The hypotonic infant is a common clinical scenario that is encountered by a pediatric neurologist. Such presentation can be nonspecific, making the diagnosis challenging. A systematic diagnostic approach is important to localization, beginning with distinguishing between central and peripheral causes of hypotonia. This chapter describes how to apply the clinical evaluation and ancillary testing including electrodiagnostic, biochemical, and genetic testing, imaging, and histopathological analysis to differentiate between neuropathic and myopathic disorders and then arrive to an etiology. This chapter describes the most common disorders including spinal muscular atrophies (SMA), neuropathies, and various forms of myopathic disorders such as congenital muscular dystrophies (CMDs) and congenital myopathies. In addition, we describe the management and treatment approach for infants with neuropathic and myopathic disorders. Availability of treatment for SMA with nusinersen is described, making an early diagnosis a high priority.
- Congenital muscular dystrophies (CMDs)
- Congenital myopathies
- Congenital myotonic dystrophy (DM)
- Hypotonic infant
- Spinal muscular atrophy (SMA)