In the present project, the investigators aim at proposing innovative ways of investigating spinal motoneuron hyperexcitability to counteract the associated impairments by using wide pulse high frequency neuromuscular electrical stimulation (WPHF NMES) in various populations. The investigators will use WPHF NMES contractions as a model to gain insights into the mechanisms underlying muscle cramps, restless legs syndrome or stroke-induced spasticity as there is evidence that they share common underlying mechanisms. The investigators will then use WPHF NMES as a training modality to improve plantar flexor neuromuscular function in stroke patients by taking advantage of their motoneuronal hyperexcitability.
Diagnosis of first-ever stroke (ischemic or hemorrhagic) with unilateral motor deficits from at least 6 months. Stroke will have to be confirmed from medical records and/or radiological imaging (CT scan or MRI)
Inadequate ankle control during gait defined as ankle dorsiflexion less than 5° during stance phase and 0° during swing phase; 0° = ankle neutral position)
Passive range of motion of ankle dorsiflexion at least to neutral position
Ability to walk at least 10 m with or without assistive devices
None
Parallel
wide pulse high frequency neuromuscular electrical stimulation training
Other interventionPlantar flexors will be stimulated with wide pulse high frequency neuromuscular electrical stimulation 3 times a week for 6 weeks
Change in maximal voluntary contraction force
Change from baseline maximal voluntary contraction force after the six-week training period in stroke patients
Change in NMES-evoked force
Change from baseline NMES-evoked force after the six-week training period
NMES-evoked force
Comparison of NMES-evoked force in plantar flexor muscles between patients (prone to cramps or restless legs) and healthy volunteers
Change in estimates of persistent inward current (Delta F assessed with high-density surface electromyography and/ or the torque measured during vibration after the last bout of NMES)
Change from baseline estimates of persistent inward current after the six-week training period in stroke patients
Change in voluntary activation level and contractile properties of the plantar flexor muscles
Change from baseline voluntary activation level and contractile properties of the plantar flexor muscles after the six-week training period in stroke patients
voluntary activation level and contractile properties of the plantar flexor muscles
comparison of voluntary activation level and contractile properties of the plantar flexor muscles between patients (prone to cramps or restless legs) and healthy volunteers
change in spasticity at the ankle joint level for stroke patients
Change from baseline Ashworth scale score (minimal score 0, maximal score 4, a higher score means a worst outcome) after the six-week training period in stroke patients
10-m walking test (s)
functional test
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University of Lausanne
Lead sponsor
Swiss National Science Foundation
Collaborator
