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Myoclonus as a Manifestation of Reflex Seizures. J Clin Neurophysiol 2023; 40:109-116. [PMID: 36735459 DOI: 10.1097/wnp.0000000000000915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
SUMMARY Myoclonus is a motor symptom commonly associated with reflex seizures in people with idiopathic generalized epilepsies. The most frequently observed triggers of myoclonus are related to visual stimuli, including flashing lights or patterns; nonetheless, myoclonus can also be activated by movement, speech or reading, calculations, and praxis. Reflex myoclonic seizures may be the hallmark of a reflex epilepsy, but it may lead to the diagnosis of generalized epilepsy syndromes. In the setting of idiopathic generalized epilepsies, reflex myoclonus can persist despite optimal medical therapies and may be a marker for active, even medically intractable, epilepsy. In this article, the clinical significance, diagnosis, and treatment of myoclonus, associated with visual stimulation, movement, and praxis, will be reviewed.
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Italiano D, Striano P, Russo E, Leo A, Spina E, Zara F, Striano S, Gambardella A, Labate A, Gasparini S, Lamberti M, De Sarro G, Aguglia U, Ferlazzo E. Genetics of reflex seizures and epilepsies in humans and animals. Epilepsy Res 2016; 121:47-54. [PMID: 26875109 DOI: 10.1016/j.eplepsyres.2016.01.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 01/22/2016] [Accepted: 01/29/2016] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Reflex seizures are epileptic events triggered by specific motor, sensory or cognitive stimulation. This comprehensive narrative review focuses on the role of genetic determinants in humans and animal models of reflex seizures and epilepsies. METHODS References were mainly identified through MEDLINE searches until August 2015 and backtracking of references in pertinent studies. RESULTS Autosomal dominant inheritance with reduced penetrance was proven in several families with photosensitivity. Molecular genetic studies on EEG photoparoxysmal response identified putative loci on chromosomes 6, 7, 13 and 16 that seem to correlate with peculiar seizure phenotype. No specific mutation has been found in Papio papio baboon, although a genetic etiology is likely. Mutation in synaptic vesicle glycoprotein 2A was found in another animal model of photosensitivity (Fayoumi chickens). Autosomal dominant inheritance with incomplete penetrance overlapping with a genetic background for IGE was proposed for some families with primary reading epilepsy. Musicogenic seizures usually occur in patients with focal symptomatic or cryptogenic epilepsies, but they have been reported in rare genetic epilepsies such as Dravet syndrome. A single LGI1 mutation has been described in a girl with seizures evoked by auditory stimuli. Interestingly, heterozygous knockout (Lgi1(+/-)) mice show susceptibility to sound-triggered seizures. Moreover, in Frings and Black Swiss mice, the spontaneous mutations of MASS1 and JAMS1 genes, respectively, have been linked to audiogenic seizures. Eating seizures usually occur in symptomatic epilepsies but evidences for a genetic susceptibility were mainly provided by family report from Sri Lanka. Eating seizures were also reported in rare patients with MECP2 duplication or mutation. Hot water seizures are genetically heterogeneous but two loci at chromosomes 4 and 10 were identified in families with likely autosomal dominant inheritance. Startle-induced seizures usually occur in patients with symptomatic epilepsies but have also been reported in the setting chromosomal disorders or genetically inherited lysosomal storage diseases. DISCUSSION The genetic background of reflex seizures and epilepsies is heterogeneous and mostly unknown with no major gene identified in humans. The benefits offered by next-generation sequencing technologies should be merged with increasing information on animal models that represent an useful tool to study the mechanism underlying epileptogenesis. Finally, we expect that genetic studies will lead to a better understanding of the multiple factors involved in the pathophysiology of reflex seizures, and eventually to develop preventive strategies focused on seizure control and therapy optimization.
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Affiliation(s)
- Domenico Italiano
- Department of Clinical and Experimental Medicine, University of Messina, Via Consolare Valeria, 1, Messina, Italy
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genova, Italy
| | - Emilio Russo
- Science of Health Department, School of Medicine, University of Catanzaro, Viale Europa, Catanzaro, Italy
| | - Antonio Leo
- Science of Health Department, School of Medicine, University of Catanzaro, Viale Europa, Catanzaro, Italy
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Via Consolare Valeria, 1, Messina, Italy
| | - Federico Zara
- Laboratory of Neurogenetics and Neurosciences, Department of Neurosciences, "G. Gaslini" Institute, Genova, Italy
| | - Salvatore Striano
- Epilepsy Center, Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Naples, Italy
| | - Antonio Gambardella
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Viale Europa, Catanzaro, Italy; Institute of Molecular Bioimaging and Physiology of the National Research Council (IBFM-CNR), Viale Europa, Catanzaro, Italy
| | - Angelo Labate
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Viale Europa, Catanzaro, Italy; Institute of Molecular Bioimaging and Physiology of the National Research Council (IBFM-CNR), Viale Europa, Catanzaro, Italy
| | - Sara Gasparini
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Viale Europa, Catanzaro, Italy; Regional Epilepsy Centre, Bianchi-Melacrino-Morelli Hospital, Reggio Calabria, Italy
| | - Marco Lamberti
- Department of Clinical and Experimental Medicine, University of Messina, Via Consolare Valeria, 1, Messina, Italy
| | - Giovambattista De Sarro
- Science of Health Department, School of Medicine, University of Catanzaro, Viale Europa, Catanzaro, Italy
| | - Umberto Aguglia
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Viale Europa, Catanzaro, Italy; Institute of Molecular Bioimaging and Physiology of the National Research Council (IBFM-CNR), Viale Europa, Catanzaro, Italy; Regional Epilepsy Centre, Bianchi-Melacrino-Morelli Hospital, Reggio Calabria, Italy.
| | - Edoardo Ferlazzo
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Viale Europa, Catanzaro, Italy; Institute of Molecular Bioimaging and Physiology of the National Research Council (IBFM-CNR), Viale Europa, Catanzaro, Italy; Regional Epilepsy Centre, Bianchi-Melacrino-Morelli Hospital, Reggio Calabria, Italy
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Onwuli DO, Beltran-Alvarez P. An update on transcriptional and post-translational regulation of brain voltage-gated sodium channels. Amino Acids 2015; 48:641-651. [PMID: 26503606 PMCID: PMC4752963 DOI: 10.1007/s00726-015-2122-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 11/29/2022]
Abstract
Voltage-gated sodium channels are essential proteins in brain physiology, as they generate the sodium currents that initiate neuronal action potentials. Voltage-gated sodium channels expression, localisation and function are regulated by a range of transcriptional and post-translational mechanisms. Here, we review our understanding of regulation of brain voltage-gated sodium channels, in particular SCN1A (NaV1.1), SCN2A (NaV1.2), SCN3A (NaV1.3) and SCN8A (NaV1.6), by transcription factors, by alternative splicing, and by post-translational modifications. Our focus is strongly centred on recent research lines, and newly generated knowledge.
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Affiliation(s)
- Donatus O Onwuli
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hardy Building Cottingham Road, Hull, HU6 7RX, UK
| | - Pedro Beltran-Alvarez
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hardy Building Cottingham Road, Hull, HU6 7RX, UK.
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