Further evidence for a somatic KRAS mutation in a pilocytic astrocytoma

Astrocytomas are the most common brain tumors of childhood. However, knowledge of the molecular etiology of astrocytomas WHO grade I and II is limited. Germline mutations in the Ras-guanosine triphosphatase-activating protein, neurofibromin, in individuals with neurofibromatosis type I predispose to pilocytic astrocytomas. This association suggests that constitutive activation of the Ras signaling pathway plays a fundamental role in astrocytoma development. We screened 25 WHO I and II astrocytomas for mutations of PTPN11, NRAS, KRAS, and HRAS genes and identified the somatic G12A KRAS mutation in one pilocytic astrocytoma. These data suggest that Ras is rarely mutated in these tumors. Analyzed astrocytomas without mutations in Ras or neurofibromin may harbor mutations in other proteins of this pathway leading to hyperactive Ras signaling.

Clinical presentation and course of childhood Guillain-Barré syndrome: a prospective multicentre study

Presenting symptoms, clinical course and paraclinical findings in childhood Guillain-Barré syndrome (GBS) have rarely been investigated prospectively. We performed a multicentre study in GBS diagnosed according to international criteria. Clinical findings were recorded using an ordinal GBS score and additional scores for arm, cranial nerve and vegetative function, and pain. Electrophysiological and CSF investigations followed individual procedures in the local hospitals. Ninety-five children with a median age of 6.2 years were registered over 40 months (53 boys, 42 girls). 70 had suffered an infection and 8 had been vaccinated during the previous 6 weeks. The first symptom was usually a disturbance of gait or neuropathic pain. The symptoms progressed for a median of 7 days. At the height of the disease, 60% of patients were unable to walk and 24% could not use their arms. 46% showed cranial nerve involvement, and 51% autonomous dysfunction. 13% required artificial ventilation. 79% complained of neuropathic pain, half of them to a severe degree. Electrophysiological examination showed demyelination in 74%, and 26% of these presented with very low amplitude compound action potentials. Purely axonal changes were found in 11%. All but eight were treated with I.V. immunoglobulin. Improvement began on day 13 after the first symptom (median). Ability to walk unaided returned after 27 days. In the children observed over the long-term, it took 118 days for them to be free of symptoms. Transient deterioration after immunoglobulin treatment occurred in seven patients, two suffered relapsing GBS, and three developed CIDP. At the end of the observation period (288 days), 75% of patients were free of symptoms. 21% suffered residual symptoms having no effect on daily functioning. The more severely disabled 4% either suffered from CIDP or concurrent myelitis. With this prospective study, the results of earlier retrospective investigations are confirmed. Besides pareses and respiratory compromise, severe neuropathic pain frequently is a therapeutic challenge during the acute phase of the disease. The long-term prognosis is good for most children. However, a change to CIDP and concurrent myelitis can give rise to a worse prognosis.

Prospective study on anti-ganglioside antibodies in childhood Guillain-Barré syndrome

BACKGROUND

Antiganglioside antibodies have been reported to play a part in the pathophysiology of Guillain-Barré syndrome (GBS).

AIMS

To investigate the prevalence and correlation of anti-ganglioside antibodies with clinical data in children with GBS in a multicentre clinical trial.

METHODS

Immunoglobin (Ig)G and IgM to GM1, GM1b, GD1a, GalNAc-GD1a, GD1b, GT1a, and GQ1b were measured by ELISA in sera obtained before treatment. In addition, serological testing for Campylobacter jejuni was carried out. In parallel, a group of adults with GBS and a control group of children without GBS or other inflammatory diseases were evaluated.

RESULTS

Sera from 63 children with GBS, 36 adults with GBS and 41 children without GBS were evaluated. Four of the children with GBS showed positive IgG to GM1, in one case combined with anti-GalNAc-GD1a and in one with anti-GD1b. Two others showed isolated positive IgG to GD1b and GT1a. One showed increased anti-GalNAc-GD1a IgM. In 5 of the 63 children, serological evidence of a recent infection with C jejuni was found, and this correlated significantly with the raised antibodies (p = 0.001). In the control group without GBS, no child showed positive IgG, but one showed anti-GalNAc-GD1a IgM. Compared with the adults with GBS, the frequency of antibodies in children was insignificantly lower. In our study, patients with positive antibodies did not show a more severe GBS course or worse outcome than those who were seronegative, and we could not show an increased incidence of axonal dysfunction.

CONCLUSIONS

In some children with GBS, one can detect raised IgG against various gangliosides, similar to that in adults. A recent infection with C jejuni is markedly associated with the presence of these antibodies. However, in contrast with what has been reported in adults, in this study we were unable to show a negative effect of these findings on the clinical course.

Facing the genetic heterogeneity in neuromuscular disorders: Linkage analysis as an economic diagnostic approach towards the molecular diagnosis

The identification of an ever increasing number of gene defects in patients with neuromuscular disorders has disclosed both marked phenotype and genotype variability and considerable disease overlap. In order to offer an economic strategy to characterise the molecular defect in patients with unclassified neuromuscular disorders, we designed DNA marker sets for linkage analysis of 62 distinct neuromuscular disorders gene loci, including all known muscular dystrophies, congenital myopathies, congenital myasthenic syndromes and myotonias. Genotyping of marker loci of 140 clinically well-characterised families with unclassified neuromuscular disorders reduced the number of candidates to one or two genes in 49 % of the families. Subsequent mutation analysis and genome-wide scans enabled the determination of the genetic defect in 31 % of the families including the identification of a new gene and a new mutation in an unexpected candidate gene. This highlights the effective application of this approach both for diagnostic strategies as well as for the identification of new loci and genes.

Recruitment of the sensorimotor cortex--a developmental FMRI study

INTRODUCTION

The growing mastery of motor tasks is one of the most visible changes in the developing child. The cortex is known to play a central role in learning, planning, and performance of motor tasks. We investigated the age dependency of motor cortex activation using functional magnetic resonance imaging (fMRI).

METHODS

Thirty-two right-handed subjects were studied: 11 children (median age 9 years, range 6 - 10 years), 10 adolescents (median age 13 years, range 11 - 15 years), and 11 adults (median age 27 years, range 23 - 42 years). The subjects performed a simple, paced unilateral motor task (repetitive squeezing of a ball with the right hand). Also, we set up a control experiment (visual stimulation using an alternating checkerboard pattern) in which no age-related differences were expected.

RESULTS

Compared to children, adults showed significantly increased activation of the bilateral sensorimotor cortex, parietal areas, the supplementary motor area, and the cerebellum. In the visual stimulation experiment there were no age-related differences.

CONCLUSION

Children show a significant difference in the degree of cortical activation compared to adults when performing a simple motor task. The change in fMRI activation patterns may reflect a maturation process of primary and secondary motor areas.

Echocardiographic and electrocardiographic findings of cardiomyopathy in Duchenne and Becker-Kiener muscular dystrophies

We assessed the cardiac findings in Duchenne muscular dystrophy (DMD) and Becker-Kiener muscular dystrophy (BMD) patients in the large outpatient group of our single-center institution. The analysis included the revision of patient records (retrospectively) and current echocardiography, electrocardiogram (ECG), and Holter ECG data (prospectively). Reduced left ventricular fraction shortening (FS) < 25% was found in 24% of all patients (50 DMD, 12.1 +/- 4.7 years: 20 BMD, 17.1 +/- 8.5 years). Median age of onset of FS < 25% was 16.8 +/- 1.0 in DMD and 30.4 +/- 3.4 in BMD; (p < 0.05). Holter ECG in DMD demonstrated sinus tachycardia in 26% deprivation of circadian rhythm in 31%, and reduced heart rate variability in 51%. For these reasons, we recommend carrying out echocardiography annually in DMD and BMD > 10 years. Because the rate of disturbances in the cardiac autonomic nervous system is high in DMD, we also recommend Holter ECG annually. Further investigation should be conducted to determine if treatment with ss-blockers and ACE inhibitors in combination reduces cardiac autonomic nervous imbalance, thus improving patient outcome in DMD.

Low level of intracortical inhibition in children shown by transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) is an established neurophysiological tool to evaluate the integrity and maturation of the corticospinal tract. TMS was used in this study to compare intracortical inhibition (ICI) in children, adolescents, and adults. The paired-pulse technique of TMS with interstimulus intervals of 2 ms was used to determine the ratio of conditioned (cMEP) and unconditioned amplitudes (ucMEP) that measures ICI. In experiment 1 (Exp 1) stimulus intensity was adapted to motor threshold (50 healthy subjects; 24 male, 26 female, median age 13.5 years, range 6.3 - 34 years) and in experiment 2 (Exp 2) stimulus intensity was adapted to the ucMEP (200 - 400 microV). Children (quotient of cMEP and ucMEP: Exp. 1: 0.71 +/- 0.41, Exp. 2: 0.82 +/- 0.25) had significantly less ICI compared to adults (Exp. 1: 0.21 +/- 0.19, mean +/- STD, Exp. 2: 0.35 +/- 0.22, in both experiments p < 0.001). Recently, ICI has been linked to the regulating function of GABAergic cortical interneurons on practice-dependent neuronal plasticity. Therefore, the lower ICI in children points to maturation processes that may have implications for the greater capacity of practice-dependent neuronal plasticity in children.

Identification of a novel LAMP2 mutation responsible for X-chromosomal dominant Danon disease

Danon disease (DD) is a rare lysosomal glycogen storage disease with normal acid maltase activity, which is characterised clinically by cardiomyopathy and myopathy, and a variable degree of mental retardation. The causative gene, LAMP2, has been mapped to chromosome Xq24-q25. LAMP2 encodes a lysosome-associated membrane glycoprotein. We identified a novel LAMP2 mutation of the exon 8 splice acceptor site (IVS7-1G --> A) in an affected male and female, which predicts abnormal splicing. Both affected individuals presented solely with hypertrophic cardiomyopathy. Muscle weakness and mental impairment were absent. Diagnosis of Danon disease was established by muscle biopsy, when the male index patient developed transient severe muscle weakness following heart transplantation. Typical biopsy findings were also found in a heart muscle specimen. Demonstration of the LAMP2 mutation in affected male and female siblings is compatible with X-linked dominant inheritance. Danon disease should be actively looked for in cardiomyopathy patients.

Identification of seven novel mutations in the GAN gene

Giant axonal neuropathy (GAN) is a severe early onset neurodegenerative disorder affecting both the peripheral nerves and the central nervous system. The diagnosis is based on the presence of characteristic giant axons on nerve biopsy. In GAN, the integrity of the intermediate filament network is altered. Indeed, abnormal accumulation of the intermediate filaments has been reported in different cell types, including in the swollen axons, which are filled with neurofilaments. We identified the defective protein, gigaxonin, of unknown function, and reported fourteen distinct mutations in twelve families of various origins. Two additional mutations have been recently reported. In the present study, we analysed the GAN gene in 6 families, and identified seven novel mutations: three nonsense and two missense mutations and two deletions. In addition, the molecular result for an already reported family was re-evaluated. In this family, the R269Q "polymorphism" is in fact the pathogenic mutation.

Classical infantile spinal muscular atrophy with SMN deficiency causes sensory neuronopathy

OBJECTIVE

Classic infantile spinal muscular atrophy (SMA) is believed to be a purely motor disorder, affecting neurons of the spinal anterior horn and nuclei of the lower cranial nerves. Other organ malformations or peripheral nerve involvement have been regarded as exclusion criteria for infantile SMA. Whether SMN protein deficiency can also lead to loss of sensory neurons has not been systematically addressed.

METHODS

The authors evaluated the sural nerve biopsies of 19 patients with infantile SMA of varying severity. The diagnosis of SMA was confirmed by the presence of a homozygous deletion of the SMN1 gene in all patients.

RESULTS

In seven unrelated infants with SMA type I, axonal degeneration of the sural nerve was noted. Five patients showed abnormal sensory conduction, thus prompting sural nerve biopsy. Sural nerves showed different degrees of axonal loss: fiber density ranged from 3.482 to 22.076/mm2 and was markedly reduced in four patients. There was no evidence of primary demyelination: the ratio of total myelinated fiber thickness to axon diameter (g-ratio) was normal in the patients examined. In seven patients with SMA II and five patients with SMA III, no sural nerve alterations were seen, and conduction velocity was normal. In addition to SMN1 gene deletions, homozygous NAIP gene deletions were detected in six out of seven infants with peripheral neuropathy, whereas there was no evidence of a large deletion including the multicopy markers C212 and Ag1-CA in two out of three families tested.

CONCLUSIONS

In this series of patients with SMA I through III who underwent sural nerve biopsy, there was significant sensory nerve pathology in severely affected patients with SMA type I, whereas there were no sensory nerve alterations clinically or morphologically in patients with milder SMA type II or III.

Pro- and anticoagulatory factors under sodium valproate-therapy in children

OBJECTIVE

To evaluate sodium valproate-induced hemostatic side effects in children.

METHODS

A variety of both pro- and anticoagulatory parameters were longitudinally investigated in 80 children before therapy and up to 720 days after initiation of sodium valproate (VPA) therapy.

RESULTS

VPA caused a significant reduction in platelet count (309,000/ micro l +/- 122,000 before treatment to 261,000/ micro l +/- 150,000 under VPA therapy, p = 0.007). However platelet function was not impaired. While vWF antigen was reduced during VPA therapy (1.05 U/ml +/- 0.4 U/ml before therapy, 0.95 +/- 0.4 U/ml under VPA therapy), the in vivo activity of vWF (ratio between function and antigen concentration) increased significantly (1.06 +/- 0.2 before therapy, 1.36 +/- 0.3 under VPA therapy, p = 0.01). Both procoagulatory and anticoagulatory factors were significantly reduced (fibrinogen: 264.5 +/- 64.5 mg/dl before therapy, 221.4 +/- 47.5 mg/dl under therapy, p = 0.001; protein C: 81.3 % +/- 18 before therapy, 65.6 % +/- 21.4 under VPA therapy, p = 0.005, antithrombin: 122.7 % +/- 23.7 before therapy, 101.7 % +/- 18 under VPA therapy, p = 0.04). With the exception of fibrinogen, these effects were identical in children treated either with monotherapy or with polytherapy.

CONCLUSIONS

Besides already known alterations of a variety of procoagulatory parameters, a relevant influence of VPA on the anticoagulatory system is demonstrated. We hypothesize that this additional alteration of anticoagulatory parameters might reduce the absolute bleeding risk of children treated with VPA.

Polyradiculoneuritis with myelitis: a rare differential diagnosis of Guillain-Barré syndrome

AIM

To describe the symptoms, signs, findings and prognosis in children suffering simultaneously from polyradiculoneuritis and myelitis.

METHODS

Retrospective review of eight patients aged 2 to 13 years out of 210 patients with polyradiculoneuritis reported from 70 hospitals. Diagnostic criteria for polyradiculoneuritis were: flaccid paresis with loss of tendon reflexes, increased CSF protein and slowing of nerve conduction velocity. Criteria for myelitis were: severe and persistent bladder dysfunction, a sharply defined sensory level and/or evolving spastic paresis, with or without myelitic changes in spinal MRI.

RESULTS

In the disease's earliest stage it was difficult to differentiate polyradiculoneuritis with myelitis from classical GBS. However, onset was often unusually rapid compared to GBS. Five patients developed a sensory level and seven suffered from severe bladder dysfunction. Four of the six children studied showed focal myelitic changes in MRI. All seven children with sufficient follow-up remained with residual paresis and significant long-term motor deficits.

CONCLUSION

Due to its severe long-term prognosis, polyradiculoneuritis with myelitis must be differentiated from classical GBS. In the disease's early stage, the detection of a sensory level, severe bladder dysfunction and an unusually rapid onset can be helpful. The effect of high-dose corticosteroids is not yet clear. After the acute phase, most children require extended rehabilitation.

Hashimoto encephalopathy - is it underdiagnosed in pediatric patients?

Hashimoto encephalopathy (HE) is associated with Hashimoto thyroiditis. Clinically it presents with variable symptoms like seizures, neuropsychiatric changes or focal neurological deficits. Autoimmune phenomena are hypothesized for the pathogenesis. HE has mainly been described in the adult population. We present two 14-year-old patients who presented with recurrent seizures and mental decline. SPECT and PET scans showed distinctly pathological changes. Both patients were diagnosed with HE and improved dramatically on steroids. We feel that HE is a rare but important differential diagnosis of encephalopathy also in the pediatric population. As this disease responds well to steroids, we recommend to obtain basic thyroid function tests as well as thyroid antibodies in all cases of unexplained encephalopathy or unexplained status epilepticus.

Medium-term functional benefits in children with cerebral palsy treated with botulinum toxin type A: 1-year follow-up using gross motor function measure

One of the main goals when treating spasticity is to relieve pain and improve function. Intramuscular injection of botulinum toxin type A (BTX-A) has gained widespread acceptance in the treatment of spastic cerebral palsy. Several studies have clearly shown the short-term functional benefit of BTX-A treatment. Information is limited, however, on the efficacy of medium and long-term regimens, using repeated injection of BTX-A. The aim of the present open-label, prospective study was to evaluate functional outcome in children with spastic cerebral palsy after 1 year of treatment with BTX-A, using the Gross Motor Function Measure (GMFM) as a validated outcome measure. Patients (n=25, age 1.5--15.5 years) were treated with BTX-A for adductor spasm (n=12) or pes equinus (n=13). The local effect was evaluated using passive range of motion and modified Ashworth Scale. Apart from a significant improvement in joint mobility and reduction of spasticity compared to pretreatment values (P < 0.01), we demonstrated a significant improvement of gross motor function after 12 months of treatment, with a median gain of 6% in total and goal scores (P < 0.001). An increase in GMFM scores was particularly evident in younger and moderately impaired children (Gross Motor Function Classification System level III). Whether the observed improvement in gross motor function in children with cerebral palsy is specifically related to therapy with BTX-A or represents at least in part the natural course of motor development still needs clarification.