Archive | February 2013

Primitive reflexes (or, cool party tricks you can do with your newborn)

I’ve taken a several-month hiatus from blogging, but with good reason. In December, I welcomed this little guy to my family.

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Look at those cheeks!

The fatigue of late pregnancy and the early newborn weeks – combined with a busy work schedule, my two older boys and husband, and a host of other “real-life” obligations – left me little time for blogging over the past several months. But I’m ready to re-enter the blogosphere. And, since I’m living with a newborn and will be teaching physical therapy students about infant development later this spring, it makes perfect sense to create a series of posts on newborn development. Today’s post is on primitive reflexes.

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Primary standing & stepping

When most people think about reflexes, they think about sitting on the table in the doctor’s office getting hit on the knee with a rubber hammer. Those types of reflexes are called deep tendon reflexes and are completely different than the primitive reflexes I’m writing about today.

Primitive reflexes are a set of involuntary movements that are typically seen in the newborn infant. These reflexes originate in the lower, more primitive parts of the central nervous system (hence the name primitive reflexes). Parents are often surprised and sometimes even entertained when I show them primitive reflexes in their baby – because they are involuntary, they can be elicited in a newborn baby almost any time and are often times quite strong. But primitive reflexes are more than cool newborn party tricks (Look, Grandma! I’m 2 weeks old and I can stand!). They give healthcare providers important information about a baby’s neurological function.

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Asymmetrical tonic neck reflex

When a baby is born, the higher centers of the central nervous system – areas that allow for voluntary movement – are not fully developed. This means that lower areas of the brain are in control and primitive reflexes dominate movement. In the first few months of life, the presence of primitive reflexes tells us that the lower portions of the central nervous system are functioning as they should. If primitive reflexes are absent or otherwise abnormal (weak or asymmetrical), we may suspect neurological injury or dysfunction in these lower areas of the central nervous system.

By 6-12 months of age, the higher, more sophisticated areas of the brain mature and voluntary movements dominate. In older babies, we expect primitive reflexes to integrate or “disappear” as more purposeful movements emerge. If we continue to see primitive reflexes in the older infant, we suspect that the higher centers of the brain may not be developing normally. Persistence of primitive reflexes can inhibit future development, making it difficult for the baby to learn to roll over, creep and crawl, reach and grasp, stand, and walk. Of course, primitive reflexes never really disappear – they continue to “live” in the lower brain and spinal cord and are simply masked by more mature brain function. This is why primitive reflexes may also be assessed in an older child or adult with neurological disease or injury – the reappearance of primitive reflexes may indicate damage to higher centers of the brain.

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Plantar grasp

The following primitive reflexes are frequently tested by physicians, nurses, and physical and occupational therapists as part of a newborn neurological exam:

  • Asymmetrical tonic neck reflex (also known as the “fencing” reflex) – When baby’s head is turned to the side, he assumes a “fencing” posture by extending one arm in front of his face and bending the other arm behind his head.
  • Rooting/sucking – When the skin next to baby’s lips is stroked, she turns her head to find the stimulus and attempts to “latch” on and suck.
  • Palmar and plantar grasp – Pressing into the palm of the hand or ball of the foot causes the baby to grasp with his fingers/toes.
  • Primary standing and stepping – When held in a supported standing position, the newborn “stands” and even takes some steps.
  • Galant reflex – Stroking along the side of the baby’s spine causes the spine to curve toward that side.
  • Moro reflex – When the baby’s head is dropped backward, it elicits a “startle” (he quickly extends both arms), recovery (arms back to midline), and a cry.

For more information or to see primitive reflexes in action, check out the video:

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