Abstract/Details

Neurophysiologic bases for abnormal muscle coactivation patterns in hemiparetic stroke

Dewald, Julius Paulus Antonius.   Loma Linda University ProQuest Dissertations & Theses,  1992. 9409126.

Abstract (summary)

To study disturbed muscle activation patterns in hemiparetic stroke, the EMG activity in spastic-paretic and contralateral elbow muscles of 10 stroke subjects were compared during graded directionally varying voluntary isometric contractions. We observed significant shifts in the peak EMG angle and increases in the angular range of EMG activity in the impaired upper limb. Furthermore, we observed stereotypic coactivation of many muscles acting at the same joint or at different joints across all subjects.

The effect of elbow angle changes on muscle coactivation patterns was studied by examining isometric torque-angle relations under passive and active conditions in 8 stroke subjects. Active torques were elicited voluntarily, or with electrical stimulation. Passive elastic stiffness was not significantly altered, however, shifts of torque-angle curves to more extended elbow positions were found in all but one subject during voluntary activation, but not during electrical stimulation. These results indicate the lack of significant alterations of muscle-tendon properties and may reflect differences in muscle coactivational strategies between the impaired and unimpaired elbow as a function of angle. Increases in muscle mechanoreceptor feedback due to alterations in flexor reflex interneuronal bias would also explain these observations.

The influence of cutaneous afferents on muscle coactivation patterns was studied in the upper limbs of 8 hemiparetic stroke subjects using electrical stimulation of the index finger of both the impaired and unimpaired upper limbs. In the unimpaired limb, shoulder muscle activity preceded elbow flexor activation in the unimpaired limb, under passive and active conditions, across all subjects. A more synchronized but delayed onset was observed in all muscles in the impaired limb. Furthermore, the unimpaired limb produced shoulder extension-retraction followed by elbow flexion, while only the elbow flexion response was present for the impaired limb. Obligatory coupling between certain elbow and shoulder muscles were observed in the impaired limb similar to those observed under voluntary activation conditions.

The obligatory muscle coactivation patterns observed in these studies may be caused by changes in interneuronal bias, more specifically of the flexor reflex interneurons, due to a loss of dorsolateral descending input at the impaired side.

Indexing (details)


Subject
Anatomy & physiology;
Animals;
Neurology;
Biomedical research
Classification
0317: Neurosciences
0541: Biomedical engineering
0719: Physiology
Identifier / keyword
Applied sciences; Biological sciences; strokes
Title
Neurophysiologic bases for abnormal muscle coactivation patterns in hemiparetic stroke
Author
Dewald, Julius Paulus Antonius
Number of pages
156
Degree date
1992
School code
0106
Source
DAI-B 54/11, Dissertation Abstracts International
ISBN
979-8-208-00085-4
Advisor
Rymer, W. Zev
University/institution
Loma Linda University
University location
United States -- California
Degree
Ph.D.
Source type
Dissertation or Thesis
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
9409126
ProQuest document ID
304023420
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
https://www.proquest.com/docview/304023420