After completing this article, readers should be able to:

The “floppy infant” represents a diagnostic challenge to general pediatricians. Infants can present with hypotonia that is due to central or peripheral nervous system abnormalities, myopathies, genetic disorders, endocrinopathies, metabolic diseases, and acute or chronic illness (Table 1). A systematic approach to a child who has hypotonia, paying attention to the history and clinical examination, is paramount in localizing the problem to a specific region of the nervous system.

It is important to distinguish weakness from hypotonia. Hypotonia is described as reduced resistance to passive range of motion in joints; weakness is reduction in the maximum power that can be generated. A more useful definition of hypotonia is an impairment of the ability to sustain postural control and movement against gravity. Thus, floppy infants exhibit poor control of movement, delayed motor skills, and hypotonic motor movement patterns. The abnormal motor...

You do not currently have access to this content.