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Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessive disorder caused by mutations in the cystatin B gene (CSTB). Affected individual’s manifest stimulus-sensitive and action myoclonus and tonic-clonic epileptic seizures. In this study, we have generated iPSCs from an EPM1 patient’s skin fibroblasts with Sendai virus mediated transgene delivery. The iPSCs retained the patient specific promoter region expansion mutation, expressed pluripotency markers, differentiated into all three germ layers, and presented a normal karyotype. The line can in future be used to develop an in-vitro model for EPM1 and may help in understanding disease mechanisms at cellular and molecular level.

Objective: The aim of this study was to develop a feasible method for the detection of negative myoclonus (NM) through long-term home measurements in patients with progressive myoclonus epilepsy type 1., Methods: The number and duration of silent periods (SP) associated with NM were detected during a 48 h home recording using wearable surface electromyography (EMG) sensors., Results: A newly developed algorithm was able to find short (50-69 ms), intermediate (70-100 ms), and long (101- 500 ms) SPs from EMG data. Negative myoclonus assessed by the algorithm correlated significantly with the video-recorded and physician-evaluated unified myoclonus rating scale (UMRS) scores of NM and action myoclonus. Silent period duration, number, and their combination, correlated strongly and significantly also with the Singer score, which assesses functional status and ambulation., Conclusions: Negative myoclonus can be determined objectively using long-term EMG measurements in home environment. With long-term measurements, we can acquire more reliable quantified information about NM as a symptom, compared to short evaluation at the clinic., Significance: As measured using SPs, NM may be a clinically useful measure for monitoring disease progression or assessing antimyoclonic drug effects objectively., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: A.S. Declarations of interest: none. L.S. Declarations of interest: none. J.H. Declarations of interest: none. K.S. has received speaker’s honorarium by Jazz Pharma. R.K. has received speaker’s honoraria from Eisai, Jazz Pharmaceuticals, Orion, and UCB and honoraria for membership of the advisory boards/consultation of Angelini Pharma, Eisai, Jazz Pharmaceuticals, Orion and UCB. E.M. Declarations of interest: none. P.A.K. is a co-founder in Adamant Health Ltd. He is an inventor in patent applications WO2019166557A1 and WO2020174122A1. S.M.R. is a co-founder in Adamant Health Ltd that develops EMG-based analysis software. She is an inventor in patent applications WO2019166557A1 and WO2020174122A1., (Copyright © 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessive disorder caused by mutations in the cystatin B gene (CSTB). Affected individual's manifest stimulus-sensitive and action myoclonus and tonic-clonic epileptic seizures. In this study, we have generated iPSCs from an EPM1 patient's skin fibroblasts with Sendai virus mediated transgene delivery. The iPSCs retained the patient specific promoter region expansion mutation, expressed pluripotency markers, differentiated into all three germ layers, and presented a normal karyotype. The line can in future be used to develop an in-vitro model for EPM1 and may help in understanding disease mechanisms at cellular and molecular level., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Cystatin B (CSTB) gene mutations cause Unverricht–Lundborg disease (ULD), a rare form of myoclonic epilepsy. The previous identification of a Portuguese patient, homozygous for a unique splicing defect (c.66G>A; p.Q22Q), provided awareness regarding the existence of variant forms of ULD. In this work we aimed at the characterization of this mutation at the population level and at the cellular level. The cellular fractionation studies here carried out showed mislocalization of the protein and add to the knowledge on this disease.

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.

Objective: To develop and test wearable monitoring of surface electromyography and motion for detection and quantification of positive and negative myoclonus in patients with progressive myoclonic epilepsy type 1 (EPM1)., Methods: Surface electromyography and three-dimensional acceleration were measured from 23 EPM1 patients from the biceps brachii (BB) of the dominant and the extensor digitorum communis (EDC) of the non-dominant arm for 48 hours. The patients self-reported the degree of myoclonus in a diary once an hour. Severity of myoclonus with action was evaluated by using video-recorded Unified Myoclonus Rating Scale (UMRS). Correlations of monitored parameters were quantified with the UMRS scores and the self-reported degrees of myoclonus., Results: The monitoring-based myoclonus index correlated significantly (p < 0.001) with the UMRS scores (ρ = 0.883 for BB and ρ = 0.823 for EDC) and with the self-reported myoclonus degrees (ρ = 0.483 for BB and ρ = 0.443 for EDC). Ten patients were assessed as probably having negative myoclonus in UMRS, while our algorithm detected that in twelve patients., Conclusions: Wearable monitoring was able to detect both positive and negative myoclonus in EPM1 patients., Significance: Our method is suitable for quantifying objective, real-life treatment effects at home and progression of myoclonus., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: S.M.R. is a co-founder in Adamant Health Ltd that develops EMG-based analysis software. J.H. Declarations of interest: none. K.S. Declarations of interest: none. L.S. Declarations of interest: none. P.A.K. is a co-founder in Adamant Health Ltd. E.M. Declarations of interest: none. R.K. is a medical advisor of Adamant Health Ltd. RK has received grants from the Academy of Finland and Saastamoinen Foundation, speaker’s honoraria from Eisai, Omamedica, Orion, Sandoz, Sanofi and UCB and honoraria for membership of the advisory boards/consultation of Eisai, Marinus Pharmaceuticals, Orion and UCB., (Copyright © 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Objectives: To describe the EEG characteristics of patients with Unverricht-Lundborg disease (ULD) and their changes during the long-term evolution of the disease., Methods: A retrospective study including all patients with ULD confirmed by molecular biology and more than 15 years' duration of disease progression at the time of inclusion. EEGs were recorded at inclusion, 2 years and 5 years of follow-up. Patients who discontinued treatment during follow-up had an EEG monitoring 1 year after reintroduction of therapy., Results: Forty-seven EEGs were performed in 17 patients. The mean age at onset was 12.0±5.5 years. The mean duration of follow-up was 26.5±6.9 years. The average background rhythm was 8.2 c/s, and was normal in 30 EEGs (64%), slow in 17 (36%) and disorganized in 11 (23%). Epileptic abnormalities were found in 22 EEGs (47%). Myoclonic jerks were found in 13 EEGs (28%). After re-adaptation of antiepileptic medication in patients who had previously stopped treatment, control EEG showed a normal background rhythm with no epileptic abnormalities throughout the monitoring period., Conclusion: This study shows that the progressive disappearance of EEG abnormalities is rather due to antiepileptic treatment than a gradual spontaneous tendency to decrease over time., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Purpose: To delineate chronological changes of cortical hyperexcitability by long-term follow-up of the amplitudes of somatosensory evoked potentials (SEPs) in patients with Japanese Unverricht-Lundborg disease (ULD)., Method: SEPs to median nerve stimulation were repeatedly examined in 7 genetically diagnosed ULD patients with the mean interval of 11.9 years. The degree of temporal changes in the amplitude of 3 early cortical components, N20, P25 and N35, to the age was analyzed and compared with that of healthy subjects., Results: Their clinical course was almost stable during the follow-up period, namely cessation of generalized tonic-clonic seizures and little or no progression of myoclonus. SEP amplitudes of P25 and N35 were enlarged in all patients and were gradually decreased with aging in ULD on average. The degree of temporal changes of P25 and N35 in ULD was similar or even lower than that of healthy subjects., Conclusion: Enlarged but relatively stable SEP amplitudes had a consistency with so-called self-limited clinical course in Japanese ULD. SEP amplitude could be one of the surrogate markers of the degree of cortical hyperexcitability in ULD during the long-term follow-up period., (Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.)