Heads up on keeping our heads up

NR Times is a communication channel which is grounded around managing disorders of the nervous system. The core of our nervous system is our brain and this is surrounded in the skull by a periphery of key sensory input devices, each of which has a major impact on how other parts of our nervous system can operate effectively, and on how we can live our lives optimally. In this month’s article we offer examples of what we can do to assist optimising the head’s positioning, and hence functionality, when our muscle motor systems are letting us down.

Our heads are multisensory and multifunctional, so whatever we can do to make full use of these attributes, the better the quality of our lives. An appropriate head position is important for hearing, balance, breathing, and eating and swallowing. Probably most important, alongside these, is vision – not only for practical reasons such as seeing what our hands are doing, where we are going, what’s going on around us, etc., but also for social interactions.  For children in school, visual interaction with teachers and classmates leads to better learning outcomes. 

We have what is known as our ‘cone of vision’, and this relates to how close to our head’s centreline (both vertically and horizontally) that an object needs to placed for us to be able to see it properly: for full colour perception it should be within 15 to 20 degrees of this centre line (green is the most angle sensitive colour, whereas blue can be seen somewhat more easily in our peripheral vision). It is therefore important that we can move our head into a position that aligns our cone of vision with the object(s) that we wish to focus on, or that the objects can be moved into this zone.

Controlling the head

Our head weighs around 6 kilograms, and is perched on top of a couple of relatively small vertebrae, that are responsible for our being able to nod and rotate our heads. To maintain control of these movements and return to the midline is dependent on the muscular control offered by the muscles in our necks. 

A further influence can be the degree of curvature of the spine leading to the need for cervical extension to get the head into an upright position, so let’s bear in mind what we can do with pelvic and trunk positioning to offset the kyphotic effects: first, a pelvic positioning belt firmly adjusted across the thighs will get a person’s seating base stabilised, and the backside firmly back in the seat. Next, a good back support, with appropriately placed thoracic lateral supports, and often a anterior chest harness, will stabilise the upper body. Finally, having the head in an upright stable position will assist the individual with, for example, swallowing challenges – good body positioning helps with feeding by avoiding the need for the head to be pulled back to raise the mouth off the chest (pulling the head back is what we do to open up the airway for mouth-to-mouth resuscitation, the opposite of what we need during feeding!).

Resting the head

On a wheelchair there is often a pad placed behind the head, but what is it for? If it is there to protect the head from snapping back under fast acceleration, then its function is comparable with the item we will find in our car seat i.e. as a ‘restraint’.  

More frequently, it will be positioned so that as a seat is reclined and/or tilted, then the pad acts as a head rest to support the weight of the head as the head is moved backwards. In these cases, the assumption is that the wheelchair occupant has reasonable head control, and therefore has no problems in keeping their head in the midline position, and aligned with a simple pad.  But what if there is not sufficient muscular control of the neck position?

Head support

It is important to distinguish between a rest and a support, and consider whether we are looking to exert support directly at the head, or via the neck. A head rest will usually be more two dimensional in its approach, and working against gravity in just the one direction, by stopping the head from moving backwards further than needed, whereas a support will be assisting the neck muscles’ work against the effects of gravity in all three dimensions.

When working with parts of the body which can move in three dimensions, then we usually are looking for three points of control.  Around the pelvis we have many choices, but around the head and neck we have greater restrictions.

Around the head, we do not want to apply pads that might restrict any of the sensory organs. Around the neck, we need to avoid any risks of strangulation or restricting blood flow to the brain. The result has been that in the marketplace there are various solutions which get more complex as the wheelchair occupant’s needs become more complex. Some are applied to the head (Figure 1) and some around the neck. 

Around the head, the best position for support is under the occiput, provided that it is pronounced enough to get a pad under it.  Some of these posterior pads have the means to mount additional small lateral and even somewhat anterior pads (and/or switches) (Figure 2). 

Neck Supports

Providing more circumferential support under the head can best come from a neck support. Here there are options, such as the ‘Headmaster Collar’ (Figure 3) which provides some load-bearing under the chin¹.

In motor racing, we see drivers wearing a Hans neck support (Figure 4), which helps keep their head in position when under strong acceleration and deceleration forces².  

For the wheelchair user, there are parallel styled ‘assistive technology’ devices which give support around the neck when gravity is trying to pull the head off the midline, and where the anterior support for the device can be across the chest, such as employed in the i2i (Figure 5.)

The i2i is a favourite of speech therapists where it’s a great tool to position the head to facilitate improved eating and swallowing where the head is also positioned safely to decrease the risk of choking – for a film of the benefits visit reference 3.

A separate application for a neck device is the TOT Collar (Figure 6) which was designed originally for children with infant muscular torticollis⁴. The TOT Collar is designed to provide a stimulus to the lateral aspect of the skull.  The user moves away from this stimulus towards a new central corrected position. Adoption of a new, normal head position provides the ability to reset perception of horizontal, and so maintain the corrected head position. This is also used with adults where it’s appropriate to provide a stimulus to encourage realignment of the head.

Use in transport and crashworthiness

Despite claims made by some manufacturers, head supports cannot be tested on their own, and there is no standard to test them against for transportation. The risk is around the seat, the chair, and the tie down system, from the equipment point of view, and the individual’s weaknesses etc from the user’s point of view. Either way, first of all the chair, and its tie-downs need to be crashworthy. 

The use of any attached head supports will need an individual risk assessment to be carried out, since the suitability will depend on the individual’s diagnosis and circumstances. There will be cases where the person will be better off by having the head stabilised (see below), and others where the individual might be at greater risk. Overall, in many cases the individual will be better off with than without a head support, but each case has to be assessed individually.

Mrs Mackay’s experience

Mrs H Mackay from Stirling acquired an i2i for her wheelchair, and reported:

“My i2i was bought for use when I was in transport – this has been a real boon to me. 

“For 6 weeks of the year we have the chance to go on day trips with our dial-a-journey wheelchair transport. Up to now I have only been able to go on one trip a week as I was in so much pain by the time I came back. I had to stay in bed for a couple of days, at least, to recuperate, and was wondering how long it would be before I would have to stop going altogether. 

“I wore the i2i on our first trip this season and could not get over how good I felt the next morning. I had chosen a trip which was longer than my normal one (wanting to test this product as much as I could). I was up and about the next morning with no extra pain to that which I normally experience. The next week I booked two trips and neither being short journeys, realised I was ‘pushing my luck’. Again I was delighted with how I was the following day. Not only has it improved my life, but also my husband’s as he has the advantage of the longer trips too.” 

1. https://www.symmetric-designs.com/headmaster-collar
2. https://www.hansdevice.com/
3. https://www.youtube.com/watch?v=3ozdphoB4nk
4. https://www.symmetric-designs.com/tot-collar
5. barend@beshealthcare.net