Infant Muscle Stiffness or Rigidity

Parents are always excited to see what their newborn babies are going to look like, sound, and behave. Though most of these traits are a mystery until the baby is born, there are some things that almost all babies can be expected to have in common. Crying, a lack of speech, unusual feeding and sleeping patterns are all typical things parents can expect.

Babies have a certain amount of looseness in their limbs and bodies which is very typical which is why babies all require a lot of support of their heads and trunks when being picked up, carried, and moved. When a baby does not seem as relaxed as it should be, it can be a sign that something is wrong. In general, an infant with muscle stiffness or rigidity may be suffering from some sort of medical condition and must be evaluated immediately.

Common Medical Causes of Infant Muscle Stiffness or Rigidity

Among the more common causes for a baby’s body to be less relaxed and loose than is expected are:

Cerebral Palsy

This is something that is most often the result of a birth injury. Due to lack of oxygen to the brain, it creates a neurological disorder and can be mild to severe. The condition causes children to be unable to always control their muscular actions, and while some cases involve only mild spasms, there are also many that cause the infant to have stiffened muscles.

An infant with CP may be unable to move or may move with difficulty due to the stiffness of the muscles or because of constant muscle spasticity. While there are therapies and treatments for CP, it is a lifelong condition that must be identified and dealt with as soon as it is discovered.

Klumpke’s Palsy

This is related directly to another sort of palsy known as Erb’s palsy. Both are due to birth injuries to the nerves. Often these palsies develop because a baby is pulled or moved in a way that breaks or somehow disrupts nerves in the neck, shoulder, and collar area.

In the case of Klumpke’s palsy, the baby’s nerves are harmed during labor and delivery and it creates stiffness in the muscles of the arms and wrists. A common symptom in a baby with this condition is a hand that is held in a claw-like manner. Therapy can help to overcome the condition, but as a child grows special care is needed to be sure that progress continues and that the nerve damage is not continually triggered by body growth.


Many babies are born with jaundice or develop it shortly after delivery because their mother’s bodies are no longer processing the substance known as bilirubin. The condition known as kernicterus is something that results from jaundice in newborns. If the bilirubin cannot be put under control, it can cause serious brain damage. This then leads to muscle stiffness, and though it can be treated, it is something that a physician should be able to detect immediately and to begin treating before the harm is done.


Just as its name sounds, this condition is one in which there is just too much muscle tone in the limbs, and it leads to stiffness and rigidity. It occurs when the brain no longer communicates clearly with the spinal cord, and this usually happens in infants due to a birth injury.

Babies are not stiff and rigid by nature, unless they quickly tense up their muscles due to pain or emotional turmoil. Because some instances of infant muscle stiffness are due to underlying issues, and many birth injury related issues, it is of the utmost importance to report and document any symptoms and begin treatment immediately.

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