ABSTRACT
Hypotonia in infancy may be due to a paralytic or a non-paralytic disorder. Paralytic conditions cause hypotonia with weakness and may affect the anterior horn cells, nerve fibres, neuromuscular junctions or muscles. Non-paralytic conditions cause hypotonia without significant weakness. The commonest cause of a floppy baby is perinatal asphyxia. The paralytic causes of floppiness are rare, and many are genetically determined, the commonest being spinal muscular atrophy.
