TauG-guidance of dynamic balance control during gait initiation in patients with CFS and FM

[mango]

TauG-guidance of dynamic balance control during gait initiation in patients with chronic fatigue syndrome and fibromyalgia

Rasouli O1, Stensdotter AK2, Van der Meer AL3.

Author information
1. Institute of Health Science, Faculty of Health and Social Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
2 Institute of Health Science, Faculty of Health and Social Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
3 Developmental Neuroscience Laboratory, Department of Psychology, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.

Clin Biomech (Bristol, Avon). 2016 Jul 22;37:147-152. doi: 10.1016/j.clinbiomech.2016.07.008. [Epub ahead of print]

Abstract
BACKGROUND:
Impaired postural control has been reported in static conditions in chronic fatigue syndrome and fibromyalgia, but postural control in dynamic tasks have not yet been investigated. Thus, we investigated measurements from a force plate to evaluate dynamic balance control during gait initiation in patients with chronic fatigue syndrome and fibromyalgia compared to matched healthy controls.

METHODS:
Thirty female participants (10 per group) performed five trials of gait initiation. Center of pressure (CoP) trajectory of the initial weight shift onto the supporting foot in the mediolateral direction (CoPX) was analyzed using General Tau Theory. We investigated the hypothesis that tau of the CoPX motion-gap (τCoPx) is coupled onto an intrinsic tauG-guide (τG) by keeping the relation τCoPx=KτG, where K is a scaling factor that determines the relevant kinematics of a movement.

FINDINGS:
Mean K values were 0.57, 0.55, and 0.50 in fibromyalgia, chronic fatigue syndrome, and healthy controls, respectively. Both patient groups showed K values significantly higher than 0.50 (P<0.05), indicating that patients showed poorer dynamic balance control, CoPX colliding with the boundaries of the base of support (K>0.5).

INTERPRETATION:
The findings revealed a lower level of dynamic postural control in both fibromyalgia and chronic fatigue syndrome compared to controls.

Keywords: Base of support; Chronic widespread pain; Myalgic encephalomyelitis; Postural control; TauG analysis

http://www.ncbi.nlm.nih.gov/pubmed/27474799

 

[Dolphin]

Postural control deficits such as postural instability, larger postural sway and falls have been reported in patients with FM (Jones et al., 2011) as well as in CFS patients, compared to healthy controls (Ash-Bernal et al., 1995).

Ash-Bernal, R., Wall 3rd, C., Komaroff, A.L., Bell, D., Oas, J.G., Payman, R.N., Fagioli, L.R., 1995. Vestibular function test anomalies in patients with chronic fatigue syndrome. Acta Otolaryngol. 115, 9–17.

Jones, K.D., King, L.A.,Mist, S.D., Bennett, R.M., Horak, F.B., 2011. Postural control deficits in people with fibromyalgia: a pilot study. Arthritis Res. Ther. 13, R127.

Acta Otolaryngol. 1995 Jan;115(1):9-17.
Vestibular function test anomalies in patients with chronic fatigue syndrome.
Ash-Bernal R1, Wall C 3rd, Komaroff AL, Bell D, Oas JG, Payman RN, Fagioli LR.
Author information

Abstract
Chronic fatigue syndrome (CFS) is distinguished by the new onset of debilitating fatigue that lasts at least 6 months, concomitant with other symptoms to be described later. Many CFS patients complain of disequilibrium, yet the exact type of the balance dysfunction and its function and its location (peripheral vs. central) have not been described. Herein we report results of vestibular function testing performed on 11 CFS patients. These results revealed no predominant pattern of abnormalities. Patients typically performed below average in dynamic posturography testing, with a significant number of falls in the tests requiring subjects to depend heavily on the vestibular system. One patient had abnormal caloric testing, while 3 had abnormally low earth vertical axis rotation (EVA) gains at the higher frequencies tested. As a group, the average gain of EVA was significantly lower than normals in the 0.1 - 1.0 Hz range (p < 0.05). In earth horizontal axis rotation, the CFS group had a higher than normal bias value for the optokinetic (OKN) and eyes open in the dark conditions (p < 0.05), but had normal scores during visual vestibular reflex testing. Five of the 11 subjects had an abnormal OKN bias build up over the course of the run, equal to or actually exceeding the 60 degrees/s target velocity by as much as 14 degrees/s. Altogether, these results are more suggestive of central nervous system deficits than of peripheral vestibular disfunction.

PMID:
7762393
[PubMed - indexed for MEDLINE]

This also showed up in PubMed:

Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S109-11.
Testing of vestibular function: an adjunct in the assessment of chronic fatigue syndrome.
Furman JM1.
Author information

• 1Department of Otolaryngology, University of Pittsburgh, Pennsylvania.

Abstract
Patients with chronic fatigue syndrome (CFS) often complain of dysequilibrium that is nonspecific. The basis of this complaint is unknown but may be related to vestibular system abnormalities, in that an association between inner-ear deficits and infectious mononucleosis has been established in the medical literature. An overview of quantitative vestibular function testing is given, including vestibulo-ocular and vestibulospinal tests. The basic principles of caloric and rotational testing are provided, including the interaction between vision and the vestibular system. Moving-platform posturography is described. Preliminary results from quantitative vestibular function testing of a small group of individuals with CFS are provided.

PMID:
2020795

 

[Dolphin]

(Aside)

This description is not exactly the same as in the Fukuda definition:

CFS is characterized by unexplained, persistent and debilitating fatigue that does not disappear after rest (Fukuda et al., 1994)

A case of the chronic fatigue syndrome is defined by the presence of the following: 1) clinically evaluated, un- explained, persistent or relapsing chronic fatigue that is of new or definite onset (has not been lifelong); is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction in previous levels of occupational, educational, social, or personal activities; and

I prefer the description in the current paper. Rest can help people with ME/CFS.

What is particularly annoying is that description from Fukuda definition is often given as:

"is not alleviated by rest".

If people with ME/CFS are excluded from ME/CFS using this, it would be very unfortunate.

 

[Dolphin]

Only women were included in this study as more than 80% of patients with CFS and FM are females and ages 19–49 were selected to avoid any effect of aging on postural control (Spencer and Van der Meer, 2012).

 

[Dolphin]

The paper has no drawings with exactly what they are talking about. I do have an idea. I googled "mediolateral" images and it has some relevant images along with lots of images of an operation/incision that I will never have (as I'm a man)!

 

[Dolphin]

When 0 < K ≤ 0.5, the movement is controlled and ends with touch contact with the boundaries of the BoS. When 0.5 < K ≤ 1, the movement is less controlled and ends with hard contact with the boundaries of the BoS. Such a movement is characterized by a steeper decrease in closure rate, resulting in a movement where velocity peaks in the second half of the movement with a shorter deceleration period. When K ≥ 1, the movement has no deceleration phase such that, even upon reaching its goal, the velocity is still increasing, causing the movement to result in a non-controlled collision with the boundaries of the BoS (Lee, 1998).

BoS=base of support

 

[Dolphin]

Also, there was no significant main effect of trial which indicates there was no significant pattern between the five trials caused by a learning effect or fatigue.

 

[Dolphin]

Measured mean peak velocities did not reveal any differences between HC, CFS and FM groups. Therefore, it indicates that the significantly higher K-values in the patient groups cannot be explained by that they moved faster than the controls but that the patients reached their peak velocity later, i.e. they had a longer acceleration and shorter deceleration phase.

 

[Dolphin]

Discussion of possible causes (seems quite speculative to me)

According to previous studies, patients with CFS and FM not only have deficient postural control in the static condition such as larger postural sway (Ash-Bernal et al., 1995; Jones et al., 2011), but the present findings also show impaired dynamic control during initiation of gait. Postural control may be more critical in dynamic situations than in static ones. For example, the majority of falls in the elderly happen in transition phases (Polcyn et al., 1998). Postural stability is a complex task, which comprises of dynamic integration of sensory, cognitive and motor inputs to produce proper neuromuscular activities to maintain balance (Horak, 2006). Thus, this process can be disrupted at any stage. There are several possible explanations for the lower degree of control in CFS and FM. Lee suggested that dysfunction in the visual and vestibular systemsmay result in increasing K value because sensory feedback is not accurate to control the movement precisely (Lee, 2009). Although patients did not have any diagnosed visual or vestibular deficits, perception or processing of visual and vestibular information may be reduced (Ash-Bernal et al., 1995; Jones et al., 2011). The interplay between sensory feedback and motor output is essential for motor control to produce smooth, coordinated movements and recognition of body position (McCabe et al., 2009). Therefore, deficits in the sensory-motor processing may be another explanation for higher K value in FM and CFS that has been reported at both peripheral and central levels Fig. 3. (Clauw, 2010;McCabe et al., 2009). In particular, there is evidence of alterations in the peripheral and cortical processing in chronic pain conditions, whichmay result in disruption of the somatosensory system. Also, abnormalities in peripheral muscles have been reported in FM (Vierck, 2006) and CFS (Jones et al., 2010). For example, Ciubotariu et al. (2007) showed that experimental muscle pain results in decreasing the motor activity of the painful muscle and related synergistic muscles, and also that a pain inhibitory mechanism may be the source of the pain-fatigue interaction (Ciubotariu et al., 2007). Therefore, this may also potentially explain worse control in the FM group with mainly higher pain level and subsequent changes in the body aswe thoroughly explained above.

Moreover, studies on CFS and FM have found the significant acceleration of age-related decrease in both white and gray matter (Kuchinad et al., 2007; Puri et al., 2012). Accordingly, it is plausible to expect that CFS and FM patients show similar results as the elderly with impaired dynamic postural control and less controlled CoPX movement (higher K value).