Muscle Weakness (Hypotonia)

What is hypotonia?

Hypotonia means decreased muscle tone. It can be a condition on its own, called benign congenital hypotonia, or it can be indicative of another problem where there is progressive loss of muscle tone, such as muscular dystrophy or cerebral palsy. It is usually detected during infancy.

  • An infant with hypotonia exhibits a floppy quality or "rag doll" feeling when he or she is held.
  • Infants may lag behind in acquiring certain fine and gross motor developmental milestones that enable a baby to hold his or her head up when placed on the stomach, balance themselves or get into a sitting position and remain seated without falling over.
  • There is a tendency for hip, jaw, and neck dislocations to occur.
  • Some children with hypotonia may have trouble feeding, if they are unable to suck or chew for long periods.
  • A child with hypotonia may also have problems with speech or exhibit shallow breathing.

What causes muscle weakness?

Hypotonia can be caused by a variety of conditions, including those that involve the central nervous system, muscle disorders, and genetic disorders. Some common causes can include but are not limited to:

What are the symptoms of muscle weakness?

The following are common symptoms associated with hypotonia. Each child may experiences symptoms differently. Symptoms vary depending on the underlying cause of the problem.

  • decreased muscle tone; muscles feel soft and doughy
  • ability to extend limb beyond its normal limit
  • failure to acquire motor-related developmental milestones (such as holding head up without support from parent, rolling over, sitting up without support, walking)
  • problems with feeding (inability to suck or chew for prolonged periods)
  • shallow breathing
  • mouth hangs open with tongue protruding (under-active gag reflex)

Some hypotonias are not progressive and are of an unknown origin, a condition known as benign congenital hypotonia.

  • Central nervous system function and intelligence in children is normal.
  • Children with benign congenital hypotonia may not experience developmental delay.
  • Some children acquire gross motor skills (sitting, walking, running, jumping) more slowly than most.

The signs and symptoms of hypotonia resemble that of other conditions. Always consult a physician for a diagnosis.

Hypotonia and muscle weakness can be caused by several different diseases.How Boston Children's Hospital approaches muscle weakness

Your child's muscle weakness can be caused by several different diseases, and treatment cannot begin without sussing out the real cause. At Boston Children's, doctors have several tests available to diagnose the cause of your child's weakness. Once the diagnosis is nailed down, several treatment programs, including physical therapy programs, are at hand to help your child live a normal life.