In our last article, we discussed the asymmetrical tonic neck reflex, what its implications are if it is not integrated, and what we can do to break the pattern. This month, we are going to take a look at another reflex, known as the symmetrical tonic neck reflex, or STNR.
When the STNR is elicited, it has an effect on the child’s muscle tone. When the child’s head is flexed, or bent forwards, the influence on tone causes the child’s arms to bend and their lower legs to straighten. When the head is extended, or bent backwards, the influence on tone causes the child’s arms to straighten and their legs to bend.
The STNR emerges at around 4 – 6 months, and should be integrated by the latest 12 months of age. The reflex is important to help the child come into a crawling position.
If the STNR is not fully integrated but remains present in our children, the following difficulties may occur. In younger infants, the presence of the STNR may make crawling itself difficult as the child’s arms will want to bend every time he looks down. Eye-hand coordination is implicated as the reflex is elicited with head movement, causing involuntary movement of the arms and thus making tracking and catching difficult. These children are often perceived as clumsy and may be messy eaters.
In less severe cases where the presence of the reflex is not as noticeable, the reflex may remain unintegrated in a child into their school years. The top and bottom half of the body are constantly working against each other, making postural endurance and table top working difficult. Children may adopt unwanted sitting positions, such as W sitting on the floor, or wrapping their legs around their chair when sitting at the table. The reflex will have a negative effect on their ability to copy from the board.
Identification of this reflex is thus very important as sometimes the effect of the reflex may be so slight that it is difficult to pick up. A comprehensive occupational therapy assessment tests for the presence of an STNR. This is done by getting the child to kneel on all fours with their head in neutral position. If their head is bent forwards and their pelvis lifts, and their head is bent backwards and their pelvis drops, then the STNR is not yet integrated.
Luckily, integration of this reflex is still possible with a little work. In order for the reflex to disappear, we need to break the natural and unconscious pattern that takes place. This means that when the child’s head is flexed, we want his arm to extend. This can be achieved through activities over a roller or leaning over the edge of the bed, requiring the child to support their body weight with their arms while working and looking for items. Playing on all fours or crawling on the floor while looking at surrounding stimuli is also a good way to integrate the STNR.
In summary, the symmetrical tonic neck reflex is naturally found in infants up until the age of 6 months. It results in involuntary movement when the head is bent or straightened, causing flexion or extension of both arms. If not integrated, it can have a negative effect on gross motor skills as well as skills necessary for reading and writing. Integrating of the reflex involves activities where the child is encouraged to support their body on outstretched arms while playing and looking below them.
I hope this article offers some understanding on this primitive reflex and the implications it can have if it is still present in your child, even if the presence is slight. Remember, integration of this reflex is still possible through the use of occupational therapy and home activities. Keep an eye out for our next articles where more primitive reflexes will be discussed.