June 6, 2013
TESTING 1-2-3 TESTING
A while ago I talked about prone extension – how this skill develops and why repeating the prone extension test as treatment isn’t effective (see Where is Superman?). This time around we’re addressing the issue of head control.
There has been coverage in the press about the research that indicates a head lag may be an early indicator of autism (1). Now those of us who work in paediatrics already understand that a head lag doesn’t have to do with autism specifically, rather it is associated the low muscle tone that often occurs in children with ASD and indeed, in many neurodevelopmental disorders.
The Pull-to-sit test for head control is part of a normal infant assessment. The first video shows a typical newborn and the second video is a typical 6-month old infant. We can see the 6 month old activating balanced flexion and extension at the neck, shoulder and upper trunk, keeping his head in line with his trunk as he is coming up into sitting and also, going back down into supine. The test doesn’t demonstrate how the baby developed head control, it is simply the assessment of the skill.
Babies develop head control through their emerging skills in supine and prone. The very beginning of anti-gravity head control is a response to vestibular input through the Tonic Labyrinthine Reflex. This activates primary sensory and motor wiring in the brain. The anticipatory (=inner) core muscles begin to come online to provide central stability. As the neck flexors activate bilaterally, the baby can maintain a midline head position in supine. In prone, the baby begins to activate the neck extensors, the posterior oblique synergist (contralateral latissimus dorsi and gluteus max.) and the rotator cuff muscles of the shoulder when pushing off the surface. Almost as soon as these muscles are activated on dorsal surface, the anterior oblique synergist (contralateral abdominal obliques and hip adductors) and pec major are activated on the ventral surface. When all of this comes together, there is an active base of support for the head. Head control therefore, depends on active shoulder, upper and lower trunk muscles. The trunk provides a stable platform for the head (and the head provides a stable platform for the eyes, but that’s another story).
For children with motor challenges, head control is a crucial step. For comparison, view this video of a child with low tone.
When difficulty arises secondary to alignment and muscle tone issues, they will seek to stabilize their head in end range extension and as development continues, they will seek to stabilize their trunk by breath holding (see Taking A Detour on the Road to Oz).
Babies experiencing difficulties with head control don’t need to practice pull-to-sit. They need vestibular and visual input, they need to experience maintenance of a midline head position in supine and they need to activate anticipatory and reactive core muscles during weight bearing with small weight shifts in prone.
Head control is the process that occurs as a result of all of these experiences. Our treatment should reflect the developmental complexity of this skill.
1. Place a folded receiving blanket under a baby’s head during treatment. This brings the head and cervical spine (and possibly the thoracic spine) out of extension and into slight flexion allowing the baby to activate the neck flexors bilaterally. Make sure the blanket isn’t too thick. You want to encourage midline in all planes and this is a good place to start.
2. Working in prone doesn’t have to begin with the elbows under the shoulders in the full prone propping position (this requires a great deal of activity from the muscles involved). We all use modified prone positions but try combining modified prone (on your chest, on a ball etc.) with the upper extremities flexed and elbows close to the body. Then encourage the child to raise their head slightly to turn it from side to side. This will begin to activate the muscles but in a much less challenging position, much as a typical baby does when they first activate head extension. You can then progress towards the full prone position as well as gradually progress the elbows towards the classic prone propping position. (Remember that if a child holds their breath here, they are compensating for a lack of central stability and this activity is then occurring without the inner core muscles. We then need to modify the activity.)
1. Flanagan JE, Landa R, Bhat A, Bauman M. Head lag in infants at risk for autism: a preliminary study. Am J Occup Ther. 2012; 66(5): 577-85.
photo credit: she knows.co.uk