Mutations or exon deletions of the epsilon-sarcoglycan (SGCE) gene cause myoclonus-dystonia (M-D), but a subset of M-D patients are mutation-negative and the sensitivity and specificity of current genetic testing criteria are unknown. We screened 46 newly enrolled M-D patients for SGCE mutations and deletions; moreover, 24 subjects previously testing negative for SGCE mutations underwent gene dosage analysis. In our combined cohorts, we calculated sensitivity, specificity, positive and negative predictive values, and area under the curve of 2 published sets of M-D diagnostic criteria. A stepwise logistic regression was used to assess which patients' characteristics best discriminated mutation carriers and to calculate a new mutation predictive score ("new score"), which we validated in previously published cohorts. Nine of 46 (19.5%) patients of the new cohort carried SCGE mutations, including 5 novel point mutations and 1 whole-gene deletion; in the old cohort, 1 patient with a complex phenotype carried a 5.9-Mb deletion encompassing SGCE. Current diagnostic criteria had a poor ability to discriminate SGCE-positive from SGCE-negative patients in our cohort; conversely, age of onset, especially if associated with psychiatric features (as included in the new score), showed the best discriminatory power to individuate SGCE mutation carriers, both in our cohort and in the validation cohort. Our results suggest that young age at onset of motor symptoms, especially in association with psychiatric disturbance, are strongly predictive for SGCE positivity. We suggest performing gene dosage analysis by multiple ligation-dependent probe amplification (MLPA) to individuate large SGCE deletions that can be responsible for complex phenotypes. © 2013 Movement Disorder Society.

Antibodies directed against glutamic acid decarboxylase (GAD) are present in many patients with stiff person syndrome and increasingly found in patients with other symptoms indicative of central nervous system (CNS) dysfunction, such as ataxia. The classic clinical features of stiff person syndrome include muscular stiffness with superimposed painful muscular spasms. Gait is often impaired. Other CNS disorders associated with GAD antibodies include progressive encephalomyelitis with rigidity and myoclonus (PERM), limbic encephalitis, and even epilepsy. Glutamic acid decarboxylase is the rate-limiting enzyme in the production of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter. Presumably, antibodies directed against GAD impair GABA production, but the precise pathogenic mechanism of GAD-antibody-related neurologic disorders is uncertain. Many patients respond to treatment with immunomodulating therapy. Symptomatic treatment with agents that enhance GABA activity, such as benzodiazepines and baclofen, is also helpful for many patients.

Since the first description of alpha-synuclein (SNCA) mutations in 1997, this gene has probably become the most intensely investigated one associated with monogenic Parkinson disease (PD). Prompted by the finding of a novel SNCA mutation, H50Q, we systematically explored the 145 published SNCA mutation carriers for a possible mutation (type)-specific clinical expression, which appears to be rather unique to SNCA mutations compared with other PD genes. The A53T mutation is associated with an approximately 10-year earlier age at onset than the other 3 known missense mutations, including the new H50Q mutation. Similarly, SNCA triplication carriers have an approximately 10-year earlier onset and a more rapid disease course than duplication carriers, who, overall closely resemble patients with idiopathic PD. Furthermore, higher order SNCA multiplications are associated with additional neurologic features, such as myoclonus. For the nonmotor features, their mere frequency appears less striking than their severity, with an early age of onset of depression or dementia, suicidal ideation, and multimodal hallucinations. We conclude that, (1) although SNCA mutations are a rare cause of PD, it remains worth testing for new mutations in this gene; (2) a differential view of SNCA mutations and variants may allow important pathophysiologic inferences even beyond monogenic PD and is warranted in the context of clinical counseling. © 2013 Movement Disorder Society.

During the 3rd International Symposium on Dietary Therapies held in Chicago, Illinois, there was a first-ever, half-day session devoted to the management of adults with epilepsy and other disorders with dietary treatments. Speakers from 3 different continents shared their successes, challenges, and future directions in their management of these patients. Diets used to treat adults included the classic ketogenic diet, the modified Atkins diet, and a low glycemic index treatment. The utility of dietary therapies was demonstrated not only in patients with epilepsy but also patients with propriospinal myoclonus, astrocytoma, type 2 diabetes, obesity, hyperlipidemia, and metabolic disorder. The session provided evidence that dietary therapies are safe and effective in adults.

INTRODUCTION:

The normal startle response is a form of physiological myoclonus. Its anatomic origin is probably the brain stem. Pathologic startles are defined as reproducible exaggerated startle responses to trivial and not surprising stimuli. Symptomatic forms of an exaggerated startle response can be due to a variety of brain stem disorders. We have, however, found scant data about an exaggerated startle reflex induced by Lyme neuroborreliosis. We therefore report the case of a patient with this unusual presentation.

CASE PRESENTATION:

A 69-year old Caucasian man presented with a two-week history of a pronounced startle myoclonus, as well as a four-week history of double vision, gait disturbance and severe lancinating pain in his upper thoracic region. Neurological examination showed an excessive startle reaction of his upper trunk evoked by visual and tactile stimulation, a positive sign of Lhermitte, mild right-sided palsy of his sixth and seventh cranial nerve, moderate dysarthria, very brisk deep tendon reflexes, pallhypesthesia of his legs, and an atactic gait disturbance. A diagnosis of a Lyme neuroborreliosis was confirmed by cerebrospinal fluid examination. Under intravenous treatment with ceftriaxone, our patient improved considerably with complete remission in a follow-up at two months.

CONCLUSIONS:

This case illustrates the chameleon role that neuroborreliosis likes to play: although the wide spectrum of different symptoms that neuroborreliosis can present with has been described, to the best of our knowledge this is the first case report about a symptomatic form of a pathologic startle response as the predominating sign of Lyme neuroborreliosis.

Introduction: Myoclonic seizures can be observed in various clinical settings and different epileptic conditions, including some forms of both diopathic and symptomatic epilepsies. Relatively little has been written on treatment of myoclonic seizures. Some old antiepileptic drugs, such as valproate and some benzodiazepines, are widely used but more treatment options exist today for some newer antiepileptic drugs. Nevertheless, patients can be refractory to drug treatment and some drugs may exacerbate or even induce myoclonus. Areas covered: Key safety, tolerability, and efficacy data are presented for different antiepileptic drugs with antimyoclonic effect, alone and/or in combination. Expert opinion: Treatment of myoclonic seizures in children is mainly based on prospective and retrospective studies, with little evidence from randomized clinical trials. Valproate is commonly the first choice alone or in combination with some benzodiazepines or levetiracetam. There is still insufficient evidence for the use of topiramate and zonisamide as monotherapy. Of major importance remains avoidance of medication that may aggravate the seizures. Better understanding of pathophysiologic mechanisms of myoclonic seizures and myoclonic epilepsies could yield great improvement in the treatment and quality of life of patients.

PURPOSE:

We describe the clinical, neurophysiologic, and genetic features of a new, large family with familial cortical myoclonic tremor and epilepsy (FCMTE).

METHODS:

Reliable clinical information was obtained on the 127 members. Thirty-one collaborative individuals were assessed by a detailed clinical interview and a complete neurologic examination. A polygraphic study was conducted in 15 patients, back-averaging analysis and somatosensory evoked potentials with C-reflex study in four. The genetic study investigated 30 subjects with microsatellite markers at three loci on chromosomes 8q (FCMTE1), 2p (FCMTE2), and 5p (FCMTE3). KEY

FINDINGS:

The pedigree included 25 affected members (M/F: 9/16). We studied 16 of the 19 living affected members (M/F: 5/11; mean age 47.8 years). Cortical myoclonic tremor (CMT) was associated with generalized seizures in 10 patients (62.5%). The mean age at onset of CMT and seizures was 28.1 and 33.8 years, respectively. Four patients (25%) reported a slow progression of CMT, with severe gait impairment in one. Psychiatric disorders of variable severity recurred in 37.5% of cases. Rhythmic bursts at 7-15 Hz were recorded in all 11 affected members tested. Additional neurophysiologic investigations disclosed a cortical origin of myoclonus in all patients tested. Generalized epileptiform discharges were recorded in 25% of cases, and a photoparoxysmal response in 31%. Genetic analysis established linkage to the FCMTE2 locus on chromosome 2p11.1-2q12.2 (OMIM 607876) and narrowed the critical interval to a 10.4 Mb segment. Haplotype analysis in the present family identified a founder haplotype identical to that previously observed in families from the same geographic area.

SIGNIFICANCE:

This study confirms evidence of a founder effect in Italian families and reduces the number of positional candidate genes in the FCMTE2 locus to 59, thereby contributing to future gene identification by Next Generation Sequencing approaches.

Myoclonic epilepsy with red ragged fibres (MERRF) is a rare mitochondrial disorder presenting with progressive myoclonus, epilepsy, and cognitive decline. Here, the authors present a case of a 29-year-old lady presenting with myoclonus and describe the subsequent investigations that led to a diagnosis of MERRF. In addition, we examine her cognitive decline over a 9-year period, demonstrating a feature commonly seen in mitochondrial cytopathies.

To define cytokine concentrations and detectability in children with noninflammatory neurological disorders (NIND). The multiplex bead assay technology was used for simultaneous measurement of 34 soluble cytokines/chemokines in cerebrospinal fluid (CSF) from 73 NIND. Sera from 36 healthy children and 37 NIND also were analyzed. In CSF, CXCL10 had the highest concentration; CCL2, CXCL10, and interleukin (IL)-6 were detectable in all samples, and CXCL8, CCL22, CXCL1, IL-16, and IL-1 receptor antagonist were found in ≥50% of the samples. In serum, CXCL1 had the highest concentration; sIL-2Ra, CXCL1, CXCL10, and CCL22 were detectable in all samples, and CCL2, IL-12, CCL5, and granulocyte monocyte colony-stimulating factor (GM-CSF) were found in ≥50% of the samples. The mean CSF:serum ratio for CCL2 was several-fold higher than the rest, with the CXCL10 and CXCL8 ratios also >1. Intercorrelations between CSF cytokines included CCL2 versus CXCL8 and IL-6, and CXCL1 versus CCL22, reflecting both T-helper-1 (Th1)/Th1 and Th1/Th2 relations. Serum correlations included CCL11 versus CCL2, GM-CSF, and IL-4. For serum cytokines, the agreement between healthy children and NIND was good, with the exception of higher CCL4 in NIND. Cytokines in children varied greatly in concentration and detectability, with chemokines predominating in the CSF. These data allow investigators to select their own kit cytokines, instead of manufacturer-selected cytokines, for greater cost-effectiveness and interpretability.

AIMS:

Mutations in the SCABR2 gene cause a rare autosomal recessive disease, progressive myoclonus epilepsy (PME) with or without renal failure, the former also being designated action myoclonus-renal failure syndrome. Although reported cases have been accumulating, only a few have described its neuropathology. We studied two Japanese patients with PME without renal failure, in whom the ages at onset and disease durations were 45 and 20 years, and 14 and 8.5 years, respectively.

METHODS:

Sequencing and restriction analysis of the SCARB2 gene and neuropathological examination with immunohistochemistry were performed.

RESULTS:

Gene analyses revealed novel homozygous frame-shift and nonsense mutations in the SCARB2 gene. Both cases exhibited deposition of brown pigment in the brain, especially the cerebellar and cerebral cortices. Ultrastructurally, the pigment granules were localized in astrocytes. Neuronal loss and gliosis were also evident in the brain, including the pallido-luysian and cerebello-olivary systems. The spinal cord was also affected. Such changes were less severe in one patient with late-onset disease than in the other patient with early-onset disease. In brain and kidney sections, immunostaining with an antibody against the C-terminus of human SCARB2 revealed decreased levels and no expression of the protein, respectively.

CONCLUSIONS:

The frame-shift mutation detected in the patient with late-onset disease is a hitherto undescribed, unique type of SCABR2 gene mutation. The present two patients are the first reported to have clearly demonstrated both extraneuronal brown pigment deposition and system neurodegeneration as neuropathologic features of PME with SCABR2 mutations.