Mitochondrial stroke-like episodes: The search for new therapies.

A mitochondrial stroke-like event is an evolving subacute neurological syndrome linked to seizure activity and focal metabolic brain derangement in a genetically determined mitochondrial disorder. The acronym "MELAS" (mitochondrial encephalopathy associated with lactic acidosis and stroke-like lesions) identifies subjects with molecular, biochemical and/or histological evidence of mitochondrial disorder who experience stroke-like lesions. MELAS is a rare inherited mitochondrial disease linked to severe multiorgan involvement and stress-induced episodes of metabolic decompensation and lactic acidosis. Unfortunately, there are no etiopathogenetic therapies for stroke-like episodes to date, and the treatment is mainly based on anti-epileptic drugs and supportive therapies. This perspective opinion article discusses the current care standards for MELAS patients and revises current and innovative emerging therapies for mitochondrial stroke-like episodes.

Fabry-Stroke Italian Registry (FSIR): a nationwide, prospective, observational study about incidence and characteristics of Fabry-related stroke in young-adults. Presentation of the study protocol.

BACKGROUND: TIA and stroke, both ischemic and hemorrhagic, may complicate Fabry disease at young-adult age and be the first manifestation that comes to the clinician's attention. No definite indications have yet been elaborated to guide neurologists in Fabry disease diagnostics. In current practice, it is usually sought in case of cryptogenic strokes (while Fabry-related strokes can also occur by classical pathogenic mechanisms) or through screening programs in young cerebrovascular populations. Data on recurrence and secondary prevention of Fabry's stroke are scanty. METHODS: The study had a prospective observational design involving 33 Italian neurological Stroke Units. Considering the incidence of TIA/stroke in the European population aged < 60 years and the frequency of Fabry disease in this category (as foreseen by a pilot study held at the Careggi University-Hospital, Florence), we planned to screen for Fabry disease a total of 1740 < 60-year-old individuals hospitalized for TIA, ischemic, or hemorrhagic stroke. We investigated TIA and stroke pathogenesis through internationally validated scales and we gathered information on possible early signs of Fabry disease among all cerebrovascular patients. Every patient was tested for Fabry disease through dried blood spot analysis. Patients who received Fabry disease diagnosis underwent a 12-month follow-up to monitor stroke recurrence and multi-system progression after the cerebrovascular event. DISCUSSION: The potential implications of this study are as follows: (i) to add information about the yield of systematic screening for Fabry disease in a prospective large cohort of acute cerebrovascular patients; (ii) to deepen knowledge of clinical, pathophysiological, and prognostic characteristics of Fabry-related stroke.

Mitochondrial epilepsy: a cross-sectional nationwide Italian survey.

Many aspects of epilepsy in mitochondrial disorders (MDs) need to be further clarified. To this aim, we explored retrospectively a cohort of individuals with MDs querying the "Nationwide Italian Collaborative Network of Mitochondrial Diseases" (NICNMD) database (1467 patients included since 2010 to December 2016). We collected information on age at epilepsy onset, seizure type and frequency, genetic findings, and antiepileptic drugs (AEDs). At the time of our survey, 147/1467 (10%) patients in the NICNMD database had epilepsy. Complete information was available only for 98 patients, 52 males and 46 females, aged 5-92 years (mean age 40.4 ± 18.4; 14/98 children/teenagers and 84 adults). Epilepsy was the presenting feature of MD in 46/98 (47%) individuals, with onset at a median age of 19 years (range, 0.2-68; < 3 years in 14/97 (14%), 3-19 years in 36/97 (37%), > 19 years in 47/97 (49%)). Moreover, 91/98 patients (93%) displayed multiple seizures, with daily or weekly frequency in 25/91 (28%). Interictal EEG was abnormal in 70/78 (90%) patients, displaying abnormal background (47/70; 67%) and/or interictal paroxysms (53/70; 76%). Eighty of 90 patients (89%) displayed a 50-100% reduction of seizures on AEDs; levetiracetam was the most commonly used. Forty-one patients (42%) carried the m.3243A>G mutation, 16 (16%) the m.8344A>G, and 9 (9%) nuclear DNA (nDNA) mutations. Individuals with early-onset seizures mainly carried nDNA mutations and had a more severe epilepsy phenotype, higher seizure frequency, and disorganized background EEG activity. A better definition of epilepsy in MDs may foster the diagnostic workup, management, and treatment of affected patients, and allow more homogeneous patient stratification.

Myoclonus in mitochondrial disorders.

Myoclonus is a possible manifestation of mitochondrial disorders, and its presence is considered, in association with epilepsy and the ragged red fibers, pivotal for the syndromic diagnosis of MERRF (myoclonic epilepsy with ragged red fibers). However, its prevalence in mitochondrial diseases is not known. The aims of this study are the evaluation of the prevalence of myoclonus in a big cohort of mitochondrial patients and the clinical characterization of these subjects. Based on the database of the "Nation-wide Italian Collaborative Network of Mitochondrial Diseases," we reviewed the clinical and molecular data of mitochondrial patients with myoclonus among their clinical features. Myoclonus is a rather uncommon clinical feature of mitochondrial diseases (3.6% of 1,086 patients registered in our database). It is not strictly linked to a specific genotype or phenotype, and only 1 of 3 patients with MERRF harbors the 8344A>G mutation (frequently labeled as "the MERRF mutation"). Finally, myoclonus is not inextricably linked to epilepsy in MERRF patients, but more to cerebellar ataxia. In a myoclonic patient, evidences of mitochondrial dysfunction must be investigated, even though myoclonus is not a common sign of mitochondriopathy. Clinical, histological, and biochemical data may predict the finding of a mitochondrial or nuclear DNA mutation. Finally, this study reinforces the notion that myoclonus is not inextricably linked to epilepsy in MERRF patients, and therefore the term "myoclonic epilepsy" seems inadequate and potentially misleading.

Novel MTCYB mutation in a young patient with recurrent stroke-like episodes and status epilepticus.

The acronym "MELAS" (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) denotes patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Here we report on a girl with repeated stroke-like episodes and status epilepticus, who was diagnosed with MELAS due to a novel mitochondrial cytochrome b gene (MTCYB) mutation (m.15092G>A, which predicts p.G116S). Western blotting and in silico analyses suggested that this mutation could affect the stability of complex III. Cytochrome b is the only mtDNA-encoded subunit of respiratory chain complex III. Mutations in MTCYB have been associated with isolated mitochondrial myopathy and exercise intolerance, and rarely with multisystem and/or central nervous system involvement. If the m.3243A>G and other common MELAS mutations are absent in several tissues, MTCYB should be sequenced from muscle in patients with stroke-like episodes, especially if muscle histology does not support a mitochondrial myopathy and lactic acidosis is absent.

Primary Coenzyme Q10 Deficiency-Related Ataxias.

Cerebellar ataxia is a neurological syndrome characterized by the imbalance (e.g., truncal ataxia, gait ataxia) and incoordination of limbs while executing a task (dysmetria), caused by the dysfunction of the cerebellum or its connections. It is frequently associated with other signs of cerebellar dysfunction, including abnormal eye movements, dysmetria, kinetic tremor, dysarthria, and/or dysphagia. Among the so-termed mitochondrial ataxias, variants in genes encoding steps of the coenzyme Q10 biosynthetic pathway represent a common cause of autosomal recessive primary coenzyme Q10 deficiencies (PCoQD)s. PCoQD is a potentially treatable condition; therefore, a correct and timely diagnosis is essential. After a brief presentation of the illustrative case of an Italian woman with this condition (due to a novel homozygous nonsense mutation in COQ8A), this article will review ataxias due to PCoQD.

Prevalence of Fabry disease and GLA variants in young patients with acute stroke: The challenge to widen the screening. The Fabry-Stroke Italian Registry.

BACKGROUND: Fabry disease (FD) is a treatable X-linked lysosomal storage disorder caused by GLA gene variants leading to alpha-galactosidase A deficiency. FD is a rare cause of stroke, and it is still controversial whether in stroke patients FD should be searched from the beginning or at the end of the diagnostic workup (in cryptogenic strokes). METHODS: Fabry-Stroke Italian Registry is a prospective, multicentric screening involving 33 stroke units. FD was sought by measuring α-galactosidase A activity (males) and by genetic tests (males with reduced enzyme activity and females) in patients aged 18-60 years hospitalized for TIA, ischemic stroke, or intracerebral hemorrhage. We diagnosed FD in patients with 1) already known pathogenic GLA variants; 2) novel GLA variants if additional clinical, laboratory, or family-derived criteria were present. RESULTS: Out of 1906 patients, we found a GLA variant in 15 (0.79%; 95%CI 0.44-1.29) with a certain FD diagnosis in 3 (0.16%; 95%CI 0.03-0.46) patients, none of whom had hemorrhage. We identified 1 novel pathogenic GLA variant. Ischemic stroke etiologies in carriers of GLA variants were: cardioaortic embolism (33%), small artery occlusion (27%), other causes (20%), and undetermined (20%). Mild severity, recurrence, previous TIA, acroparesthesias, hearing loss, and small artery occlusion were predictors of GLA variant. CONCLUSION: In this large multicenter cohort the frequency of FD and GLA variants was consistent with previous reports. Limiting the screening for GLA variants to patients with cryptogenic stroke may miss up to 80% of diagnoses. Some easily recognizable clinical features could help select patients for FD screening.

Beyond RCTs: Short-term dual antiplatelet therapy in secondary prevention of ischemic stroke and transient ischemic attack.

BACKGROUND AND PURPOSE: Randomized controlled trials (RCTs) proved the efficacy of short-term dual antiplatelet therapy (DAPT) in secondary prevention of minor ischemic stroke or high-risk transient ischemic attack (TIA). We aimed at evaluating effectiveness and safety of short-term DAPT in real-world, where treatment use is broader than in RCTs. METHODS: READAPT (REAl-life study on short-term Dual Antiplatelet treatment in Patients with ischemic stroke or Transient ischemic attack) (NCT05476081) was an observational multicenter real-world study with a 90-day follow-up. We included patients aged 18+ receiving short-term DAPT soon after ischemic stroke or TIA. No stringent NIHSS and ABCD2 score cut-offs were applied but adherence to guidelines was recommended. Primary effectiveness outcome was stroke (ischemic or hemorrhagic) or death due to vascular causes, primary safety outcome was moderate-to-severe bleeding. Secondary outcomes were the type of ischemic and hemorrhagic events, disability, cause of death, and compliance to treatment. RESULTS: We included 1920 patients; 69.9% started DAPT after an ischemic stroke; only 8.9% strictly followed entry criteria or procedures of RCTs. Primary effectiveness outcome occurred in 3.9% and primary safety outcome in 0.6% of cases. In total, 3.3% cerebrovascular ischemic recurrences occurred, 0.2% intracerebral hemorrhages, and 2.7% bleedings; 0.2% of patients died due to vascular causes. Patients with NIHSS score ⩽5 and those without acute lesions at neuroimaging had significantly higher primary effectiveness outcomes than their counterparts. Additionally, DAPT start >24 h after symptom onset was associated with a lower likelihood of bleeding. CONCLUSIONS: In real-world, most of the patients who receive DAPT after an ischemic stroke or a TIA do not follow RCTs entry criteria and procedures. Nevertheless, short-term DAPT remains effective and safe in this population. No safety concerns are raised in patients with low-risk TIA, more severe stroke, and delayed treatment start.

Psychiatric involvement in adult patients with mitochondrial disease.

Mitochondrial disorders are caused by impairment of the respiratory chain. Psychiatric features often represent part of their clinical spectrum. However, the real incidence of psychiatric disorders in these diseases is unknown. The aim of this study was to evaluate psychiatric involvement in a group of patients with mitochondrial disorders and without already diagnosed mental illness. Twenty-four patients with mitochondrial disorder and without already diagnosed mental diseases have been studied by means of the mini-international neuropsychiatric interview (MINI) and the newcastle mitochondrial diseases adult scale (NMDAS). In patients with mitochondrial disease, psychiatric conditions were far more common than in general Italian population (about 60 vs. 20-25%), and included major depression, agoraphobia and/or panic disorder, generalized anxiety disorder, social anxiety disorder, psychotic syndromes. Psychiatric involvement did not seem to depend on disease progression. Large, multicenter studies are strongly needed to better characterize the natural history of mitochondrial disorders and of their psychiatric involvement. Moreover, the possibility of mitochondrial diseases should be considered in patients with psychiatric diseases. Finally, we encourage psychiatric evaluation as a routinary approach to mitochondrial patients.

Clinical and electrophysiological features of SCN8A variants causing episodic or chronic ataxia.

BACKGROUND: Variants in SCN8A are associated with a spectrum of epilepsies and neurodevelopmental disorders. Ataxia as a predominant symptom of SCN8A variation has not been well studied. We set out to investigate disease mechanisms and genotype-phenotype correlations of SCN8A-related ataxia. METHODS: We collected genetic and electro-clinical data of ten individuals from nine unrelated families carrying novel SCN8A variants associated with chronic progressive or episodic ataxia. Electrophysiological characterizations of these variants were performed in ND7/23 cells and cultured neurons. FINDINGS: Variants associated with chronic progressive ataxia either decreased Na+ current densities and shifted activation curves towards more depolarized potentials (p.Asn995Asp, p.Lys1498Glu and p.Trp1266Cys) or resulted in a premature stop codon (p.Trp937Ter). Three variants (p.Arg847Gln and biallelic p.Arg191Trp/p.Asp1525Tyr) were associated with episodic ataxia causing loss-of-function by decreasing Na+ current densities or a hyperpolarizing shift of the inactivation curve. Two additional episodic ataxia-associated variants caused mixed gain- and loss-of function effects in ND7/23 cells and were further examined in primary murine hippocampal neuronal cultures. Neuronal firing in excitatory neurons was increased by p.Arg1629His, but decreased by p.Glu1201Lys. Neuronal firing in inhibitory neurons was decreased for both variants. No functional effect was observed for p.Arg1913Trp. In four individuals, treatment with sodium channel blockers exacerbated symptoms. INTERPRETATION: We identified episodic or chronic ataxia as predominant phenotypes caused by variants in SCN8A. Genotype-phenotype correlations revealed a more pronounced loss-of-function effect for variants causing chronic ataxia. Sodium channel blockers should be avoided under these conditions. FUNDING: BMBF, DFG, the Italian Ministry of Health, University of Tuebingen.

Telemedicine in Neuromuscular Diseases During Covid-19 Pandemic: ERN-NMD European Survey.

BACKGROUND: Telemedicine (TM) contributes to bridge the gap between healthcare facilities and patients' homes with neuromuscular disease (NMD) because of mobility issues. However, its deployment is limited due to difficulties evaluating subtle neurological signs such as mild weakness or sensory deficits. The COVID-19 pandemic has disrupted healthcare delivery worldwide, necessitating rapid measures implementation by health care providers (HCPs) to protect patients from acquiring SARS-CoV-2 while maintaining the best care and treatment. OBJECTIVES: Given the challenges faced by remote healthcare assistance of NMD patients, we aim to evaluate the use of TM in NMD during the COVID-19 pandemic. METHODS: Based on the Model for Assessment-of-Telemedicine-Applications (MAST), we conducted a survey amongst clinicians of the ERN EURO NMD (European-Reference-Network-for-Rare-Neuromuscular-Diseases). RESULTS: Based on 42 responses over 76 expected ones, our results show that the COVID-19 pandemic significantly increased the number of HCPs using TM (from 60% to 100%). The TM types most used during the COVID-19 period are teleconsultation and consultation by phone, particularly in the context of symptoms worsening in NMD patients with COVID-19 infection. Most European HCPs were satisfied when using TM but as a complementary option to physical consultations. Many responses addressed the issue of technical aspects needing improvement, particularly for elderly patients who need caregivers' assistance for accessing the TM platform. CONCLUSIONS: TM has been essential during COVID-19, but its use still presents some limitations for NMD patients with cognitive deficits or for first-time diagnosis. Thus, TM should be used as complement to, rather than substitute, for face-to-face consultations.

Nerve and muscle involvement in mitochondrial disorders: an electrophysiological study.

Involvement of the peripheral nervous system in mitochondrial disorders (MD) has been previously reported. However, the exact prevalence of peripheral neuropathy and/or myopathy in MD is still unclear. In order to evaluate the prevalence of neuropathy and myopathy in MD, we performed sensory and motor nerve conduction studies (NCS) and concentric needle electromyography (EMG) in 44 unselected MD patients. NCS were abnormal in 36.4% of cases, and were consistent with a sensori-motor axonal multineuropathy (multifocal neuropathy), mainly affecting the lower limbs. EMG evidence of myopathy was present in 54.5% of patients, again mainly affecting the lower limbs. Nerve and muscle involvement was frequently subclinical. Peripheral nerve and muscle involvement is common in MD patients. Our study supports the variability of the clinical expression of MD. Further studies are needed to better understand the molecular basis underlying the phenotypic variability among MD patients.

Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): A Gender Perspective.

Although larger trinucleotide expansions give rise to a neurodevelopmental disorder called fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by a "premutation" (55-200 CGG repeats) in the FMR1 gene. FXTAS is one of the more common single-gene forms of late-onset ataxia and tremor that may have a more complex development in women, with atypical presentations. After a brief presentation of the atypical case of an Italian woman with FXTAS, who had several paroxysmal episodes suggestive of acute cerebellar and/or brainstem dysfunction, this article will revise the phenotype of FXTAS in women. Especially in females, FXTAS has a broad spectrum of symptoms, ranging from relatively severe diseases in mid-adulthood to mild cases beginning in later life. Female FXTAS and male FXTAS have a different symptomatic spectrum, and studies on the fragile X premutation should be conducted separately on women or men. Hopefully, a better understanding of the molecular processes involved in the polymorphic features of FXTAS will lead to more specific and effective therapies for this complex disorder.

Inflammatory myopathy in a patient with postural and kinetik tremor.

Essential tremor (ET) is a common neurological disease of unknown etiopathogenesis, possibly neurodegenerative, characterized by kinetic tremor at the arms. Here we reported the case of an HCV-positive patient with inflammatory myopathy, who did not develop typical neuromuscular signs or symptoms during at least 7 years of hyperCKemia, in whom kinetic tremor of the arms was the prominent clinical feature, suggesting a possible diagnosis of ET. After 3 months of treatment with corticosteroids/methotrexate, creatine kinase (CK) levels were nearly normal and the tremor was remarkably improved. To our knowledge, similar cases have not been previously reported. Postural tremor can be present in muscular diseases, but only very rarely tremor has been reported as a major clinical feature. Because inflammatory myopathies are potentially treatable conditions it is very important to consider this diagnosis. Our case suggests that in patients with isolated postural and kinetic tremor routine laboratory assays should include CK blood screening.

Clock T3111C and Per2 C111G SNPs do not influence circadian rhythmicity in healthy Italian population.

A possible relationship between human circadian rhythmicity and polymorphisms in clock genes have been documented. However, these data are controversial, and studies both corroborating and denying them have been reported. T3111C Clock polymorphism had been associated with the human evening preference, however, this association has not been confirmed. Moreover, C111G Per2 polymorphism has been associated with the "morning larks" chronotype in one study, not yet replicated. We have, therefore, performed this study to evaluate whether Per2 C111G and Clock T3111C polymorphisms might influence sleep circadian rhythmicity in a sample of 219 Italian volunteers. A possible interaction between these polymorphisms was also investigated. No differences in Per2 C111G and Clock T3111C allele and genotype frequencies were found, and none of the combined Clock T3111C-Per2 C11G genotypes resulted more frequent in one group compared to the others. Present results do not support a role of these polymorphisms in the circadian phenotypes.

Anti-Ri-associated paraneoplastic cerebellar degeneration. Report of a case and revision of the literature.

Paraneoplastic cerebellar degeneration associated with anti-Ri antibodies mainly presents with opsoclonus-myoclonus-ataxia. We report here the case of a patient with anti-Ri-antibody paraneoplastic syndrome, who presented four years after treatment for small-cell lung cancer (SCLC) with oscillopsia and gait disorder. On neurological examination vertical nystagmus, ataxic gait and postural tremor of all four limbs was detected. He died one year after the onset of the symptoms because of a acute exacerbation of his severe chronic obstructive pulmonary disease. No SCLC relapse or new cancer has been detected during the one-year follow-up period.To our knowledge, our patient is the first case of anti-Ri associated disorder with oscillopsia and vertical nystagmus as the initially prominent clinical features. The findings of this case study support the variability of anti-Ri-antibody-associated paraneoplastic syndrome. Further studies must be directed to better characterize the mechanisms underlying this syndrome. Finally, paraneoplastic neurological syndromes should be kept in mind also when a neoplastic disease is not demonstrated.

How Next-Generation Sequencing Is Changing Clinical Neurogenetics.

Until recently, most general neurologists were not interested in neurogenetics [...].

Mitochondrial Medicine in the COVID-19 Era.

Mitochondrial disorders are a remarkably complex group of diseases caused by impairment of the mitochondrial respiratory chain (or electron transport chain) [...].

Response to 'Presentation and pathophysiology of neuro-COVID'.

Letter to the Editor in response to Finsterer J, Scorza FA, Scorza CA. Presentation and pathophysiology of neuro-COVID. Drugs Context. 2021;10:2021-6-5. https://doi.org/10.7573/dic.2021-6-5.