Medical Spastic Patient Machine Interface MSPMI : Biomechanical and Electrophysiological Assessment of the Triceps Surae Spasticity

Spasticity, Muscle

Spasticity, electrophysiology, biomechanics, objective assessment

Spasticity is a disorder of the muscular tonus that occurs in disease including the upper motor neuron (strokes, spinal cord injuries, multiple sclerosis, traumatic brain injuries or cerebral palsies). It begins few hours after the neural aggression and last until the grave. The most accepted definition refers to a velocity-dependent increase in stretch reflexes elicited by passive stretch (Lance definition) but new approaches prefers to distinguish neural (reflex) and non-neural (soft tissues alterations) components of the increase resistance to a passive stretch. This deficiency is a major cause of complications as walking impairment, pain or bone deformities and may require intensive therapies (intrathecal baclofen infusion, intramuscular toxin botulinium injection, surgery, etc). Despite its high frequency and the potential complications, only clinical scales (modified Ashworth scale and modified Tardieu scale essentially) with criticized metrological properties are available for daily assessment. The SPASM Consortium has published on 2005 recommendations for developing devices using both mechanical and electrophysiological parameters. The principle challenge was to ally parameters accuracy and utilization facility allowing quickly evaluation to the patient's bed. Few research team works on this topic but mostly on specific population and nowadays, no device has really crossed the door of laboratories. This kind of tool would help us to improve the quality of the follow-up and to guide us between the choices of specific therapies. The MSPMI has been created following these recommendations in the University of Technology of Compiègne, thanks to the collaboration between researchers of the UMR 7338 CNRS and a brain surgeon of the Nantes University Hospital. The patent was obtained on 2012. This device allows the assessment of the ankle plantar extensor (triceps surae) during a manually applied stretch movement. This muscle was selected as it is frequently involved and treated for spasticity. This study aims to evaluate the metrological properties of the MSPMI (reliabilities, responsiveness, known group validity, construct validity, measurement errors and internal consistency) among a large cohort of patients with no restriction of etiologies recruited in the Nantes University Hospital.

Evaluation will include medical histories and specific information about spasticity management and consequences. The patient will be assessed by two evaluators with the MSPMI installed on the foot and the shank. MSPMI allows the record of angular movement of the ankle (position, speed and acceleration), of biomechanics (stiffness, torque, work and power) and electromyography (root mean squared and integrated electromyography signals) of two chiefs of the triceps surae (medial gastrocnemius and soleus). Electromyography data will be recorded on a maximum voluntary contraction when the deficiency will permit it. After that, data will be recorded at 3 velocities (with respect to the clinical scale recommendations) on two different positions (knee flexed and extended), according to our clinical practice. The evaluation on day 0 will allow the assessment of inter-rater intra-session reproductibility, internal consistency, construct validity, measurement error and known group validity. If the patient is hospitalized, he will be included on the hospitalization group and a second evaluation following the same protocol will be done 7 days later (assessment of inter and intra-rater inter-session reproductibility). If a specific therapy (selective tibial neurotomy, anesthetic block or botulinum toxin intramuscular injection) is proposed, the patient will be included on the treatment group and a new evaluation will be done after the therapy (30 minutes - 2 hours after an anesthetic block, 2-3 months after neurotomy or botulinium toxin injection) allowing assessment of the responsiveness of the MSPMI. If the patient is not on these two situations, he will be included on the simple evaluation group and his participation will end.

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