Cyril Gitiaux

Epileptic and nonepileptic features in patients with early onset epileptic encephalopathy and STXBP1 mutations

Purpose:  STXBP1 (MUNC18‐1) mutations have been associated with various types of epilepsies, mostly beginning early in life. To refine the phenotype associated with STXBP1 aberrations in early onset epileptic syndromes, we studied this gene in a cohort of patients with early onset epileptic encephalopathy.

Mutations in the telomere capping complex in bone marrow failure and related syndromes

Dyskeratosis congenita and its variants have overlapping phenotypes with many disorders including Coats plus, and their underlying pathology is thought to be one of defective telomere maintenance. Recently, biallelic CTC1 mutations have been described in patients with syndromes overlapping Coats plus. CTC1, STN1 and TEN1 are part of the telomere-capping complex involved in maintaining telomeric structural integrity. Based on phenotypic overlap we screened 73 genetically uncharacterized patients with dyskeratosis congenita and related bone marrow failure syndromes for mutations in this complex. Biallelic CTC1 mutations were identified in 6 patients but none in either STN1 or TEN1. We have expanded the phenotypic spectrum associated with CTC1 mutations and report that intracranial and retinal abnormalities are not a defining feature, as well as showing that the effect of these mutations on telomere length is variable. The study also demonstrates the lack of disease-causing mutations in other components of the telomere-capping complex.

Early electro-clinical features may contribute to diagnosis of the anti-NMDA receptor encephalitis in children

OBJECTIVE To describe initial and follow-up electroencephalographic (EEG) characteristics in anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. METHODS Consecutive polygraphic video-EEG recordings were analyzed in nine pediatric patients with anti-NMDAR encephalitis at the initial stage of the disease and during the intermediate period until motor recovery. EEG characteristics in waking and sleep stages as well as EEG correlates of abnormal movements are described. RESULTS In six patients, [corrected] the waking EEG showed preserved background activity and either focal or unilateral hemispheric slowing. These children had more favorable outcome than the three children with diffuse slowing. Unilateral [corrected] abnormal movements contra-lateral to hemispheric or focal slowing were also indicative of milder severity when compared to generalized abnormal movements and diffuse slowing. During non-rapid eye movement (NREM) sleep, a decrease in the expected slow waves and unilateral or diffuse theta-alpha band rhythms were observed in six children, not correlated with the outcome, representing a suggestive EEG pattern of anti-NMDAR encephalitis. [corrected]. CONCLUSIONS In pediatric patients presenting behavioral disorders and abnormal movements, early EEG patterns may be suggestive of anti-NMDAR encephalitis. Moreover early electro-clinical presentation contributes to outcome prediction. SIGNIFICANCE This case series demonstrates that early EEG patterns may be suggestive of anti-NMDAR encephalitis in pediatric patients with behavioral disorders and abnormal movements.

Spectrum of movement disorders associated with glutaric aciduria type 1: a study of 16 patients.

Glutaric aciduria type 1 (GA1) is an autosomal recessive neurometabolic disorder due to glutaryl CoA dehydrogenase deficiency. Comprehensive descriptions of GA1‐associated movement disorders are rare. In order to refine the description of the motor phenotype, we prospectively studied 16 consecutive pediatric and adult GA1 patients, focusing on the movement disorders and their time course. In most patients, generalized dystonia, superimposed on baseline axial hypotonia, remained the predominant feature throughout the disease course. With aging, it tended to evolve from mobile to fixed dystonia and to be associated with akinetic‐rigid parkinsonism. Prominent orofacial involvement was a consistent feature in GA1 patients with movement disorders, resulting in speech disorders with features of combined hyperkinetic dysarthria and speech apraxia. The types and outcome of movement disorders in this setting should be taken into consideration during rehabilitation and for patient selection and evaluation in therapeutic trials.

Misleading behavioural phenotype with adenylosuccinate lyase deficiency.

Adenylosuccinate lyase deficiency is a rare autosomal disorder of de novo purine synthesis, which results in the accumulation of succinylpurines in body fluids. Patients with adenylosuccinate lyase deficiency show a variable combination of mental retardation, epilepsy and autistic features and are usually discovered during screens for unexplained encephalopathy using the Bratton–Marshall assay that reveals the excretion of the succinylaminoimidazolecarboxamide riboside (SAICAr). Here, we report on two sisters aged 11 and 12 years presented with global developmental delay, motor apraxia, severe speech deficits, seizures and behavioural features, which combined excessive laughter, a very happy disposition, hyperactivity, a short attention span, the mouthing of objects, tantrums and stereotyped movements that gave a behavioural profile mimicking Angelman syndrome. Both patients had an increased succinyladenosine/SAICAr ratio of 1.6, and exhibited a novel homozygous missense mutation (c.674T>C; p.Met225Thr) in the exon 6 of the ADSL gene. We suggest that these clinical features might be a new presentation of adenylosuccinate lyase deficiency. On the basis of this observation, although adenylosuccinate lyase deficiency is a rare disorder, this diagnosis should be considered in patients with mental retardation and a behavioural profile suggestive of Angelman syndrome.

Whole microvascular unit deletions in dermatomyositis

Objectives The pathophysiology of dermatomyositis (DM) remains unclear, combining immunopathological mechanisms with ischaemic changes regarded as a consequence of membranolytic attack complex (MAC)-induced capillary destruction. The study is a reappraisal of the microvascular involvement in light of the microvascular organisation in normal human muscle. Methods Muscle microvasculature organisation was analysed using 3D reconstructions of serial sections immunostained for CD31, and histoenzymatic detection of endogenous alkaline phosphatase activity of microvessels. An unbiased point pattern analysis-based method was used to evaluate focal capillary loss. Double immunostainings identified cell types showing MAC deposits. Results The normal arterial tree includes perimysial arcade arteries, transverse arteries penetrating perpendicularly into the endomysium and terminal arterioles feeding a microvascular unit (MVU) of six to eight capillaries contacting an average of five myofibres. Amyopathic DM cases (n=3) and non-necrotic fascicles of early DM cases (n=27), showed patchy capillary loss in the form of 6-by-6 capillary drop-out, corresponding to depletion of one or multiple MVUs. MAC deposits were also clustered (5–8 immunostained structures, including endothelial cells, but also pericytes, mesenchymal cells and myosatellite cells). Conclusions Capillary loss may not be the primary cause of muscle ischaemia in DM. The primary event rather stands upstream, probably at the level of perimysial arcade arteries around which inflammatory infiltrates predominate and which lumen may show narrowing in chronic DM. Ischaemia-reperfusion injury, which is favoured by autoimmune backgrounds in experimental models and which activates the complement cascade in capillaries, could represent an hitherto unsuspected (and potentially preventable) mechanism of muscle damage in DM.

Brain magnetic resonance imaging pattern and outcome in children with haemolytic‐uraemic syndrome and neurological impairment treated with eculizumab

The aim of this study was to describe the magnetic resonance imaging (MRI) findings and the neurological and neuropsychological outcomes in paediatric, diarrhoea‐associated haemolytic–uraemic syndrome (D+HUS) with central nervous system impairment treated with eculizumab, a monoclonal antibody.

Cerebral vasculitis in severe Kawasaki disease: early detection by magnetic resonance imaging and good outcome after intensive treatment

Kawasaki disease is an acute vasculitis, that has a classic complication of acquired coronary artery aneurysm. Severe forms with multi‐organ involvement or neurological dysfunction are rare. Cerebral vascular involvement has been related to large‐vessel injury or cardioembolism, leading to focal brain infarction. A 4‐year‐old female presented with unusual, rapidly catastrophic Kawasaki disease with refractory shock, acute renal failure, and coma, requiring intensive haemodynamic management. The observation of diffuse micro‐haemorrhages (T2*‐weighted sequence) associated with white matter injury on brain magnetic resonance imaging (MRI) pointed towards lesions of the medium/small blood vessels. Cerebral vasculitis was suspected and the immunosuppressive treatment was increased Subsequently, the patient’s recovery was rapid. On follow‐up severe, bilateral vitritis was evident and surgery improved visual outcome. Early recognition of severe or unusual forms of Kawasaki disease could lead to more favourable outcome using appropriate treatment strategies. Diffuse cerebral micro‐haemorrhages on T2* brain MRI sequences might be a key sign for the diagnosis of medium or small cerebral vessel involvement.

Vasculopathy-related clinical and pathological features are associated with severe juvenile dermatomyositis

OBJECTIVE Outcome of JDM is highly heterogeneous. Our objective was to determine clinical and muscle biopsy features associated with poor outcome and response to treatment. METHODS Clinical data and muscle biopsy were obtained from a monocentric cohort of 29 patients. Clinical subgroups were defined by latent class model analysis of initial and follow-up parameters. Myopathological features were analysed using validated scores. Capillary loss was determined on reconstructions of transversal sections and assessed in the different age groups to take into account variations of muscle capillarization during post-natal development. Regression models were used to identify initial predictors of therapeutic response. RESULTS Two distinct homogeneous subgroups of patients were identified according to clinical severity and pathological findings. The smallest group of patients (7/29) presented with severe JDM. Compared with the other group (22/29), patients had more severe muscle weakness at disease onset, low remission rate at 12 months, frequent subcutaneous limb oedema or gastrointestinal (GI) involvement and higher myopathological scores (capillary dropout, perifascicular necrosis/regeneration, fibres with internal myonuclei and fibrosis subscores). Relevance of capillary dropout to JDM severity was substantiated by age-based analysis, confirming its major role in JDM pathophysiology. Most of these manifestations could be related to vasculopathy (limb oedema, GI involvement, capillary dropout). Furthermore, Childhood Myositis Assessment Scale <34 with either GI involvement or muscle endomysial fibrosis at disease onset were the best predictors of poor response to treatment. CONCLUSION Vasculopathy is prominent in severe JDM. Simple criteria can be used at initial evaluation to identify patients requiring a more intensive therapy.

Skeletal Muscle Microvasculature: A Highly Dynamic Lifeline

Skeletal muscle is highly irrigated by blood vessels. Beyond oxygen and nutrient supply, new vessel functions have been identified. This review presents vessel microanatomy and functions at tissue, cellular, and molecular levels. Mechanisms of vessel plasticity are described during skeletal muscle development and acute regeneration, and in physiological and pathological contexts.