Amnesia!

[emad]

please bernard

try again , i will try with you :wink: :wink:


cheers
emad :(

[bernard]

Pubmed gave it to me again! 8)

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10404574

Spine. 1999 Jul 1;24(13):1322-7.

The effect of lumbar fatigue on the ability to sense a change in lumbar position. A controlled study.

Taimela S, Kankaanpaa M, Luoto S.

DBC International, Vantaa, Finland.

STUDY DESIGN: A cross-sectional study in patients with recurrent/chronic low back trouble and healthy control subjects. OBJECTIVE: To evaluate the effect of paraspinal muscle fatigue on the ability to sense a change in lumbar position.

SUMMARY OF BACKGROUND DATA: Protection against spinal injury requires proper anticipation of events, appropriate sensation of body position, and reasonable muscular responses. Lumbar fatigue is known to delay lumbar muscle responses to sudden loads. It is not known whether the delay is because of failure in the sensation of position, output of the response, or both.

METHODS: Altogether, 106 subjects (57 patients with low back trouble [27 men and 30 women] and 49 healthy control subjects [28 men and 21 women]) participated in the study. Their ability to sense a change in lumbar position while seated on a special trunk rotation unit was assessed. A motor rotated the seat with an angular velocity of 1 degree per second. The task in the test involved reacting to the perception of lumbar movement (rotation) by releasing a button with a finger movement. The test was performed twice, before and immediately after a fatiguing procedure. During the endurance task, the participants performed upper trunk repetitive extensions against a resistance, with a movement amplitude adjusted between 25 degrees flexion and 5 degrees extension, until exhaustion.

RESULTS: Patients with chronic low back trouble had significantly poorer ability than control subjects on the average to sense a change in lumbar position (P = 0.007), which was noticed before and after the fatiguing procedure. Lumbar fatigue induced significant impairment in the sensation of position change (P < 0.000001).

CONCLUSIONS: Lumbar fatigue impairs the ability to sense a change in lumbar position. This feature was found in patients and control subjects, but patients with low back trouble had poorer ability to sense a change in lumbar position than control subjects even when they were not fatigued. There seems to be a period after a fatiguing task during which the available information on lumbar position and its changes is inaccurate.

Publication Types:
Clinical Trial
Controlled Clinical Trial

PMID: 10404574 [PubMed - indexed for MEDLINE]

[bernard]

This paper is quite fascinating for understanding the complex process of chronic pain patients.

It asked me some questions;
1/ why chronic pain patients do not feel less their backs?
2/ how the process was created in place?

And perhaps the most important?
3/ how can we change this strange behavior?

[BB]

Hi Bernard,
I think it has a lot to do with the various imbalances that occur in those with low back pain. Shut down of the lumbar stabilizers and resulting decrease in propriocetive input..

A lot of the issues we once discussed in the "movers and stabilizers" thread I think are very relevent here.

Cory

[bernard]

Hello Cory,

Yes, we have already discussed on the theme previously. I thought that this paper was a bit clearer to my mind?

Brain has an only and unique way to forget incoming stimuli. These stimuli must be quite constant and perceived as non dangerous. In these conditions thus it must reduce them to permit a normal functioning => concentration on important events.

[pablo]

I read this study a few years ago, when I did a review of literature pertaining to pain and proprioception. Fatigue does impair proprioception, but is it really a surprise that in back pain there is an impaired ability to detect changes in position? There is evidence that there is also an impairment in re-positioning after movement, that is people with back pain have a greater error rate when returning to their starting position than pain-free controls. Both these features are not specific to back pain alone. In peripheral joints this is well recognised. Ankle proprioception is impaired after injury. So is knee proprioception. The same thing happens in the shoulder, and the jaw. The same thing happens in the cervical spine.

How do we interpret all this? Is it a peripheral problem, where prorioceptors are damaged and unable to provide appropriate information? Is it that muscle function becomes abnormal (and there is evidence that it does) so that muscle spindles and golgi tendon organs change their input? Is it a central problem, where spinal cord, thalamus, or various cortical areas behave abnormally? It may be a combination of these and more. What I did conclude from these studies was that pain per se changes a person's capacity for detecting movement as well as increasing their repositioning error. That is, pain has an influence on proprioception and kinasthetic ability iver the area of pain (and probably more widespread), regardless of the area. The effect is a general effect of pain. This links in nicely with the concept of sensorimotor amnesia, if that's what we want to call it. It also makes sense from the perspective of the motor system losing some of its repertoir, becoming less flexible and more rigid in terms of response. But it may be acting on faulty information.

I think there is probably a number of levels of processing that give rise to this, from the periphery to the central nervous system and back again. I don't know which of these is the most important, but helping people change these deficits for the better is worthwhile.

Pablo

[bernard]

Hello Pablo and all Somasimplers,

I agree with these conclusions and I had some thoughts, while suffering from sun, on the beach.

1/ while we are learning a new movement it takes several steps; we realize it, a first time, virtually? Then we try it and correct it, just in time, and then we reproduce it more and more smoothly. At the beginning, we use enormously our concentration and with time and experience, the movement is done without any intervention; we learnt it. We create a neural process that is draft at the beginning using, certainly, too much neurons resources and with experience, we refine this process until a kind of perfection, done with fewer neurons. We selected our better resources.

2/ with chronic pain, our perfect program is perturbed by a parasite constant (virtual/real) stimulus, pain. The movement is done less and less of a good manner and pain remains quite at a same level?

3/ If we accept that muscles are sensitive (incoming stimuli) but do not suffer by their own, we must conceive that brain translate/transform some incoming muscle stimuli as imbalanced and then needing a strong reaction (pain?). There is an imbalance between preparation and realization and this difference is warned (and corrected?) certainly with principle enounced in 1 and 2.

Just some crazy ideas.

[Diane]

(Welcome back from your holidays Bernard..:))

Pablo, I remember reading in Jay Ingram's The Burning House about how we all have 'phantom limbs' and some of the experiments Melzack has done to show this, hiding someone's (normal) arm under a screen, numbing it with a blood pressure cuff, asking them to point at a target, moving the target, asking them to correct their aim.. meanwhile they can't see their hand and can't feel their arm, so they are pointing with their "phantom arm." Turns out they are usually way off the mark. The really interesting thing was, that as soon as they "saw" their arm, the visual input immediately overrode the "phantom" input, and subjects immediately melted away their "phantom" arm's position, i.e. their delusion about where they believed their arm was.

The idea of phantom parts of the body not overlapping exactly with actual parts has interested me ever since, and the overwhelming capacity of vision to correct the "problem" if one exists.. It makes me wonder about the possibility that pain is a result of the brain's struggle/failure to line up the "phantom" with the physical.

When we have patients move to diminish pain, are we trying to get them to line their phantom or virtual parts up with their physical parts?

Another more underlying possibility that weaves through this: If bloodflow etc. is run from a more "local" part of a body, say the ganglia or the cord, or even from a different bit of the cortex through different descending pathways that the voluntary movement is, the insula perhaps... what if the bloodflow virtual movement map is incongruent with the voluntary motor virtual map? Would that not hurt after a while?

I get a picture of soft tissues, nerves etc. starving for O2, because one part of the brain thinks an arm or some part of the back is over there, when in fact it's over here, and needs a different "set" in its vascular tone.. that could be an example of a peripheral pain driver mixed up in a problem that is ultimately more central.

Perhaps we should look closer at eye relaxation exercises, way further upstream in the "problem", to help the brain "see" the body more congruently with how it really is positioned...

Just some meandering thougts this morning, after too many moments spent watching athletes for the last several days on TV. (Nice work, Aus!)
Diane