Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses

Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs

Therapeutic Drug Monitoring of Quinidine in Pediatric Patients with KCNT1 Genetic Variants

Quinidine (QND) is an old antimalarial drug that was used in the early 20th century as an antiarrhythmic agent. Currently, QND is receiving attention for its use in epilepsy of infancy with migrating focal seizures (EIMFS) due to potassium sodium-activated channel subfamily T member 1 (KCNT1) genetic variants. Here, we report the application of Therapeutic Drug Monitoring (TDM) in pediatric patients carrying KCNT1 genetic variants and orally treated with QND for developmental and epileptic encephalopathies (DEE). We measured plasma levels of QND and its metabolite hydroquinidine (H-QND) by using a validated method based on liquid chromatography coupled with mass spectrometry (LC-MS/MS). Three pediatric patients (median age 4.125 years, IQR 2.375-4.125) received increasing doses of QND. Cardiac toxicity was monitored at every dose change. Reduction in seizure frequency ranged from 50 to 90%. Our results show that QND is a promising drug for pediatric patients with DEE due to KCNT1 genetic variants. Although QND blood levels were significantly lower than the therapeutic range as an anti-arrhythmic drug, patients showed a significant improvement in seizure burden. These data underlie the utility of TDM for QND not only to monitor its toxic effects but also to evaluate possible drug-drug interactions

POLG1-Related Epilepsy. Review of Diagnostic and Therapeutic Findings

Background: The clinical spectrum associated with POLG1 gene mutations ranges from non-syndromic epilepsy or mild isolated neurological signs to neurodegenerative disorders. Our aim was to review diagnostic findings, therapeutic approaches and outcomes of reported cases of epilepsy related to POLG1 mutation. Methods: The articles for review were identified through a systematic research on PubMed and EMBASE databases from January 2003 to April 2020, searching for the terms "Epilepsy AND POLG OR polymerase gamma," OR "POLG1". Results: Forty-eight articles were selected for review, which included 195 patients. Two main peaks of age at epilepsy onset were found: at ages 1 and 13 years. The most frequent seizure type was myoclonic. The occurrence of Status Epilepticus was reported in 46.4% of cases. Epileptiform and slow abnormalities were most frequently seen over occipital regions. Brain Magnetic Resonance Imaging (MRI) revealed increased T2 signal intensities in thalamic regions. Genetic analysis revealed a prevalence of A467T, W748S and G848S (74.2% of patients) mutations. Survival at 5 years was estimated at very low levels (30.2% of patients). Conclusion: In this review, we included cases with both pediatric and adult epilepsy onset. The analysis of data regarding prognosis showed that survival is related to age at onset of epilepsy

Refractory Status Epilepticus in Genetic Epilepsy-Is Vagus Nerve Stimulation an Option?

Refractory and super-refractory status epilepticus (RSE, SRSE) are severe conditions that can have long-term neurological consequences with high morbidity and mortality rates. The usefulness of vagus nerve-stimulation (VNS) implantation during RSE has been documented by anecdotal cases and in systematic reviews; however, the use of VNS in RSE has not been widely adopted. We successfully implanted VNS in two patients with genetic epilepsy admitted to hospital for SRSE; detailed descriptions of the clinical findings and VNS parameters are provided. Our patients were implanted 25 and 58 days after status epilepticus (SE) onset, and a stable remission of SE was observed from the seventh and tenth day after VNS implantation, respectively, without change in anti-seizure medication. We used a fast ramp-up of stimulation without evident side effects. Our results support the consideration of VNS implantation as a safe and effective adjunctive treatment for SRSE

CDKL5 deficiency disorder: progressive brain atrophy may be part of the syndrome

The clinical phenotype of Cyclin-Dependent Kinase-Like 5 (CDKL5) deficiency disorder (CDD) has been delineated but neuroimaging features have not been systematically analyzed. We studied brain magnetic resonance imaging (MRI) scans in a cohort of CDD patients and reviewed age at seizure onset, seizure semiology, head circumference. Thirty-five brain MRI from 22 unrelated patients were included. The median age at study entry was 13.4 years. In 14/22 patients (85.7%), MRI in the first year of life was unremarkable in all but two. In 11/22, we performed MRI after 24 months of age (range 2.5-23 years). In 8 out of 11 (72.7%), MRI showed supratentorial atrophy and in six cerebellar atrophy. Quantitative analysis detected volumetric reduction of the whole brain (-17.7%, P-value = 0.014), including both white matter (-25.7%, P-value = 0.005) and cortical gray matter (-9.1%, P-value = 0.098), with a reduction of surface area (-18.0%, P-value = 0.032), mainly involving the temporal regions, correlated with the head circumference (& rho; = 0.79, P-value = 0.109). Both the qualitative structural assessment and the quantitative analysis detected brain volume reduction involving the gray and white matter. These neuroimaging findings may be related to either progressive changes due to CDD pathogenesis, or to the extreme severity of epilepsy, or both. Larger prospective studies are needed to clarify the bases for the structural changes we observed

Insights into cognitive and behavioral comorbidities of SLC6A1-related epilepsy: five new cases and literature review

IntroductionSLC6A1 pathogenic variants have been associated with epilepsy and neurodevelopmental disorders. The clinical phenotype includes different seizure types, intellectual disability, and psychiatric symptoms affecting mood and behavior. Few data regarding neuropsychological features have been described, and details on cognitive profiles are often missing due to the lack of standardized tests.MethodsWe retrospectively reviewed the neuropsychological assessments of five subjects carrying heterozygous missense genetic variants in SLC6A1. We also collected data on epileptic features, EEGs, and brain MRIs. Additionally, we reviewed neuropsychological data from 204 previously reported patients with SLC6A1 pathogenic variants.ResultsIn our series, at the last evaluation (median 12.6 years), three patients had borderline intellectual functioning, one patient had mild cognitive impairment, and one patient presented with a moderate cognitive disability. Three out of five patients underwent at least two neuropsychological evaluations, which revealed a worsening of cognitive functions over time. We detected attention deficits in all patients. In addition, we observed anxiety, disruptive behavior disorder, emotional instability, and hetero aggressiveness. We also performed a literature review that highlighted that most of the patients with SLC6A1 pathogenic variants have mild-to-moderate intellectual disability and that one-third of cases have autistic traits.DiscussionBased on the literature review and the detailed description of our cases, we conclude that patients with SLC6A1-related epilepsy mostly present with mild-to-moderate intellectual disability, often associated with attention disorders. Such symptoms may worsen over time. Periodic standardized neuropsychological tests may be useful tools to follow development over time, and patient-specific rehabilitation programs could be tailored consistently

The Role of KRAS Mutations in Cortical Malformation and Epilepsy Surgery: A Novel Report of Nevus Sebaceous Syndrome and Review of the Literature

The rare nevus sebaceous (NS) syndrome (NSS) includes cortical malformations and drug-resistant epilepsy. Somatic RAS-pathway genetic variants are pathogenetic in NS, but not yet described within the brain of patients with NSS. We report on a 5-year-old boy with mild psychomotor delay. A brown-yellow linear skin lesion suggestive of NS in the left temporo-occipital area was evident at birth. Epileptic spasms presented at aged six months. EEG showed continuous left temporo-occipital epileptiform abnormalities. Brain MRI revealed a similarly located diffuse cortical malformation with temporal pole volume reduction and a small hippocampus. We performed a left temporo-occipital resection with histopathological diagnosis of focal cortical dysplasia type Ia in the occipital region and hippocampal sclerosis type 1. Three years after surgery, he is seizure-and drug-free (Engel class Ia) and showed cognitive improvement. Genetic examination of brain and skin specimens revealed the c.35G > T (p.Gly12Val) KRAS somatic missense mutation. Literature review suggests epilepsy surgery in patients with NSS is highly efficacious, with 73% probability of seizure freedom. The few histological analyses reported evidenced disorganized cortex, occasionally with cytomegalic neurons. This is the first reported association of a KRAS genetic variant with cortical malformations associated with epilepsy, and suggests a possible genetic substrate for hippocampal sclerosis

Characterization of a new epileptic syndrome due to PCDH19 gene mutation

Razionale e Obiettivi: Lo spettro clinico dell’epilessia dovuta a mutazione del gene PCDH19 è molto variabile, essendo riportati sia pazienti con epilessia farmacoresistente, disabilità intellettuale (ID) e disturbo dello spettro autistico (ASD) sia pazienti con buon controllo delle crisi e normale sviluppo cognitivo. Scopo di questo studio analizzare un’ampia popolazione di pazienti con mutazione PCDH19 al fine di definire il fenotipo elettro-clinico, la correlazione genotipo-fenotipo, definire l’outcome a lungo termine e identificare i fattori prognostici, e gli aspetti clinici importanti per la diagnosi differenziale con la sindrome di Dravet (DS). La tramissione x-linked, ha permesso di ipotizzare una differente espressione genica dei geni che codificano per gli enzimi AKR1C1-3, coinvolti nel metabolismo degli steroidi, con conseguente riduzione dei livelli plasmatici di allopregnanolone e questo studio si propone si verificare tale ipotesi mediante misurazione dei neurosteroidi nelle pazienticon mutazione PCDH19. Metodi: Sono stati retrospettivamente collezionati i dati genetici, clinici ed EEG di 61 pazienti con epilessia dovuta a mutazione del gene PCDH19, provenienti da 15 centri italiani. I pazienti sono stati divisi in due gruppi a seconda dell’outcome e sono state analizzate le seguenti variabili: mutazione, età di esordio, età al follow-up, tipo di crisi, occorrenza di stato epilettico, anomalie EEG. La ROC analisi è stata utilizzata per verificare la presenza di una eventuale età di riduzione della frequenza delle crisi. 15 pazienti con mutazione PCDH19 sono stati confrontati con 19 pazienti con DS Fisher's exact test o Student's t-test. Per verificare la riduzione di allopregnanolone, è stato condotto uno studio caso-controllo prospettico (12 pazienti-15 controlli). L’analisi dei neurosteroidi è stata effettuata sia in condizioni basali che dopo stimolo con ACTH, mediante spettroscopia. Risultati: All’ultimo follow-up (mediana 12 anni; range 1.9-42.1), 13 pazienti (21,3%) avevano crisi settimanali, mensili, 78,8% crisi annuali, e 12 pazienti (19.7%) erano seizure-free da almeno 2 anni. La curva ROC ha mostrato una riduzione delle crisi dopo 10.5 anni (sensibilità 81.0%; specificità 70.0%). 36 pazienti avevano ID, 31 pazienti ASD. L’ètà d’esordio dell’epilessia più precoce è risultata l’unico fattore predittivo di ID (p=0.05) e ASD (p<0.014). Al contrario non sono stati identificati fattori predittivi dell’outcome dell’epilessia. L’età di esordio più precoce è risultata essere un fattore clinico utile per la diagnosi differenziale con la DS (5.0+2.1 vs 11.2+7.0 mesi; p<0.05) così come la latenza tra la prima e la seconda crisi (10.1+13.6 vs 2.2+2.1 mesi; p<0.05). Dall’analisi dei livelli plasmatici dei neurosteroidi è risultata una ridotta produzione nei pazienti rispetto ai controlli, confermata anche dopo il test con ACTH. Conclusioni: Questo studio ha premesso di identificare l’età di esodio precoce quale indicatore prognostico di un outcome peggiore caratterizzato da epilessia farmacoresistente e disabilità cognitiva. La riduzione della frequenza delle crisi con la pubertà ben correla con l’ipotesi della down-regulation dei neurosteroidi che è stata confermata con l’analisi dei livelli plasmatici. Questo risultato apre a nuove possibilità terapeutiche, essendo i neurosteroidi e in particolare l’allopregnanolone un modulatore allosterico del recettore GABA-A e quindi modulatore dell’eccitabilità neuronale.Objective: PCDH19-related epilepsy is an epileptic syndrome, arising within the first three years of life and characterized by clustered and fever-induced seizures. In most of cases it is associated with Intellectual Disability (ID) and autistic features. Aim of this study is to analyze a large Italian population with PCDH19-related epilepsy in order to better define the epileptic phenotype, identify genotype-phenotype correlation, predicting factors for outcome, and markers for differential diagnosis with Dravet Syndrome (DS). The unusual, gender reversed X-chromosome inheritance of PCDH19-FE led also to speculate that genes with different expression between the two sexes may play a role in the pathogenesis and that AKR1C1-3 genes, could be dysregulated, thus resulting in allopegnanolone reduced blood levels. Methods: We retrospectively collected genetic, clinical and EEG data of 61 patients affected by PCDH19-related Epilepsy, coming from 15 Italian hospitals. We stratified patients into two groups according the outcome. We analysed the following variables: mutation type, age at onset, age at study, seizure type, occurrence of status epilepticus, EEG abnormalities, cognitive and behavioural disorders. ROC curve analysis was performed in order to discriminate the age at which seizures could decrease in frequency. A group of 15 patients with PCDH19-related epilepsy were compared with 19 patients with DS. Comparisons were performed with Fisher's exact test or Student's t-test. In order to ascertain allopregnanolone deficiency, we performed a prospective case-control study. We enrolled 12 patients affected by PCDH19-related epilepsy and 15 controls, age-and sex-matched. Controls were recruited among subjects evaluated for praecox puberty or hyperandrogenism. In both groups blood samples were taken at basal (T0) and 60 min after (ACTH) administration (T1). Quantitative analysis of neuroactive steroids in serum was performed by liquid chromatography-electrospray tandem mass spectrometry. Results: At last follow-up (median 12 years; range 1.9-42.1), 13 patients (21.3%) had monthlyweekly seizures, 78.7% annual seizures/clusters or less frequent. Twelve patients (19.7%) were seizure-free since > 2 years. ROC analysis showed a significant decreasing of seizure frequency after the age of 10.5 years (sensitivity 81.0%; specificity 70.0%). Thirty-six patients (59.0%) had ID and behavioral disturbances. ID was moderate-severe in almost half of them. Autistic spectrum disorder was present in 31 patients. An earlier age at epilepsy onset resulted the only predictor factor for ID (p=0.05) and autistic spectrum disorder (p<0.014). Conversely, age at onset was not a predictor factor for seizure outcome (p<0.214). Epilepsy onset was earlier in DS (5.0+2.1 vs 11.2+7.0 months; p<0.05). The second seizure/cluster occurred after a longer latency in PCDH19- related epilepsy rather than in DS (10.1+13.6 vs 2.2+2.1 months; p<0.05). All neuroactive steroids resulted down produced in patients with PCDH19-related epilepsy rather than controls and this data was confirmed after ACTH stimulus. Conclusions: We found that an earlier age at epilepsy onset is linked with a significant risk for ID and autistic spectrum disorder. The decreasing of seizure frequency after the age of 10.5 years supports the hypothesis of a down-regulation of neurosteroid-metabolizing enzymes and allopregnanolone deficiency in PCDH19-related epilepsy. We also documented a down regulation of all steroidogenesis in PCDH19-related epilepsy. Particularly we found allopregnanolone and pregnenolone sulfate deficiency. Allopregnanolone is a GABA-A receptor modulator influencing the neuronal excitability, thus representing a realistic therapeutic target for PCDH19-related epilepsy. We failed to identify any genotype-phenotype correlation considering the site and type of PCDH19 mutations. We were able to find out some distinctive features, which could address the diagnosis towards DS or PCDH19-related epilepsy, since first manifestation. These considerations suggest to definitively considering PCDH19 gene as cause of a proper epileptic phenotype

Bilateral putaminal necrosis and bronopol toxicity

Among alcohols, methanol intoxication is the most frequently associated with cerebral toxicity, causing retinal damage and putaminal necrosis. This consequence is believed to be due to the transformation of methanol into formic acid. We describe the case of a patient who presented with acute impairment of consciousness and tetraparesis after she had been drinking several bottles of a topical antiseptic solution (Lysoform Medical) containing 2-bromo-2-nitro-1,3-propandiol (bronopol) among excipients, in order to lose weight during previous months. Moreover, she had been on a strict slimming diet. Soon after admission, a severe respiratory and metabolic impairment became rapidly evident, requiring an intensive care unit admission. Cerebral MRI showed the presence of bilateral putaminal necrosis. She recovered in 10 days, surprisingly, without any evident clinical neurological signs. Methanol, also bronopol, when diluted in aqueous solution, at warm temperature and/or higher pH, may release formaldehyde, which is converted into formic acid, a basal ganglia toxic compound