Unclassified white matter disorders: A diagnostic journey requiring close collaboration between clinical and laboratory services.

BACKGROUND: Next generation sequencing studies have revealed an ever-increasing number of causes for genetic disorders of central nervous system white matter. A substantial number of disorders are identifiable from their specific pattern of biochemical and/or imaging findings for which single gene testing may be indicated. Beyond this group, the causes of genetic white matter disorders are unclear and a broader approach to genomic testing is recommended. AIM: This study aimed to identify the genetic causes for a group of individuals with unclassified white matter disorders with suspected genetic aetiology and highlight the investigations required when the initial testing is non-diagnostic. METHODS: Twenty-six individuals from 22 families with unclassified white matter disorders underwent deep phenotyping and genome sequencing performed on trio, or larger, family groups. Functional studies and transcriptomics were used to resolve variants of uncertain significance with potential clinical relevance. RESULTS: Causative or candidate variants were identified in 15/22 (68.2%) families. Six of the 15 implicated genes had been previously associated with white matter disease (COL4A1, NDUFV1, SLC17A5, TUBB4A, BOLA3, DARS2). Patients with variants in the latter two presented with an atypical phenotype. The other nine genes had not been specifically associated with white matter disease at the time of diagnosis and included genes associated with monogenic syndromes, developmental disorders, and developmental and epileptic encephalopathies (STAG2, LSS, FIG4, GLS, PMPCA, SPTBN1, AGO2, SCN2A, SCN8A). Consequently, only 46% of the diagnoses would have been made via a current leukodystrophy gene panel test. DISCUSSION: These results confirm the importance of broad genomic testing for patients with white matter disorders. The high diagnostic yield reflects the integration of deep phenotyping, whole genome sequencing, trio analysis, functional studies, and transcriptomic analyses. CONCLUSIONS: Genetic white matter disorders are genetically and phenotypically heterogeneous. Deep phenotyping together with a range of genomic technologies underpin the identification of causes of unclassified white matter disease. A molecular diagnosis is essential for prognostication, appropriate management, and accurate reproductive counseling.

Australian clinical consensus guideline for the subacute rehabilitation of childhood stroke.

Childhood stroke results in long-term, multifaceted difficulties, affecting motor, cognitive, communication, and behavioral domains of function which impact on participation and quality of life. The Childhood Stroke Consensus Rehabilitation Guideline was developed to improve the care of children with stroke by providing health professionals with recommendations to assist in their rehabilitative treatment. Clinical questions were formulated to inform systematic database searches from 2001 to 2016, limited to English and pediatric studies. SIGN methodology and the National Health and Medical Research Council system were used to screen and classify the evidence. The Grade of Recommendation, Assessment, Development and Evaluation system was used to grade evidence as strong or weak. Where evidence was inadequate or absent, a modified Delphi consensus process was used to develop consensus-based recommendations. The guideline provides 56 recommendations (1 evidence-based recommendation and 55 consensus recommendations). These relate to the framework of rehabilitation service delivery as well as domain-specific rehabilitation treatment strategies for each domain of function. It is anticipated that this guideline will provide health professions with recommendations to improve the subacute care of children with stroke both in Australia and internationally.

Clinical and Imaging Characteristics of Arteriopathy Subtypes in Children with Arterial Ischemic Stroke: Results of the VIPS Study.

BACKGROUND AND PURPOSE: Childhood arteriopathies are rare but heterogenous, and difficult to diagnose and classify, especially by nonexperts. We quantified clinical and imaging characteristics associated with childhood arteriopathy subtypes to facilitate their diagnosis and classification in research and clinical settings. MATERIALS AND METHODS: The Vascular Effects of Infection in Pediatric Stroke (VIPS) study prospectively enrolled 355 children with arterial ischemic stroke (2010-2014). A central team of experts reviewed all data to diagnose childhood arteriopathy and classify subtypes, including arterial dissection and focal cerebral arteriopathy-inflammatory type, which includes transient cerebral arteriopathy, Moyamoya disease, and diffuse/multifocal vasculitis. Only children whose stroke etiology could be conclusively diagnosed were included in these analyses. We constructed logistic regression models to identify characteristics associated with each arteriopathy subtype. RESULTS: Among 127 children with definite arteriopathy, the arteriopathy subtype could not be classified in 18 (14%). Moyamoya disease (n = 34) occurred mostly in children younger than 8 years of age; focal cerebral arteriopathy-inflammatory type (n = 25), in children 8-15 years of age; and dissection (n = 26), at all ages. Vertigo at stroke presentation was common in dissection. Dissection affected the cervical arteries, while Moyamoya disease involved the supraclinoid internal carotid arteries. A banded appearance of the M1 segment of the middle cerebral artery was pathognomonic of focal cerebral arteriopathy-inflammatory type but was present in <25% of patients with focal cerebral arteriopathy-inflammatory type; a small lenticulostriate distribution infarct was a more common predictor of focal cerebral arteriopathy-inflammatory type, present in 76%. It remained difficult to distinguish focal cerebral arteriopathy-inflammatory type from intracranial dissection of the anterior circulation. We observed only secondary forms of diffuse/multifocal vasculitis, mostly due to meningitis. CONCLUSIONS: Childhood arteriopathy subtypes have some typical features that aid diagnosis. Better imaging methods, including vessel wall imaging, are needed for improved classification of focal cerebral arteriopathy of childhood.

Evidence-based guideline update: medical treatment of infantile spasms. Report of the Guideline Development Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society.

OBJECTIVE: To update the 2004 American Academy of Neurology/Child Neurology Society practice parameter on treatment of infantile spasms in children. METHODS: MEDLINE and EMBASE were searched from 2002 to 2011 and searches of reference lists of retrieved articles were performed. Sixty-eight articles were selected for detailed review; 26 were included in the analysis. RECOMMENDATIONS were based on a 4-tiered classification scheme combining pre-2002 evidence and more recent evidence. RESULTS: There is insufficient evidence to determine whether other forms of corticosteroids are as effective as adrenocorticotropic hormone (ACTH) for short-term treatment of infantile spasms. However, low-dose ACTH is probably as effective as high-dose ACTH. ACTH is more effective than vigabatrin (VGB) for short-term treatment of children with infantile spasms (excluding those with tuberous sclerosis complex). There is insufficient evidence to show that other agents and combination therapy are effective for short-term treatment of infantile spasms. Short lag time to treatment leads to better long-term developmental outcome. Successful short-term treatment of cryptogenic infantile spasms with ACTH or prednisolone leads to better long-term developmental outcome than treatment with VGB. RECOMMENDATIONS: Low-dose ACTH should be considered for treatment of infantile spasms. ACTH or VGB may be useful for short-term treatment of infantile spasms, with ACTH considered preferentially over VGB. Hormonal therapy (ACTH or prednisolone) may be considered for use in preference to VGB in infants with cryptogenic infantile spasms, to possibly improve developmental outcome. A shorter lag time to treatment of infantile spasms with either hormonal therapy or VGB possibly improves long-term developmental outcomes.

Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology Society.

OBJECTIVE: To determine the current best practice for treatment of infantile spasms in children. METHODS: Database searches of MEDLINE from 1966 and EMBASE from 1980 and searches of reference lists of retrieved articles were performed. Inclusion criteria were the documented presence of infantile spasms and hypsarrhythmia. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, and presence or absence of epilepsy or an epileptiform EEG. One hundred fifty-nine articles were selected for detailed review. Recommendations were based on a four-tiered classification scheme. RESULTS: Adrenocorticotropic hormone (ACTH) is probably effective for the short-term treatment of infantile spasms, but there is insufficient evidence to recommend the optimum dosage and duration of treatment. There is insufficient evidence to determine whether oral corticosteroids are effective. Vigabatrin is possibly effective for the short-term treatment of infantile spasm and is possibly also effective for children with tuberous sclerosis. Concerns about retinal toxicity suggest that serial ophthalmologic screening is required in patients on vigabatrin; however, the data are insufficient to make recommendations regarding the frequency or type of screening. There is insufficient evidence to recommend any other treatment of infantile spasms. There is insufficient evidence to conclude that successful treatment of infantile spasms improves the long-term prognosis. CONCLUSIONS: ACTH is probably an effective agent in the short-term treatment of infantile spasms. Vigabatrin is possibly effective.

Malformations of cortical development with balloon cells: clinical and radiologic correlates.

BACKGROUND: Balloon cells are a key feature of tuberous sclerosis (TS) but are also seen in focal cortical dysplasia (FCD). The authors compare the clinical and MRI characteristics in children with medically refractory localization-related epilepsy who were found to have balloon cells on histology after cortical resections. METHODS: A retrospective review of clinical and MRI data in cases ascertained from a search of pathology records from 1990 until 2000 for those with a diagnosis of FCD or TS. Seventeen patients were identified with malformations of cortical development with balloon cells on histology. Seven had clinical diagnosis of TS and the remaining 10, FCD with balloon cells (FCDBC). RESULTS: Seventy percent of patients with FCDBC (mean follow-up 3.3 years) and 33% of patients with TS (mean follow-up 5.1 years) are seizure free after surgery. There was agreement between the diagnosis based on preoperative MR imaging and on histology in 60% of patients with FCDBC and 71% of patients with TS. Myelin depletion and calcification were noted more frequently in patients with TS. CONCLUSIONS: No significant differences were noted between patients with refractory epilepsy caused by TS or FCDBC. There was a trend toward better postoperative seizure control in the FCDBC group. These two conditions are difficult to distinguish on the basis of MR and histologic appearances. The authors conclude that FCDBC likely represents a phenotypic variation of TS, and as such, all patients with balloon cell dysplasias should be carefully screened for other features of TS to enable appropriate genetic counseling.

Benign acute childhood myositis: laboratory and clinical features.

BACKGROUND: Benign acute myositis of childhood is a disorder of midchildhood, typically affecting boys. Symptoms include calf pain and difficulty walking after a viral illness. There is an epidemiologic association with influenza. OBJECTIVES: To describe the clinical and laboratory features of benign acute myositis. RESULTS: Thirty-eight children (32 boys, 6 girls) were seen with 41 episodes of myositis between 1978 and 1997. Two were siblings and three had recurrent episodes. Mean age at onset of symptoms was 8.1 years. Children remained ambulant during 33 of 41 episodes. Two characteristic gaits were noted: toe-walking in 13, with a wide-based stiff-legged gait in another 7. Muscle tenderness was isolated to the gastrocnemius-soleus muscles in 82% of episodes. Recovery occurred within 1 week. Creatine kinase levels were elevated during all episodes. Viral studies were positive in 10 of 24 episodes, 5 because of influenza B. CONCLUSION: Benign acute myositis is a syndrome of midchildhood that can be differentiated from more serious causes of walking difficulty by the presence of calf tenderness, normal power, intact tendon reflexes, and elevated creatine kinase. The gait patterns noted may minimize power generation of the calf muscles by splinting the ankles. Onset in childhood may reflect an age-related response to viral infection, and occurrence primarily in boys may reflect a genetic predisposition or an as-yet unknown metabolic defect.

Congenital muscular dystrophy, white-matter abnormalities, and neuronal migration disorders: the expanding concept.

The congenital muscular dystrophies are a heterogeneous, recessively inherited group of disorders that have been subclassified on the basis of clinical central nervous system involvement. We report two children with "pure" congenital muscular dystrophy, one merosin negative and one merosin positive with extensive white matter and occipital cortical neuromigration abnormalities on magnetic resonance imaging (MRI). The first patient (merosin-negative congenital muscular dystrophy) presented with hypotonia and weakness in the neonatal period and subsequently was found to have a leukoencephalopathy and occipital cortical dysplasia on magnetic resonance imaging. The second patient presented with developmental delay without definite weakness. Initial investigations revealed a leukoencephalopathy and cortical dysplasia, but the patient subsequently was shown to have merosin-positive congenital muscular dystrophy. These patients illustrate that white-matter changes are not specific for merosin-negative congenital muscular dystrophy alone and that extensive cortical abnormality can be found in both groups of patients. In addition, our second patient illustrates a nonmuscular mode of congenital muscular dystrophy presentation that should be considered in patients with a "nonprogressive leukodystrophy."