Unusual Voltage-Gated Sodium and Potassium Channelopathies Related to Epilepsy

Background@#and Purpose There is extensive literature on monogenic epilepsies caused by mutations in familiar channelopathy genes such as SCN1A. However, information on other lesscommon channelopathy genes is scarce. This study aimed to explore the genetic and clinical characteristics of patients diagnosed with unusual voltage-gated sodium and potassium channelopathies related to epilepsy. @*Methods@#This observational, retrospective study analyzed pediatric patients with epilepsy who carried pathogenic variants of unusual voltage-gated sodium and potassium channelopathy genes responsible for seizure-associated phenotypes. Targeted next-generation sequencing (NGS) panel tests were performed between November 2016 and June 2022 at Severance Children’s Hospital, Seoul, South Korea. Clinical characteristics and the treatment responses to different types of antiseizure medications were further analyzed according to different types of gene mutation. @*Results@#This study included 15 patients with the following unusual voltage-gated sodium and potassium channelopathy genes: SCN3A (n=1), SCN4A (n=1), KCNA1 (n=1), KCNA2 (n=4), KCNB1 (n=6), KCNC1 (n=1), and KCNMA1 (n=1). NGS-based genetic testing identified 13 missense mutations (87%), 1 splice-site variant (7%), and 1 copy-number variant (7%). Developmental and epileptic encephalopathy was diagnosed in nine (60%) patients. Seizure freedom was eventually achieved in eight (53%) patients, whereas seizures persisted in seven (47%) patients. @*Conclusions@#Our findings broaden the genotypic and phenotypic spectra of less-common voltage-gated sodium and potassium channelopathies associated with epilepsy.

Nusinersen for Spinal Muscular Atrophy Type I with Chronic Respiratory Failure: A Retrospective Study in South Korea

Purpose@#To analyze the efficacy and safety of nusinersen in patients with spinal muscular atrophy (SMA) type I with chronic respiratory failure. @*Materials and Methods@#We retrospectively reviewed seven patients diagnosed with SMA type I and chronic respiratory failure who were on permanent ventilation and treated with nusinersen at Gangnam Severance Hospital between January 2018 and July 2023. Patient demographics and clinical characteristics were recorded, and treatment progress was evaluated according to Hammersmith Infant Neurological Examination (HINE-2) and Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scores. @*Results@#Patients initially developed hypotonia at a mean age of 3.7 months. Mean age at start of nusinersen was 7.3 years; the mean duration of follow-up after starting nusinersen was 46.2 months. At 6-, 18-, 38-, 58-, and 74-month follow-up, the mean changes in CHOP-INTEND scores were 1.0, 2.9, 1.8, 1.5, and 1.5, respectively, and the proportions of patients who showed disease amelioration were 28.6%, 71.4%, 75.0%, 100%, and 100%, respectively. @*Conclusion@#Nusinersen is safe and effective in patients with SMA type I, even those with chronic respiratory failure and those on permanent ventilation. No significant adverse effects of nusinersen were observed.

Acute Necrotizing Myelitis Associated with COVID-19

Acute ascending hemorrhagic longitudinally extensive transverse myelitis is a rare inflammatory demyelinating disorder, which invades several vertebral segments and progresses rapidly and manifests severe symptoms. We present a case of acute necrotizing myelitis associated with COVID-19 infection. A 10-year-old female, with no previous medical history and no prior administration of COVID-19 vaccination, contracted COVID-19 in early April 2022. Two weeks later, she suffered from severe posterior neck pain and also presented with motor weakness and numbness in both lower extremities, making it difficult to walk independently and spontaneously void urine. Initial spinal cord MR showed longitudinally segmental extensive T2 hyperintensities. Cerebrospinal fluid (CSF) analysis revealed elevated red blood cell, normal white blood cell, and elevated protein levels and absence of oligoclonal bands. CSF culture and viral polymerase chain reaction were negative. Autoimmune work-up was negative. She was started on intravenous methylprednisolone 1g/day for 5 days and immunoglobulin (Ig) 2 g/kg for 5 days. She was also treated with six courses of therapeutic plasma exchange. Nevertheless, her pain and motor weakness persisted. She eventually developed respiratory failure. Follow-up MR presented a newly noted small hemorrhagic component. She was consequently treated with two additional courses of methylprednisolone and Ig. At 6-months follow-up, neurological examination showed improvement with normal sensory function and motor grade IV function in both upper extremities. We present the case of acute necrotizing myelitis associated with COVID-19 infection. Multiple courses of methylprednisolone and Ig showed mild improvement in motor and sensory function. However, poor prognosis was unavoidable due to rapid progression of the disease.