Monday, February 24, 2014

Motor Monday-Primitive Reflexes Part Two

Here's the promised part two of primitive reflexes and why they matter. This is a short one because we haven't been getting much sleep around here lately and I'm not functioning at the top of my game cognitively!  Like I said last week, we still don't fully understand the role of primitive reflexes and their relationship to motor development though I talked a bit about how primitive reflexes are hypothesized to help with motor development.  Primitive reflexes are controlled by the brainstem and as the higher level parts of a baby's brain develop they learn movement patterns that are more complex that take over for the reflex patterns.

The important thing to know about primitive reflexes is that they aren't normally "obligatory" in that they don't happen to the extreme every time the stimulus happens. Sure, most of the time if you touch a baby's cheek they will turn toward the touch because of the rooting reflex, but it doesn't happen every time.  Obligatory reflexes where the baby or older child can't NOT do the movement is a red flag that there is something atypical going on with the nervous system.  Cerebral palsy is a good example of a diagnosis that might involve primitive reflexes that are obligatory.  Another red flag is when reflexes don't fade away as much as they should or when they should, known as persistent reflex patterns.  One study of very low birthweight infants (i.e. tiny preemies) found a clear association between the strength of primitive reflexes and motor delays (i.e. infants with very strong reflexes at 4 months were more likely to have motor delays), while another found no association between primitive reflexes and motor skills in term babies.  Persistent reflexes may also be associated with delays in other areas like reading skills.

Last week I included a picture of Isaiah in ATNR or fencer's pose. Can you picture how ATNR could seriously get in the way of rolling back to belly?  Baby looks to the left and tries to roll that way to get to mom but that darn left arm is sticking out to the side like a kickstand?!  ATNR typically fades by 4-6 months, which happens to be just when babies are learning to roll from back to belly.  A persistent ATNR could also interfere with crawling.  Picture the infant below who turns his head to the left to see his dad.  If he has persistent ATNR (which you'll remember should be integrated by 6 months), his right elbow would bend or buckle, which would be pretty inconvenient and might mean a good head bonk for baby. 
When crawling we need to be able to look side to side without
our support arm collapsing
One other interesting thing to note about primitive reflexes before I sign off on this post is that they sometimes show up again in older adults, particularly those with severe dementia or Alzheimers.  I think this is fascinating! Okay, time to try to get some sleep before the babies wake up again!

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