Unverricht-Lundborg Disease, a Condition with Self-limited Progression: Long-term Follow-up of 20 Patients

CSTB gene replacement improves neuroinflammation, neurodegeneration and ataxia in murine type 1 progressive myoclonus epilepsy

EPM1 is the most common form of Progressive Myoclonus Epilepsy characterized by late-childhood onset, ever-worsening and disabling myoclonus, seizures, ataxia, psychiatric disease, and shortened lifespan. EPM1 is caused by expansions of a dodecamer repeat sequence in the promoter of CSTB (cystatin B), which dramatically reduces, but does not eliminate, gene expression. The relatively late onset and consistent presence of a minimal amount of protein product makes EPM1 a favorable target for gene replacement therapy. If treated early, these children's normally developed brains could be rescued from the neurodegeneration that otherwise follows, and their cross-reactive immunological material (CRIM) positive status greatly reduces transgene related toxicity. We performed a proof-of-concept CSTB gene replacement study in Cstb knockout mice by introducing full-length human CSTB driven by the CBh promoter packaged in AAV9 and administered at postnatal days 21 and 60. Mice were sacrificed at 2 or 9 months of age, respectively. We observed significant improvements in expression levels of neuroinflammatory pathway genes and cerebellar granule cell layer apoptosis, as well as amelioration of motor impairment. The data suggest that gene replacement is a promising therapeutic modality for EPM1 and could spare affected children and families the ravages of this otherwise severe neurodegenerative disease.

ILAE Genetics Literacy series: Progressive myoclonus epilepsies

Progressive Myoclonus Epilepsy (PME) is a rare epilepsy syndrome characterized by the development of progressively worsening myoclonus, ataxia, and seizures. A molecular diagnosis can now be established in approximately 80% of individuals with PME. Almost fifty genetic causes of PME have now been established, although some remain extremely rare. Herein, we provide a review of clinical phenotypes and genotypes of the more commonly encountered PMEs. Using an illustrative case example, we describe appropriate clinical investigation and therapeutic strategies to guide the management of this often relentlessly progressive and devastating epilepsy syndrome. This manuscript in the Genetic Literacy series maps to Learning Objective 1.2 of the ILAE Curriculum for Epileptology (Epileptic Disord. 2019;21:129).

Negative myoclonus causes locomotory disability in progressive myoclonus epilepsy type EPM1- Unverricht-Lundborg disease

OBJECTIVE

Patients with Unverricht-Lundborg disease/EPM1 develop increasing locomotory disability or ataxia in the course of their disease. To test our hypothesis that negative myoclonus is the reason for this increasing ataxia, we investigated a possible correlation over time.

METHODS

In 15 patients with EPM1who were confirmed to have a mutation in the CSTB gene, polygraphic video-EEG-EMG recordings were performed in freely moving or standing patients. The criterion for the duration of the negative myoclonus was the measured length of the silent periods on the EMG.

RESULTS

All 15 patients had documented negative myoclonus when standing and walking. The mean duration of silent periods significantly increased from 100 (SD: 19.1) ms at time point T1 to 128 (SD: 26.6) ms at T2 in seven of eight patients, based on two recordings and a mean interval of 12.8 (SD: 4.9) years. Using a cross-sectional approach, all 15 patients were classified based on whether they were ambulatory, could walk with aid, or needed a wheelchair. Ambulatory patients had a mean duration of 97.3 (SD: 16.5) ms, patients who could walk with aid had a mean duration of 106.7 (SD: 16) ms, and patients who were wheelchair-bound had a mean duration of 138 (SD: 23.6) ms. In addition to the prolongation of the silent periods, there was an observed increase in frequency of the negative myoclonus, becoming more continuous and tremulous.

SIGNIFICANCE

Using simultaneous EEG/EMG recordings in freely moving or standing patients, we have shown that the locomotor disability or ataxia is due to negative myoclonus in voluntary innervated muscles. The reason for the progression is the prolongation of the silent periods as measured by the duration of the negative myoclonus and their increase in frequency.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset at a variable age: position statement by the ILAE Task Force on Nosology and Definitions

The goal of this paper is to provide updated diagnostic criteria for the epilepsy syndromes that have a variable age of onset, based on expert consensus of the International League Against Epilepsy Nosology and Definitions Taskforce (2017-2021). We use language consistent with current accepted epilepsy and seizure classifications and incorporate knowledge from advances in genetics, electroencephalography, and imaging. Our aim in delineating the epilepsy syndromes that present at a variable age is to aid diagnosis and to guide investigations for etiology and treatments for these patients.

Clinical and molecular characterization of Unverricht-Lundborg disease among Egyptian patients

BACKGROUND AND PURPOSE

Unverricht-Lundborg disease (ULD) is a common type of progressive myoclonic epilepsy (PME). It is caused mostly by biallelic dodecamer repeat expansions in the promoter region of CSTB gene. Despite highly prevalent in the Mediterranean countries, no studies have been reported from Egypt. This article study the presence of CSTB gene mutations among Egyptian patients clinically suspected with ULD, and describes the clinical and genetic characteristics of those with confirmed gene mutation.

METHODS

Medical records of patients following up in two specialized epilepsy clinics in Cairo, Egypt were retrospectively reviewed. Twenty patients who belonged to 13 unrelated families were provisionally diagnosed with ULD based on the clinical presentation. Genetic testing was done. Clinical characteristics, demographic data and EEG findings were documented.

RESULTS

Genetic studies confirmed the presence of the CSTB dodecamer repeat expansion in 14 patients from 8 families (frequency 70 %). The mean duration of the follow-up was 5 years. Male to female distribution was 1:1 with a mean age of onset 9.7 years. Consanguinity was noted in 4 families. Eight patients had their first seizure between the age of 10 and 20 years. Myoclonic jerks ranged in severity from mild in three unrelated patients to severe in one. Only 3 had cognitive impairment.

CONCLUSION

Our study confirms the presence of CSTB mutation among Egyptian patients suspected with ULD. There was no clear phenotype-genotype correlation among the studied group of patients. In addition, we noticed variable inter and intra familial severity among patients from the same family.

Cognitive functioning in progressive myoclonus epilepsy type 1 (Unverricht-Lundborg Disease, EPM1)

OBJECTIVE

The aim of this neuropsychological study of a large cohort of patients with progressive myoclonus epilepsy type 1 (Unverricht-Lundborg disease, EPM1) was to characterize the cognitive function of EPM1 patients and to explore the association between the disability caused by the disease and cognitive performance.

METHOD

Sixty-eight genetically verified EPM1 patients homozygous for the expansion mutation in the CSTB gene (37 males and 31 females aged 35 ± 11) participated in a neuropsychological assessment of intellectual ability, verbal memory, and executive and psychomotor function. The clinical evaluation comprised administering (and video-recording) the unified myoclonus rating scale (UMRS) to assess the severity of each patient's myoclonus. Forty-six healthy volunteers (19 males and 27 females aged 32 ± 11) served as the control group for the neuropsychological tests.

RESULTS

The cognitive performance of the EPM1 patient group was impaired. Verbal Intelligence Quotient (VIQ) was below the average range (VIQ < 85) in 49% of the patients; further, Performance Intelligence Quotient (PIQ) was below average in 75% of the patients. The patients performed worse than the controls in both immediate and delayed story recall (p = 0.001); however, in the word list learning task, the patients performed only slightly worse than the controls. The one-hour delayed recall of the learned words was similar in both groups, and the percentage of retained words and story contents did not differ between the patients and controls. The patients were impaired in all of the executive function tests as well as in the psychomotor speed tests (p < 0.001 for all). Also, the patients' simple psychomotor speed in the tapping task was significantly slowed in comparison to controls (p < 0.001).

CONCLUSION

The patients had impaired performance in the majority of the cognitive measures; they showed the highest level of impairment in all the executive function tests and in the psychomotor speed tests. The measures of these cognitive domains are timed-therefore, it is clear that severe myoclonus limits patients' performance. In contrast, verbal memory, especially delayed recall, was the least affected cognitive domain.

Cortico-muscular and cortico-cortical coherence changes resulting from Perampanel treatment in patients with cortical myoclonus

OBJECTIVE

To investigate the mechanisms by which Perampanel (PER) reduces the severity of action myoclonus, we studied on MEG signals the changes occurring in cortico-muscular coherence (CMC) and cortico-cortical connectivity in patients with progressive myoclonus epilepsies.

METHODS

The subjects performed an isometric extension of the hand; CMC and cortico-cortical connectivity were assessed using autoregressive models and generalized partial-directed coherence. The contralateral (Co) sensors showing average CMC values >0.7 of the maximum (set to 1) were grouped as central (C) regions of interest (ROI), while adjacent sensors showing CMC values >0.3 were grouped as Surrounding (Sr) ROIs.

RESULTS

Under PER treatment, CMC decreased on Co C and Sr ROIs, but also on homologous ipsilateral (Ip) ROIs; out-degrees and betweenness centrality increased in Co ROIs and decreased in Ip ROIs. The flow from Ip to Co ROIs and from activated muscles to Ip C ROI decreased.

CONCLUSION

The improvement of myoclonus corresponded to decreased CMC and recovered leadership of the cortical regions directly involved in the motor task, with a reduced interference of ipsilateral areas.

SIGNIFICANCE

Our study highlights on mechanisms suitable to treating myoclonus and suggests the role of a reduced local synchronization together a better control of distant synaptic effects.

Myoclonus-Ataxia Syndromes: A Diagnostic Approach

Background

A myriad of disorders combine myoclonus and ataxia. Most causes are genetic and an increasing number of genes are being associated with myoclonus-ataxia syndromes (MAS), due to recent advances in genetic techniques. A proper etiologic diagnosis of MAS is clinically relevant, given the consequences for genetic counseling, treatment, and prognosis.

Objectives

To review the causes of MAS and to propose a diagnostic algorithm.

Methods

A comprehensive and structured literature search following PRISMA criteria was conducted to identify those disorders that may combine myoclonus with ataxia.

Results

A total of 135 causes of combined myoclonus and ataxia were identified, of which 30 were charted as the main causes of MAS. These include four acquired entities: opsoclonus-myoclonus-ataxia syndrome, celiac disease, multiple system atrophy, and sporadic prion diseases. The distinction between progressive myoclonus epilepsy and progressive myoclonus ataxia poses one of the main diagnostic dilemmas.

Conclusions

Diagnostic algorithms for pediatric and adult patients, based on clinical manifestations including epilepsy, are proposed to guide the differential diagnosis and corresponding work-up of the most important and frequent causes of MAS. A list of genes associated with MAS to guide genetic testing strategies is provided. Priority should be given to diagnose or exclude acquired or treatable disorders.

Genetic testing and the phenotype of Polish patients with Unverricht-Lundborg disease (EPM1) - A cohort study

AIM OF THE STUDY

The aim of this study was to explore genetic findings and the phenotype in Polish patients with Unverricht-Lundborg disease (ULD).

MATERIALS AND METHODS

We retrospectively evaluated mutations in the cystatin B (CSTB) gene and clinical presentation in a cohort of patients with ULD. The study population consisted of 19 (14 males) patients with genetically confirmed disease.

RESULTS

Sixteen patients were homozygous for the expanded dodecamer repeat mutation alleles, one subject was compound heterozygous for the dodecamer repeat expansion and other mutation, in two, the type of mutation has not yet been established. The numbers of repeats in the CSTB gene varied from 60 to 81. Clinical information was available for 16 subjects. The disease course was progressive in all patients, leading to severe disability, mainly due to myoclonus, in nine.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Genetic findings and the clinical picture of our patients with ULD were in accordance with available studies. The most common genetic defect underlying ULD was homozygosity for an unstable expansion of a dodecamer repeat in the CSTB gene. Patients with action or/and stimulus sensitive myoclonus or intractable myoclonus epilepsy, especially with onset in late childhood/adolescence should be screened for ULD.

Unverricht-Lundborg disease (EPM1) in Finland: A nationwide population-based study

OBJECTIVE

To investigate the epidemiology and prognosis of Unverricht-Lundborg disease (EPM1) in a nationwide, population-based setting.

METHODS

Data from multiple registries were combined and analyzed. Clinical data were obtained from medical records. All patients treated for EPM1 in Finland between January 1, 1998, and December 31, 2016 were included.

RESULTS

A total of 135 persons with EPM1 (54% women) were identified and 105 were alive on December 31, 2016 (point prevalence 1.91/100,000 persons). The age-standardized (European Standard Population 2013) prevalence was 1.53/100,000 persons. Annual incidence during the study period was 0.022/100,000 person-years, with a mean age at onset of 9.4 ± 2.3 years (range 7.0-14.6 years, no sex difference). The median age at death (n = 34) was 53.9 years (interquartile range 46.4, 60.3; range 23.2-63.8), with no sex differences. The immediate cause of death was a lower respiratory tract infection in 56% of deaths. The survival rates of the patients were comparable to matched controls up to 40 years of age, but poorer during long-term follow-up (cumulative survival 26.4% vs 78.0%), with a hazard ratio (HR) for death of 4.61. The risk of death decreased with increasing age at onset (HR 0.76 per year, 95% confidence interval 0.65-0.89). In approximately 10% of all cases, the disease progression appeared very mild; some patients retained functional independence for decades.

CONCLUSIONS

Unverricht-Lundborg disease is rare in Finland but still more common than anywhere else in the world. The disease course appears somewhat more severe than elsewhere, disability mounts early, and death occurs prematurely.

A detailed description of the phenotypic spectrum of North Sea Progressive Myoclonus Epilepsy in a large cohort of seventeen patients

INTRODUCTION

In 2011, a homozygous mutation in GOSR2 (c.430G > T; p. Gly144Trp) was reported as a novel cause of Progressive Myoclonus Epilepsy (PME) with early-onset ataxia. Interestingly, the ancestors of patients originate from countries bound to the North Sea, hence the condition was termed North Sea PME (NSPME). Until now, only 20 patients have been reported in literature. Here, we provide a detailed description of clinical and neurophysiological data of seventeen patients.

METHODS

We collected clinical and neurophysiological data from the medical records of seventeen NSPME patients (5-46 years). In addition, we conducted an interview focused on factors influencing myoclonus severity.

RESULTS

The core clinical features of NSPME are early-onset ataxia, myoclonus and seizures, with additionally areflexia and scoliosis. Factors such as fever, illness, heat, emotions, stress, noise and light (flashes) all exacerbated myoclonic jerks. Epilepsy severity ranged from the absence of or incidental clinical seizures to frequent daily seizures and status epilepticus. Some patients made use of a wheelchair during their first decade, whereas others still walked independently during their third decade. Neurophysiological features suggesting neuromuscular involvement in NSPME were variable, with findings ranging from indicative of sensory neuronopathy and anterior horn cell involvement to an isolated absent H-reflex.

CONCLUSION

Although the sequence of symptoms is rather homogeneous, the severity of symptoms and rate of progression varied considerably among individual patients. Common triggers for myoclonus can be identified and myoclonus is difficult to treat; to what extent neuromuscular involvement contributes to the phenotype remains to be further elucidated.

Automatic assessment of the myoclonus severity from videos recorded according to standardized Unified Myoclonus Rating Scale protocol and using human pose and body movement analysis

PURPOSE

Myoclonus in progressive myoclonus epilepsy type 1 (EPM1) patients shows marked variability, which presents a substantial challenge in devising treatment and conducting clinical trials. Consequently, fast and objective myoclonus quantification methods are needed.

METHODS

Ten video-recorded unified myoclonus rating scale (UMRS) myoclonus with action tests were performed on EPM1 patients who were selected for the development and testing of the automatic myoclonus quantification method. Human pose and body movement analyses of the videos were used to identify body keypoints and further analyze movement smoothness and speed. The automatic myoclonus rating scale (ARMS) was developed. It included the jerk count during movement score and the log dimensionless jerk (LDLJ) score to evaluate changes in the smoothness of movement.

RESULTS

The scores obtained with the automatic analyses showed moderate to strong significant correlation with the UMRS myoclonus with action scores. The jerk count of the primary keypoints and the LDLJ scores were effective in the evaluation of the myoclonic jerks during hand movements. They also correlated moderately to strongly with the total UMRS test panel scores (r2 = 0,77, P = 0,009 for the jerk count score and r2 = 0,88, P = 0,001 for the LDLJ score). The automatic analyses was weaker in quantification of the neck, trunk, and leg myoclonus.

CONCLUSION

Automatic quantification of myoclonic jerks using human pose and body movement analysis of patients' videos is feasible and was found to be quite consistent with the accepted clinical gold standard quantification method. Based on the results of this study, the automatic analytical method should be further developed and validated to improve myoclonus severity follow-up for EPM1 patients.

The best evidence for progressive myoclonic epilepsy: A pathway to precision therapy

Progressive Myoclonus Epilepsies (PMEs) are a group of uncommon clinically and genetically heterogeneous disorders characterised by myoclonus, generalized epilepsy, and neurological deterioration, including dementia and ataxia. PMEs may have infancy, childhood, juvenile or adult onset, but usually present in late childhood or adolescence, at variance from epileptic encephalopathies, which start with polymorphic seizures in early infancy. Neurophysiologic recordings are suited to describe faithfully the time course of the shock-like muscle contractions which characterize myoclonus. A combination of positive and negative myoclonus is typical of PMEs. The gene defects for most PMEs (Unverricht-Lundborg disease, Lafora disease, several forms of neuronal ceroid lipofuscinoses, myoclonus epilepsy with ragged-red fibers [MERRF], and type 1 and 2 sialidoses) have been identified. PMEs are uncommon disorders, difficult to diagnose in the absence of extensive experience. Thus, aetiology is undetermined in many patients, despite the advance in molecular medicine. Treatment of PMEs remains essentially symptomaticof seizures and myoclonus, together with palliative, supportive, and rehabilitative measures. The response to therapy may initially be relatively favourable, afterwards however, seizures may become more frequent, and progressive neurologic decline occurs. The prognosis of a PME depends on the specific disease. The history of PMEs revealed that the international collaboration and sharing experience is the right way to proceed. This emerging picture and biological insights will allow us to find ways to provide the patients with meaningful treatment.

An Italian multicentre study of perampanel in progressive myoclonus epilepsies

Perampanel (PER) is a novel anti-seizure medication useful in different types of epilepsy. We intended to assess the effectiveness of PER on cortical myoclonus and seizure frequency in patients with progressive myoclonus epilepsy (PME), using quantitative validated scales. Forty-nine patients aged 36.6 ± 15.6 years with PME of various aetiology (18 EPM1, 12 EPM2, five with sialidosis, one with Kufs disease, one with EPM7, and 12 undetermined) were enrolled between January 2017 and June 2018. PER at the dose of 2-12 mg (5.3 ± 2.5) was added to existing therapy. Myoclonus severity was assessed using a minimal myoclonus scale (MMS) in all the patients before and after 4-6 months of steady PER dose, and by means of the Unified Myoclonus Rating Scale (UMRS) in 20 patients. Logistic regression analysis was used to identify the factors potentially predicting treatment efficacy. Four patients dropped out in the first two months due to psychiatric side effects. In the remaining patients, PER reduced myoclonus severity as assessed using MMS (Wilcoxon test: p < 0.001) and UMRS (p < 0.001), with the 'Action myoclonus' section of the UMRS showing the greatest improvement. The patients with EPM1 or EPM1-like phenotype were more likely to improve with PER (p = 0.011). Convulsive seizures which have recurred at least monthly in 17 patients were reduced by >50%. Side effects occurred in 22/49 (44.8%) patients, the most common being irritability followed by drowsiness. PER is effective in treating myoclonus and seizures in PME patients. The frequency of psychiatric side effects suggests the need for careful patient monitoring.

Update on Pharmacological Treatment of Progressive Myoclonus Epilepsies

BACKGROUND

Progressive myoclonus epilepsies (PMEs) are a group of rare inherited diseases featuring a combination of myoclonus, seizures and variable degree of cognitive impairment. Despite extensive investigations, a large number of PMEs remain undiagnosed. In this review, we focus on the current pharmacological approach to PMEs.

METHODS

References were mainly identified through PubMed search until February 2017 and backtracking of references in pertinent studies.

RESULTS

The majority of available data on the efficacy of antiepileptic medications in PMEs are primarily anecdotal or observational, based on individual responses in small series. Valproic acid is the drug of choice, except for PMEs due to mitochondrial diseases. Levetiracetam and clonazepam should be considered as the first add-on treatment. Zonisamide and perampanel represent promising alternatives. Phenobarbital and primidone should be reserved to patients with resistant disabling myoclonus or seizures. Lamotrigine should be used with caution due to its unpredictable effect on myoclonus. Avoidance of drugs known to aggravate myoclonus and seizures, such as carbamazepine and phenytoin, is paramount. Psychiatric (in particular depression) and other comorbidities need to be adequately managed. Although a 3- to 4-drug regimen is often necessary to control seizures and myoclonus, particular care should be paid to avoid excessive pharmacological load and neurotoxic side effects. Target therapy is possible only for a minority of PMEs.

CONCLUSIONS

Overall, the treatment of PMEs remains symptomatic (i.e. pharmacological treatment of seizures and myoclonus). Further dissection of the genetic background of the different PMEs might hopefully help in the future with individualised treatment options.

Unverricht-Lundborg disease: Clinical course and seizure management based on the experience of polish centers

The purpose of this paper was to present our experience following the longterm treatment of 11 patients with Unverricht-Lundborg disease (ULD) confirmed by molecular testing.

METHODS

We analyzed the clinical course, cognitive state, neuroimaging and neurophysiology results.

RESULTS

The data were collected from 9 unrelated families (F/M: 4/7) aged 25-49. The most frequent early manifestations of ULD include generalized tonic-clonic seizures (GTCS) accompanied by myoclonus 2 years later. Myoclonus was observed in all of the patients; its severity made it impossible for 91% to move independently. In two patients- mild atrophy of brain were observed in the MRI. More than half of the patients who underwent evoked potential presented no abnormalities. The dominant EEG-change was slow background activity in all of the patients. Seven patients had generalized seizure activity. The patients received antiepileptic therapy modifications depending on the severity of symptoms and stage of the disease. Five patients received N-acetyl-cysteine.

CONCLUSIONS

ULD patients require anti-epileptic polytherapy, mostly benefitting from managing GTCS and myoclonus with valproic acid and clonazepam treatment. Patients may benefit from add-on therapy with levetiracetam or topiramate. An increase in myoclonus, resulting from the progressive nature of the disease leads to significant disability in the majority of patients.

Abnormal motor cortical adaptation to external stimulus in Unverricht-Lundborg disease (progressive myoclonus type 1, EPM1)

Unverricht-Lundborg disease (EPM1) is associated with progressive functional and anatomic changes in the thalamus and motor cortex. The neurophysiological mechanisms behind the impaired thalamocortical system were studied through short-term adaptation of the motor cortex to transcranial magnetic stimulation (TMS) via repetition suppression (RS) phenomenon. RS is considered to be related to neural processing of external stimuli. We hypothesized that this neural processing is progressively impaired in EPM1 from adolescence to adulthood. Eight adult patients with EPM1 (age: 40 ± 13 yr), six adolescent patients with EPM1 (age: 16 ± 1 yr), and ten adult controls (age: 35 ± 12 yr) were studied using navigated TMS and RS study protocol including trains of four repeated stimuli with intertrain interval of 20 s and interstimulus interval of 1 s. Changes in RS were investigated from adolescence to adulthood in EPM1 by comparing with adult controls. In controls, the RS was seen as 50-55% reduction in motor response amplitudes to TMS after the first stimulus. RS was mild or missing in EPM1. RS from first to second stimulus within the stimulus trains was significantly stronger in adolescent patients than in adult patients ( P = 0.046). Abnormal RS correlated with the myoclonus severity of the patients. In agreement with our hypothesis, neural processing of external stimuli is progressively impaired in EPM1 possibly due to anatomically impaired thalamocortical system or inhibitory tonus preventing sufficient adaptive reactiveness to stimuli. Our results suggest that RS abnormality might be used as a biomarker in the therapeutic trials for myoclonus. NEW & NOTEWORTHY Unverricht-Lundborg disease (EPM1) is associated with impaired thalamocortical function, which we studied in 8 adult and 6 adolescent patients and in 10 adult controls through repetition suppression (RS) of the motor cortex. We hypothesized that neural processing is progressively impaired in EPM1 from adolescence to adulthood. RS was normal in controls, whereas it was mild or missing in EPM1. Stronger RS was seen in adolescent patients than in adult patients correlating with the myoclonus severity.

Variable course of Unverricht-Lundborg disease

Objective:

To explore the course of Unverricht-Lundborg disease (EPM1) and identify the risk factors for severity, we investigated the time course of symptoms and prognostic factors already detectable near to disease onset.

Methods:

We retrospectively evaluated the features of 59 Italian patients carrying the CSTB expansion mutation, and coded the information every 5 years after the disease onset in order to describe the cumulative time-dependent probability of reaching disabling myoclonus, relevant cognitive impairment, and inability to work, and evaluated the influence of early factors using the log-rank test. The risk factors were included in a Cox multivariate proportional hazards regression model.

Results:

Disabling myoclonus occurred an average of 32 years after disease onset, whereas cognitive impairment occurred a little later. An age at onset of less than 12 years, the severity of myoclonus at the time of first assessment, and seizure persistence more than 10 years after onset affected the timing of disabling myoclonus and cognitive decline. Most patients became unable to work years before the appearance of disabling myoclonus or cognitive decline.

Conclusions:

A younger age at onset, early severe myoclonus, and seizure persistence are predictors of a more severe outcome. All of these factors may be genetically determined, but the greater hyperexcitability underlying more severe seizures and myoclonus at onset may also play a role by increasing cell damage due to reduced cystatin B activity.

Methodological issues associated with clinical trials in epilepsy

INTRODUCTION

despite methodological advances in epilepsy clinical trials, the proportion of patients reaching seizure-freedom has not substantially changed over the years. We review the main methodological limitations of current trials, the possible strategies to overcome these limits, and the issues that need to be addressed in next future. Area covered: references were identified by PubMed search until March 2017 and unpublished literature was searched on ClinicalTrials.gov. Add-on trials mainly involve refractory epilepsy subjects, reducing overall response to the investigational drug. The inclusion of subjects with earlier disease from less developed countries has partially allowed overcoming this limitation, but has introduced more random variability of results. Monotherapy trials rise methodological, economical, and ethical concerns with different regulatory requirements in European Union and in the United States of America. Newer trial designs, such as futility trials or 'time-to-event' design, have been implemented. Moreover, both add-on and monotherapy trials results might be affected by patient's ability to recognize and record seizures, and by randomness of seizures occurrence over time. Possible strategies to achieve more reliable outcomes are detailed. Expert commentary: clinical trial methodology needs to be optimized to better address regulatory agencies requirements and to encounter both patients' and clinicians' needs.

Myoclonus epilepsy and ataxia due to KCNC1 mutation: Analysis of 20 cases and K+ channel properties

OBJECTIVE

To comprehensively describe the new syndrome of myoclonus epilepsy and ataxia due to potassium channel mutation (MEAK), including cellular electrophysiological characterization of observed clinical improvement with fever.

METHODS

We analyzed clinical, electroclinical, and neuroimaging data for 20 patients with MEAK due to recurrent KCNC1 p.R320H mutation. In vitro electrophysiological studies were conducted using whole cell patch-clamp to explore biophysical properties of wild-type and mutant K_V 3.1 channels.

RESULTS

Symptoms began at between 3 and 15 years of age (median = 9.5), with progressively severe myoclonus and rare tonic-clonic seizures. Ataxia was present early, but quickly became overshadowed by myoclonus; 10 patients were wheelchair-bound by their late teenage years. Mild cognitive decline occurred in half. Early death was not observed. Electroencephalogram (EEG) showed generalized spike and polyspike wave discharges, with documented photosensitivity in most. Polygraphic EEG-electromyographic studies demonstrated a cortical origin for myoclonus and striking coactivation of agonist and antagonist muscles. Magnetic resonance imaging revealed symmetrical cerebellar atrophy, which appeared progressive, and a prominent corpus callosum. Unexpectedly, transient clinical improvement with fever was noted in 6 patients. To explore this, we performed high-temperature in vitro recordings. At elevated temperatures, there was a robust leftward shift in activation of wild-type K_V 3.1, increasing channel availability.

INTERPRETATION

MEAK has a relatively homogeneous presentation, resembling Unverricht-Lundborg disease, despite the genetic and biological basis being quite different. A remarkable improvement with fever may be explained by the temperature-dependent leftward shift in activation of wild-type K_V 3.1 subunit-containing channels, which would counter the loss of function observed for mutant channels, highlighting KCNC1 as a potential target for precision therapeutics. Ann Neurol 2017;81:677-689.

A clinical and neurophysiological motor signature of Unverricht-Lundborg disease

OBJECTIVES

Unverricht-Lundborg disease (ULD) is the most common form of progressive myoclonus epilepsy. Cerebellar dysfunction may appear over time, contributing along with myoclonus to motor disability. The purpose of the present work was to clarify the motor and neurophysiological characteristics of ULD patients.

METHODS

Nine patients with genetically proven ULD were evaluated clinically (medical history collected from patient charts, the Scale for the Assessment and Rating of Ataxia and Unified Myoclonus Rating Scale). Neurophysiological investigations included EEG, surface polymyography, long-loop C-reflexes, somatosensory evoked potentials, EEG jerk-locked back-averaging (JLBA) and oculomotor recordings. All patients underwent brain MRI. Non-parametric Mann-Whitney tests were used to compare ULD patients' oculomotor parameters with those of a matched group of healthy volunteers (HV).

RESULTS

Myoclonus was activated by action but was virtually absent at rest and poorly induced by stimuli. Positive myoclonus was multifocal, often rhythmic and of brief duration, with top-down pyramidal temporospatial propagation. Cortical neurophysiology revealed a transient wave preceding myoclonus on EEG JLBA (n=8), enlarged somatosensory evoked potentials (n=7) and positive long-loop C-reflexes at rest (n=5). Compared with HV, ULD patients demonstrated decreased saccadic gain, increased gain dispersion and a higher frequency of hypermetric saccades associated with decreased peak velocity.

CONCLUSION

A homogeneous motor pattern was delineated that may represent a ULD clinical and neurophysiological signature. Clinical and neurophysiological findings confirmed the pure cortical origin of the permanent myoclonus. Also, oculomotor findings shed new light on ULD pathophysiology by evidencing combined midbrain and cerebellar dysfunction.

Perampanel in 12 patients with Unverricht-Lundborg disease

OBJECTIVE

Perampanel (PER) was used in 12 patients with Unverricht-Lundborg disease (ULD) to evaluate its efficacy against myoclonus and seizures.

METHODS

We treated 11 patients with EPM1 mutations (6 F, 5 M, aged 13-62 years) and a 43-year-old man with de novo KCNC1 mutation. PER was introduced by 2 mg steps at 2-4 week intervals until 6 mg/day, with a possible dose reduction or dose increase.

RESULTS

Ten patients had a clear clinical response of myoclonus, and five were able to reduce concomitant therapy. Improvement was noted sometimes as soon as with 2 mg/day. Epileptic seizures stopped on PER in the six patients who still had experienced generalized tonic-clonic or myoclonic seizures (100%). Some abatement of efficacy on myoclonus was seen in two patients who still retained some benefit. Weight gain was reported in six patients (50%). Psychological and behavioral side-effects were observed in six patients (50%) and led to withdrawal of PER in three cases and dose reduction in three, with abatement of the problems.

SIGNIFICANCE

This study provides evidence that for ULD patients, PER may show marked efficacy even in severe cases, particularly against myoclonus, but also against seizures. PER should thus be tried in ULD patients whose seizures are not satisfactorily controlled. Its use is limited because of psychological and behavioral side effects, with higher doses of approximately 6 mg/day or greater likely risk factors.

The network sustaining action myoclonus: a MEG-EMG study in patients with EPM1

Background

To explore the cortical network sustaining action myoclonus and to found markers of the resulting functional impairment, we evaluated the distribution of the cortico-muscular coherence (CMC) and the frequency of coherent cortical oscillations with magnetoencephalography (MEG). All patients had EPM1 (Unverricht-Lundborg) disease known to present with prominent and disabling movement-activated myoclonus.

Methods

Using autoregressive models, we evaluated CMC on MEG sensors grouped in regions of interests (ROIs) above the main cortical areas. The movement was a repeated sustained isometric extension of the right hand and right foot. We compared the data obtained in 10 EPM1 patients with those obtained in 10 age-matched controls.

Results

As expected, CMC in beta band was significantly higher in EPM1 patients compared to controls in the ROIs exploring the sensorimotor cortex, but, it was also significantly higher in adjacent ROIs ipsilateral and contralateral to the activated limb. Moreover, the beta-CMC peak occurred at frequencies significantly slower and more stable frequencies in EPM1 patients with respect to controls. The frequency of the beta-CMC peak inversely correlated with the severity of myoclonus.

Conclusions

the high and spatially extended beta-CMC peaking in a restricted range of low-beta frequencies in EPM1 patients, suggest that action myoclonus may result not only from an enhanced local synchronization but also from a specific oscillatory activity involving an expanded neuronal pool. The significant relationship between beta-CMC peak frequency and the severity of the motor impairment can represent a useful neurophysiological marker for the patients’ evaluation and follow-up.

Cerebellar Involvement in Patients with Mild to Moderate Myoclonus Due to EPM1: Structural and Functional MRI Findings in Comparison with Healthy Controls and Ataxic Patients

EPM1 (epilepsy, progressive myoclonic 1; Unverricht-Lundborg disease, OMIM #254800) is the most frequent form of progressive myoclonus epilepsy. Previous findings have suggested that its pathophysiology mainly involves the cerebellum, but the evaluation of cerebellar dysfunction is still unsatisfactory. The aim of this study was to assess the structural and functional involvement of the cerebellum in EPM1. We used voxel-based morphometry and spatially unbiased infra-tentorial template analyses of structural magnetic resonance imaging (MRI) scans, and functional MRI (fMRI) scans during block and event-related go/no-go motor tasks to study 13 EPM1 patients with mild to moderate myoclonus. We compared the results with those obtained in 12 age-matched healthy controls (HCs) and in 12 patients with hereditary spinocerebellar ataxia (SCA). Structural analyses revealed different patterns of atrophic changes in the EPM1 and SCA patients: in the former, they involved both cerebrum and cerebellum but, in the latter, only the cerebellum. During fMRI, block and event-related go/no-go tasks similarly activated the cerebellum and cerebrum in the EPM1 patients and HCs, whereas both tasks revealed much less cerebellar activation in the SCA patients than in the other two groups. Volumetric evaluation of the EPM1 patients showed that the cerebellum seemed to be marginally involved in a widespread atrophic process, and fMRI showed that it was not functionally impaired during motor tasks.

Clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy

OBJECTIVE

Familial cortical myoclonic tremor with epilepsy is a rare epilepsy syndrome. Herein, we report on nine Chinese familial cortical myoclonic tremor with epilepsy pedigrees to delineate its clinical and neurophysiological features.

METHODS

Detailed clinical and neurophysiological data were obtained. Somatosensory evoked potential amplitudes and clinical profile were analyzed using multilevel statistical models. Age-at-onset anticipation was analyzed using Kaplan-Meier survival analysis.

RESULTS

Fifty-five patients were interviewed directly, whose mean age at onset of cortical tremor and generalized tonic-clonic seizures were 31.0 ± 8.3 and 36.0 ± 7.9 years. Giant somatosensory evoked potential was detected in 87.5% (28 of 32) of patients, and long-latency cortical reflex was detected in 93.5% (29 of 31). Cortical tremor severity was significantly higher in patients with longer disease duration of cortical tremor (P = 0.0061). Somatosensory evoked potential amplitudes were significant higher in patients with higher level of cortical tremor severity (P = 0.0003) and those using antiepileptic drugs (P = 0.0150). Age-at-onset anticipation of cortical tremor with paternal transmission was found with statistical significance (P = 0.022).

CONCLUSION

We provided the clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy patients. This study is reported for the presentation of this rare disease in a Chinese population with the largest single report on familial cortical myoclonic tremor with epilepsy worldwide. Age-at-onset anticipation of cortical tremor with paternal transmission was statistically significant, which further confirmed a possibility of unstable expanding repeat in the genetic mechanism of familial cortical myoclonic tremor with epilepsy. © 2016 International Parkinson and Movement Disorder Society.

Brivaracetam: review of its pharmacology and potential use as adjunctive therapy in patients with partial onset seizures

Brivaracetam (BRV), a high-affinity synaptic vesicle protein 2A ligand, reported to be 10–30-fold more potent than levetiracetam (LEV), is highly effective in a wide range of experimental models of focal and generalized seizures. BRV and LEV similarly bind to synaptic vesicle protein 2A, while differentiating for other pharmacological effects; in fact, BRV does not inhibit high voltage Ca²⁺ channels and AMPA receptors as LEV. Furthermore, BRV apparently exhibits inhibitory activity on neuronal voltage-gated sodium channels playing a role as a partial antagonist. BRV is currently waiting for approval both in the United States and the European Union as adjunctive therapy for patients with partial seizures. In patients with photosensitive epilepsy, BRV showed a dose-dependent effect in suppressing or attenuating the photoparoxysmal response. In well-controlled trials conducted to date, adjunctive BRV demonstrated efficacy and good tolerability in patients with focal epilepsy. BRV has a linear pharmacokinetic profile. BRV is extensively metabolized and excreted by urine (only 8%–11% unchanged). The metabolites of BRV are inactive, and hydrolysis of the acetamide group is the mainly involved metabolic pathway; hepatic impairment probably requires dose adjustment. BRV does not seem to influence other antiepileptic drug plasma levels. Six clinical trials have so far been completed indicating that BRV is effective in controlling seizures when used at doses between 50 and 200 mg/d. The drug is generally well-tolerated with only mild-to-moderate side effects; this is confirmed by the low discontinuation rate observed in these clinical studies. The most common side effects are related to central nervous system and include fatigue, dizziness, and somnolence; these apparently disappear during treatment. In this review, we analyzed BRV, focusing on the current evidences from experimental animal models to clinical studies with particular interest on potential use in clinical practice. Finally, pharmacological properties of BRV are summarized with a description of its pharmacokinetics, safety, and potential/known drug–drug interactions.

Familial epilepsy in Algeria: Clinical features and inheritance profiles

PURPOSE

To document the clinical characteristics and inheritance pattern of epilepsy in multigeneration Algerian families.

METHODS

Affected members from extended families with familial epilepsy were assessed at the University Hospital of Oran in Algeria. Available medical records, neurological examination, electroencephalography and imaging data were reviewed. The epilepsy type was classified according to the criteria of the International League Against Epilepsy and modes of inheritance were deduced from pedigree analysis.

RESULTS

The study population included 40 probands; 23 male (57.5%) and 17 female subjects (42.5%). The mean age of seizure onset was 9.5 ± 6.1 years. According to seizure onset, 16 patients (40%) had focal seizures and 20 (50%) had generalized seizures. Seizure control was achieved for two patients (5%) for 10 years, while 28 (70%) were seizure-free for 3 months. Eleven patients (27.5%) had prior febrile seizures, 12 were diagnosed with psychiatric disorders and four families had syndromic epilepsy. The consanguinity rate among parents of affected was 50% with phenotypic concordance observed in 25 families (62.5%). Pedigree analysis suggested autosomal dominant (AD) inheritance with or without reduced penetrance in 18 families (45%), probable autosomal recessive (AR) inheritance in 14 families (35%), and an X-linked recessive inheritance in one family.

CONCLUSION

This study reveals large Algerian families with multigenerational inheritance of epilepsy. Molecular testing such as exome sequencing would clarify the genetic basis of epilepsy in some of our families.

Profile of brivaracetam and its potential in the treatment of epilepsy

Brivaracetam (BRV) (UCB 34714) is currently under review by the US Food and Drug Administration and European Medicines Agency for approval as an add-on treatment for adult patients with partial seizures. Similar to levetiracetam (LEV), BRV acts as a high-affinity ligand of the synaptic vesicle protein 2A, however, it has been shown to be 10- to 30-fold more potent than LEV. Moreover, BRV does not share the LEV inhibitory activity on the high voltage Ca(2+) channels and AMPA receptors, and it has been reported to act as a partial antagonist on neuronal voltage-gated sodium channels. The pharmacokinetic profile of BRV is favorable and linear, and it undergoes an extensive metabolism into inactive compounds, mainly through the hydrolysis of its acetamide group. Furthermore, it does not significantly interact with other antiepileptic drugs and more than 95% is excreted through the urine, with an unchanged fraction of 8%-11%. BRV has a half-life of approximately 8-9 hours and it is usually given twice daily. To date, a wide range of experimental studies have reported the effectiveness of BRV with regards to partial and generalized seizures. In humans, six randomized, placebo-controlled trials and two meta-analyses highlighted the efficacy, or good tolerability, of BRV as an add-on treatment for patients with uncontrolled partial seizures. A wide dose range of BRV has been evaluated in those trials (5-200 mg), but the most suitable for clinical use appears to be 50-100 mg/day. The most common adverse reactions to BRV are mild to moderate, transient, often improve during the course of the treatment, and mainly consist of central nervous system symptoms, such as fatigue, dizziness, and somnolence. The aim of this paper is to critically review the literature data regarding experimental animal models and clinical trials on BRV, and to define its potential usefulness for the clinicians who manage patients with epilepsy.

Transition for patients with epilepsy due to metabolic and mitochondrial disorders

The transition of adolescents with refractory epilepsy to the care of adult neurologists can be challenging. For those patients with epilepsy due to mitochondrial disorders, Lafora disease, Unverricht-Lundborg disease, and GLUT1 deficiency syndrome, a successful transition can be even more problematic for both caregivers and neurologists. Many of these patients require dietary treatments (ketogenic and modified Atkins diets) for long-term management of their epilepsy. For these patients, coordinating transfer of their dietary management is necessary.

Progressive myoclonic epilepsy type 1: Report of an Emirati family and literature review

PURPOSE

Progressive myoclonic epilepsy type one is a neurodegenerative disorder characterized by action- and stimulus-sensitive myoclonus, tonic-clonic seizures, progressive cerebellar ataxia, preserved cognition, and poor outcome. The authors report clinical, neurophysiological, radiological, and genetic findings of an Emirati family with five affected siblings and review the literature.

METHODS

All data concerning familial and clinical history, neurologic examination, laboratory tests, electroencephalogram, brain imaging, and DNA analysis were examined.

RESULTS

Genetic testing confirmed the diagnosis of autosomal recessive progressive myoclonic epilepsy type 1 (EPM1) in two males and three females. The median age at onset was three years. Action- or stimulus-sensitive myoclonus and generalized seizures were recorded in 100% of our patients, at median age at onset of 3 and 4 years, respectively. Multisegmental myoclonus and generalized status myoclonicus were observed in 80% of our patients. Dysarthria and ataxia developed in 100% of our patients. Vitamin D deficiency and recurrent viral infections were noticed in 100% of our cohort. Cognitive, learning, and motor dysfunctions were involved in 100% of our patients. The sphincters were affected in 60% of our patients. Abnormal EEG was recorded in 100% of our cohort. Generalized brain atrophy progressively occurred in 60% of our patients. Phenytoin and carbamazepine were used in 60% of our patients with worsening effect. Valproate and levetiracetam were used in 100% of our patients with improving effect.

CONCLUSIONS

This is the first to report a family with EPM1 in UAE. Our study emphasized a particular phenotype expressed as earlier disease onset, severe myoclonus, and generalized seizures. Cognitive, cerebellar, motor, and autonomic dysfunctions and brain atrophy were also earlier at onset and more severe than previously reported. Recurrent viral infections are another unique feature. This constellation in tout à fait was not previously reported in the literature.

Progressive myoclonic epilepsies: definitive and still undetermined causes

OBJECTIVE

To define the clinical spectrum and etiology of progressive myoclonic epilepsies (PMEs) in Italy using a database developed by the Genetics Commission of the Italian League against Epilepsy.

METHODS

We collected clinical and laboratory data from patients referred to 25 Italian epilepsy centers regardless of whether a positive causative factor was identified. PMEs of undetermined origins were grouped using 2-step cluster analysis.

RESULTS

We collected clinical data from 204 patients, including 77 with a diagnosis of Unverricht-Lundborg disease and 37 with a diagnosis of Lafora body disease; 31 patients had PMEs due to rarer genetic causes, mainly neuronal ceroid lipofuscinoses. Two more patients had celiac disease. Despite extensive investigation, we found no definitive etiology for 57 patients. Cluster analysis indicated that these patients could be grouped into 2 clusters defined by age at disease onset, age at myoclonus onset, previous psychomotor delay, seizure characteristics, photosensitivity, associated signs other than those included in the cardinal definition of PME, and pathologic MRI findings.

CONCLUSIONS

Information concerning the distribution of different genetic causes of PMEs may provide a framework for an updated diagnostic workup. Phenotypes of the patients with PME of undetermined cause varied widely. The presence of separate clusters suggests that novel forms of PME are yet to be clinically and genetically characterized.

3D texture analysis reveals imperceptible MRI textural alterations in the thalamus and putamen in progressive myoclonic epilepsy type 1, EPM1

Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessively inherited neurodegenerative disorder characterized by young onset age, myoclonus and tonic-clonic epileptic seizures. At the time of diagnosis, the visual assessment of the brain MRI is usually normal, with no major changes found later. Therefore, we utilized texture analysis (TA) to characterize and classify the underlying properties of the affected brain tissue by means of 3D texture features. Sixteen genetically verified patients with EPM1 and 16 healthy controls were included in the study. TA was performed upon 3D volumes of interest that were placed bilaterally in the thalamus, amygdala, hippocampus, caudate nucleus and putamen. Compared to the healthy controls, EPM1 patients had significant textural differences especially in the thalamus and right putamen. The most significantly differing texture features included parameters that measure the complexity and heterogeneity of the tissue, such as the co-occurrence matrix-based entropy and angular second moment, and also the run-length matrix-based parameters of gray-level non-uniformity, short run emphasis and long run emphasis. This study demonstrates the usability of 3D TA for extracting additional information from MR images. Textural alterations which suggest complex, coarse and heterogeneous appearance were found bilaterally in the thalamus, supporting the previous literature on thalamic pathology in EPM1. The observed putamenal involvement is a novel finding. Our results encourage further studies on the clinical applications, feasibility, reproducibility and reliability of 3D TA.

Lifetime prognosis of juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy (JME) is among the most common types of genetic epilepsies, displaying a good prognosis when treated with appropriate drugs, but with a well-known tendency to relapse after withdrawal. The majority of patients with JME have continuing seizures after a follow-up of two decades. However, 17% are able to discontinue medication and remain seizure-free thereafter. Clinicians should remember that there is a small but still considerable subgroup of JME patients whose seizures are difficult to treat before informing patients with newly-diagnosed JME about their "benign" prognosis. This resistant course is not fully explained, though there are many suggested factors. The dominating myoclonic seizures disappear or diminish in severity in the fourth decade of life. Despite the favorable seizure outcome in most of the cases, 3/4 of patients with JME have at least one major unfavorable social outcome. The possible subsyndromes of JME, its genetic background, and its pathophysiological and neuroimaging correlates should be further investigated.

Progressive myoclonus epilepsy

The progressive myoclonus epilepsies (PMEs) consist of a group of diseases with myoclonic seizures and progressive neurodegeneration, with onset in childhood and/or adolescence. Lafora disease is a neuronal glycogenosis in which normal glycogen is transformed into starch-like polyglucosans that accumulate in the neuronal somatodendritic compartment. It is caused by defects of two genes of yet unknown function, one encoding a glycogen phosphatase (laforin) and the other an ubiquitin E3 ligase (malin). Early cognitive deterioration, visual seizures affecting over half, and slowing down of EEG basic activity are three major diagnostic clues. Unverricht-Lundborg disease is presently thought to be due to damage to neurons by lysosomal cathepsins and reactive oxygen species due to absence of cystatin B, a small protein that inactivates cathepsins and, by ways yet unknown, quenches damaging redox compounds. Preserved cognition and background EEG activity, action myoclonus early morning and vertex spikes in REM sleep are the diagnostic clues. Sialidosis, with cherry-red spot, neuronopathic Gaucher disease, with paralysis of verticality, and ataxia-PME, with ataxia at onset in the middle of the first decade, are also lysosomal diseases. How the lysosomal defect culminates in myoclonus and epilepsy in these conditions remains unknown.

Thickened skull, scoliosis and other skeletal findings in Unverricht-Lundborg disease link cystatin B function to bone metabolism

PURPOSE

Unverricht-Lundborg disease (EPM1) is a rare type of inherited progressive myoclonic epilepsy resulting from mutations in the cystatin B gene, CSTB, which encodes a cysteine cathepsin inhibitor. Cystatin B, cathepsin K, and altered osteoclast bone resorption activity are interconnected in vitro. This study evaluated the skeletal characteristics of patients with EPM1.

METHODS

Sixty-six genetically verified EPM1 patients and 50 healthy controls underwent head MRI. Skull dimensions and regional calvarial thickness was measured perpendicular to each calvarial bone from T1-weighted 3-dimensional images using multiple planar reconstruction tools. All clinical X-ray files of EPM1 patients were collected and reviewed by an experienced radiologist. A total of 337 X-ray studies were analyzed, and non-traumatic structural anomalies, dysplasias and deformities were registered.

RESULTS

EPM1 patients exhibited significant thickening in all measured cranial bones compared to healthy controls. The mean skull thickness was 10.0±2.0mm in EPM1 patients and 7.6±1.2mm in healthy controls (p<0.001). The difference was evident in all age groups and was not explained by former phenytoin use. Observed abnormalities in other skeletal structures in EPM1 patients included thoracic scoliosis (35% of EPM1 patients) and lumbar spine scoliosis (35%), large paranasal sinuses (27%), accessory ossicles of the foot, and arachnodactyly (18%).

CONCLUSIONS

Skull thickening and an increased prevalence of abnormal findings in skeletal radiographs of patients with EPM1 suggest that this condition is connected to defective cystatin B function. These findings further emphasize the role of cystatin B in bone metabolism in humans.

Genetics of epilepsy and relevance to current practice

Genetic factors are likely to play a major role in many epileptic conditions, spanning from classical idiopathic (genetic) generalized epilepsies to epileptic encephalopathies and focal epilepsies. In this review we describe the genetic advances in progressive myoclonus epilepsies, which are strictly monogenic disorders, genetic generalized epilepsies, mostly exhibiting complex genetic inheritance, and SCN1A-related phenotypes, namely genetic generalized epilepsy with febrile seizure plus and Dravet syndrome. Particular attention is devoted to a form of familial focal epilepsies, autosomal-dominant lateral temporal epilepsy, which is a model of non-ion genetic epilepsies. This condition is associated with mutations of the LGI1 gene, whose protein is secreted from the neurons and exerts its action on a number of targets, influencing cortical development and neuronal maturation.

Clinical and neurophysiologic features of progressive myoclonus epilepsy without renal failure caused by SCARB2 mutations

PURPOSE

Mutations of the SCARB2 gene cause action myoclonus renal failure syndrome (AMRF), a rare condition that combines progressive myoclonus epilepsy (PME) with severe renal dysfunction. We describe the clinical and neurophysiologic features of PME associated with SCARB2 mutations without renal impairment.

METHODS

Clinical and neurophysiologic investigations, including wakefulness and sleep electroencephalography (EEG), polygraphic recording (with jerk-locked back-averaging and analysis of the EEG-EMG (electromyography) relationship by coherence spectra and phase calculation), multimodal evoked potentials, and electromyography were performed on five Italian patients with SCARB2 mutations.

KEY FINDINGS

The main clinical features were adolescent-young adulthood onset, progressive action myoclonus, ataxia, absence of cognitive deterioration and, in most cases, epilepsy. The severity of the epilepsy could vary from uncontrolled seizures and status epilepticus in patients with adolescent onset to absent or rare seizures in patients with adult onset. Relevant neurophysiologic findings were a pronounced photosensitivity and massive action myoclonus associated with rhythmic myoclonic jerks at a frequency of 12-20 Hz, clinically resembling a postural tremor. The cortical origin of rhythmic myoclonus was demonstrated mainly by coherence and phase analysis of EEG-EMG signals indicating a significant EEG-EMG coupling and a direct corticospinal transfer.

SIGNIFICANCE

Our patients with SCARB2 mutations showed the clinical and neurophysiologic phenotype of PME, in which epilepsy could be extremely severe, extending the spectrum reported in the typical AMRF syndrome. Patients with PME of unknown origin of adolescent or young adult onset, with these neurophysiologic features, should be tested for SCARB2 mutations, even in the absence of renal impairment.

Natural history and long-term evolution in families with autosomal dominant cortical tremor, myoclonus, and epilepsy

PURPOSE

To investigate for the first time the natural history and long-term evolution of "familial cortical tremor, myoclonus, and epilepsy."

METHODS

We evaluated the clinical, electrophysiologic, and treatment data of 14 patients from three families linked to 2p11.1-q12.2. A simplified scale was used to score myoclonus severity. Electroencephalography (EEG) studies were reviewed for the evaluation of background activity, paroxysmal abnormalities, and photoparoxysmal response. Data were organized for age groups. Correlation and logistic regression analysis were performed.

KEY FINDINGS

Patients' mean age was 47.8 ± 22.0 years (range 20-86 years). Mean age at disease onset was 20.2 ± 7.8 years (range 11-40 years); mean follow-up duration was 14.0 ± 5.8 years (range 7-28 years). Evaluation at different age groups revealed a gradual, progressive worsening of the myoclonus in 10 patients (71.4%). Two subjects aged >80 years showed myoclonus interfering with autonomous walking. Myoclonus severity was correlated with disease duration (p<0.001) and patients' age (p=0.001). Six patients (42.8%) experienced seizures, usually between the second and sixth decades of life. Evaluation of EEG long-term evolution revealed progressive slowing of background activity in parallel with the gradual worsening of myoclonus. In contrast, paroxysmal activity and photosensitivity were particularly evident during the intermediate phases of the disease. In addition, psychiatric and neuropsychological dysfunction occurred in more than one third of the patients.

SIGNIFICANCE

We provide data for a slight age-dependent progression and the presence of neuropsychiatric and neuropsychological dysfunction in this unique syndrome, for which the definition of familial or autosomal dominant cortical tremor, myoclonus, and epilepsy (FCTME/ADCME) seems to be, therefore, more appropriate.

Chronic high-frequency deep-brain stimulation in progressive myoclonic epilepsy in adulthood--report of five cases

PURPOSE

To assess the efficacy and tolerability of chronic high-frequency deep brain stimulation (DBS) in adult patients with progressive myoclonic epilepsy (PME) syndromes.

METHODS

Five adult patients (four male, 28-39 years) with PME underwent chronic high-frequency DBS according to a study protocol that had been approved by the local ethics committee. Electrodes were implanted in the substantia nigra pars reticulata (SNr)/subthalamic nucleus (STN) region in the first patient and additionally in the ventral intermediate nucleus (VIM) bilaterally in the following four cases. Follow-up took place in intervals of 3 months and DBS effects were compared with baseline frequency of passive and activation-induced myoclonic jerks and daily life performance 8 weeks prior to implantation.

KEY FINDINGS

Follow-up periods ranged from 12-42 months (median 24 months). The best clinical effects were seen with SNr/STN DBS in all patients. VIM stimulation failed to achieve acute therapeutic effects and revealed low side-effect thresholds and even triggering of myoclonia. In all patients the reduction of myoclonic seizures was observed and ranged between 30% and 100% as quantified by a standardized video protocol. All patients reported clinically relevant improvements of various capabilities such as free standing and walking or improved fine motor skills. In one patient with an excellent initial response generalized tonic-clonic seizures increased after 3 months of stimulation following extensive trauma-related surgery. The best effect was seen in the least impaired patient.

SIGNIFICANCE

DBS of the SNr/STN may be an effective treatment option for patients with PME. Less impaired patients may benefit more markedly.