Early onset ataxia with comorbid myoclonus and epilepsy: A disease spectrum with shared molecular pathways and cortico-thalamo-cerebellar network involvement.

OBJECTIVES: Early onset ataxia (EOA) concerns a heterogeneous disease group, often presenting with other comorbid phenotypes such as myoclonus and epilepsy. Due to genetic and phenotypic heterogeneity, it can be difficult to identify the underlying gene defect from the clinical symptoms. The pathological mechanisms underlying comorbid EOA phenotypes remain largely unknown. The aim of this study is to investigate the key pathological mechanisms in EOA with myoclonus and/or epilepsy. METHODS: For 154 EOA-genes we investigated (1) the associated phenotype (2) reported anatomical neuroimaging abnormalities, and (3) functionally enriched biological pathways through in silico analysis. We assessed the validity of our in silico results by outcome comparison to a clinical EOA-cohort (80 patients, 31 genes). RESULTS: EOA associated gene mutations cause a spectrum of disorders, including myoclonic and epileptic phenotypes. Cerebellar imaging abnormalities were observed in 73-86% (cohort and in silico respectively) of EOA-genes independently of phenotypic comorbidity. EOA phenotypes with comorbid myoclonus and myoclonus/epilepsy were specifically associated with abnormalities in the cerebello-thalamo-cortical network. EOA, myoclonus and epilepsy genes shared enriched pathways involved in neurotransmission and neurodevelopment both in the in silico and clinical genes. EOA gene subgroups with myoclonus and epilepsy showed specific enrichment for lysosomal and lipid processes. CONCLUSIONS: The investigated EOA phenotypes revealed predominantly cerebellar abnormalities, with thalamo-cortical abnormalities in the mixed phenotypes, suggesting anatomical network involvement in EOA pathogenesis. The studied phenotypes exhibit a shared biomolecular pathogenesis, with some specific phenotype-dependent pathways. Mutations in EOA, epilepsy and myoclonus associated genes can all cause heterogeneous ataxia phenotypes, which supports exome sequencing with a movement disorder panel over conventional single gene panel testing in the clinical setting.

[Dystonia in cerebral palsy; what are the treatment options?] / Dystonie bij cerebrale parese.

Cerebral palsy (CP) is the most common cause of motor disability in children. The largest group of children with CP present with spasticity. Dystonia is estimated to be present in approximately 15% of children with CP, referred to as dyskinetic CP. Still, dystonia in CP remains underdiagnosed. Dystonia and spasticity can occur together in a subgroup of children with CP as well. Dystonia is characterized by fluctuating hypertonia and involuntary movement and postures. Dystonia in children with CP can interfere with motor function, caregiving and comfort. It is important to recognize dystonia in children with CP as specific treatment is indicated. In this paper we describe three cases of children with dystonia in CP and we review the pharmacological treatment options for dystonia in CP and the surgical options including intrathecal baclofen pump and deep brain stimulation.

North Sea Progressive Myoclonus Epilepsy is Exacerbated by Heat, A Phenotype Primarily Associated with Affected Glia.

Progressive myoclonic epilepsies (PMEs) comprise a group of rare disorders of different genetic aetiologies, leading to childhood-onset myoclonus, myoclonic seizures and subsequent neurological decline. One of the genetic causes for PME, a mutation in the gene coding for Golgi SNAP receptor 2 (GOSR2), gives rise to a PME-subtype prevalent in Northern Europe and hence referred to as North Sea Progressive Myoclonic Epilepsy (NS-PME). Treatment for NS-PME, as for all PME subtypes, is symptomatic; the pathophysiology of NS-PME is currently unknown, precluding targeted therapy. Here, we investigated the pathophysiology of NS-PME. By means of chart review in combination with interviews with patients (n = 14), we found heat to be an exacerbating factor for a majority of NS-PME patients (86%). To substantiate these findings, we designed a NS-PME Drosophila melanogaster model. Downregulation of the Drosophila GOSR2-orthologue Membrin leads to heat-induced seizure-like behaviour. Specific downregulation of GOSR2/Membrin in glia but not in neuronal cells resulted in a similar phenotype, which was progressive as the flies aged and was partially responsive to treatment with sodium barbital. Our data suggest a role for GOSR2 in glia in the pathophysiology of NS-PME.

[Deep brain stimulation for movement disorders]. / Diepe hersenstimulatie voor bewegingsstoornissen.

Deep brain stimulation (DBS) is a treatment which uses high-frequency electric stimulation to suppress pathological brain activity. DBS has been applied for over 30 years now, particularly in patients with severe movement disorders, such as Parkinson's disease, dystonia and tremor. Although there is clearly scientific evidence for the effectiveness of DBS in these three movement disorders, the effect size of the treatment remains limited. Furthermore, DBS is not curative and can only be applied in a select subset of patients. In this article, we discuss the key indications and contraindications for DBS, and the outcomes achieved when it is applied in the aforementioned movement disorders. We discuss the most notable controversies and new developments in the field of deep brain stimulation, in order to offer referrers and fellow healthcare professionals an accessible introduction to this mode of therapy.

[Facial tics and spasms]. / Trekkingen in het gelaat.

Facial tics and spasms are socially incapacitating, but effective treatment is often available. The clinical picture is sufficient for distinguishing between the different diseases that cause this affliction.We describe three cases of patients with facial tics or spasms: one case of tics, which are familiar to many physicians; one case of blepharospasms; and one case of hemifacial spasms. We discuss the differential diagnosis and the treatment possibilities for facial tics and spasms. Early diagnosis and treatment is important, because of the associated social incapacitation. Botulin toxin should be considered as a treatment option for facial tics and a curative neurosurgical intervention should be considered for hemifacial spasms.