The goal of this case control study is to evaluate the use of inertial navigation systems to detect and characterize early locomotor disorders in patients with multiple sclerosis (MS). The study aims to:

• Validate the contribution and inefficiency indexes obtained by the Trigno® Avanti Sensor inertial units, in comparison with indexes calculated with 3D motion analysis during walking and tandem in early-stage MS patients.

Researchers will compare MS patients, to healthy controls.

Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system, and the leading cause of non-traumatic neurological disability in young adults. It affects around 100,000 people in France, and 5,000 are newly diagnosed each year. It generally begins between the ages of 20 and 40, and mainly affects women (sex ratio 3 women/1 man).

The clinical presentation of MS is highly polymorphic. Patients may present with motor deficits, sensory disorders, spasticity, gait disorders, balance disorders, visual disturbances, etc. The symptoms that have the greatest impact on patients' quality of life in the first 5 years following diagnosis are gait and balance disorders. However, these early disorders are barely visible on clinical examination, and are not highlighted by the balance and gait tests frequently used in routine practice. These sub-clinical locomotor disorders are also not taken into account by the Expanded Disability Status Scale (EDSS). However, the discomfort reported by patients is objectified using the Multiple Sclerosis Walking Scale-12 (MSWS-12) questionnaire.

The management of balance and gait disorders is essential to limit deconditioning during exercise and reduce their impact on patients' quality of life. Detecting these disorders is therefore a key factor in improving our understanding of them, and enabling us to provide appropriate rehabilitation.

In the early stages, gait and balance disorders can be detected by means of three-dimensional movement analysis.

Certain parameters, such as contribution and inefficiency indexes, have proved useful in detecting and quantifying gait and balance disorders in early-stage MS patients. These indexes are based on the calculation of linear moments. The contribution index reflects the contribution of each body segment to body forward motion, while the inefficiency index reflects the motor performance of a segment in carrying out a locomotor task. These indices could provide physical markers for quantifying balance and gait disorders and their progression, and thus help in disease monitoring.

However, 3D motion analysis is costly in both human and technical terms, and is restricted to a laboratory environment.

At present, in France, movement analysis laboratories are not widely available for clinical evaluation, which limits the screening of balance and gait disorders in the early stages of MS, and their follow-up in private practice. On the other hand, inertial measurement systems are inexpensive, easy-to-use tools that could help detect balance and gait disorders at an early stage in MS. In fact, inertial units comprise at least an accelerometer and a gyroscope, which can also be combined with a magnetometer. The kinematics of body segments could be used to calculate contribution and inefficiency indexes, in an ecological approach geared towards everyday practice, thus democratizing and facilitating the monitoring of these disorders.

In this study, the medical device used is Trigno® Avanti Sensor. This research evaluates a medical strategy that would enable to validate the transposition of a method for calculating contribution and inefficiency indexes from data obtained by the medical device.

Inclusion Criteria for patient:

• Age 18 to 65 (inclusive)
• Expanded Disability Status Scale (EDSS) ≤ 4
• Proficient in French
• Agreeing to participate in the study and having signed the informed consent form
• Affiliated with a social security scheme

Inclusion Criteria for Volunteers:

• Age 18 to 65 (inclusive)
• Proficient in French
• Agreeing to participate in the study and having signed the informed consent form
• Affiliated with a social security plan

Exclusion Criteria for patient:

• MS crisis within the last 6 weeks
• Botulinum toxin injection in the last 3 months
• Neurological pathology other than MS
• Disabling musculoskeletal pathology
• Unstable cardiac and respiratory pathology
• Pregnant women
• Patients with comprehension or cognitive disorders
• Recent change in background treatment (< 3 months)
• Patients under guardianship or curatorship
• Presence of implanted electronic devices of any kind, including pacemakers or similar assistive devices, electronic infusion pumps and implanted pacemakers
• Allergy to silver

Exclusion Criteria for Volunteers:

• Neurological pathology
• Rheumatological pathology
• Antecedent of sprains (< 3 months), fractures (< 1 year) in the lower limbs
• Pregnant women
• Person under guardianship or trusteeship
• Presence of implanted electronic devices of any kind, including pacemakers or similar assistive devices electronic infusion pumps and implanted pacemakers
• Allergy to silver

Multiple sclerosis patients and volunteers