NINDS Hypotonia Information Page

What is Hypotonia?

Hypotonia is a medical term used to describe decreased muscle tone.  Normally, even when relaxed, muscles have a very small amount of contraction that gives them a springy feel and provides some resistance to passive movement.  It is not the same as muscle weakness, although the two conditions can co-exist.  Muscle tome is regulated by signals that travel from the brain to the nerves and tell the muscles to contract.  Hypotonia can happen from damage to the brain, spinal cord, nerves, or muscles.  The damage can be the result of trauma, environmental factors, or genetic, muscle, or central nervous system disorders.  For example, it can be seen in Down syndrome, muscular dystrophy, cerebral palsy, Prader-Willi syndrome, myotonic dystrophy, and Tay-Sachs disease.  Sometimes it may not be possible to find what causes the hypotonia.  Infants with hypotonia have a floppy quality or “rag doll” appearance because their arms and legs hang by their sides and they have little or no head control.  Other symptoms of hypotonia include problems with mobility and posture, breathing and speech difficulties, ligament and joint laxity, and poor reflexes.  Hypotonia does not affect intellect.  The opposite of hypotonia is hypertonia.

Is there any treatment?

What is the prognosis?

What research is being done?