Neonatal seizures as onset of Inborn Errors of Metabolism (IEMs): from diagnosis to treatment. A systematic review

Identifying Metabolic Diseases That Precipitate Neonatal Seizures

Although a rare cause of neonatal seizures, inborn errors of metabolism (IEMs) remain an essential component of a comprehensive differential diagnosis for poorly controlled neonatal epilepsy. Diagnosing neonatal-onset metabolic conditions proves a difficult task for clinicians; however, routine state newborn screening panels now include many IEMs. Three in particular-pyridoxine-dependent epilepsy, maple syrup urine disease, and Zellweger spectrum disorders-are highly associated with neonatal epilepsy and neurocognitive injury yet are often misdiagnosed. As research surrounding biomarkers for these conditions is emerging and gene sequencing technologies are advancing, clinicians are beginning to better establish early identification strategies for these diseases. In this literature review, the authors aim to present clinicians with an innovative clinical guide highlighting IEMs associated with neonatal-onset seizures, with the goal of promoting quality care and safety.

Neonatal seizures: Etiologies, clinical characteristics, and radiological features: A cross-sectional study

Seizures are a common clinical indication of central nervous system damage or abnormality in neonates. We aimed to identify the etiologies, clinical characteristics, and radiological features of neonatal seizures. This is a cross-sectional, retrospective, descriptive study using data obtained from the neonatal intensive care unit in King Abdulaziz Medical City (KAMC), a governmental, academic tertiary hospital in Riyadh, Saudi Arabia. The population of interest were neonates diagnosed with a neonatal seizure at KAMC between April 2015 and March 2019. A total of 61 patients with neonatal seizures were included in the study. The most common etiology was hypoxic-ischemic encephalopathy (43%). A total of 32 patients were full-term (52.5%). Around one-fifth of the study sample (21.3%) had a family history of neonatal seizures. Around 43.0% of the patients had epilepsy episodes. More than half of the patients (57.0%) were on one anti-seizure medication. Patients were followed up after 1 year, they had multiple comorbidities, including developmental delay, epilepsy, and cerebral palsy. Developmental delay was identified in 62.3% of the patients. A total of 19 patients have passed away (31%). Neonatal seizures are a common manifestation of neurologic disorders in neonates and are associated with high morbidity and mortality. Therefore, early identification of seizure etiology and proper management may help to improve the outcome.

Epilepsy: Mitochondrial connections to the 'Sacred' disease

Over 65 million people suffer from recurrent, unprovoked seizures. The lack of validated biomarkers specific for myriad forms of epilepsy makes diagnosis challenging. Diagnosis and monitoring of childhood epilepsy add to the need for non-invasive biomarkers, especially when evaluating antiseizure medications. Although underlying mechanisms of epileptogenesis are not fully understood, evidence for mitochondrial involvement is substantial. Seizures affect 35%-60% of patients diagnosed with mitochondrial diseases. Mitochondrial dysfunction is pathophysiological in various epilepsies, including those of non-mitochondrial origin. Decreased ATP production caused by malfunctioning brain cell mitochondria leads to altered neuronal bioenergetics, metabolism and neurological complications, including seizures. Iron-dependent lipid peroxidation initiates ferroptosis, a cell death pathway that aligns with altered mitochondrial bioenergetics, metabolism and morphology found in neurodegenerative diseases (NDDs). Studies in mouse genetic models with seizure phenotypes where the function of an essential selenoprotein (GPX4) is targeted suggest roles for ferroptosis in epilepsy. GPX4 is pivotal in NDDs, where selenium protects interneurons from ferroptosis. Selenium is an essential central nervous system micronutrient and trace element. Low serum concentrations of selenium and other trace elements and minerals, including iron, are noted in diagnosing childhood epilepsy. Selenium supplements alleviate intractable seizures in children with reduced GPX activity. Copper and cuproptosis, like iron and ferroptosis, link to mitochondria and NDDs. Connecting these mechanistic pathways to selenoproteins provides new insights into treating seizures, pointing to using medicines including prodrugs of lipoic acid to treat epilepsy and to potential alternative therapeutic approaches including transcranial magnetic stimulation (transcranial), photobiomodulation and vagus nerve stimulation.

Clinical Presentation of Inherited Metabolic Diseases in Newborns Hospitalised in an Intensive Care Unit

BACKGROUND

The first clinical manifestations of inherited metabolic diseases occur in the neonatal period in up to half of cases, often with nonspecific symptoms, making their recognition challenging. This study aimed to characterise inherited metabolic disease cases with neonatal presentation requiring admission to the paediatric intensive care unit in a Portuguese reference centre for inherited metabolic diseases.

MATERIAL AND METHODS

An observational study with retrospective data collection was performed, including all newborns with an inherited metabolic disease admitted to the pediatric intensive care unit between June 2011 and June 2022. Three 'pathophysiological' groups were defined: cases due to small molecules, energy deficiency and complex molecules.

RESULTS

Twenty newborns, with a median age at admission of 7.5 days, were included. Thirteen (65%) were female, sixteen (80%) had a small molecule disorder, and four (20%) had diseases of energy defects. Neurological manifestations were the most common, with most newborns presenting symptomatically in the first week of life. There was no difference between the groups in neurological, cardiac, and hepatic involvement and shock at presentation. A symptom-free interval was more frequent in patients with small molecule disorders than the others (p=0.01). The main metabolic changes found were altered plasma amino acids (n=13) and organic aciduria (n=10), creatine kinase elevation (n=13), hyperlactatemia (n=12), metabolic acidosis with increased anion gap (n=8) and hyperammonaemia (n=7). Newborn screening of metabolites helped make a diagnosis in 60% of cases. Five newborns died due to multiorgan failure (n=3) or refractory cardiogenic shock (n=1), and in one, therapeutic efforts were limited due to an adverse neurological prognosis.

CONCLUSION

Although the symptoms and signs are often nonspecific, we should suspect inherited metabolic disease when a newborn presents with neurological symptoms after a symptom-free period, however short it might be. Newborns with suspected inherited metabolic disease should be evaluated with simple biochemical tests, and newborn screening should be urgently expanded to start specific treatment earlier, reducing mortality and morbidity.

Neonatal seizures: diagnostic updates based on new definition and classification

Neonatal seizures are the most common neurological symptoms caused by various etiologies in the neonatal period, but their diagnosis and treatment are challenging because their pathophysiology and electroclinical manifestations differ from those of patients in older age groups. Many seizures present as electrographic-only events without clinical signs or as obscure clinical manifestations that are difficult to distinguish from other neonatal behaviors. Accordingly, a new definition and classification of neonatal seizures was recently proposed by the International League Against Epilepsy Task Force on neonatal seizures, highlighting the role of electroencephalography in diagnosing and treating neonatal seizures. Neonatal seizures are defined as electrographic events with sudden, paroxysmal, and abnormal alteration of activity and divided into electroclinical seizures and electrographic-only seizures according to their clinical signs, thus excluding clinical events without an electrographic correlation. Seizure types are described by their predominant clinical features and divided into motor (automatisms, clonic, epileptic spasms, myoclonic, tonic, and sequential), nonmotor (autonomic and behavioral arrest), and unclassified. Although many neonatal seizures are acute reactive events caused by hypoxic-ischemic encephalopathy or vascular insults, structural, genetic, or metabolic etiologies of neonatal-onset epilepsy should also be thoroughly evaluated to determine their appropriate management.

Multidisciplinary Care of Patients with Inherited Metabolic Diseases and Epilepsy: Current Perspectives

More than 650 inherited metabolic diseases may present with epilepsy or seizures. These diseases are often multisystem, life-long and induce complex needs of patients and families. Multidisciplinary care involves all stages of disease management: diagnostics, specific or symptomatic, acute and chronic treatments, and integrated care that takes into account not only medical, but also manifold psychosocial, educational, vocational and other needs of patients and their caregivers. Care coordination is indispensable to ensure smooth transitions of care across life and disease stages, including management of emergencies, transition from pediatric to adult services and palliative care. Care pathways are highly diverse and have to find the right balance between highly specialized and locally provided services. While multidisciplinary teams consist of many professionals, a named supervising physician in a highly specialized healthcare setting and a care coordinator are highly important. As the greatest burden of care always falls onto the shoulders of patients and/or families, patient empowerment should be a part of every care pathway and include provision of required information, involvement into common decision-making, patient’s and family’s education, support for self-management, liaison with peer support groups and emotional/ psychological support. Due to the rarity and complexity of these diseases, sufficient expertise may not be available in a national healthcare system and cross-border services (virtual or physical) in the recently developed European Reference Networks should be ensured through the proper organization of referral systems in each EU and EEA country. Finally, digital technologies are particularly important in the provision of services for patients with rare diseases and can significantly increase the availability of highly specialized services and expertise.