Tuesday, September 25, 2012

On piano tops and proprioception

OK so I haven't let my inner R. Buckminster Fuller out for a walk lately so I think it is time to address a problem that I perceive with some aspects of clinical problem solving in occupational therapy.

Here is some background first:

In this month's AJOT there is an article on Proprioceptive processing difficulties among children with autism spectrum disorders and developmental disabilities (Blanche, Reinoso, Chang, & Bodison, 2012).  It is an interesting article that demonstrates differences in test performance on an observational measure of proprioception between children who have disabilities and their typically developing peers.

The authors correctly point out that we only have limited means to actually measure proprioception.  The Standing and Walking Balance subtest of the SIPT is a good measure, but like other measures of balance it is confounded by proprioceptive processing, labyrinthine righting, and optical righting.  It is difficult to really know how much proprioception actually contributes to balance because we are measuring other functions at the same time.  Measurement with eyes closed removes an optical righting component but still does not bring us to a particularly 'clean' measure of proprioception.  So, this subtest is limited as a measure of proprioception.  The Kinesthesia subtest has known test-retest reliability problems (Ayres, 1989) and itself is not a good measure of proprioception.  These difficulties with measuring proprioception are well-established and probably not really disputed in the field.

The idea of a functional observational measure of proprioception is interesting.  However, it is really confusing as to why the AJOT editors would choose to publish this article demonstrating differences between groups on an observational measure BEFORE they publish the observational measure itself!! (Blanche, Bodison, Chang, Reinoso, in press).  It makes it a little difficult to interpret a research study on a test that has never before been published.  I don't understand this editorial choice.

The assessment tool includes observation of categories like 'Decreased muscle tone' and 'Joint Hypermobility.'  Of course we don't have the actual assessment for detailed analysis of these categories but a question in my mind relates to the fact that children may have low tone and joint laxity for many reasons that are not related at all to altered proprioceptive processing. For example, low muscle tone may be theoretically caused by poor registration of proprioceptive inputs at the local level, dysfunctional cerebellar processing at the central level, or even something entirely different like a collagen or fascial or connective tissue defect - or even a muscular dystrophy or other condition for that matter.  The point is that we don't know from observation that low tone and hypermobility are necessarily proprioceptive problems.

Additionally, there are behavioral measures on this assessment like 'Enjoyment when being pulled' and 'Tendency to lean on others.'  There are literally thousands of possible reasons why children may engage in these behaviors and they most certainly are not all related to proprioceptive processing.

These are just big questions I have about this assessment and I hope AJOT publishes it soon so that I can make better sense out of these categories.  I am hopeful that we don't have another 'Sensory Profile' type of report or assessment that includes a multitude of observed and recorded behaviors that could possibly be attributed to many different problems. 

This is R. Buckminster Fuller talking now - because in occupational therapy we have this tendency to want to solve the problem by constricting our interpretation of observed behavior so that it fits neatly in with our preconceived notions and existing models.  We may have an idea in our minds about proprioceptive processing because it is part and parcel of our theory base related to sensory processing disorders. 

Fuller stated,

I am enthusiastic over humanity’s extraordinary and sometimes very timely ingenuities. If you are in a shipwreck and all the boats are gone, a piano top buoyant enough to keep you afloat that comes along makes a fortuitous life preserver. But this is not to say that the best way to design a life preserver is in the form of a piano top. I think that we are clinging to a great many piano tops in accepting yesterday’s fortuitous contrivings as constituting the only means for solving a given problem. Our brains deal exclusively with special-case experiences. Only our minds are able to discover the generalized principles operating without exception in each and every special-experience case which if detected and mastered will give knowledgeable advantage in all instances. 


Even though we have ideas, we have to be careful not to fall into the trap of attribution or correspondence bias when we make observations.  It is possible that disordered or disorganized behavior like 'Tendency to lean on others' may be somehow related to a sensory seeking strategy associated with inefficient processing of proprioceptive afferents - but it might also be something else entirely.  We have to stop making automatic assumptions about these behaviors just because that is how we make sense out of the information when we constrict our thinking to a specific model.

Anyway, publishing the darn assessment FIRST might have prevented some of this gear spinning!

There are other issues to look at in the article though - one that caught my attention specifically is that the group of 32 children included in the study who were diagnosed with ASD reportedly did NOT have any additional motor difficulties.  That does not make any sense to me.  I understand that motor delays are not part of the diagnostic criteria for ASD but in my clinical practice I don't know that I have ever seen a child who has ASD that HAS NOT had an accompanying developmental motor delay.  Research indicates that these motor delays are quite common in this population (Provost, Lopez, Heimerl, 2007).  I am kind of wondering if the article meant to convey that they don't have an organic motor disorder?  That is really a little unclear because the study says "without any additional motor difficulties."  Very confusing.

I am hopeful that I can update some of these observations when the assessment itself is published.   Stay tuned.



 References:


Ayres, A. J. (1989). Sensory Integration and Praxis Tests. Los Angeles: Western Psychological Services.

Blanche, E.I., Reinoso, G., Chang, M. & Bodison, S. (2012).  Proprioceptive processing difficulties among children with autism spectrum disorders and developmental disabilities, American Journal of Occupational Therapy, 66, 621-624.

Blanche, E.I., Bodison, S., Chang, M. & Reinoso, G. (in press).  Development of the Comprehensive Observations of Proprioception: Validity, reliability and factor analysis, American Journal of Occupational Therapy. 

Fuller, R.B. (1968). Operating manual for Spaceship Earth, Carbondale: Southern Illinois University Press.    

Provost, B., Lopez, B.R., Heimerl, S. (2007).  A comparison of motor delays in young children: autism spectrum disorder, developmental delay, and developmental concerns. Journal of Autism and Developmental Disorders,  37(2), 321-328.
 

2 comments:

Your Therapy Source Inc said...

Thanks Chris for your opinion on this. As you know, I too was confused regarding the Comprehensive Observations of Proprioception. I would love to see the assessment in order to make a better opinion of the tool but have to agree with you that upon first glance it is all observable actions but we do not know if the cause is an impairment in processing proprioceptive input. And just for fun lets say we do know that the cause is the aforementioned all the treatment strategies for this have not been well researched either.

Regarding your comments about the root of proprioceptive processing problems, it is my opinion (and I strongly stress the word opinion) that the basal ganglia is where we should be directing research. Some brain imaging studies have shown changes in basal ganglia shape and volume in individuals with autism. Not to say this would determine construct validity either but I think it would get us a step closer than simply observational tools. Would love to see brain imaging studies done comparing children with sensory processing deficits to neurotypical children. In my experience as a PT all the children with autism spectrum disorders I have encountered have some sort of gross motor skill delay. Recent research in Autism indicated that motor impairment constitutes a core characteristic of autism - http://yourtherapysource.blogspot.com/2012/02/autism-and-motor-skills.html.

Regardless of what the research states currently, I follow a motor learning model when teaching children with autism motor skills and motor skill refinement. Practice, practice, practice motor skills in many environments. Encourage intrinsic motivation but start with extrinsic rewards for physical activity. Try different physical activities always keeping in mind the individuals sensory preferences. I think I have gone off topic a bit...

Barbara @therextras said...

I agree with Margaret (YTS) on going neural for exploring meaningful diagnosis and treatment of autism. I read the book The Neurology of Autism, now a bit dated, but still a useful read to me. I doubt a singular brain-part-dysfunction will define autism - part of the reason I think treatment needs to come from a neural premise - not observational or behavioral (the means by which autism is diagnosed).

LOVE the synopsis of your treatment approach, Margaret. I may have to repeat your words to others but promise to give you credit!

Thanks, Chris, for another excellent post.