Changes in activation timing of knee and ankle extensors during gait are related to changes in heteronymous spinal pathways after stroke

 Useless. Describes a problem, OFFERS NO EXACT SOLUTION.

Absolutely nothing here is going to help the 85% of survivors with gait abnormalities. Solve stroke, don't just beat around the edges.

The latest here:

Changes in activation timing of knee and ankle extensors during gait are related to changes in heteronymous spinal pathways after stroke

2014, Journal of neuroengineering and rehabilitation

 Joseph-Omer Dyer 1,2*, 

Eric Maupa 3, 

Sibele de Andrade Melo 1,2, 

Daniel Bourbonnais 1,2, 

Sylvie Nadeau 1,2
and Robert Forget 1,2

* Correspondence: joseph.omer.dyer@umontreal.ca
1 Centre de recherche interdisciplinaire en réadaptation, Institut de réadaptationGingras-Lindsay de Montréal, Montréal, Canada
2 School of Rehabilitation, Faculty of Medicine, Université de Montréal, P.O.Box 6128, Station Centre-Ville, Montréal, Quebec H3C 3 J7, CanadaFull list of author information is available at the end of the article

Abstract

Background:
 Extensor synergy is often observed in the paretic leg of stroke patients. Extensor synergy consists of an abnormal stereotyped co-activation of the leg extensors as patients attempt to move. As a component of this synergy,the simultaneous activation of knee and ankle extensors in the paretic leg during stance often affects gait pattern after stroke. The mechanisms involved in extensor synergy are still unclear. The first objective of this study is to compare the co-activation of knee and ankle extensors during the stance phase of gait between stroke and healthy individuals. The second objective is to explore whether this co-activation is related to changes in heteronymous spinal modulations between quadriceps and soleus muscles on the paretic side in post-stroke individuals.
Methods:
 Thirteen stroke patients and ten healthy individuals participated in gait and heteronymous spinal modulation evaluations. Co-activation was measured using peak EMG activation intervals (PAI) and co-activation amplitude indexes (CAI) between knee and ankle extensors during the stance phase of gait in both groups. The evaluation of heteronymous spinal modulations was performed on the paretic leg in stroke participants and on one leg in healthy participants. This evaluation involved assessing the early facilitation and later inhibition of soleus voluntary EMG induced by femoral nerve stimulation.
Results:
 All PAI were lower and most CAI were higher on the paretic side of stroke participants compared with the co-activation indexes among control participants. CAI and PAI were moderately correlated with increased heteronymous facilitation of soleus on the paretic side in stroke individuals.
Conclusions:
 Increased co-activation of knee and ankle extensors during gait is related to changes in intersegmental facilitative pathways linking quadriceps to soleus on the paretic side in stroke individuals. Malfunction of intersegmental pathways could contribute to abnormal timing of leg extensors during the stance phase of gait in hemiparetic individuals.
Keywords:
 Hemiparesis, Gait, Sensory afferents, Leg extensors, Spinal pathways, Propriospinal

Introduction

Following stroke, impaired coordination is frequently observed and manifests by the incapacity to activate muscles selectively [1]. This lack of voluntary control produces abnormal coupling of joint movements on the paretic side that can hamper motor task performance[1-3]. Altered motor coordination in the paretic leg among stroke patients is associated with functional deficits [4]. Asa result of this lack of coordination, these patients often produce stereotypical co-activation of several muscles on the paretic side as they voluntarily attempt to move [1,5]. These co-activations, which are commonly referred to as abnormal synergies, are defined as the simultaneous recruitment of muscles at multiple joints resulting in a stereotypical pattern of movement [6]. In the paretic leg of stroke patients, prevalent extensor synergy consisting of the co-contraction (i.e., co-activation) of the majority