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.
Treatment begins with a thorough diagnostic evaluation, usually performed by a neurologist, including an assessment of motor
and sensory skills, balance and coordination, mental status, reflexes, and functioning of the nerves. Diagnostic tests that
may be helpful include a CT or MRI scan of the brain, an EMG to evaluate nerve and muscle function, or an EEG to measure electrical
activity in the brain. Once a diagnosis has been made, the underlying condition is treated first, followed by symptomatic
and supportive therapy for the hypotonia. Physical therapy can improve fine motor control and overall body strength. Occupational
and speech-language therapy can help breathing, speech, and swallowing difficulties. Therapy for infants and young children
may also include sensory stimulation programs.
Hypotonia can be a life-long condition. In some cases, however, muscle tone improves over time.
The NINDS supports research on conditions that can result from neurological disorders, such as hypotonia. Much of this research
is aimed at learning more about these conditions and finding ways to prevent and treat them.
Muscular Dystrophy Association 3300 East Sunrise Drive Tucson, AZ 85718-3208 mda@mdausa.org http://www.mda.org Tel: 520-529-2000 800-572-1717 Fax: 520-529-5300 |
March of Dimes 1275 Mamaroneck Avenue White Plains, NY 10605 askus@marchofdimes.com http://www.marchofdimes.com Tel: 914-997-4488 888-MODIMES (663-4637) Fax: 914-428-8203 |
National Organization for Rare Disorders (NORD) 55 Kenosia Avenue Danbury, CT 06810 orphan@rarediseases.org http://www.rarediseases.org Tel: 203-744-0100 Voice Mail 800-999-NORD (6673) Fax: 203-798-2291 |
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Last updated October 11, 2011