Case report: Marked electroclinical improvement by fluoxetine treatment in a patient with KCNT1-related drug-resistant focal epilepsy

Variants in KCNT1 are associated with a wide spectrum of epileptic phenotypes, including epilepsy of infancy with migrating focal seizures (EIMFS), non-EIMFS developmental and epileptic encephalopathies, autosomal dominant or sporadic sleep-related hypermotor epilepsy, and focal epilepsy. Here, we describe a girl affected by drug-resistant focal seizures, developmental delay and behavior disorders, caused by a novel, de novo heterozygous missense KCNT1 variant (c.2809A > G, p.S937G). Functional characterization in transiently transfected Chinese Hamster Ovary (CHO) cells revealed a strong gain-of-function effect determined by the KCNT1 p.S937G variant compared to wild-type, consisting in an increased maximal current density and a hyperpolarizing shift in current activation threshold. Exposure to the antidepressant drug fluoxetine inhibited currents expressed by both wild-type and mutant KCNT1 channels. Treatment of the proband with fluoxetine led to a prolonged electroclinical amelioration, with disappearance of seizures and better EEG background organization, together with an improvement in behavior and mood. Altogether, these results suggest that, based on the proband's genetic and functional characteristics, the antidepressant drug fluoxetine may be repurposed for the treatment of focal epilepsy caused by gain-of-function variants in KCNT1. Further studies are needed to verify whether this approach could be also applied to other phenotypes of the KCNT1-related epilepsies spectrum.

Iatrogenic cerebral amyloid angiopathy: A multinational case series and individual patient data analysis of the literature

BACKGROUND

The transmission of amyloid β (Aβ) in humans leading to iatrogenic cerebral amyloid angiopathy (iCAA) is a novel concept with analogies to prion diseases. However, the number of published cases is low, and larger international studies are missing.

AIMS

We aimed to build a large multinational collaboration on iCAA to better understand the clinical spectrum of affected patients.

METHODS

We collected clinical data on patients with iCAA from Austria, Croatia, Italy, Slovenia, and Spain. Patients were included if they met the proposed Queen Square diagnostic criteria (QSC) for iCAA. In addition, we pooled data on disease onset, latency, and cerebrospinal fluid (CSF) biomarkers from previously published iCAA cases based on a systematic literature review.

RESULTS

Twenty-seven patients (22% women) were included in this study. Of these, 19 (70%) met the criteria for probable and 8 (30%) for possible iCAA. Prior neurosurgical procedures were performed in all patients (93% brain surgery, 7% spinal surgery) at median age of 8 (interquartile range (IQR) = 4-18, range = 0-26 years) years. The median symptom latency was 39 years (IQR = 34-41, range = 28-49). The median age at symptom onset was 49 years (IQR = 43-55, range = 32-70). Twenty-one patients (78%) presented with intracranial hemorrhage and 3 (11%) with seizures.

CONCLUSIONS

Our large international case series of patients with iCAA confirms a wide age boundary for the diagnosis of iCAA. Dissemination of awareness of this rare condition will help to identify more affected patients.

A real-world comparison among third-generation antiseizure medications: Results from the COMPARE study

OBJECTIVE

There are few comparative data on the third-generation antiseizure medications (ASMs). We aimed to assess and compare the effectiveness of brivaracetam (BRV), eslicarbazepine acetate (ESL), lacosamide (LCM), and perampanel (PER) in people with epilepsy (PWE). Efficacy and tolerability were compared as secondary objectives.

METHODS

This multicenter, retrospective study collected data from 22 Italian neurology/epilepsy centers. All adult PWE who started add-on treatment with one of the studied ASMs between January 2018 and October 2021 were included. Retention rate was established as effectiveness measure and described using Kaplan-Meier curves and the best fitting survival model. The responder status and the occurrence of adverse events (AEs) were used to evaluate efficacy and safety, respectively. The odds of AEs and drug efficacy were estimated by two multilevel logistic models.

RESULTS

A total of 960 patients (52.92% females, median age = 43 years) met the inclusion criteria. They mainly suffered from structural epilepsy (52.29%) with monthly (46.2%) focal seizures (69.58%). Compared with LCM, all the studied ASMs had a higher dropout risk, statistically significant in the BRV levetiracetam (LEV)-naïve (hazard ratio [HR] = 1.97, 95% confidence interval [CI] = 1.17-3.29) and PER groups (HR = 1.64, 95% CI = 1.06-2.55). Women were at higher risk of discontinuing ESL (HR = 5.33, 95% CI = 1.71-16.61), as well as PER-treated patients with unknown epilepsy etiology versus those with structural etiology (HR = 1.74, 95% CI = 1.05-2.88). BRV with prior LEV therapy showed lower odds of efficacy (odds ratio [OR] = .08, 95% CI = .01-.48) versus LCM, whereas a higher efficacy was observed in women treated with BRV and LEV-naïve (OR = 10.32, 95% CI = 1.55-68.78) versus men. PER (OR = 6.93, 95% CI = 3.32-14.44) and BRV in LEV-naïve patients (OR = 6.80, 95% CI = 2.64-17.52) had a higher chance of AEs than LCM.

SIGNIFICANCE

Comparative evidence from real-world studies may help clinicians to tailor treatments according to patients' demographic and clinical characteristics.

Perampanel as only add-on epilepsy treatment in elderly: A subgroup analysis of real-world data from retrospective, multicenter, observational study

INTRODUCTION

Drug management of epilepsy in the elderly presents unique but data on this population are scarce. This study aimed to assess the effectiveness and tolerability of perampanel (PER) used as only add-on to a background anti-seizure medication (ASM) in the elderly in a real-world setting.

METHODS

We performed a subgroup analysis of patients aged ≥65 years included in a previous 12-month multicenter study on adults. Treatment discontinuation, seizure frequency, and adverse events were recorded at 3, 6 and 12 months after PER introduction. Sub-analyses by early (≤1 previous ASM) or late PER add-on were also conducted.

RESULTS

The sample included 65 subjects (mean age: 75.7 ± 7.2 years), with mainly focal (73.8%) epilepsy. The mean PER daily dose was ≈4 mg during all follow-up. Retention rates at 3, 6, and 12 months were 90.5%, 89.6%, and 79.4%ly. The baseline median normalized per 28-day seizure number significantly decreased at 3-, 6- and 12-month visits. One year after PER introduction, the responder rate (≥50% reduction in baseline seizure frequency) was 89.7%, with a seizure freedom rate of 72.4%. Adverse events occurred in 22 (34.9%) patients with dizziness and irritability being the most frequent. No major differences between early (41 patients, 63.1%), and late add-on groups were observed.

CONCLUSION

Adjunctive PER was effective and well-tolerated when used as only add-on treatment in elderly people with epilepsy in clinical practice, thus representing a suitable therapeutic option in this age category.

A novel de novo HCN2 loss-of-function variant causing developmental and epileptic encephalopathy treated with a ketogenic diet

Missense variants of hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels cause variable phenotypes, ranging from mild generalized epilepsy to developmental and epileptic encephalopathy (DEE). Although variants of HCN1 are an established cause of DEE, those of HCN2 have been reported in generalized epilepsies. Here we describe the first case of DEE caused by the novel de novo heterozygous missense variant c.1379G>A (p.G460D) of HCN2. Functional characterization in transfected HEK293 cells and neonatal rat cortical neurons revealed that HCN2 p.G460D currents were strongly reduced compared to wild-type, consistent with a dominant negative loss-of-function effect. Immunofluorescence staining showed that mutant channels are retained within the cell and do not reach the membrane. Moreover, mutant HCN2 also affect HCN1 channels, by reducing the Ih current expressed by the HCN1-HCN2 heteromers. Due to the persistence of frequent seizures despite pharmacological polytherapy, the patient was treated with a ketogenic diet, with a significant and long-lasting reduction of episodes. In vitro experiments conducted in a ketogenic environment demonstrated that the clinical improvement observed with this dietary regimen was not mediated by a direct action on HCN2 activity. These results expand the clinical spectrum related to HCN2 channelopathies, further broadening our understanding of the pathogenesis of DEE.

Progressive myoclonus epilepsies due to SEMA6B mutations. New variants and appraisal of published phenotypes

Variants of SEMA6B have been identified in an increasing number of patients, often presenting with progressive myoclonus epilepsy (PME), and to lesser extent developmental encephalopathy, with or without epilepsy. The exon 17 is mainly involved, with truncating mutations causing the production of aberrant proteins with toxic gain of function. Herein, we describe three adjunctive patients carrying de novo truncating SEMA6B variants in this exon (c.1976delC and c.2086C > T novel; c.1978delC previously reported). These subjects presented with PME preceded by developmental delay, motor and cognitive impairment, worsening myoclonus, and epilepsy with polymorphic features, including focal to bilateral seizures in two, and non-convulsive status epilepticus in one. The evidence of developmental delay in these cases suggests their inclusion in the "PME plus developmental delay" nosological group. This work further expands our knowledge of SEMA6B variants causing PMEs. However, the data to date available confirms that phenotypic features do not correlate with the type or location of variants, aspects that need to be further clarified by future studies.

The epidemiology of epilepsy in older adults: A narrative review by the ILAE Task Force on Epilepsy in the Elderly

In an aging world, it is important to know the burden of epilepsy affecting populations of older persons. We performed a selective review of epidemiological studies that we considered to be most informative, trying to include data from all parts of the world. We emphasized primary reports rather than review articles. We reviewed studies reporting the incidence and prevalence of epilepsy that focused on an older population as well as studies that included a wider age range if older persons were tabulated as a subgroup. There is strong evidence that persons older than approximately 60 years incur an increasing risk of both acute symptomatic seizures and epilepsy. In wealthier countries, the incidence of epilepsy increases sharply after age 60 or 65 years. This phenomenon was not always observed among reports from populations with lower socioeconomic status. This discrepancy may reflect differences in etiologies, methods of ascertainment, or distribution of ages; this is an area for more research. We identified other areas for which there are inadequate data. Incidence data are scarcer than prevalence data and are missing for large areas of the world. Prevalence is lower than would be expected from cumulative incidence, possibly because of remissions, excess mortality, or misdiagnosis of acute symptomatic seizures as epilepsy. Segmentation by age, frailty, and comorbidities is desirable, because "epilepsy in the elderly" is otherwise too broad a concept. Data are needed on rates of status epilepticus and drug-resistant epilepsy using the newer definitions. Many more data are needed from low-income populations and from developing countries. Greater awareness of the high rates of seizures among older adults should lead to more focused diagnostic efforts for individuals. Accurate data on epilepsy among older adults should drive proper allocation of treatments for individuals and resources for societies.

Management of epilepsy in older adults: A critical review by the ILAE Task Force on Epilepsy in the elderly

Older adults represent a highly heterogeneous population, with multiple diverse subgroups. Therefore, an individualized approach to treatment is essential to meet the needs of each unique subgroup. Most comparative studies focusing on treatment of epilepsy in older adults have found that levetiracetam has the best chance of long-term seizure freedom. However, there is a lack of studies investigating other newer generation antiseizure medications (ASMs). Although a number of randomized clinical trials have been performed on older adults with epilepsy, the number of participants studied was generally small, and they only investigated short-term efficacy and tolerability. Quality of life as an outcome is often missing but is necessary to understand the effectiveness and possible side effects of treatment. Prognosis needs to move beyond the focus on seizure control to long-term patient-centered outcomes. Dosing studies with newer generation ASMs are needed to understand which treatments are the best in the older adults with different comorbidities. In particular, more high-level evidence is required for older adults with Alzheimer's disease with epilepsy and status epilepticus. Future treatment studies should use greater homogeneity in the inclusion criteria to allow for clearer findings that can be comparable with other studies to build the existing treatment evidence base.

Perampanel in Brain Tumor-Related Epilepsy: A Systematic Review

Brain tumor-related epilepsy (BTRE) is a common comorbidity in patients with brain neoplasms and it may be either the first symptom or develop after the tumor diagnosis. Increasing evidence suggests that brain tumors and BTRE share common pathophysiological mechanisms. Glutamatergic mechanisms can play a central role in promoting both primary brain tumor growth and epileptogenesis. Perampanel (PER), which acts as a selective antagonist of glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, may play a role both in the reduction in tumor growth and the control of epileptiform activity. This systematic review aimed to summarize the pre-clinical and clinical evidence about the antitumor properties, antiseizure effects and tolerability of PER in BTRE. Eight pre-clinical and eight clinical studies were identified. The currently available evidence suggests that PER can be an effective and generally well-tolerated therapeutic option in patients with BTRE. In vitro studies demonstrated promising antitumor activity of PER, while no role in slowing tumor progression has been demonstrated in rat models; clinical data on the potential antitumor activity of PER are scarce. Additional studies are needed to explore further the effects of PER on tumor progression and fully characterize its potentialities in patients with BTRE.

Epilepsy in cerebral amyloid angiopathy: an observational retrospective study of a large population

OBJECTIVE

Cerebral amyloid angiopathy (CAA) is a major cause of spontaneous intracranial hemorrhage in older adults. Epilepsy represents a possible sequela of the disease. To date, studies on epilepsy in CAA are lacking, and the few data available mainly focus on CAA-related inflammation (CAA-ri), the inflammatory form of the disease.

METHODS

In this retrospective observational study, we consecutively recruited CAA patients observed over a time span of 10 years, collecting demographic, clinical, and instrumental data. Significant baseline characteristics were evaluated as potential risk factors for the development of epilepsy in the CAA population, and in the subgroups of CAA-ri and CAA without inflammatory reaction (CAA-nri). The effect of potential risk factors for epilepsy was measured as odds ratio with 95% confidence interval.

RESULTS

Within 96 recruited CAA cases, 33 (34.4%) developed epilepsy during follow-up (median = 13.5 months). The prevalent type of seizure was focal (81.3%); 12.1% of the epileptic patients presented status epilepticus, and 6.1% developed drug-resistant epilepsy. Electroencephalographic traces revealed slow and epileptic discharge activity in the majority of epileptic patients, but also in those without epilepsy. The presence of focal or disseminated cortical superficial siderosis (cSS) was associated with an increased risk of epilepsy in the CAA-nri group, and the association with CAA-ri and epilepsy was present in the overall population.

SIGNIFICANCE

Epilepsy is a common manifestation during the course of CAA, where CAA-ri and cSS represent predisposing factors for the development of seizures. These data suggest the importance of a deep characterization of CAA patients, to better select those more prone to develop epilepsy.

Association of Microglial Activation With Spontaneous ARIA-E and CSF Levels of Anti-Aβ Autoantibodies

BACKGROUND AND OBJECTIVES

Amyloid-related imaging abnormalities suggestive of vasogenic edema or sulcal effusion (ARIA-E) are the most common adverse events complicating Alzheimer disease (AD) immunotherapy with anti-β-amyloid (Aβ) monoclonal antibodies. ARIA-E can also occur spontaneously in cerebral amyloid angiopathy-related inflammation (CAA-ri), a rare autoimmune encephalopathy associated with increased CSF levels of anti-Aβ autoantibodies. Although the pathophysiologic mechanisms of ARIA-E remain to be fully elucidated, experimental evidence from ex vivo studies suggests that gantenerumab and aducanumab enable microglial activation. However, the in vivo evidence for a direct association between neuroinflammation and ARIA-E in patients with high CSF anti-Aβ (auto)antibody levels has never been demonstrated.

METHODS

The spatial distribution and temporal variations of microglial activation associated with levels of anti-Aβ autoantibodies at (sub)acute presentation of ARIA-E and after corticosteroid therapy were evaluated in a longitudinal case series of patients with CAA-ri, the spontaneous variant of the iatrogenic ARIA-E reported in Aβ-lowering immunotherapy with monoclonal antibodies. Multimodal and multiparametric MRI was used for CAA and ARIA-E severity quantification, according to validated scoring system; CSF testing for anti-Aβ autoantibodies and AD biomarkers; 11C-PK11195 PET for activated microglia.

RESULTS

At (sub)acute presentation, we found focal peaks of microglial activation having a greater spatial colocalization with ARIA-E compared with chronic age-related white matter change imaging abnormalities. The severity of ARIA-E and the magnitude of the associated microglial activation were greater in patients having AD and severe CAA concomitant disease compared with patients having CAA only. CSF anti-Aβ autoantibodies at presentation were high in all patients and markedly decreased at posttreatment follow-up, in parallel with clinical resolution of acute symptoms, reduced ARIA-E severity, and reduced microglial activation.

DISCUSSION

Our findings extend the current notion of ARIA-E by providing the first in vivo 11C-PK11195 PET evidence for an association between microglial activation and the magnitude and severity of ARIA-E in patients with increased CSF concentration of anti-Aβ autoantibodies and comorbid AD and CAA disease. Our results highlight CSF testing for anti-Aβ autoantibodies as a promising diagnostic, prognostic, and therapy response biomarker to help guide future treatment and management decisions in real clinical practice and clinical trials.

Effectiveness of Perampanel as the Only Add-on: Retrospective, Multicenter, Observational Real Life Study on epilepsy patients

OBJECTIVE

Perampanel (PER) is indicated as adjunctive antiseizure medication (ASM) in adolescents and adults with epilepsy. Data from clinical trials show good efficacy and tolerability, while limited information is available on the routine clinical use of PER, especially when used as only add-on treatment.

METHODS

we performed an observational, retrospective, multicenter study on people with focal or generalized epilepsy aged >12 years, consecutively recruited from 52 Italian epilepsy centers. All patients received PER as the only add-on treatment to a background ASM according to standard clinical practice. Retention rate, seizure frequency and adverse events were recorded at 3, 6 and 12 months after PER introduction. Sub-analyses by early or late use of PER and by concomitant ASM were also conducted.

RESULTS

503 patients were included (age 36.5±19.9 years). Eighty-one per cent had focal epilepsy. Overall, the retention rate was very high in the whole group (89% at 12 months) according with efficacy measures. No major differences were observed in the sub-analyses, although patients who used PER as early add-on, as compared with late add-on, more often reached early seizure freedom at 3 months follow-up (66% vs. 53%, p=0.05). Treatment-emergent adverse events occurred in 25%, far less commonly than in PER randomized trials.

SIGNIFICANCE

this study confirms the good efficacy and safety of PER for focal or generalized epilepsy in real-life conditions. We provide robust data about its effectiveness as only add-on treatment even in patients with a long-standing history of epilepsy and previously treated with many ASMs.

Functional Characterization of Two Variants at the Intron 6—Exon 7 Boundary of the KCNQ2 Potassium Channel Gene Causing Distinct Epileptic Phenotypes

Pathogenic variants in KCNQ2 encoding for Kv7.2 potassium channel subunits have been found in patients affected by widely diverging epileptic phenotypes, ranging from Self-Limiting Familial Neonatal Epilepsy (SLFNE) to severe Developmental and Epileptic Encephalopathy (DEE). Thus, understanding the pathogenic molecular mechanisms of KCNQ2 variants and their correlation with clinical phenotypes has a relevant impact on the clinical management of these patients. In the present study, the genetic, biochemical, and functional effects prompted by two variants, each found in a non-familial SLNE or a DEE patient but both affecting nucleotides at the KCNQ2 intron 6-exon 7 boundary, have been investigated to test whether and how they affected the splicing process and to clarify whether such mechanism might play a pathogenetic role in these patients. Analysis of KCNQ2 mRNA splicing in patient-derived lymphoblasts revealed that the SLNE-causing intronic variant (c.928-1G > C) impeded the use of the natural splice site, but lead to a 10-aa Kv7.2 in frame deletion (Kv7.2 p.G310Δ10); by contrast, the DEE-causing exonic variant (c.928G > A) only had subtle effects on the splicing process at this site, thus leading to the synthesis of a full-length subunit carrying the G310S missense variant (Kv7.2 p.G310S). Patch-clamp recordings in transiently-transfected CHO cells and primary neurons revealed that both variants fully impeded Kv7.2 channel function, and exerted strong dominant-negative effects when co-expressed with Kv7.2 and/or Kv7.3 subunits. Notably, Kv7.2 p.G310S, but not Kv7.2 p.G310Δ10, currents were recovered upon overexpression of the PIP2-synthesizing enzyme PIP5K, and/or CaM; moreover, currents from heteromeric Kv7.2/Kv7.3 channels incorporating either Kv7.2 mutant subunits were differentially regulated by changes in PIP2 availability, with Kv7.2/Kv7.2 G310S/Kv7.3 currents showing a greater sensitivity to PIP2 depletion when compared to those from Kv7.2/Kv7.2 G310Δ10/Kv7.3 channels. Altogether, these results suggest that the two variants investigated differentially affected the splicing process at the intron 6-exon 7 boundary, and led to the synthesis of Kv7.2 subunits showing a differential sensitivity to PIP2 and CaM regulation; more studies are needed to clarify how such different functional properties contribute to the widely-divergent clinical phenotypes.

Clinical and Instrumental Characterization of Patients With Late-Onset Epilepsy

Epilepsy is classically considered a childhood disease. However, it represents the third most frequent neurological condition in the elderly, following stroke, and dementia. With the progressive aging of the general population, the number of patients with Late-Onset Epilepsy (LOE) is constantly growing, with important economic and social consequences, in particular for the more developed countries where the percentage of elderly people is higher. The most common causes of LOE are structural, mainly secondary to cerebrovascular or infectious diseases, brain tumors, trauma, and metabolic or toxic conditions. Moreover, there is a growing body of evidence linking LOE with neurodegenerative diseases, particularly Alzheimer's disease (AD). However, despite a thorough characterization, the causes of LOE remain unknown in a considerable portion of patients, thus termed as Late-Onset Epilepsy of Unknown origin (LOEU). In order to identify the possible causes of the disease, with an important impact in terms of treatment and prognosis, LOE patients should always undergo an exhaustive phenotypic characterization. In this work, we provide a detailed review of the main clinical and instrumental techniques for the adequate characterization of LOE patients in the clinical practice. This work aims to provide an easy and effective tool that supports routine activity of the clinicians facing LOE.

COVID-19-associated immune-mediated encephalitis mimicking acute-onset Creutzfeldt-Jakob disease

We report a subtype of immune‐mediated encephalitis associated with COVID‐19, which closely mimics acute‐onset sporadic Creutzfeldt–Jakob disease. A 64‐year‐old man presented with confusion, aphasia, myoclonus, and a silent interstitial pneumonia. He tested positive for SARS‐CoV‐2. Cognition and myoclonus rapidly deteriorated, EEG evolved to generalized periodic discharges and brain MRI showed multiple cortical DWI hyperintensities. CSF analysis was normal, except for a positive 14‐3‐3 protein. RT‐QuIC analysis was negative. High levels of pro‐inflammatory cytokines were present in the CSF and serum. Treatment with steroids and intravenous immunoglobulins produced EEG and clinical improvement, with a good neurological outcome at a 6‐month follow‐up.

Spontaneous ARIA-like Events in Cerebral Amyloid Angiopathy-Related Inflammation: A Multicenter Prospective Longitudinal Cohort Study

BACKGROUND AND OBJECTIVES

The goal of this work was to investigate the natural history and outcomes after treatment for spontaneous amyloid-related imaging abnormalities (ARIA)-like in cerebral amyloid angiopathy-related inflammation (CAA-ri).

METHODS

This was a multicenter, hospital-based, longitudinal, prospective observational study of inpatients meeting CAA-ri diagnostic criteria recruited through the Inflammatory Cerebral Amyloid Angiopathy and Alzheimer's Disease βiomarkers International Network from January 2013 to March 2017. A protocol for systematic data collection at first-ever presentation and at subsequent in-person visits, including T1-weighted, gradient recalled echo-T2*, fluid-suppressed T2-weighted (fluid-attenuated inversion recovery), and T1 postgadolinium contrast-enhanced images acquired on 1.5T MRI, was used at the 3-, 6-, 12-, and 24-month follow-up. Centralized reads of MRIs were performed by investigators blinded to clinical, therapeutic, and time-point information. Main outcomes were survival, clinical and radiologic recovery, intracerebral hemorrhage (ICH), and recurrence of CAA-ri.

RESULTS

The study enrolled 113 participants (10.6% definite, 71.7% probable, and 17.7% possible CAA-ri). Their mean age was 72.9 years; 43.4% were female; 37.1% were APOEε4 carriers; 36.3% had a history of Alzheimer disease; and 33.6% had a history of ICH. A history of ICH and the occurrence of new ICH at follow-up were more common in patients with cortical superficial siderosis at baseline (52.6% vs 14.3%, p < 0.0001 and 19.3% vs 3.6%, p < 0.009, respectively). After the first-ever presentation of CAA-ri, 70.3% (95% confidence interval [CI] 61.6%-78.5%) and 84.1% (95% CI 76.2%-90.6%) clinically recovered within 3 and 12 months, followed by radiologic recovery in 45.1% (95% CI 36.4%-54.8%) and 77.4% (95% CI 67.7%-85.9%), respectively. After clinicoradiologic resolution of the first-ever episode, 38.3% (95% CI 22.9%-59.2%) had at least 1 recurrence within the following 24 months. Recurrence was more likely if IV high-dose corticosteroid pulse therapy was suddenly stopped compared to slow oral tapering off (hazard ratio 4.68, 95% CI 1.57-13.93; p = 0.006).

DISCUSSION

These results from the largest longitudinal cohort registry of patients with CAA-ri support the transient and potentially relapsing inflammatory nature of the clinical-radiologic acute manifestations of the disease and the effectiveness of slow oral tapering off after IV corticosteroid pulse therapy in preventing recurrences. Our results highlight the importance of differential diagnosis for spontaneous ARIA-like events in β-amyloid-driven diseases, including treatment-related ARIA in patients with Alzheimer disease exposed to immunotherapy drugs.

Comorbidities in patients with epilepsy: Frequency, mechanisms and effects on long-term outcome

OBJECTIVE

To assess frequency, types, and mechanisms of comorbidities in people with epilepsy and verify their association with disease features and outcome.

METHODS

This cohort study was performed in 13 Italian epilepsy centers with nationwide distribution and accurate records. Eligible patients were children and adults diagnosed before December 31, 2005, and followed for a minimum of 10 years. Two pairs of raters independently reviewed patients' records and classified each comorbidity. In case of disagreement, a third reviewer made the final decision. Comorbidities were classified according to type (organ/system) and underlying mechanism (causal, shared risk factors, chance association). Comorbidity types and mechanisms were described in the entire sample and according to epilepsy prognostic patterns (sustained remission, relapsing-remitting course, no remission).

RESULTS

Of 1006 included patients, 266 (26.4%) had at least one comorbidity. The most common were developmental/perinatal (7.5% of cases), psychiatric (6.2%), cardiovascular (5.3%), and endocrine/metabolic (3.8%). Among 408 reported comorbidities, the underlying mechanisms were, in decreasing order, chance association (42.2%), shared risk factors (31.1%), and causal (26.7%). Psychiatric diseases were present in 13.3% of patients with no remission, 5.9% of patients with relapsing-remitting course, and 4.8% of patients with sustained remission (p = .016). The corresponding numbers for endocrine/metabolic diseases were respectively, 9.6%, 3.4%, and 2.9% (p = .013); for respiratory diseases were 3.6%, .3%, and .3% (p = .001), and for urogenital diseases were 3.6%, .7%, and 1.6% (p = .048). The association of endocrine/metabolic, psychiatric, and respiratory comorbidities with epilepsy prognosis was confirmed by multivariable analysis adjusted for the main demographic and clinical variables, with patients with these comorbidities showing a lower probability of achieving remission.

SIGNIFICANCE

Comorbidities in epilepsy are not uncommon and reflect differing underlying mechanisms. Psychiatric, endocrine/metabolic, and respiratory disorders are associated with a worse long-term epileptological outcome.

Do the functional properties of HCN1 mutants correlate with the clinical features in epileptic patients?

The altered function of the Hyperpolarization-activated Cyclic-Nucleotide-gated (HCN) ion channels plays an important role in the pathogenesis of epilepsy in humans. In particular, HCN1 missense mutations have been recently identified in patients with different epileptic phenotypes, varying from mild to severe. Their electrophysiological characterization shows that mutated channels can act both with loss-of-function and gain-of-function mechanisms of action, without an evident correlation with the phenotype. In search for a correlation between clinical features and biophysical properties of the mutations, in this work we considered sixteen HCN1 mutations, found in eighteen Early Infantile Epileptic Encephalopathy (EIEE) patients. Statistical analysis did not establish any significant correlation between the clinical parameters and the current properties of the mutant channels. The lack of significance of our results could depend on the small number of mutations analyzed, epilepsy-associated with certainty. With the progressive increase of Next Generation Sequencing in patients with early-onset epilepsy, it is expected that the number of patients with HCN1 mutations will grow steadily. Functional characterization of epilepsy-associated HCN1 mutations remains a fundamental tool for a better understanding of the pathogenetic mechanisms leading to the disease in humans.

Temporal lobe dysfunction in late-onset epilepsy of unknown origin

OBJECTIVE

Epilepsy with onset in the adulthood is an increasing health problem, due to the progressive aging of the worldwide population. Whether the causes remain undetermined, the disease is defined as Late-Onset Epilepsy of Unknown origin (LOEU). The aim of this study was to evaluate the semiological, electroencephalographic, metabolic, and neuropsychological features of LOEU.

METHODS

We selected patients with late-onset epilepsy (LOE) (≥55 years), whose causes of the disease have been excluded with a deep clinical-instrumental characterization, including brain MRI, EEG, ¹⁸F-labeled fluoro-2-deoxyglucose positron emission tomography (FDG-PET), and neuropsychological assessment.

RESULTS

Twenty-three LOEU cases were retrospectively recruited. Half presented focal-onset seizures (FOS), the others focal to bilateral tonic-clonic seizures (FBTCS). All demonstrated a mild phenotype, with no recurrence of seizures on single antiseizure treatment at prolonged follow-up. Brain MRI scans were normal in 12 patients (52.3%) and showed nonspecific gliosis or mild atrophy in ten (43.5%); hippocampal sclerosis (HS) was observed in one. In 17/23 (73.9%), the EEG showed slow and/or epileptiform activity of the temporal areas. Brain FDG-PET revealed temporal lobe hypometabolism, mostly ipsilateral to EEG abnormal activity, or multifocal temporal and extra-temporal (cortical, subcortical and subtentorial) clusters of hypometabolism. The neuropsychological analysis demonstrated three different profiles: normal (43.5%), with focal deficits (39.1%) or mild multidomain impairment (17.4%).

SIGNIFICANCE

Late-Onset Epilepsy of Unknown origin can present as FOS or FBTCS, both with good prognosis. The application of metabolic imaging and neurophysiology techniques in these patients points to the dysfunction of the temporal structures, whose role in the pathogenetic process of the disease remains to be clarified.

Effect of the ketogenic diet in excitable tissues

In the past decade, ketogenic diet (KD) has gained some popularity as a potential treatment for a wide range of diseases, including neurological and metabolic disorders, thanks to a beneficial role mainly related to its anti-inflammatory properties. The high-fat and carbohydrate-restricted regimen causes changes in the metabolism, leading, through the β-oxidation of fatty acids, to the hepatic production of ketone bodies (KBs), which are used by many extrahepatic tissues as energy fuels. Once synthetized, KBs are delivered through the systemic circulation to all the tissues of the organism, where they play pleiotropic roles acting directly and indirectly on various targets, and among them ion channels and neurotransmitters. Moreover, they can operate as signaling metabolites and epigenetic modulators. Therefore, it is inappropriate to consider that the KD regimen can improve the patients' clinical condition simply by means of specific and localized effects; rather, it is more correct to think that KBs affect the organism as a whole. In this review, we tried to summarize the recent knowledge of the effects of KBs on various tissues, with a particular attention on the excitable ones, namely the nervous system, heart, and muscles.

Cardiac and neuronal HCN channelopathies

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. In the voltage range of activation, HCN channels carry an inward current mediated by Na⁺ and K⁺, termed I_f in the heart and I_h in neurons. Altered function of HCN channels, mainly HCN4, is associated with sinus node dysfunction and other arrhythmias such as atrial fibrillation, ventricular tachycardia, and atrioventricular block. In recent years, several data have also shown that dysfunctional HCN channels, in particular HCN1, but also HCN2 and HCN4, can play a pathogenic role in epilepsy; these include experimental data from animal models, and data collected over genetic mutations of the channels identified and characterized in epileptic patients. In the central nervous system, alteration of the I_h current could predispose to the development of neurodegenerative diseases such as Parkinson's disease; since HCN channels are widely expressed in the peripheral nervous system, their dysfunctional behavior could also be associated with the pathogenesis of neuropathic pain. Given the fundamental role played by the HCN channels in the regulation of the discharge activity of cardiac and neuronal cells, the modulation of their function for therapeutic purposes is under study since it could be useful in various pathological conditions. Here we review the present knowledge of the HCN-related channelopathies in cardiac and neurological diseases, including clinical, genetic, therapeutic, and physiopathological aspects.

Late-Onset Epilepsy With Unknown Etiology: A Pilot Study on Neuropsychological Profile, Cerebrospinal Fluid Biomarkers, and Quantitative EEG Characteristics

Introduction: Despite the fact that epilepsy has been associated with cognitive decline, neuropsychological, neurobiological, and neurophysiological features in patients with late-onset epilepsy of unknown etiology (LOEU) are still unknown. This cross-sectional study aims to investigate the neuropsychological profile, cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD), and resting-state quantitative electroencephalographic (qEEG) cortical rhythms in LOEU patients with mild cognitive impairment (LOEU-MCI) and with normal cognition (LOEU-CN), compared to non-epileptic MCI (NE-MCI) and cognitively normal (CN) controls. Methods: Consecutive patients in two clinical Units diagnosed with LOEU-CN (19), LOEU-MCI (27), and NE-MCI (21) were enrolled, and compared to age and sex-matched cognitively normal subjects CN (11). Patients underwent standardized comprehensive neuropsychological evaluation and CSF core AD biomarkers assessment (i.e., CSF Aβ42, phospho-tau and total tau, classified through A/T/(N) system). Recordings of resting-state eyes-closed electroencephalographic (EEG) rhythms were collected and cortical source estimation of delta (<4 Hz) to gamma (>30 Hz) bands with exact Low Resolution Electromagnetic Tomography (eLORETA) was performed. Results: Most LOEU patients had an MCI status at seizure onset (59%). Patients with LOEU-MCI performed significantly worse on measures of global cognition, visuo-spatial abilities, and executive functions compared to NE-MCI patients (p < 0.05). Regarding MCI subtypes, multiple-domain MCI was 3-fold more frequent in LOEU-MCI than in NE-MCI patients (OR 3.14, 95%CI 0.93-10.58, p = 0.06). CSF Aβ42 levels were lower in the LOEU-MCI compared with the LOEU-CN group. Finally, parietal and occipital sources of alpha (8-12 Hz) rhythms were less active in the LOEU-MCI than in the NE-MCI and CN groups, while the opposite was true for frontal and temporal cortical delta sources. Discussion: MCI status was relatively frequent in LOEU patients, involved multiple cognitive domains, and might have been driven by amyloidosis according to CSF biomarkers. LOEU-MCI status was associated with abnormalities in cortical sources of EEG rhythms related to quiet vigilance. Future longitudinal studies should cross-validate our findings and test the predictive value of CSF and EEG variables.

HCN1 mutation spectrum: from neonatal epileptic encephalopathy to benign generalized epilepsy and beyond

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control neuronal excitability and their dysfunction has been linked to epileptogenesis but few individuals with neurological disorders related to variants altering HCN channels have been reported so far. In 2014, we described five individuals with epileptic encephalopathy due to de novo HCN1 variants. To delineate HCN1-related disorders and investigate genotype-phenotype correlations further, we assembled a cohort of 33 unpublished patients with novel pathogenic or likely pathogenic variants: 19 probands carrying 14 different de novo mutations and four families with dominantly inherited variants segregating with epilepsy in 14 individuals, but not penetrant in six additional individuals. Sporadic patients had epilepsy with median onset at age 7 months and in 36% the first seizure occurred during a febrile illness. Overall, considering familial and sporadic patients, the predominant phenotypes were mild, including genetic generalized epilepsies and genetic epilepsy with febrile seizures plus (GEFS+) spectrum. About 20% manifested neonatal/infantile onset otherwise unclassified epileptic encephalopathy. The study also included eight patients with variants of unknown significance: one adopted patient had two HCN1 variants, four probands had intellectual disability without seizures, and three individuals had missense variants inherited from an asymptomatic parent. Of the 18 novel pathogenic missense variants identified, 12 were associated with severe phenotypes and clustered within or close to transmembrane domains, while variants segregating with milder phenotypes were located outside transmembrane domains, in the intracellular N- and C-terminal parts of the channel. Five recurrent variants were associated with similar phenotypes. Using whole-cell patch-clamp, we showed that the impact of 12 selected variants ranged from complete loss-of-function to significant shifts in activation kinetics and/or voltage dependence. Functional analysis of three different substitutions altering Gly391 revealed that these variants had different consequences on channel biophysical properties. The Gly391Asp variant, associated with the most severe, neonatal phenotype, also had the most severe impact on channel function. Molecular dynamics simulation on channel structure showed that homotetramers were not conducting ions because the permeation path was blocked by cation(s) strongly complexed to the Asp residue, whereas heterotetramers showed an instantaneous current component possibly linked to deformation of the channel pore. In conclusion, our results considerably expand the clinical spectrum related to HCN1 variants to include common generalized epilepsy phenotypes and further illustrate how HCN1 has a pivotal function in brain development and control of neuronal excitability.

Generation and validation of algorithms to identify subjects with dementia using administrative data

OBJECTIVES

To generate and validate algorithms for the identification of individuals with dementia in the community setting, by the interrogation of administrative records, an inexpensive and already available source of data.

METHODS

We collected and anonymized information on demented individuals 65 years of age or older from ten general practitioners (GPs) in the district of Brianza (Northern Italy) and compared this with the administrative data of the local health protection agency (Agenzia per la Tutela della Salute). Indicators of the disease in the administrative database (diagnosis of dementia in the hospital discharge records; use of cholinesterase inhibitors/memantine; neuropsychological tests; brain CT/MRI; outpatient neurological visits) were used separately and in different combinations to generate algorithms for the detection of patients with dementia.

RESULTS

When used individually, indicators of dementia showed good specificity, but low sensitivity. By their combination, we generated different algorithms: I-therapy with ChEI/memantine or diagnosis of dementia at discharge or neuropsychological tests (specificity 97.9%, sensitivity 52.5%); II-therapy with ChEI/memantine or diagnosis of dementia at discharge or neuropsychological tests or brain CT/MRI or neurological visit (sensitivity 90.8%, specificity 70.6%); III-therapy with ChEI/memantine or diagnosis of dementia at discharge or neuropsychological tests or brain CT/MRIMRI and neurological visit (specificity 89.3%, sensitivity 73.3%).

CONCLUSIONS

These results show that algorithms obtained from administrative data are not sufficiently accurate in classifying patients with dementia, whichever combination of variables is used for the identification of the disease. Studies in large patient cohorts are needed to develop further strategies for identifying patients with dementia in the community setting.

Early Treatment with Quinidine in 2 Patients with Epilepsy of Infancy with Migrating Focal Seizures (EIMFS) Due to Gain-of-Function KCNT1 Mutations: Functional Studies, Clinical Responses, and Critical Issues for Personalized Therapy

Epilepsy of infancy with migrating focal seizures (EIMFS) is a rare early-onset developmental epileptic encephalopathy resistant to anti-epileptic drugs. The most common cause for EIMFS is a gain-of-function mutation in the KCNT1 potassium channel gene, and treatment with the KCNT1 blocker quinidine has been suggested as a rational approach for seizure control in EIMFS patients. However, variable results on the clinical efficacy of quinidine have been reported. In the present study, we provide a detailed description of the clinical, genetic, in vitro, and in vivo electrophysiological profile and pharmacological responses to quinidine of 2 EIMFS unrelated patients with a heterozygous de novo KCNT1 mutation: c.2849G>A (p.R950Q) in patient 1 and c.2677G>A (p.E893K) in patient 2. When expressed heterologously in CHO cells, KCNT1 channels carrying each variant showed gain-of-function effects, and were more effectively blocked by quinidine when compared to wild-type KCNT1 channels. On the basis of these in vitro results, add-on quinidine treatment was started at 3 and 16 months of age in patients 1 and 2, respectively. The results obtained reveal that quinidine significantly reduced seizure burden (by about 90%) and improved quality of life in both patients, but failed to normalize developmental milestones, which persisted as severely delayed. Based on the present experience, early quinidine intervention associated with heart monitoring and control of blood levels is among the critical factors for therapy effectiveness in EIMFS patients with KCNT1 gain-of-function mutations. Multicenter studies are needed to establish a consensus protocol for patient recruitment, quinidine treatment modalities, and outcome evaluation, to optimize clinical efficacy and reduce risks as well as variability associated to quinidine use in such severe developmental encephalopathy.

A Loss-of-Function HCN4 Mutation Associated With Familial Benign Myoclonic Epilepsy in Infancy Causes Increased Neuronal Excitability

HCN channels are highly expressed and functionally relevant in neurons and increasing evidence demonstrates their involvement in the etiology of human epilepsies. Among HCN isoforms, HCN4 is important in cardiac tissue, where it underlies pacemaker activity. Despite being expressed also in deep structures of the brain, mutations of this channel functionally shown to be associated with epilepsy have not been reported yet. Using Next Generation Sequencing for the screening of patients with idiopathic epilepsy, we identified the p.Arg550Cys (c.1648C>T) heterozygous mutation on HCN4 in two brothers affected by benign myoclonic epilepsy of infancy. Functional characterization in heterologous expression system and in neurons showed that the mutation determines a loss of function of HCN4 contribution to activity and an increase of neuronal discharge, potentially predisposing to epilepsy. Expressed in cardiomyocytes, mutant channels activate at slightly more negative voltages than wild-type (WT), in accordance with borderline bradycardia. While HCN4 variants have been frequently associated with cardiac arrhythmias, these data represent the first experimental evidence that functional alteration of HCN4 can also be involved in human epilepsy through a loss-of-function effect and associated increased neuronal excitability. Since HCN4 appears to be highly expressed in deep brain structures only early during development, our data provide a potential explanation for a link between dysfunctional HCN4 and infantile epilepsy. These findings suggest that it may be useful to include HCN4 screening to extend the knowledge of the genetic causes of infantile epilepsies, potentially paving the way for the identification of innovative therapeutic strategies.

Adult-Onset Epilepsy in Presymptomatic Alzheimer's Disease: A Retrospective Study

BACKGROUND

The prevalence of epilepsy with onset in adulthood increases with age, mainly due to the accumulation of brain damage. However, a significant proportion of patients experience seizures of unknown cause. Alzheimer's disease (AD) is associated with an increased risk of seizures. Seizure activity is interpreted as a secondary event related to hyperexcitability caused by amyloid-β aggregation.

OBJECTIVE

Since neurodegenerative processes begin several years before clinical symptoms, epilepsy could be more frequent in the presymptomatic stages of dementia.

METHODS

We retrospectively reviewed the prevalence of epilepsy of unknown origin with adult onset before cognitive decline in a large cohort of AD patients (EPS-AD) recruited based on clinical and neuropsychological data. Data of patients with epilepsy followed by AD were compared with two control groups: patients with AD without seizures (no EPS-AD) and a large reference population (RP).

RESULTS

In AD patients, the prevalence of epilepsy of unknown origin, with onset in the adulthood before cognitive decline is 17.1 times higher compared with the RP (95% CI: 10.3-28.3). In EPS-AD, seizures begin on average 4.6 years (median 2.0) before the onset of cognitive symptoms and cognitive decline starts 3.6 years earlier compared with noEPS-AD.

CONCLUSIONS

Neurodegenerative processes of dementia could play a key role in the pathogenesis of epilepsy in a subgroup of individuals intended to develop cognitive decline. Adult-onset epilepsy of undefined cause could thus represent a risk factor for the ongoing neurodegenerative damage, even preceding by years the onset of clinical symptoms of dementia.

A novel de novo HCN1 loss-of-function mutation in genetic generalized epilepsy causing increased neuronal excitability

The causes of genetic epilepsies are unknown in the majority of patients. HCN ion channels have a widespread expression in neurons and increasing evidence demonstrates their functional involvement in human epilepsies. Among the four known isoforms, HCN1 is the most expressed in the neocortex and hippocampus and de novo HCN1 point mutations have been recently associated with early infantile epileptic encephalopathy. So far, HCN1 mutations have not been reported in patients with idiopathic epilepsy. Using a Next Generation Sequencing approach, we identified the de novo heterozygous p.Leu157Val (c.469C > G) novel mutation in HCN1 in an adult male patient affected by genetic generalized epilepsy (GGE), with normal cognitive development. Electrophysiological analysis in heterologous expression model (CHO cells) and in neurons revealed that L157V is a loss-of-function, dominant negative mutation causing reduced HCN1 contribution to net inward current and responsible for an increased neuronal firing rate and excitability, potentially predisposing to epilepsy. These data represent the first evidence that autosomal dominant missense mutations of HCN1 can also be involved in GGE, without the characteristics of epileptic encephalopathy reported previously. It will be important to include HCN1 screening in patients with GGE, in order to extend the knowledge of the genetic causes of idiopathic epilepsies, thus paving the way for the identification of innovative therapeutic strategies.

Biopsy-proven multiple sclerosis in an adult patient with atypical craniometaphyseal dysplasia

Craniometaphyseal dysplasia (CMD) is a rare condition characterised by progressive, diffuse hyperostosis of cranial and long bones, with compression of cranial nerves, linked to mutations in ANKH or GJA1 genes. Here we describe an adult case with clinical features of CMD, who developed cerebral expansive lesion of undetermined nature. Brain biopsy revealed active demyelinating lesions, consistent with multiple sclerosis. The genetic screening of target genes for CMD (ANKH and GJA1) resulted negative in this patient. The peculiar clinical association and the negativity of genetic analyses allow to hypothesise that other genetic causes, not already known, are responsible for the combination of these pathological conditions. Future studies aim to identify the genetic causes of CMD, which will be important to further understand the pathogenetic mechanism of this rare and invalidating disease.

Idiopathic infratentorial superficial siderosis of the central nervous system: case report and review of literature

The superficial siderosis (SS) of the central nervous system (CNS) is a rare condition characterized by a wide range of neurological manifestations directly linked to an acquired iron-mediated neurodegeneration. First described more than 100 years ago, only recently SS has been divided into two distinct entities, according to the distribution of iron deposition in the CNS: cortical superficial siderosis (cSS) and infratentorial superficial siderosis (iSS). Here we describe an adult case of iSS, with detailed clinical and radiological features. Moreover, we extensively review the literature of SS, particularly focusing on the pathogenesis, clinical-radiological classification, diagnostic algorithm and treatment options of this rare condition.

Alternating Hemiplegia and Epilepsia Partialis Continua: A new phenotype for a novel compound TBC1D24 mutation

Mutations in the TBC1D24 gene (MIM 613577) cause familial infantile myoclonic epilepsy (FIME; 605021) and early infantile epileptic encephalopathy-16 (EIEE16; 615338), both inherited with an autosomal recessive trait. The TBC1D24 gene encodes a member of the TBC family domain proteins, involved in cell signaling and oxidative stress resistance. We studied, by a Next Generation Sequencing (NGS) target re-sequencing gene approach, the DNA of a 5 year-old girl, affected by recurrent attacks of Alternating Hemiplegia (AH) and by recurrent episodes of Epilepsia Partialis Continua (EPC). The NGS study showed the presence of two different heterozygous, probably pathogenic variants in the TBC1D24 gene, inherited in trans from her parents: the c.116C>T (p.Ala39Val) and the c.457G>A (p.Glu153Lys). This study describes for the first time the association between TBC1D24 variants and AH expanding the phenotypic spectrum of TBC1D24-related diseases and suggesting that TBC1D24 molecular analysis should be considered in the diagnostic work up of AH patients. An additional peculiar feature is the association of AH and EPC.

Prodromal Alzheimer's disease presenting as cerebral amyloid angiopathy-related inflammation with spontaneous amyloid-related imaging abnormalities and high cerebrospinal fluid anti-Aβ autoantibodies

Cerebral amyloid angiopathy-related inflammation (CAA-ri), a rare form of vasculitis associated with amyloid-β (Aβ) deposition in vessel walls, has been proposed as a spontaneous human model of the amyloid-related imaging abnormalities (ARIA) occurring after anti-Aβ immunotherapy for the treatment of Alzheimer's disease (AD). We describe a case of a patient with biopsy-proven CAA-ri and prodromal AD, confirmed by means of neuropsychological examination after 20 months follow-up, presenting with ARIA and high levels of cerebrospinal fluid anti-Aβ autoantibodies. This case further supports the analogies between the inflammatory response driven by anti-Aβ immunotherapy and that spontaneously occurring in CAA-ri.

Anti-Aβ Autoantibodies in Amyloid Related Imaging Abnormalities (ARIA): Candidate Biomarker for Immunotherapy in Alzheimer's Disease and Cerebral Amyloid Angiopathy

Amyloid-related imaging abnormalities (ARIA) represent the major severe side effect of amyloid-beta (Aβ) immunotherapy for Alzheimer’s disease (AD). Early biomarkers of ARIA represent an important challenge to ensure safe and beneficial effects of immunotherapies, given that different promising clinical trials in prodromal and subjects at risk for AD are underway. The recent demonstration that cerebrospinal fluid (CSF) anti-Aβ autoantibodies play a key role in the development of the ARIA-like events characterizing cerebral amyloid angiopathy-related inflammation generated great interest in the field of immunotherapy. Herein, we critically review the growing body of evidence supporting the monitoring of CSF anti-Aβ autoantibody as a promising candidate biomarker for ARIA in clinical trials.

Dysfunctional HCN ion channels in neurological diseases

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed I_f (funny current) in heart and I_h in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation, and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials, and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the I_h current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson’s disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal I_h current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic, and physiopathological aspects.

Brain targets: can you believe your own eyes?

The unquestionable advantages provided by modern neuroimaging techniques have recently led some to question the duty of the neurologist, traditionally struggling first and foremost to establish the semeiotic localization of brain lesions and only then to interpret them. The present brief report of six clinical patients who came recently to our attention aims to emphasize that the interpretation of neuroimaging results always requires integration with anamnestic, clinical and laboratory data, together with knowledge of nosography and the literature. The solutions of the reported cases always originated from close interaction between the neurologist and the neuroradiologist, based on the initial diagnostic uncertainty linked to the finding of isolated or multiple brain target or ring lesions, too often considered paradigmatic examples of the pathognomonic role of neuroimaging.