389 children (0.8%), all had unclassified headache (UH). BI was not arranged for the 211 children with no RFs. None of these developed RFs or abnormal signs on follow-up for a mean of 13 months.

CONCLUSION

In addition to BI for those with neurological signs, we think BI should be considered for neurologically normal patients with UH and RFs. This would have saved imaging children needlessly: only 101 of 709 (14%) would have had scans arranged, instead of 389 of 709.

Brachial neuritis following infection with Epstein-Barr virus

A case of brachial neuritis after infection with Epstein-Barr virus in a 15-year-old girl is presented. A review of the literature contrasts the presenting features in children and adults. Diagnostic tests, treatment and prognosis are discussed.

Idiopathic central pontine myelinolysis in childhood

Central pontine myelinolysis (CPM) is rare in childhood with only a few cases reported in world literature. We report a 7-year-old male who presented with acute ataxia, swallowing difficulties, dysarthria, and radiological features consistent with the disorder. He improved remarkably with oral prednisolone therapy and was almost back to normal by 2 weeks. A review of the literature is also included.

Occult carotid pseudoaneurysm following streptococcal throat infection

Pseudoaneurysm of the internal carotid artery (PAICA) is a rare complication of neck space infection. An 8-year-old girl presented with odynophagia (painful swallowing), trismus and left peritonsillar swelling. Abscess was suspected, but aspiration was dry. The PAICA was diagnosed on computed tomography. The aneurysm and involved left internal carotid artery were occluded endovascularly. She has made an uneventful recovery.

Acute bilateral thalamic necrosis in a child with Mycoplasma pneumoniae

A previously neurodevelopmentally intact 5-year-old male was admitted to hospital with a right lower lobe pneumonia with pleural effusion, subsequently confirmed to be a Mycoplasma pneumoniae infection. On the seventh day of the illness he had a prolonged generalized tonic or tonic-clonic convulsion, requiring intubation and ventilation. He was slow to regain consciousness (Child's Glasgow Coma Score 7-10 over 6 days) and brain imaging with CT and then MRI demonstrated bilateral thalamic lesions with oedema and central haemorrhage suggestive of acute bilateral thalamic necrosis, without striatal or white-matter involvement. He was treated with a 2-week course of erythromycin, and as an autoimmune process was considered possible, 5 days of intravenous methylprednisolone (20 mg/kg/day) followed by a 4-week oral prednisolone taper. He made a slow recovery over the next few weeks with almost complete neurological recovery by 2 months but with significant dysarthria, drooling, and a mild left hemiparesis. At 9 months, significant dystonia continued to affect his speech and, together with tremor, his upper-limb fine motor function bilaterally. His gait, personality, and higher cognitive functions appeared to have recovered fully. Although acute striatal necrosis, acute disseminated encephalomyelitis, and encephalitis have been reported with Mycoplasma pneumoniae and a similar picture of acute bilateral thalamic necrosis with influenza-A ('acute necrotizing encephalopathy'), this is the first reported case of Mycoplasma pneumoniae-associated isolated acute bilateral thalamic necrosis.

Status epilepticus on the paediatric intensive care unit-the role of EEG monitoring

A pilot study was undertaken of the feasibility of continuous EEG monitoring of patients admitted to a Paediatric Intensive Care Unit (PICU) for management of status epilepticus or its immediate sequelae. Eight children were studied and seizure activity was recorded in four patients. Additional information influencing management was obtained: the bedside nurse considered decerebrate posturing in one patient to be a seizure: there were no epileptiform EEG changes. Another patient was considered to have seizures (clonic movements of both upper limbs) following cardiac arrest; the EEG showed electrocerebral silence, and thiopentone treatment was discontinued. In another patient, continuing epileptiform activity on EEG gave intensivists the confidence to use higher than usual doses of thiopentone. The problems encountered were delays in monitoring, once for a CT scan and once because of two admissions within hours of each other. We conclude that EEG monitoring on a PICU is feasible and provides clinically useful information.

An established case of dentatorubral pallidoluysian atrophy (DRPLA) with unusual features on muscle biopsy

Dentatorubral pallidoluysian atrophy (DRPLA) belongs to the group of autosomal dominant ataxias. Central nervous system pathology and inheritance are both well characterized, although the illness is rare. The presentation of a European child affected by this illness is described. He presented at 9 years of age with intractable progressive myoclonus epilepsy against a background of learning difficulties and developed progressive hypertonicity and dementia before his death at 15 years of age. Significant histological changes in a muscle biopsy were found. There was an absence of type IIB fibres and a predominance of type I fibres. Mean fibre diameter of all the fibre types was markedly reduced. All type I fibres showed an increase in lipid droplets. No previous descriptions exist of muscle histology in DRPLA. Although at least five adult family members have symptoms consistent with a diagnosis of DRPLA, their condition had not been recognized. We therefore describe the clinical picture and histological findings.

Idiopathic gait disorder among in-patients with acquired gait disorders admitted to a children's hospital

Many children are admitted to hospital for treatment of an acquired gait disorder. Some gait disorders have a definite underlying physical cause and some are idiopathic. A literature review shows that there have been few attempts to estimate the incidence or prevalence of idiopathic gait disorder in children. The economic and social impact may be substantial with regard to therapy and investigations and school absence, respectively. This study attempted to estimate the incidence and impact of idiopathic gait disorder in a tertiary children's hospital. It evaluated prospectively all the children admitted with a gait disorder requiring physiotherapy treatment at Birmingham Children's Hospital, using a standardized pro-forma, during a 3-month period between March-June 1999. One hundred and three children (aged 2-16 years) were admitted with gait disorders (57 female and 46 male). Eight had an idiopathic gait disorder. All eight children exhibited significant functional impairment, pain and school absence. Idiopathic gait disorder accounted for 8% of children admitted to hospital with an acquired gait disorder and had an annual incidence of at least 2-4 per 100,000 children. The economic and social impact of these disorders is, therefore, substantial, especially with regard to diagnosis, investigations, treatment and school absence.

Siblings with development delay, mild spasticity and subcortical cysts: a further leukoencephalopathy?

We present a family with mild neurological symptoms and intra-cerebral subcortical cysts on magnetic resonance imaging (MRI). Common clinical features are microcephaly, learning difficulties, spasticity, dyspraxia and restricted movements of the neck and shoulder. The family has features in common with vacuolating leukoencephalopathy of van de Knaap and Olivier and may represent a new variant.