the application of wide pulse high frequency neuromuscular electrical stimulation in disorders associated with motoneuron hyperexcitability

Conditions: Stroke; Cramp; Restless Legs Syndrome; Healthy Volunteers

Summary: 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.


Eligibility criteria:
stroke patients: * 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 * spasticity at the triceps surae (either soleus and/or gastrocnemii) considered as a modified ashworth sore ≥1 * being available for the study period and willing to participate * no contraindication to neuromuscular electrical stimulation contraindications for stroke patients: * surface sensory loss of affected lower leg (defined as incapacity to feel the 60-g touch using the semmes-weinstein monofilament test) * patients unable to understand indications or to provide informed consent * a history of orthopedic or other neurological disorders affecting walking function * a history of surgery to correct drop foot (ankle fixation) * patients under antispastic medication (baclofen, tizanidine, tolperisone, benzodiazepines, dantrolene or botulinum toxin to the plantar flexor muscles in the last 6 months). people prone to muscle cramps: * reporting nocturnal muscle cramps (the assessment will be done through a questionnaire) * not being treated for muscle cramps * being available for the study period and willing to participate * no contraindication to neuromuscular electrical stimulation patients with restless legs syndrome: to be included in the study, rls patients will have to satisfy the diagnostic criteria for rls published by the international restless legs syndrome studygroup (irlssg). all five key clinical features are required for the diagnosis: * an urge to move the legs, usually accompanied or caused by uncomfortable and unpleasant sensations in the legs. sometimes the urge to move is present without the uncomfortable sensations, and sometimes the arms or other body parts are involved in addition to the legs. * the urge to move or unpleasant sensations begin or worsen during periods of rest or inactivity such as lying or sitting. * the urge to move or unpleasant sensations are partially or totally relieved by movement, such as walking or stretching, at least as long as the activity continues. * the urge to move or unpleasant sensations are worse in the evening or night than during the day, or only occur in the evening or night. when symptoms are severe, the worsening at night may not be noticeable but must have been previously present. * symptoms are not solely accounted for by another medical or behavioral condition, such as leg cramps or habitual foot tapping. * no contraindication to neuromuscular electrical stimulation they will also have to satisfy the following criteria: * diagnosis of primary rls corresponding to: 1. the presence of periodic limb movements 2. a dopaminergic treatment response 3. the presence of rls in first-degree relatives 4. a lack of profound daytime sleepiness * being available for the study period and willing to participate healthy participants: * no neurological disease * no contraindication to neuromuscular electrical stimulation * being available for the study period and willing to participate

Keywords: muscle strength persistent inward current training