November 26, 2012
The Development of Atypical Postural Control Or Taking a Detour on the Road to Oz
In my last post “The Land of Oz” we discussed the development of efficient postural control – what it is and how it develops in children with typical motor skills. However, for children with motor and/or sensory challenges, postural control is always compromised. This makes it difficult for them to find their way to Oz.
photo credit www.tipsforphotographers.com
Many children who experience motor and/or sensory challenges are born either prematurely or are born with decreased postural tone (low tone or hypotonia). Both of these scenarios create a challenge to alignment at birth because the child lacks the physiological flexion we have come to know and love in baby photos. Compare the alignment of the child in the first photo with that of the child in the second; the contrast is striking.
The lack of physiological flexion alters alignment – the child on the right is not securely flexed and well supported by tissue tension. Rather, she is relatively extended which makes for baby who feels less than secure in the new world. This relative extension also alters input to the vestibular system and impacts the early tonic labyrinthine movement patterns. And so, from the earliest moments on the yellow brick road, these children encounter a detour and instead of meeting friends, they find themselves alone on the journey.
If physiological flexion isn’t going to provide stability, then what can? The answer has to do with one of the few motor functions the baby has some control over at this age – breathing. Breath holding becomes the baby’s first compensation – the postural stabilizer of choice. The respiratory diaphragm is such a wonderfully large muscle, playing roles in respiration, postural control, phonation and sensory organization. It is a dome, which spans the width and breadth of the trunk: front to back, side to side and all the way around.
photo credit www.livewellphysio.com
Unfortunately detours come with consequences. Breath holding results in the rib cage remaining high in the thorax and the ribs remaining close together. This alters the length-tension relationship of all the muscles that attach to it – the intercostals, transversus abdominis, rectus abdominis and abdominal obliques to name just a few. A high, rounded rib cage also alters the alignment of the shoulder girdle (scapula, clavicle and humerus) and impacts the alignment of the pelvis. A high, tight rib cage interferes with full activation of spinal extension as well as full activation of the inner Core muscle team (the respiratory diaphragm, pelvic floor, transversus abdominis and multifidus). Without the activation of the inner Core, anticipatory postural control is compromised – a disastrous consequence of this detour. Also breath holding creates a relative increase in activation of the sympathetic nervous system, contributing to sympathetic dominance. And further, breath holding interferes with the suck-swallow-breathe synchrony thereby interfering with both feeding and self-regulation. When kids take this detour at an early age, the journey to Oz gets a lot more complicated.
Some children do develop a measure of postural control when they are breath holding but it is limited. And this measure of control is only present when they are breath holding. So they can run or write or stabilize their eyes only as long as they can hold their breath. Then they need to stop what they are doing when they need to breathe. Clearly this is not an efficient pattern.
photo credit www.charliesmomuck.weebly.com
Another detour on the road to the postural control Land of Oz has to do with head stability. Typically, the baby immediately begins to activate neck muscles against gravity in response to visual and vestibular input. However, when the baby has low tone and is breath holding for stability, the ability to react to vestibular input is compromised. Instead of building neural networks and muscle strength in response to sensory and movement information, the child stabilizes their head by positioning their head at end range. This further interferes with the ability to interact with vestibular input, create activation and improve strength in the inner and outer core muscles.
There are many, many more possible detours on the yellow brick road. For some children, the detours are short and they manage to have only mild issues with postural control and motor function. But for many of our clients, these detours are significant – they never reach the goal of efficient postural control and this negatively impacts their motor skills, motor coordination, sensory processing and self-regulation.
The next time you assess one of your clients, watch and listen: are they breath holding during any tasks? Do they tend to stabilize their head at end range for stability during any function? Are there other movements or postures that you might identify as compensations for poor postural control? If the answer is yes, you know they are having trouble finding the Land of Oz. The happy ending here is that therapists can help them on their journey to more efficient postural control.
In part 3 of this series, we’ll discuss some specifics regarding the postural control challenges faced by children with cerebral palsy. We’ll also look at treatment principles we can use in therapy. Stay tuned for “Mapping a route to the Land of Oz”!