Examination of pediatric patients with neuromuscular diseases

Abstract

In recent years, active research has focused on neuromuscular diseases (NMD) for which no treatments are yet available. Enzyme replacement therapy for Pompe disease (PD), antisense oligonucleotide (ASO), gene therapies and oral small–molecule therapies for spinal muscular atrophy (SMA) are now available, and the first ASO for Duchenne muscular dystrophy (DMD) in Japan was approved in 2020. With these therapy developments, expectations for early diagnosis and treatment have increased, and appropriate timing of diagnosis without delay is becoming a requirement. Therefore, pediatricians must detect treatable diseases during infant health check–ups and routine medical care. Diagnostic triggers for these NMDs are general hypotonia (floppy infant) and delayed motor development in diseases with onset in infancy, such as infantile PD and SMA type I, while for NMDs of early childhood, such as DMD, childhood–onset PD and SMA type III, they are muscle weakness and incidentally detected hyperCKemia. However, detecting muscle weakness in children is often difficult because children do not complain of symptoms and are mainly observed based on their surroundings. Parents are unlikely to notice abnormalities unless they compare their children with others of the same age. To effectively detect muscle weakness, it is advisable to ask specific questions during medical interviews asking how the patient climbs stairs and whether he/she takes time to jump down from low steps. During examinations, the patient should be asked to perform gravity–defying exercises, such as jumping on both feet, climbing stairs, standing up from the floor or raising the neck from the supine position. Pediatricians are now required to diagnose children appropriately, without overlooking characteristic findings, at routine examinations.