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Indelicato E, Boesch S. CACNA1A-Related Channelopathies: Clinical Manifestations and Treatment Options. Handb Exp Pharmacol 2023; 279:227-248. [PMID: 36592223 DOI: 10.1007/164_2022_625] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In the last decade, variants in the Ca2+ channel gene CACNA1A emerged as a frequent aetiology of rare neurological phenotypes sharing a common denominator of variable paroxysmal manifestations and chronic cerebellar dysfunction. The spectrum of paroxysmal manifestations encompasses migraine with hemiplegic aura, episodic ataxia, epilepsy and paroxysmal non-epileptic movement disorders. Additional chronic neurological symptoms range from severe developmental phenotypes in early-onset cases to neurobehavioural disorders and chronic cerebellar ataxia in older children and adults.In the present review we systematically approach the clinical manifestations of CACNA1A variants, delineate genotype-phenotype correlations and elaborate on the emerging concept of an age-dependent phenotypic spectrum in CACNA1A disease. We furthermore reflect on different therapy options available for paroxysmal symptoms in CACNA1A and address open issues to prioritize in the future clinical research.
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Affiliation(s)
- Elisabetta Indelicato
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Sylvia Boesch
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
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Indelicato E, Unterberger I, Nachbauer W, Eigentler A, Amprosi M, Zeiner F, Haberlandt E, Kaml M, Gizewski E, Boesch S. The electrophysiological footprint of CACNA1A disorders. J Neurol 2021; 268:2493-2505. [PMID: 33544220 PMCID: PMC8217028 DOI: 10.1007/s00415-021-10415-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 01/16/2021] [Accepted: 01/17/2021] [Indexed: 12/14/2022]
Abstract
Objectives CACNA1A variants underlie three neurological disorders: familial hemiplegic migraine type 1 (FHM1), episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6). EEG is applied to study their episodic manifestations, but findings in the intervals did not gain attention up to date. Methods We analyzed repeated EEG recordings performed between 1994 and 2019 in a large cohort of genetically confirmed CACNA1A patients. EEG findings were compared with those of CACNA1A-negative phenocopies. A review of the related literature was performed. Results 85 EEG recordings from 38 patients (19 EA2, 14 FHM1, 5 SCA6) were analyzed. Baseline EEG was abnormal in 55% of cases (12 EA2, 9 FHM1). The most common finding was a lateralized intermittent slowing, mainly affecting the temporal region. Slowing was more pronounced after a recent attack but was consistently detected in the majority of patients also during the follow-up. Interictal epileptic discharges (IEDs) were detected in eight patients (7 EA2,1 FHM1). EEG abnormalities and especially IEDs were significantly associated with younger age at examination (16 ± 9 vs 43 ± 21 years in those without epileptic changes, p = 0.003) and with earlier onset of disease (1 (1–2) vs 12 (5–45) years, p = 0.0009). EEG findings in CACNA1A-negative phenocopies (n = 15) were largely unremarkable (p = 0.03 in the comparison with CACNA1A patients). Conclusions EEG abnormalities between attacks are highly prevalent in episodic CACNA1A disorders and especially associated with younger age at examination and earlier disease onset. Our findings underpin an age-dependent effect of CACNA1A variants, with a more severe impairment when P/Q channel dysfunction manifests early in life.
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Affiliation(s)
- Elisabetta Indelicato
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Iris Unterberger
- Epileptology Division, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Wolfgang Nachbauer
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Andreas Eigentler
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Matthias Amprosi
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Fiona Zeiner
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Edda Haberlandt
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
- Department of Pediatrics, City Hospital, Dornbirn, Austria
| | - Manuela Kaml
- Epileptology Division, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Elke Gizewski
- Department of Neuroradiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Sylvia Boesch
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
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Kaido M, Furuta M, Nakamori M, Yuasa Y, Takahashi MP. Episodic ataxia type 2 manifests as epileptiform electroencephalographic activity with no epileptic attacks in two family members. Rinsho Shinkeigaku 2016; 56:260-4. [PMID: 27025991 DOI: 10.5692/clinicalneurol.cn-000854] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Here, we report two cases of episodic ataxia type 2 (EA2) in a 63-year-old woman and her 36-year-old daughter. The mother experienced recurrent attacks of cerebellar dysfunction lasting 4 to 5 hours since the age of 41 years. On several occasions, she was admitted to the emergency room, where she was diagnosed with epilepsy or stroke. Based on these diagnoses, she was treated with antiepileptic or anticoagulant drugs, but both treatments were eventually discontinued. The frequency of the attacks increased after the patient reached the age of 62. Interictal neurological examination demonstrated signs of slight cerebellar ataxia, i.e. saccadic eye movements, gaze-directed nystagmus, and mild truncal ataxia. Brain magnetic resonance imaging (MRI) showed cerebellar vermis atrophy. Electroencephalography (EEG) revealed various spike and wave patterns: solitary spikes, spike-and-slow wave complexes, and slow wave bursts. Photoparoxysmal response (PPR) type 3 was also observed. Treatment with acetazolamide abolished the patient's attacks almost completely. The daughter started experiencing 5- to 10-minute ataxic episodes at the age of 16 years. Based on her epileptiform EEG activities with PPR (type 2), antiepileptic drugs (valproate and zonisamide) were prescribed. Despite pharmacological treatment, the attacks recurred; however, their frequency gradually decreased with time, until they almost entirely disappeared when the patient was 33. Unfortunately, migraine-like headaches arose instead. Subtle truncal ataxia was observed during interictal periods. Sanger sequencing of the exons of the CACNA1A gene revealed a novel single base deletion (c.3575delA) in both patients. Despite the difference in age of onset and clinical course, both patients showed clearly epileptiform EEG activities without experiencing the concurrent epileptic episodes. Thus, EA2 is a disease that may be misdiagnosed as epilepsy or stroke in the field of emergency medicine.
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Affiliation(s)
- Misako Kaido
- Department of Neurology, Sakai City Medical Center
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Abstract
A central theme in the quest to unravel the genetic basis of epilepsy has been the effort to elucidate the roles played by inherited defects in ion channels. The ubiquitous expression of voltage-gated calcium channels (VGCCs) throughout the central nervous system (CNS), along with their involvement in fundamental processes, such as neuronal excitability and synaptic transmission, has made them attractive candidates. Recent insights provided by the identification of mutations in the P/Q-type calcium channel in humans and rodents with epilepsy and the finding of thalamic T-type calcium channel dysfunction in the absence of seizures have raised expectations of a causal role of calcium channels in the polygenic inheritance of idiopathic epilepsy. In this review, we consider how genetic variation in neuronal VGCCs may influence the development of epilepsy.
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Affiliation(s)
- Sanjeev Rajakulendran
- UCL-Institute of Neurology, MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Michael G Hanna
- UCL-Institute of Neurology, MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
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Abnormal excitability and episodic low-frequency oscillations in the cerebral cortex of the tottering mouse. J Neurosci 2015; 35:5664-79. [PMID: 25855180 DOI: 10.1523/jneurosci.3107-14.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Ca(2+) channelopathies caused by mutations of the CACNA1A gene that encodes the pore-forming subunit of the human Cav2.1 (P/Q-type) voltage-gated Ca(2+) channel include episodic ataxia type 2 (EA2). Although, in EA2 the emphasis has been on cerebellar dysfunction, patients also exhibit episodic, nonmotoric abnormalities involving the cerebral cortex. This study demonstrates episodic, low-frequency oscillations (LFOs) throughout the cerebral cortex of tottering (tg/tg) mice, a widely used model of EA2. Ranging between 0.035 and 0.11 Hz, the LFOs in tg/tg mice can spontaneously develop very high power, referred to as a high-power state. The LFOs in tg/tg mice are mediated in part by neuronal activity as tetrodotoxin decreases the oscillations and cortical neuron discharge contain the same low frequencies. The high-power state involves compensatory mechanisms because acutely decreasing P/Q-type Ca(2+) channel function in either wild-type (WT) or tg/tg mice does not induce the high-power state. In contrast, blocking l-type Ca(2+) channels, known to be upregulated in tg/tg mice, reduces the high-power state. Intriguingly, basal excitatory glutamatergic neurotransmission constrains the high-power state because blocking ionotropic or metabotropic glutamate receptors results in high-power LFOs in tg/tg but not WT mice. The high-power LFOs are decreased markedly by acetazolamide and 4-aminopyridine, the primary treatments for EA2, suggesting disease relevance. Together, these results demonstrate that the high-power LFOs in the tg/tg cerebral cortex represent a highly abnormal excitability state that may underlie noncerebellar symptoms that characterize CACNA1A mutations.
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Paroxysmal movement disorders and episodic ataxias. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-444-52910-7.00004-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Rajakulendran S, Kaski D, Hanna MG. Neuronal P/Q-type calcium channel dysfunction in inherited disorders of the CNS. Nat Rev Neurol 2012; 8:86-96. [PMID: 22249839 DOI: 10.1038/nrneurol.2011.228] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The past two decades have witnessed the emergence of a new and expanding field of neurological diseases--the genetic ion channelopathies. These disorders arise from mutations in genes that encode ion channel subunits, and manifest as paroxysmal attacks involving the brain or spinal cord, and/or muscle. The voltage-gated P/Q-type calcium channel (P/Q channel) is highly expressed in the cerebellum, hippocampus and cortex of the mammalian brain. The P/Q channel has a fundamental role in mediating fast synaptic transmission at central and peripheral nerve terminals. Autosomal dominant mutations in the CACNA1A gene, which encodes voltage-gated P/Q-type calcium channel subunit α(1) (the principal pore-forming subunit of the P/Q channel) are associated with episodic and progressive forms of cerebellar ataxia, familial hemiplegic migraine, vertigo and epilepsy. This Review considers, from both a clinical and genetic perspective, the various neurological phenotypes arising from inherited P/Q channel dysfunction, with a focus on recent advances in the understanding of the pathogenetic mechanisms underlying these disorders.
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Affiliation(s)
- Sanjeev Rajakulendran
- Medical Research Council Center for Neuromuscular Diseases, Box 102, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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Tomlinson SE, Hanna MG, Kullmann DM, Tan SV, Burke D. Clinical neurophysiology of the episodic ataxias: insights into ion channel dysfunction in vivo. Clin Neurophysiol 2009; 120:1768-76. [PMID: 19734086 DOI: 10.1016/j.clinph.2009.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 07/03/2009] [Accepted: 07/03/2009] [Indexed: 01/02/2023]
Abstract
Clinical neurophysiology has become an invaluable tool in the diagnosis of muscle channelopathies, but the situation is less clear cut with neuronal channelopathies. The genetic episodic ataxias are a group of disorders with heterogeneous phenotype and genotype, but share in common the feature of intermittent cerebellar dysfunction. Episodic ataxia (EA) types 1 and 2 are the most widely recognised of the autosomal dominant episodic ataxias and are caused by dysfunction of neuronal voltage-gated ion channels. There are central and peripheral nervous system manifestations in both conditions, and they are therefore good models of neuronal channelopathies to study neurophysiologically. To date most work has focussed upon characterising the electrophysiological properties of mutant channels in vitro. This review summarises the role of voltage-gated potassium and calcium channels, mutations of which underlie the main types of episodic ataxia types 1 and 2. The clinical, genetic and electrophysiological features of EA1 and EA2 are outlined, and a protocol for the assessment of these patients is proposed.
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Affiliation(s)
- Susan E Tomlinson
- Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia.
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Thomas A, Onofrj M. Sporadic acetazolamide-responsive episodic ataxia. Mov Disord 1999; 14:1055-6. [PMID: 10584694 DOI: 10.1002/1531-8257(199911)14:6<1055::aid-mds1032>3.0.co;2-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- A Thomas
- Institute of Neurology, Department of Oncology and Neuroscience, University G. D'Annuzio, Chieti, Italy
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Affiliation(s)
- M Onofrj
- Department of Oncology and Neuroscience, Institute of Neurology, University G.D'Annunzio, Chieti, Italy
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Cox GA, Lutz CM, Yang CL, Biemesderfer D, Bronson RT, Fu A, Aronson PS, Noebels JL, Frankel WN. Sodium/hydrogen exchanger gene defect in slow-wave epilepsy mutant mice. Cell 1997; 91:139-48. [PMID: 9335342 DOI: 10.1016/s0092-8674(01)80016-7] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The "housekeeping" sodium/hydrogen exchanger, NHE1, mediates the electroneutral 1:1 exchange of Na+ and H+ across the plasma membrane. NHE1 is ubiquitous and is studied extensively for regulation of pHi, cell volume, and response to growth factors. We describe a spontaneous mouse mutant, slow-wave epilepsy, (swe), with a neurological syndrome including ataxia and a unique epilepsy phenotype consisting of 3/sec absence and tonic-clonic seizures. swe was fine-mapped on Chromosome 4 and identified as a null allele of Nhe1. Mutants show selective neuronal death in the cerebellum and brainstem but otherwise are healthy. This first example of a disease-causing mutation in an Nhe gene provides a new tool for studying the delicate balance of neuroexcitability and cell survival within the CNS.
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Affiliation(s)
- G A Cox
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
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