Introduction – the usual explanation and caveats – see previous posts.
NB Italics are direct quotes and BB = Bobath!
In the icsp a discussion, compensation has come up several times – about how much of a problem it is and whether it should be discouraged. There are mixed views. Jackie W feels the reason BB appears to be ineffective is because the trials have failed to measure compensation. She feels (I have paraphrased) that the essential element of BB is to find a way to get the patient to move without compensating.
Bobath tutors have contributed, saying how BB never involves preventing function. But then one way or another go on to contradict themselves by saying it is OK to prevent compensatory movement to achieve “a longer term functional outcome”. In the Bobath book, although stating that patients should be encouraged to practice functional tasks, this is with the caveat that practice functional tasks should only happen once the patient is able to do so with “appropriate activity”.
Like the book, the Vaughan-Graham et al paper makes many statements about what Bobath is, and isn’t. Here are some that relate to compensation and motor control; again I have paraphrased to keep the word count down (they can be a bit wordy)
- Clinicians practicing BB facilitate task-specific patterns of muscle activation, minimize unnecessary compensatory movement strategies, and identify potential secondary impairments which enable tasks to be completed successfully.
- Successful completion of tasks refers to doing a task in a certain way (normally/ with ‘quality’ movement) and indicators of this quality movement relate to efficiency, the muscle activity/ motor patterns used, speed, balance strategies, strength, endurance.
- Compensations may prevent recovery or prevent function in the long term if they “become established”.
- Improvements in task performance extend beyond practicing the task [presumably this refers to carry –over into functional improvements].
As ever, the statements and descriptions are presented alongside evidence about how motor control and sensory systems work, and how neuroplasticity and motor learning are promoted. But there is nothing actually connecting the evidence to Bobath. It generically applicable to any neurological physiotherapy, it is not specific to Bobath. There is no evidence that Bobath actually achieves the effects to claims, or uses the mechanisms the authors associate it with.
There is however considerable evidence that refutes the beliefs that BB appears to be based on, and the statements describing BB (above). So let’s have a look at that. Now this is easier said than done as the jargon used in BB is voluminous, ever-changing and largely undefined. It is difficult to pin down what is meant and what is done. The rest of the world has no idea what is meant by ‘selective movement’, ‘dynamic stability’, ‘arrested mobility’ or ’up against gravity’ [isn’t that just, up?]. The Bobath tutors don’t offer definitions and everyone uses terminology inconsistently. When the jargon is considered with a critical eye, much of it is pretty meaningless. It is often unclear whether folk are talking about different things, or if they are saying the same thing in a slight different way. This is probably a factor in the lack of consensus about Bobath and those famous misunderstandings about it. The excessive and inconsistent use of pseudo-scientific babble is one of the criticisms of Bobath that is most damaging to its credibility. Why not use plain English and the same clinical language as the rest of the physio world and our clinical colleagues?
Much of the discussion about compensations and motor control overlap with topics covered in the previous posts on ‘How to do Bobath’ so I won’t repeat them here. But here are a few key points. The available evidence shows:
- facilitation does not improve quality of movement
- Quality of movement is not directly related to function
- Bobath practitioners focus on impairments at the expense of activity.
- There is no automatic transfer / carry-over of the type of activities practiced in BB treatment sessions (abstract movements, practice of movement components > whole tasks, therapist- led with patients inactive, low repetition, excessive guidance, etc, etc) to sustained change after the session ends (or the hands are taken off). Ie any changes are merely practice effects, without carry-over into changes in function.
- the types of activity used in BB treatment sessions are not those that are known to promote neuroplasticity and motor learning
What I would like to pick up here, is the statement that BB facilitates task-specific patterns of muscle activation. Because the notion of task-specific patterns of muscle activation is a misunderstanding of how motor control works. The BB tutors says that the systems model of motor control underpins the BB Concept, and there is quite a good explanation of the systems model in the BB book [Steady, headline writers, steady]. Essentially, the systems model explains how and why there are many different ways to achieve a task, and how the brain does not control movement by specifying the muscle activity needed to achieve a task, but by monitoring whether the task has been achieved. Even if the task is exactly the same, then people do not move in exactly the same way to achieve it every time (especially when they are (re)learning how to do the task). So there is no such thing as task-specific patterns of muscle activation. The whole point is that the muscle activation used to achieve a task is not specific, it is variable and able to adapt to changes in task, environment and the patients ability (by compensating). Adaptation/ compensation happen automatically to ensure the patient achieves the task safely, consistently and as easily as possible.
To give a simple example, the muscle activity and movement patterns used to walk changes all the time – depending where you walking (flat, hills uneven ground, around crowds etc), what shoes you are wearing (think about the differences between walking in flat or heeled shoes) or if there is an impairment. For example, if you get a stone in your shoe and it hurts, then your movement pattern and muscle activity automatically changes to reduce weight-bearing on the part that hurts. That adaptation/ compensation is a good thing. It enables you to achieve your task/ goals in a variable world with a variable body. That principle continues if the body becomes impaired, whether something minor like a stone in the shoe, or something major, like a stroke. The motor control system will automatically adapt to enable the patient to achieve their goals as well as they are able. If a patient is able to do something (eg walk), however they do it, is the best way they can.
So compensation is a good thing. It enables patients to continue to function even with impairments. Patients can function BECASE they compensate, not despite it.
I had better provide some evidence to support this assertion that compensation is not a bad thing…. In my first ever research project I looked at quality of movement of gait after stroke (and the effect of walking aids thereon). The results showed that asymmetry (the compensation/ impairment/ marker of poor quality movement du jour) was not related to gait function. Ie people with asymmetric gait were not less able to walk that those with a more symmetric gait. Some people were able to walk BECAUSE they used an asymmetric gait pattern, not despite it. These were not the results I was expecting (I was a bit of a Bobath groupie and aspiring tutor at the time! Yes, I too have “fabulous handling skills”). But these findings have been replicated many times since.
- Tyson SF (1999) Trunk kinematics during hemiplegic gait and the effects of walking aids Clinical Rehabilitation 1999;13;295-300
- Tyson SF (1994) Hemiplegic gait symmetry and walking aids. Physiotherapy Theory and Practice 1994;10;153-159
- Tyson SF & Ashburn A (1994) The influence of walking aids on hemiplegic gait. Physiotherapy Theory and Practice 1994;10;77-86
There have also been some influential papers investigating changes over time as patients recover (or not). The examples below all investigate balance and mobility, but there is no reason to believe that the take home messages illustrated here don’t apply just as much to other areas of motor activity. Here are the references
- de Haart et al. Recovery of standing balance in post-acute stroke patients; a rehabilitation cohort study. APMR 2004;85;886-95
- Geurts et al. A review of standing balance recovery after stroke. Gait & Post 2005;22;2;267-281
- Kirker et al. Changing patterns of postural hip muscle activity during recovery from stroke. Clin Rehab 2000;14(6):618-26
- Kirker et al. Stepping before standing: hip muscle function in stepping and standing balance after stroke. JNNP 2000:68(4):458-64
- Garland et al. Recovery off standing balance and functional mobility after stroke. APMR 2003;84;1753-1759
And this is a summary of what they tell us:
- impairments improve with time & rehabilitation but show MUCH LESS improvement than disability/ function/ activity
- Impairment (in the form of compensations) persists even in people who can function.
- Some people function because of their compensations/ impairments
- Recovery is not associated with changes in timing of muscle activity
- Timing of motor activity does not become ‘more normal’ as the patient recovers function
- The way in which patients changes with time & rehab is variable. Four different responses have been identified:
Group1 demonstrate increases function & more normal motor responses in the weak limb with time. Ie they become more normal. This is a relatively small proportion of stroke survivors with the mildest impairments. Many of whom would not usually get access to physio
Group 2 show increases in function & changes in motor responses of the weak limb(s) with time but the changes are much less that Group 1.They become able to use their weak limb less abnormally (ie using compensation strategies but less ‘severe’).
Group 3 show increases in function but NO changes in the muscle activity of the weak leg BUT they do show increases in the muscle activity in the sound leg. So they become more able because they compensations more with their sound limb, not because they recover activity in the weak limb
Group 4 (who have the most severe strokes) initially had no activity or very abnormal activity in the weak and the sound limbs. They improve function by increasing activity in the sound leg (but still none in the weak limb) and thus join group 3.
These groups could be considered stages, or a continuum, of recovery as patients tend to progress through them (to a greater or lesser extent)as they recover. So those in group 4 who show some recovery, progress from no activity –> using compensations in the sound leg (group 3) to function. Those in Group 3 tend to progress –> using compensation in both legs to function (group 2). And group 2 sometimes progress –> Group 1, when compensations start to approach normal movement.
This evidence contradicts many of the statements about BB and how it works. It
- questions the importance of minimising compensations and ‘restoring ‘normal movement’ in order for patients to function
- shows that using compensation is not a barrier to developing more ‘normal’ movement or muscle activity
- shows that increase in motor activity, rather than the timing/pattern of motor activity, is what is important to regain function. Ie most patients get better at using their compensations, rather than restoring a particular pattern of muscle activity.
- Some patients became functional BECAUSE they used their sound limb to compensate and/or use compensations/ abnormal activity in their weak limb
Our professional challenge as physiotherapists is to work out how to manipulate the tasks and environment (by using aids and equipment for example) to enable patients to do as much as they can, safely, comfortably and as easily as possible. And then to work out how they can learn to get better at doing that so they are able to do more, or do the same but more easily. The evidence is that using exercise and task-specific exercise to promote motor learning and neuroplasticity is the way to go.
It is much better to get folk doing something and then train them to get better at it, than to stop folk doing something. I would suggest that the legacy of Bobath is that we have tended to focus much too much on how patients are doing things (impairments) at the expense of what they can do (function). In doing so we have inadvertently made our patients more disabled/ less active than they could be, in the mistaken beliefs that improving impairments this will automatically carry over into improvements in activity and that ‘normal’ or ‘quality’ movement is needed to function/ be active. Which isn’t saying that we shouldn’t work on impairments at all (especially if it is the impairment that is limiting the function) or try to improve someone’s movements towards becoming’ more normal’(if they are at that stage). I’m saying we have given it more prominence than is helpful for many of our patients.