Paroxysmal tonic upward gaze as a presentation of de-novo mutations in CACNA1A

A Longitudinal Exploration of CACNA1A -related Hemiplegic Migraine in Children

Introduction

Since the initial description of CACNA1A- related hemiplegic migraine (HM), the phenotypic spectrum has expanded from mild episodes in neurotypical individuals to potentially life-threatening events frequently seen in individuals with developmental and epileptic encephalopathies. However, the overall longitudinal course throughout childhood remains unknown.

Methods

We analyzed HM and seizure history in individuals with CACNA1A -related HM, delineating frequency and severity of events in monthly increments through a standardized approach. Combining these data with medication prescription information, we assessed the response of HM to different agents.

Results

Our cohort involved 15 individuals between 3 and 29 years (163 patient years) and included 11 unique and two recurrent variants (p.R1349Q and p.V1393M; both n= 2). The age of first confirmed HM ranged from 14 months to 13 years (average 3 years). 25% of all HM events were severe (lasting >3 days) and 73% of individuals had at least 1 severe occurrence. Spacing of HM events ranged from 1 month to 14 years and changes in HM severity over time of showed increases or decreases of >2 severity levels in 12/122 events. Eight individuals had epilepsy, but severity of epilepsy did not correlate with frequency and severity of HM events. While levetiracetam ( n= 6) and acetazolamide ( n= 5) were the most frequently used medications, they did not show efficacy in HM prevention or HM severity reduction. However, verapamil ( n= 3) showed efficacy in preventing HM episodes (OR 2.68, CI 1.39-5.67).

Significance

The longitudinal course of CACNA1A -related HM lacks recognizable patterns for timing and severity of HM events or correlation with seizure patterns. Our data underscores the unpredictability of CACNA1A -related HM, highlighting the need for close surveillance for reoccurring HM events even in individuals with symptom-free periods.

Key points

24% of hemiplegic migraines (HM) in CACNA1A- related disorders are severe, involving cerebral edema and greater than 4 days to recover Timing and severity of HM are unpredictable, with large changes in severity between events, and age of onset ranging from 1-13 yearsEpilepsy occurred in 53% of individuals, with neither the timing nor severity of seizures correlated with HM.

Pearls & Oy-sters: CACNA1A-Related Paroxysmal Tonic Upgaze With Ataxia Responsive to Acetazolamide

A 9-month-old male infant was evaluated for sudden onset of paroxysmal episodes of forced, conjugate upward eye deviation. Extensive in-hospital evaluation including electrophysiology and neuroimaging studies were reassuring against seizures or a structural abnormality. Given the clinical presentation of sudden onset intermittent upward eye deviations, downbeating saccades, associated ataxia, and typical development, a clinical diagnosis of paroxysmal tonic upgaze (PTU) with ataxia was made. Targeted genetic testing of CACNA1A was performed, which revealed a variant of undetermined significance, which was later classified as a de novo pathogenic variant after protein modeling and parental testing performed. Off-label use of oral acetazolamide was prescribed, which led to dose-responsive decrease in the frequency and intensity of eye movement episodes. After 6 months of episode freedom at 2 years of age, acetazolamide was discontinued without return of episodes. Neurodevelopmental assessments revealed continued typical development. This case is presented to describe the diagnostic formulation, etiologic evaluation, and symptomatic treatment of CACNA1A-related PTU with ataxia.

The genotype-phenotype correlations of the CACNA1A-related neurodevelopmental disorders: a small case series and literature reviews

BACKGROUND

Genotype-phenotype correlations of the CACNA1A-related neurodevelopmental disorders such as global developmental delay (GDD)/intellectual disability (ID), epileptic encephalopathy (EE), and autism spectrum disorder (ASD) are unknown. We aimed to summarize genotype-phenotype correlations and potential treatment for CACNA1A-related neurodevelopmental disorders.

METHODS

Six children diagnosed with CACNA1A-related neurodevelopmental disorders at Xiangya Hospital, Central South University from April 2018 to July 2021 were enrolled. The PubMed database was systematically searched for all reported patients with CACNA1A-related neurodevelopmental disorders until February 2023. Thereafter, we divided patients into several groups for comparison.

RESULTS

Six patients were recruited from our hospital. Three cases presented with epilepsy, five with GDD/ID, five with ataxia, and two with ASD. The variants included p.G701R, p.R279C, p.D1644N, p.Y62C, p.L1422Sfs*8, and p. R1664Q [two gain-of-function (GOF) and four loss-of-function (LOF) variants]. About 187 individuals with GDD/ID harboring 123 variants were found (case series plus data from literature). Of those 123 variants, p.A713T and p.R1664* were recurrent, 37 were LOF, and 7 were GOF. GOF variants were linked with severe-profound GDD/ID while LOF variants were associated with mild-moderate GDD/ID (p = 0.001). The p.A713T variant correlated with severe-profound GDD/ID (p = 0.003). A total of 130 epileptic patients harboring 83 variants were identified. The epileptic manifestations included status epilepticus (n = 64), provoked seizures (n = 49), focal seizures (n = 37), EE (n = 29), absence seizures (n = 26), and myoclonic seizures (n = 10). About 49 (42.20%) patients had controlled seizures while 67 (57.80%) individuals remained with refractory seizures. Status epilepticus correlated with variants located on S4, S5, and S6 (p = 0.000). Among the 83 epilepsy-related variants, 23 were recurrent, 32 were LOF, and 11 were GOF. Status epilepticus was linked with GOF variants (p = 0.000). LOF variants were associated with absence seizures (p = 0.000). Six patients died at an early age (3 months to ≤5 years). We found 18 children with ASD. Thirteen variants including recurrent ones were identified in those 18 cases. GOF changes were more linked to ASD.

CONCLUSION

The p.A713T variant is linked with severe-profound GDD/ID. More than half of CACNA1A-related epilepsy is refractory. The most common epileptic manifestation is status epilepticus, which correlates with variants located on S4, S5, and S6.

A neurodevelopmental disorder caused by a dysfunctional CACNA1A allele

P/Q-type Ca²⁺ flux into nerve terminals via Ca_V2.1 channels is essential for neurotransmitter release at neuromuscular junctions and nearly all central synapses. Mutations in CACNA1A, the gene encoding Ca_V2.1, cause a spectrum of pediatric neurological disorders. We have identified a patient harboring an autosomal-dominant de novo frameshift-causing nucleotide duplication in CACNA1A (c.5018dupG). The duplicated guanine precipitated 43 residues of altered amino acid sequence beginning with a glutamine to serine substitution in Ca_V2.1 at position 1674 ending with a premature stop codon (Ca_V2.1 p.Gln1674Serfs*43). The patient presented with episodic downbeat vertical nystagmus, hypotonia, ataxia, developmental delay and febrile seizures. In patch-clamp experiments, no Ba²⁺ current was observed in tsA-201 cells expressing Ca_V2.1 p.Gln1674Serfs*43 with β₄ and α₂δ-1 auxiliary subunits. The ablation of divalent flux in response to depolarization was likely attributable to the inability of Ca_V2.1 p.Gln1674Serfs*43 to form a complete channel pore. Our results suggest that the pathology resulting from this frameshift-inducing nucleotide duplication is a consequence of an effective haploinsufficiency.

Episodic Ataxias: Primary and Secondary Etiologies, Treatment, and Classification Approaches

Background

Episodic ataxia (EA), characterized by recurrent attacks of cerebellar dysfunction, is the manifestation of a group of rare autosomal dominant inherited disorders. EA1 and EA2 are most frequently encountered, caused by mutations in KCNA1 and CACNA1A. EA3-8 are reported in rare families. Advances in genetic testing have broadened the KCNA1 and CACNA1A phenotypes, and detected EA as an unusual presentation of several other genetic disorders. Additionally, there are various secondary causes of EA and mimicking disorders. Together, these can pose diagnostic challenges for neurologists.

Methods

A systematic literature review was performed in October 2022 for 'episodic ataxia' and 'paroxysmal ataxia', restricted to publications in the last 10 years to focus on recent clinical advances. Clinical, genetic, and treatment characteristics were summarized.

Results

EA1 and EA2 phenotypes have further broadened. In particular, EA2 may be accompanied by other paroxysmal disorders of childhood with chronic neuropsychiatric features. New treatments for EA2 include dalfampridine and fampridine, in addition to 4-aminopyridine and acetazolamide. There are recent proposals for EA9-10. EA may also be caused by gene mutations associated with chronic ataxias (SCA-14, SCA-27, SCA-42, AOA2, CAPOS), epilepsy syndromes (KCNA2, SCN2A, PRRT2), GLUT-1, mitochondrial disorders (PDHA1, PDHX, ACO2), metabolic disorders (Maple syrup urine disease, Hartnup disease, type I citrullinemia, thiamine and biotin metabolism defects), and others. Secondary causes of EA are more commonly encountered than primary EA (vascular, inflammatory, toxic-metabolic). EA can be misdiagnosed as migraine, peripheral vestibular disorders, anxiety, and functional symptoms. Primary and secondary EA are frequently treatable which should prompt a search for the cause.

Discussion

EA may be overlooked or misdiagnosed for a variety of reasons, including phenotype-genotype variability and clinical overlap between primary and secondary causes. EA is highly treatable, so it is important to consider in the differential diagnosis of paroxysmal disorders. Classical EA1 and EA2 phenotypes prompt single gene test and treatment pathways. For atypical phenotypes, next generation genetic testing can aid diagnosis and guide treatment. Updated classification systems for EA are discussed which may assist diagnosis and management.

Prolonged neurologic deficits with brain MRI changes following ECT in an adolescent with a CACNA1a-related disorder; a case report

BACKGROUND

Electroconvulsive therapy is used to treat depression and schizophrenia with infrequent use in pediatric patients. We report a case of an adolescent with autism spectrum disorder and acute catatonia that presented with status epilepticus (SE) and prolonged neurologic deficits with unilateral left cerebral edema on imaging following unilateral electroconvulsive therapy (ECT) on the right side, subsequently found to have a CACNA1a pathogenic variant. This case highlights a potential adverse effect of ECT in patients with CACNA1a related disorders.

CASE

The patient received unilateral ECT to the right side and subsequently had an episode of SE with right-sided hemiplegia for 72 h prior to regaining some function with persistent mild right-hand weakness that persisted for at least 1-2 weeks. A brain MRI 2 days after ECT was unremarkable, but a repeat MRI on day four of admission showed left hemisphere cortical diffusion restriction, increased perfusion and T2 prolongation suggestive of cortical edema. They had whole exome genetic testing sent after discharge that showed a known pathogenic CACNA1a variant (p.I1709T). CACNA1a encodes the P/Q type calcium channels and deleterious variants in this gene result in a channelopathy associated with a spectrum of neurodevelopmental disorders that include autism spectrum disorder, hemiplegic migraine with unilateral cerebral edema, epileptic encephalopathies, or episodic ataxia syndromes.

CONCLUSION

A literature review of ECT and neurologic deficits showed that most neurologic deficits resolve within 30 min of ECT. Case reports of prolonged deficits are rare and there are no prior reports of acute MRI changes related to ECT. Thus, the acute deterioration and MRI findings in this patient are likely related to the underlying CACNA1a channelopathy disorder with ECT as a precipitating event. This case report suggests care should be taken when using ECT in patients with pathogenic variants in CACNA1a. Furthermore, it reinforces the utility and importance of expanded genetic testing in patients with neurodevelopmental disorders as findings can provide valuable information that can guide treatment decisions.

Endocannabinoid dysfunction in neurological disease: neuro-ocular DAGLA-related syndrome

The endocannabinoid system is a highly conserved and ubiquitous signalling pathway with broad-ranging effects. Despite critical pathway functions, gene variants have not previously been conclusively linked to human disease. We identified nine children from eight families with heterozygous, de novo truncating variants in the last exon of DAGLA with a neuro-ocular phenotype characterized by developmental delay, ataxia and complex oculomotor abnormality. All children displayed paroxysms of nystagmus or eye deviation accompanied by compensatory head posture and worsened incoordination most frequently after waking. RNA sequencing showed clear expression of the truncated transcript and no differences were found between mutant and wild-type DAGLA activity. Immunofluorescence staining of patient-derived fibroblasts and HEK cells expressing the mutant protein showed distinct perinuclear aggregation not detected in control samples. This report establishes truncating variants in the last DAGLA exon as the cause of a unique paediatric syndrome. Because enzymatic activity was preserved, the observed mislocalization of the truncated protein may account for the observed phenotype. Potential mechanisms include DAGLA haploinsufficiency at the plasma membrane or dominant negative effect. To our knowledge, this is the first report directly linking an endocannabinoid system component with human genetic disease and sets the stage for potential future therapeutic avenues.

The complexities of CACNA1A in clinical neurogenetics

Variants in CACNA1A are classically related to episodic ataxia type 2, familial hemiplegic migraine type 1, and spinocerebellar ataxia type 6. Over the years, CACNA1A has been associated with a broader spectrum of phenotypes. Targeted analysis and unbiased sequencing of CACNA1A result not only in clear molecular diagnoses, but also in large numbers of variants of uncertain significance (VUS), or likely pathogenic variants with a phenotype that does not directly match the CACNA1A spectrum. Over the last years, targeted and clinical exome sequencing in our center has identified 41 CACNA1A variants. Ultimately, variants were considered pathogenic or likely pathogenic in 23 cases, with most phenotypes ranging from episodic or progressive ataxia to more complex ataxia syndromes, as well as intellectual disability and epilepsy. In two cases, the causality of the variant was discarded based on non-segregation or an alternative diagnosis. In the remaining 16 cases, the variant was classified as uncertain, due to lack of opportunities for segregation analysis or uncertain association with a non-classic phenotype. Phenotypic variability and the large number of VUS make CACNA1A a challenging gene for neurogenetic diagnostics. Accessible functional read-outs are clearly needed, especially in cases with a non-classic phenotype.

CACNA1A Mutations Causing Early Onset Ataxia: Profiling Clinical, Dysmorphic and Structural-Functional Findings

The CACNA1A gene encodes the pore-forming α_1A subunit of the voltage-gated Ca_V2.1 Ca²⁺ channel, essential in neurotransmission, especially in Purkinje cells. Mutations in CACNA1A result in great clinical heterogeneity with progressive symptoms, paroxysmal events or both. During infancy, clinical and neuroimaging findings may be unspecific, and no dysmorphic features have been reported. We present the clinical, radiological and evolutionary features of three patients with congenital ataxia, one of them carrying a new variant. We report the structural localization of variants and their expected functional consequences. There was an improvement in cerebellar syndrome over time despite a cerebellar atrophy progression, inconsistent response to acetazolamide and positive response to methylphenidate. The patients shared distinctive facial gestalt: oval face, prominent forehead, hypertelorism, downslanting palpebral fissures and narrow nasal bridge. The two α_1A affected residues are fully conserved throughout evolution and among the whole human Ca_V channel family. They contribute to the channel pore and the voltage sensor segment. According to structural data analysis and available functional characterization, they are expected to exert gain- (F1394L) and loss-of-function (R1664Q/R1669Q) effect, respectively. Among the CACNA1A-related phenotypes, our results suggest that non-progressive congenital ataxia is associated with developmental delay and dysmorphic features, constituting a recognizable syndromic neurodevelopmental disorder.

Haploinsufficiency of POU4F1 causes an ataxia syndrome with hypotonia and intention tremor

De novo, heterozygous, loss-of-function variants were identified in Pou domain, class 4, transcription factor 1 (POU4F1) via whole-exome sequencing in four independent probands presenting with ataxia, intention tremor, and hypotonia. POU4F1 is expressed in the developing nervous system, and mice homozygous for null alleles of Pou4f1 exhibit uncoordinated movements with newborns being unable to successfully right themselves to feed. Head magnetic resonance imaging of the four probands was reviewed and multiple abnormalities were noted, including significant cerebellar vermian atrophy and hypertrophic olivary degeneration in one proband. Transcriptional activation of the POU4F1 p.Gln306Arg protein was noted to be decreased when compared with wild type. These findings suggest that heterozygous, loss-of-function variants in POU4F1 are causative of a novel ataxia syndrome.

Ocular Motor Paroxysmal Events in Neonates and Infants: A Review of the Literature

BACKGROUND

Ocular paroxysmal events can accompany a variety of neurological disorders. Particularly in infants, ocular paroxysmal events often represent a diagnostic challenge. Distinguishing between epileptic and nonepileptic events or between physiological and pathologic paroxysmal events can be challenging at this age because the clinical evaluation and physical examination are often limited. Continuous polygraphic video-electroencephalography (EEG) monitoring can be helpful in these situations.

METHODS

We review ocular paroxysmal events in newborns and infants. The aim is to improve clinical recognition of ocular paroxysmal events and provide a guide to further management. Using the PubMed database, we identified studies focused on all ocular motor paroxysmal events in neonates and infants.

RESULTS

Fifty-eight articles were selected on the topic. We summarized and divided these studies into those describing nonepileptic and epileptic ocular paroxysmal events.

CONCLUSIONS

The diagnosis of ocular paroxysmal events can be difficult, but their recognition is important because of the variety of underlying etiologies. The distinction between epileptic versus nonepileptic ocular paroxysmal events often often requires polygraphic video-EEG to identify the epileptic events. For nonepileptic events, further testing can characterize pathologic ocular movements. To determine the etiology and prognosis of ocular paroxysmal events, a multimodal approach is required, including a thorough full history and clinical examination, polygraphic video-EEG monitoring, neuroimaging, and a careful follow-up plan.

From Genotype to Phenotype: Expanding the Clinical Spectrum of CACNA1A Variants in the Era of Next Generation Sequencing

Ion channel dysfunction is a key pathological substrate of episodic neurological disorders. A classical gene associated to paroxysmal movement disorders is CACNA1A, which codes for the pore-forming subunit of the neuronal calcium channel P/Q. Non-polyglutamine CACNA1A variants underlie familial hemiplegic ataxia type 1 (FHM1) and episodic ataxia type 2 (EA2). Classical paroxysmal manifestations of FHM1 are migraine attacks preceded by motor aura consisting of hemiparesis, aphasia, and disturbances of consciousness until coma. Patients with EA2 suffer of recurrent episodes of vertigo, unbalance, diplopia, and vomiting. Beyond these typical presentations, several reports highlighted manifold clinical features associated with P/Q channelopathies, from chronic progressive cerebellar ataxia to epilepsy and psychiatric disturbances. These manifestations may often outlast the burden of classical episodic symptoms leading to pitfalls in the diagnostic work-up. Lately, the spreading of next generation sequencing techniques linked de novo CACNA1A variants to an even broader phenotypic spectrum including early developmental delay, autism spectrum disorders, epileptic encephalopathy, and early onset paroxysmal dystonia. The age-dependency represents a striking new aspect of these phenotypes und highlights a pivotal role for P/Q channels in the development of the central nervous system in a defined time window. While several reviews addressed the clinical presentation and treatment of FHM1 and EA2, an overview of the newly described age-dependent manifestations is lacking. In this Mini-Review we present a clinical update, delineate genotype-phenotype correlations as well as summarize evidence on the pathophysiological mechanisms underlying the expanded phenotype associated with CACNA1A variants.

Paroxysmal tonic upgaze accompanied by occipital discharge on electroencephalography: a case report and literature review

Background

Paroxysmal tonic upgaze (PTU) is an infantile-onset paroxysmal neurological disorder that is characterized by episodes of sustained conjugate upward eye deviation. The paroxysmal abnormal eye movements need to be differentiated from seizures. We report a case of PTU with occipital discharge on electroencephalography (EEG), which made the diagnosis more complicated.

Case presentation

A 6-month-old girl presented with paroxysmal upward deviation or left strabismus of the eyes, with a bowed head, lowered jaw, raised eyebrows, closed lips, and slight grin. Each episode lasted for a few seconds, and episodes occurred multiple times per day. EEG showed spike waves in the right occipital region, and the girl was initially misdiagnosed with epilepsy. After further analysis using video EEG, we corrected her diagnosis as PTU and stopped the administration of an antiepileptic drug.

Conclusion

PTU accompanied by discharge on EEG may lead to a misdiagnosis. Video EEG monitoring, and especially the analysis of EEG traces synchronized with attacks, can provide evidence to distinguish between seizures and non-epileptic events.

Clinical phenotypes of infantile onset CACNA1A-related disorder

BACKGROUND

CACNA1A-related disorders present with persistent progressive and non-progressive cerebellar ataxia and paroxysmal events: epileptic seizures and non-epileptic attacks. These phenotypes overlap and co-exist in the majority of patients.

OBJECTIVE

To describe phenotypes in infantile onset CACNA1A-related disorder and to explore intra-familial variations and genotype-phenotype correlations.

MATERIAL AND METHODS

This study was a multicenter international collaboration. A retrospective chart review of CACNA1A patients was performed. Clinical, radiological, and genetic data were collected and analyzed in 47 patients with infantile-onset disorder.

RESULTS

Paroxysmal non-epileptic events (PNEE) were observed in 68% of infants, with paroxysmal tonic upward gaze (PTU) noticed in 47% of infants. Congenital cerebellar ataxia (CCA) was diagnosed in 51% of patients including four patients with developmental delay and only one neurological sign. PNEEs were found in 63% of patients at follow-up, with episodic ataxia (EA) in 40% of the sample. Cerebellar ataxia was found in 58% of the patients at follow-up. Four patients had epilepsy in infancy and nine in childhood. Seven infants had febrile convulsions, three of which developed epilepsy later; all three patients had CCA. Cognitive difficulties were demonstrated in 70% of the children. Cerebellar atrophy was found in only one infant but was depicted in 64% of MRIs after age two.

CONCLUSIONS

Nearly all of the infants had CCA, PNEE or both. Cognitive difficulties were frequent and appeared to be associated with CCA. Epilepsy was more frequent after age two. Febrile convulsions in association with CCA may indicate risk of epilepsy in later childhood. Brain MRI was normal in infancy. There were no genotype-phenotype correlations found.

Identification of Two de novo Variants of CACNA1A in Pediatric Chinese Patients With Paroxysmal Tonic Upgaze

Objective: Investigate the clinical manifestations and genotypes of paroxysmal tonic upgaze (PTU) in Chinese children. Patients and Methods: We report the clinical manifestations and genetic test results of four pediatric PTU patients in China. Recent articles on PTU cases are also summarized and analyzed. Results: The onset age of all four cases was at early infancy, and they presented as episodic binocular upward gaze with mild growth retardation. Two patients each carried a novel de novo variant in the CACNA1A gene, c.4046C>T (p.R1349X), and c.4415C>T (p.S1472L). Conclusion: Patients with infantile-onset paroxysmal binocular upward gaze should be considered to diagnose as PTU.

Clinical and Genetic Overview of Paroxysmal Movement Disorders and Episodic Ataxias

Paroxysmal movement disorders (PMDs) are rare neurological diseases typically manifesting with intermittent attacks of abnormal involuntary movements. Two main categories of PMDs are recognized based on the phenomenology: Paroxysmal dyskinesias (PxDs) are characterized by transient episodes hyperkinetic movement disorders, while attacks of cerebellar dysfunction are the hallmark of episodic ataxias (EAs). From an etiological point of view, both primary (genetic) and secondary (acquired) causes of PMDs are known. Recognition and diagnosis of PMDs is based on personal and familial medical history, physical examination, detailed reconstruction of ictal phenomenology, neuroimaging, and genetic analysis. Neurophysiological or laboratory tests are reserved for selected cases. Genetic knowledge of PMDs has been largely incremented by the advent of next generation sequencing (NGS) methodologies. The wide number of genes involved in the pathogenesis of PMDs reflects a high complexity of molecular bases of neurotransmission in cerebellar and basal ganglia circuits. In consideration of the broad genetic and phenotypic heterogeneity, a NGS approach by targeted panel for movement disorders, clinical or whole exome sequencing should be preferred, whenever possible, to a single gene approach, in order to increase diagnostic rate. This review is focused on clinical and genetic features of PMDs with the aim to (1) help clinicians to recognize, diagnose and treat patients with PMDs as well as to (2) provide an overview of genes and molecular mechanisms underlying these intriguing neurogenetic disorders.

Cognitive impairment in children with CACNA1A mutations

AIM

To describe the clinico-radiological phenotype of children with a CACNA1A mutation and to precisely evaluate their learning ability and cognitive status.

METHOD

Children between the ages of 3 and 18 years harboring a pathogenic CACNA1A mutation associated with episodic ataxia, hemiplegic migraine, benign paroxysmal torticollis, benign paroxysmal vertigo, or benign paroxysmal tonic upgaze, were enrolled in this cross-sectional study. Data concerning psychomotor development, academic performance, educational management, clinical examination at inclusion, and brain imaging were collected. Cognitive assessment was performed using age-standardized scales.

RESULTS

Eighteen patients (nine males, nine females; mean age at inclusion: 11y 7mo [SD 4y 5mo; range 3y-17y 11mo]) from 14 families were enrolled. Eleven patients displayed the coexistence or consecutive occurrence of more than one type of episodic event. Nine patients exhibited abnormal neurological examination at inclusion. Brain magnetic resonance imaging (MRI) showed cerebellar atrophy in five patients. Psychomotor development was delayed in nine patients and academic difficulties were reported by the parents in 15 patients; nine patients were in special education. Impairment of intellectual function was assessed in six of the 12 patients with interpretable Full-scale IQ scores and was more frequent when cerebellar atrophy was present on MRI.

INTERPRETATION

Cognitive impairment is commonly associated with CACNA1A mutations. We suggest that CACNA1A-associated phenotype should be considered a neurodevelopmental disorder.

WHAT THIS PAPER ADDS

Cognitive disabilities and academic difficulties are common in children with CACNA1A mutations associated with episodic syndromes. Cognitive function ranges from normal to moderate intellectual disorder in wheelchair-dependent children. Patients with vermian atrophy are at a higher risk of cognitive impairment.

Paroxysmal Tonic Upgaze in Children: Three Case Reports and a Review of the Literature

BACKGROUND

In clinical practice, nonepileptic paroxysmal events during infancy and childhood are common reasons for parents and caregivers to seek for medical advice. These events are mostly unrecognized and considered as an epileptic seizure because of the clinical features resembling an epileptic seizure. Paroxysmal tonic upgaze, which consists of recurrent episodes of sustained upward deviation of the eyes and incomplete downward saccades, and normal horizontal eye movements without impairment of consciousness, is a diagnostic challenge for the pediatrician and pediatric neurologist. In general, the entity was defined as an apparently benign phenomenon with normal investigations and eventual complete resolution of the symptoms, although some authors reported on patients with associated neurologic signs, such as ataxia, developmental delay, and abnormal brain magnetic resonance imaging finding.

METHODS

The patients were 3 children (1 boy and 2 girls) who were between 5 and 18 months old experiencing rapid ocular movements with sustained conjugate upward deviation of the eyes. Their attacks, which were recorded using a video or electroencephalogram system, were also investigated comprehensively, including neurologic examination, electroencephalograms, brain magnetic resonance imaging, and metabolic tests. Paroxysmal tonic upgaze attacks have decreased in number or disappeared in 2 patients, but 1 patient exhibited mild abnormalities on magnetic resonance imaging and had relatives with epilepsy.

CONCLUSIONS

In conclusion, paroxysmal tonic upgaze is an apparently benign phenomenon with unclear pathophysiology of various proposed mechanisms such as genetic predisposition, immaturity of the brain stem, neurotransmitter depletion, or immune dysregulation. It is important to recognize the clinical presentation of paroxysmal tonic upgaze and distinguish the disorders from epilepsy for deciding the treatment and prognosis of the patients.

Benign paroxysmal torticollis, benign paroxysmal vertigo, and benign tonic upward gaze are not benign disorders

AIM

Benign paroxysmal torticollis (BPT), benign paroxysmal vertigo (BPV), and benign tonic upward gaze (BTU) are characterized by transient and recurrent episodes of neurological manifestations. The purpose of this study was to analyse the clinical relationships between these syndromes, associated comorbidities, and genetic bases.

METHOD

In this cross-sectional study, clinical data of patients with BPT, BPV, or BTU were collected with a focus on developmental achievements, learning abilities, and rehabilitation. Neuropsychological assessment and genetic testing were performed.

RESULTS

Fifty patients (median age at inclusion 6y) were enrolled. Psychomotor delay, abnormal neurological examination, and low or borderline IQ were found in 19%, 32%, and 26% of the patients respectively. Cognitive dysfunction was present in 27% of the patients. CACNA1A gene mutation was identified in eight families, and KCNA1 and FGF14 mutation in one family respectively. The identification of a CACNA1A mutation was significantly associated with BTU (p=0.03) and with cognitive dysfunction (p=0.01). Patients with BPV were less likely to have cognitive dysfunction.

INTERPRETATION

Children with BPT, BPV, or BTU are at high risk of impaired psychomotor and cognitive development. These syndromes should not be regarded as benign and should be considered as part of the spectrum of a neurodevelopmental disorder.

WHAT THIS PAPER ADDS OK

Patients with benign paroxysmal torticollis (BPT), benign paroxysmal vertigo (BPV), and benign tonic upward gaze (BTU) have an increased risk of psychomotor delay. These patients also have an increased risk of abnormal neurological examination and cognitive dysfunction. Gene mutations, especially in CACNA1A, were identified in 21% of the families. BPT, BTU, and BPV should not be regarded as benign. BPT, BTU, and BPV should be considered as part of the spectrum of a neurodevelopmental disorder.

Transient benign paroxysmal movement disorders in infancy

This review summarizes the current empirical and clinical literature on benign paroxysmal movement disorders in infancy most relevant to practitioners. Paroxysmal benign movement disorders are a heterogeneous group of movement disorders characterized by their favourable outcome. We pay special attention to the recognition and management of these abnormal motor conditions strongly suggestive of epileptic disorders. They include: neonatal jitteriness; benign neonatal sleep myoclonus; benign paroxysmal tonic upgaze; paroxysmal tonic downgaze, benign paroxysmal torticollis and benign polymorphous movement disorder of infancy.

Long-term follow-up of benign positional vertical opsoclonus in infants: retrospective cohort

Background/Aims

Benign positional vertical opsoclonus in infants, also described as paroxysmal tonic downgaze, is an unsettling phenomenon that leads to extensive work-up, although benign course has been reported in sporadic cases. We describe long-term follow-up of a series of infants with the phenomenon.

Methods

This retrospective cohort included all infants diagnosed with rapid downgaze eye movement in 2012–2015 and followed until 2016. The databases of two medical centres were retrospectively reviewed. Benign positional vertical opsoclonus was diagnosed based on clinical findings of experienced neuro-ophthalmologists. Data were collected on demographics, symptoms and signs, neuro-ophthalmological and neurological evaluations, and outcome. Imaging studies were reviewed. Main outcome measures were long-term outcome and findings of the thorough investigation.

Results

The cohort included six infants. All infants were born at term. Age at presentation was several days to 12 weeks. Episodes lasted a few seconds and varied in frequency from <10 to dozens per day. In five infants, symptoms occurred in the supine position. There was a wide variability in the work-up without any pathological findings. Follow-up ranged from 1 to 2.5 years. Ocular symptoms gradually decreased until resolution. Infants reached normal developmental milestones.

Conclusions

Our identification of six patients in only 3 years suggests benign positional vertical opsoclonus may be more prevalent than previously described. In our experience, it affects otherwise healthy infants and resolves spontaneously. In view of the good long-term outcome, a comprehensive clinical investigation may not be necessary.

Marshall M. Parks Memorial Lecture: Ocular Motor Misbehavior in Children: Where Neuro-Ophthalmology Meets Strabismus

Clinical diagnosis has been supplemented by neuroimaging advances, genetic discoveries, and molecular research to generate new neurobiological discoveries pertaining to early maldevelopment of ocular motor control systems. In this focused review, I examine recent paradigm shifts that have transformed our understanding of pediatric ocular motor disease at the prenuclear and infranuclear levels. The pathogenesis of complex ocular motor disorders, such as paradoxical pupillary constriction to darkness, benign tonic upgaze of infancy, congenital fibrosis syndrome, and the constellation of unique eye movements that accompany Joubert syndrome, are elucidated.

Episodic Ataxias: Clinical and Genetic Features

Episodic ataxia (EA) is a clinically heterogeneous group of disorders that are characterized by recurrent spells of truncal ataxia and incoordination lasting minutes to hours. Most have an autosomal dominant inheritance pattern. To date, 8 subtypes have been defined according to clinical and genetic characteristics, and five genes are known to be linked to EAs. Both EA1 and EA2, which are caused by mutations in KCNA1 and CACNA1A, account for the majority of EA, but many patients with no identified mutations still exhibit EA-like clinical features. Furthermore, genetically confirmed EAs have mostly been identified in Caucasian families. In this article, we review the current knowledge on the clinical and genetic characteristics of EAs. Additionally, we summarize the phenotypic features of the genetically confirmed EA2 families in Korea.

The Genetics of Benign Paroxysmal Torticollis of Infancy: Is There an Association With Mutations in the CACNA1A Gene?

Benign paroxysmal torticollis of infancy is an unusual movement disorder, often accompanied by a family history of migraine. Some benign paroxysmal torticollis cases are associated with CACNA1A mutations. The authors sought to determine the frequency of CACNA1A mutations in benign paroxysmal torticollis by testing 8 children and their parents and by searching the literature for benign paroxysmal torticollis cases with accompanying CACNA1A mutations or other disorders linked to the same gene. In our 8 benign paroxysmal torticollis cases, the authors found 3 different polymorphisms, but no pathogenic mutations. By contrast, in the literature, the authors found 4 benign paroxysmal torticollis cases with CACNA1A mutations, 3 with accompanying family histories of 1 or more of familial hemiplegic migraine, episodic ataxia, and paroxysmal tonic upgaze. Thus, CACNA1A mutations are more likely to be found in children with benign paroxysmal torticollis if accompanied by family histories of familial hemiplegic migraine, episodic ataxia, or paroxysmal tonic upgaze.

The importance of de novo mutations for pediatric neurological disease--It is not all in utero or birth trauma

The advent of next generation sequencing (NGS, which consists of massively parallel sequencing to perform TGS (total genome sequencing) or WES (whole exome sequencing)) has abundantly discovered many causative mutations in patients with pediatric neurological disease. A surprisingly high number of these are de novo mutations which have not been inherited from either parent. For epilepsy, autism spectrum disorders, and neuromotor disorders, including cerebral palsy, initial estimates put the frequency of causative de novo mutations at about 15% and about 10% of these are somatic. There are some shared mutated genes between these three classes of disease. Studies of copy number variation by comparative genomic hybridization (CGH) proceded the NGS approaches but they also detect de novo variation which is especially important for ASDs. There are interesting differences between the mutated genes detected by CGS and NGS. In summary, de novo mutations cause a very significant proportion of pediatric neurological disease.

Genetic neurological channelopathies: molecular genetics and clinical phenotypes

Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.