Progressive myoclonic epilepsy (PME) is characterized by prominent myoclonus, generalized tonic-clonic seizures, and less often focal, tonic, or absence seizures. The KCNC1 mutation is responsible for specific clinical phenotype of PME which has been defined as myoclonic epilepsy and ataxia due to potassium channel mutation (MEAK). We present a case of a 44 years-old male patient with genetically proven MEAK who underwent subthalamic nucleus/substantia nigra (STN/SNr) deep brain stimulation (DBS) for his pharmacological-refractory myoclonus and drug-resistant epilepsy (DRE). Since the age of 4-5 years, the patient had been suffering from intention tremor, and later the myoclonic jerks, ataxia involving the upper limbs and walking difficulties worsened. The first bilateral tonic-clonic seizure (BTCS) occurred at the age of 22. The patient agreed to staged bilateral implantation of DBS electrodes placed in the STN/SNr region. The follow-up lasts more than 24 months. The myoclonic jerks assessed by Unified Myoclonus Rating Scale (UMRS) were reduced by nearly 70 % and BTCS was completely abolished. The patient\'s ataxia and dysarthria did not improve. Early diagnosis with genetic testing may significantly help in counseling patients with PME and enables to undertake the surgical approach targeting the STN/SNr.

This study describes a patient with progressive myoclonic epilepsy-11 (EPM-11), which follows autosomal dominant inheritance caused by a novel SEMA6B variant. Most patients develop this disease during infancy or adolescence with action myoclonus, generalized tonic-clonic seizures (GTCS), and progressive neurological deterioration. No cases of adult-onset EPM-11 have been reported yet. Here, we present one case of adult-onset EPM-11 who experienced gait instability, seizures, and cognitive impairment, and harbored a novel missense variant, c.432C>G (p.C144W). Our findings provide a foundation for a better understanding of the phenotypic and genotypic profiles of EPM-11. Further functional studies are recommended to elucidate the pathogenesis of this disease.

Progressive myoclonic epilepsy (PME) is a group of rare diseases characterized by progressive myoclonus, cognitive impairment, ataxia, and other neurologic deficits. PME has high genetic heterogeneity, and more than 40 genes are reportedly associated with this disorder. SEMA6B encodes a member of the semaphorin family and was first reported to cause PME in 2020. Herein, we present a rare case of PME due to a novel SEMA6B gene mutation in a 6-year-old boy born to healthy non-consanguineous Chinese parents. His developmental milestones were delayed, and he developed recurrent atonic seizures and myoclonic seizures without fever at 3 years and 11 months of age. He experienced recurrent myoclonic seizures, non-convulsive status epilepticus (NCSE), atonic seizures, and atypical absence seizures during the last 2 years. At different time points since onset, valproic acid, levetiracetam, piracetam, and clobazam were used to control the intractable seizures. Notably, NCSE was controlled by a combination of piracetam with clobazam and valproic acid instead of intravenous infusion of midazolam and phenobarbital. Due to the limited number of cases reported to date, the clinical description of our case provides a better understanding of the genotype-phenotype correlations associated with PME and indicate that piracetam may be effective against NCSE in patients with SEMA6B-related PME.

BACKGROUND: Biallelic pathogenic variants in the SCARB2 gene have been associated with action myoclonus-renal failure (AMRF) syndrome. Even though SCARB2 associated phenotype has been reported to include typical neurological characteristics, depending on the localization and the feature of the pathogenic variants, clinical course and the presentations have been shown to differ.
METHODS: Whole exome sequencing (WES) analysis revealed a homozygous truncating variant (p.N45MfsX88) in SCARB2 gene in the index case, and subsequent sanger sequencing analysis validated the variant in all affected family members from a Turkish family with the clinical characteristics associated with AMRF and related disorders. Intrafamilial clinical heterogeneity with common features including dysarthria, tremor and proteinuria, and distinct features such as peripheral neuropathy (PNP), myoclonus and seizures between the affected cases, was observed in the family. In-depth literature review enabled the detailed investigation of the reported variants associated with AMRF and suggested that while the type of the variant did not have a major impact on the course of the clinical characteristics, only the C terminal localization of the pathogenic variant significantly affected the clinical presentation, particularly the age at onset (AO) of the disease.
CONCLUSIONS: In this study we showed that biallelic SCARB2 pathogenic variants might cause a spectrum of common and distinct features associated with AMRF. Of those features while the common features include myoclonus (100%), ataxia (96%), tonic clonic seizures (82%), dysarthria (68%), tremor (65%), and renal impairment (62%), the uncommon features involve PNP (17%), hearing loss (6.8%), and cognitive impairment (13.7%). AO has been found to be significantly higher in the carriers of the p.G462DfsX34 pathogenic variant. SCARB2 pathogenic variants have not been only implicated in AMRF but also in the pathogenesis of Parkinson\'s disease (PD) and Gaucher disease (GD), suggesting the importance of genetic and functional studies in the clinical and the diagnostic settings. Given the proven role of SCARB2 gene in the pathogenesis of AMRF, PD and GD with a wide spectrum of clinical symptoms, investigation of the possible modifiers, such as progranulin and HSP7, has a great importance.

Introduction: Progressive myoclonic epilepsies (PMEs) are a heterogenous group of genetic diseases presenting with epilepsy, cognitive impairment, and severe action myoclonus, which can severely affect daily life activities and independent walking ability. Perampanel is a recent commercially available antiseizure medication with high efficacy against generalized seizures. Some reports supported the role of perampanel in ameliorating action myoclonus in PMEs. Here, we aimed to describe a case series and provide a systematic literature review on perampanel effects on PMEs. Methods: We report the perampanel effectiveness on myoclonus, daily life activities, and seizures on an original Italian multicenter case series of 11 individuals with PMEs. Then, using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we performed a systematic review on perampanel effect on myoclonus and disability in PMEs. We searched PubMed, Scopus, and Google Scholar articles on perampanel and PMEs up to June 2020. No prospective trials were found. We reviewed 11 case series manuscripts reporting 104 cases of different PMEs. Results: Here, we are reporting the effectiveness of perampanel in five individuals affected by Unverricht-Lundborg disease, three by Lafora disease, two by sialidosis, and one by an undetermined PME. Nine out of 11 individuals improved their disability related to the action myoclonus (two with Lafora disease did not). Among the 104 persons with PMEs collected by the systematic review, we found that more than half of the patients receiving perampanel exhibited an amelioration of action myoclonus and, consequently, of their independence in daily life activities. The Unverricht-Lundborg disease seemed to show the best clinical response to perampanel, in comparison with the other more severe PMEs. A significant seizure reduction was achieved by almost all persons with active epilepsy. Only 11% of PME patients dropped out due to inefficacy. Conclusions: Perampanel demonstrated a beneficial effect with regard to action myoclonus, disability, and seizures and was well-tolerated in people with PMEs, independently from their genetic diagnosis. Given the limited scientific evidence, broader prospective trials should be encouraged.

Lafora Disease (LD) is a rare, fatal, late-onset, progressive form of myoclonic epilepsy, occurring in humans and dogs. Clinical manifestations of LD usually include seizures, spontaneous and reflex myoclonus with contractions of the neck and limb muscles. We studied the electroencephalogram (EEG) patterns of two beagles in whom LD was subsequently confirmed by genetic testing. In both cases, the EEG recordings, accompanied by electromyography (EMG), have shown similar uncommon patterns. The hypovoltaged background rhythm was interrupted by waxing \"crescendo\" polyspikes-slow wave complexes appearing 80-250 ms after the start of intermittent photic stimulation, followed by myoclonic jerks after 80-150 ms. This study highlights the value of EEG in establishing a presumptive diagnosis of LD in dogs.

BACKGROUND: A number of genetic syndromes associated with variants in the BSCL2/seipin gene have been identified. Variants that cause skipping of exon 7 are associated with progressive encephalopathy with/without lipodystrophy (PELD), which is characterized by the development of progressive myoclonic epilepsy at a young age, severe progressive neurological impairment, and early death, often in childhood. Because the genetic basis of PELD is similar to that of congenital lipodystrophy type 2, we hypothesized that a patient with PELD may respond to treatments approved for other congenital lipodystrophic syndromes.
METHODS: We describe a 5-year-old boy with an extremely rare phenotype involving severe progressive myoclonic epilepsy who received metreleptin (a recombinant analogue of leptin) to control metabolic abnormalities. At the age of two, he had no subcutaneous adipose tissue, with hypertriglyceridemia, hypertransaminasemia and hepatic steatosis. He also had a moderate psychomotor delay and generalized tonic seizures. At 4 years, he had insulin resistance, hypercholesterolemia, hypertriglyceridemia, mild hepatosplenomegaly and mild hepatic steatosis; he began a hypolipidemic diet. Severe psychomotor delay and myoclonic/myoclonic atonic seizures with absences was evident. At 5 years of age, metreleptin 0.06 mg/kg/day was initiated; after 2 months, the patient\'s lipid profile improved and insulin resistance resolved. After 1 year of treatment, hepatic steatosis improved and abdominal ultrasound showed only mild hepatomegaly. Seizure frequency decreased but was not eliminated during metreleptin therapy.
CONCLUSIONS: Metreleptin may be used to control metabolic disturbances and may lead to better seizure control in children with PELD.

BACKGROUND: Progressive myoclonic epilepsy (PME) is a syndrome characterized by development of progressive myoclonus, cognitive impairment, and other neurologic deficits. Despite major advances in medical treatment of epilepsy, some PME patients remain refractory to antiepileptic drugs. This may further accentuate cognitive impairment and deteriorate functional capacity. Corpus callosotomy (CC) is used in patients with drug-resistant epilepsy who are not candidates for either excisional epilepsy surgery or neurostimulation. We report the application of the standard complete callosotomy to control medically refractory status epilepticus in a patient with PME.
METHODS: A 16-year-old boy was referred to the emergency department with generalized tonic-clonic seizures. He was known to have PME since 5 years earlier, with frequent generalized seizures requiring hospitalization and reloading of the drugs. The patient was discussed by the epilepsy surgery working group, and corpus callosotomy was considered as a last resort to control the refractory status epilepticus. The patient experienced no generalized seizures during the 3-month postoperative period (Engel class IIIB).
CONCLUSIONS: Inasmuch as surgery was the last resort to control severe disabling status epilepticus, because most of the epileptogenic discharges were originating from the parieto-occipital regions and profound cognitive impairment was present, we decided to perform a complete rather than just an anterior callosotomy. CC may be considered to prevent secondary generalized seizures as the most disabling attacks in patients with certain epilepsy syndromes. Nevertheless, the impact of palliative surgical intervention on the overall disease course of patients with an underlying diffuse pathologic state remains to be determined.

Lafora disease (LD), also known as progressive myoclonic epilepsy-2 (EPM2), is a rare, fatal autosomal recessive disorder typically starting during adolescence in otherwise neurologically normal individuals. It is clinically characterized by insidious of progressive neurological features including seizures, action myoclonus, visual hallucination, ataxia and dementia. Mutations in the laforin (EPM2A) gene on chromosome 6q24 or in the malin gene (NHLRC1) on chromosome 6p22 are responsible of LD phenotype. Diagnostic workup includes genetic analysis as well as axillary skin biopsy with evidence of typical periodic acid-Schiff (PAS)-positive polyglucosan inclusion bodies (Lafora bodies) in the apocrine glands and/or in the eccrine duct. Usually, genotype-phenotype correlations do not reveal substantial differences between patients carrying EPM2A and NHLRC1 mutations, but a few specific NHLRC1 mutations appear to correlate with a late onset and slow progressing LD. We report a case of LD due to compound heterozygote NHLRC1 mutation in an adolescent presenting with severe and atypical electro-clinical features, mimicking an autoimmune encephalopathy, and a rapidly progressive clinical course.

Lafora body disease (LBD) is a form of progressive myoclonic epilepsy, characterized by seizures, myoclonic jerks, cognitive decline, ataxia, and intracellular polyglucosan inclusion bodies (Lafora bodies) in the neurons, heart, skeletal muscle, liver, and sweat gland duct cells. Electroencephalogram (EEG) findings in LBD may include multiple spikes and wave discharges, photosensitivity, multifocal epileptiform discharges, and progressive slowing in background activity. Periodicity in epileptiform discharges has not been frequently depicted in LBD. We herein report an unusual case of LBD who showed generalized periodic epileptiform discharges in EEG.