Infant Muscle Rigidity or Stiffness

When some people refer to babies, they call them a ball of flesh. While it’s not a very attractive description of a baby, newborns aren’t characterized by a lot of movement, personality (yet), or activity, so the euphemism is somewhat fitting. Overall limpness or stiffness, however, may indicate an underlying medical problem.

Cerebral Palsy

Known as a neurological disorder that masquerades as a muscular disorder, cerebral palsy (CP)  affects the way children interact with their muscle groups. Some children with light symptoms may have muscles that only slightly vary from flabbiness to stiffness, while other children may have extremely stiff muscles that prevent them from walking. In fact, muscle stiffness is so common in some children with CP that  physicians sometimes use Botox as a method of treatment.

In addition to stiff and muscles, children with CP often have muscle spasticity, marked my involuntary muscle spasms in the arms, legs, and neck.

Klumpke’s Palsy

A severe form of Erb’s palsy, Klumpke’s palsy is an injury to the brachial plexus, a network of  nerves between the shoulder, neck, and collarbone. These nerves can be pulled, broken, disrupted, moved, or disabled during difficult labor, thus rendering the muscle group stiff. Many infants with Klumpke’s palsy cannot move their arm or wrist flexor nearly at all, and their hand may be malformed into a claw-like formation.


Hypertonia is a condition marked by excessive muscle tone in the arm and legs, resulting in stiffness and muscle rigidity. Hypertonia is a result of damaged signals to the spinal cord and brain, which can occur after a traumatic birth injury, infant stroke, or as a result of basal ganglia disorders, such as Parkinson’s disease.


Kernicterus, a rare form of brain damage, happens when the level of bilirubin climbs to an unhealthy amount. Jaundice is somewhat common in newborns as the mother’s body is no longer processing the levels of bilirubin for the baby. However, if the levels are bilirubin are too high for the infant too process, the jaundice becomes excessive, resulting in a yellow pigment to the skin, and in many instances, muscle stiffness.

Important Factors to Remember

Keep in mind that the aforementioned conditions can only be diagnosed by a physician. If your infant is experiencing stiff and/or rigid muscles, it’s important to tell your physician in order to get a proper diagnosis. In some instances, it can be indicative of something minor that will pass eventually.