Although virtual reality has attracted the attention of health professionals and neurorehabilitation field, research about mixed reality (MR) in people with neurological disorders, particularly multiple sclerosis (MS), is very limited. Furthermore, to our knowledge, studies about the effects of MR in upper limb (muscle strength and fatigability, coordination and dexterity, functionality and quality of life) in people with MS are nonexistent.

The main objective of our study are:

To know the clinical effects of mixed reality environments and re-training activities linked to their spaces (kitchen, bathroom, living room, bedroom and terrace-garden), designed for the treatment of upper limb impairments in people with MS, in combination with a conventional physiotherapy program, on manipulative skills, functionality and quality of life in people with MS.

The secundary objectives are:

To study the clinical effects on range of motion, muscle strength, coordination and manual dexterity, fatigue, functionality and quality of life in people with MS.

To analyze satisfaction and adherence to treatment, the occurrence of adverse effects and the level of workload perceived by participants.

A double-blind randomized controlled trial is proposed. The sample will be randomly divided into two groups: the experimental group will receive treatment based on mixed reality for MMSS, designed by the research team and using Meta Quest 3.0 glasses, in combination with conventional physiotherapy; and the control group will receive the same conventional therapy. Both groups will receive 2 sessions/week, 60min/session, for 10 weeks. The mixed reality environments to be designed will be a kitchen, a bathroom, a living room, a bedroom and a terrace-garden, with the tasks to be performed in each location. The pre, post-treatment and one-month follow-up outcome measures will be: range of motion, manual grip strength, manual dexterity, fatigue, functionality, quality of life, satisfaction with the technology, adherence, adverse effects and perceived workload. A statistical comparison study will be carried out establishing as an inter-subject factor the group parameter and as intra-subject factors each of the measurements and the treated side.

MS is a neurological pathology that currently affects approximately 36 people per 100,000 inhabitants (2.8 million people affected in the world) and has various clinical manifestations, such as alterations in balance and coordination, fatigue or alterations in sensitivity, with alterations in the motor control of the MMSS being one of the main problems faced by people with MS from the time of diagnosis, the main consequence of which is an alteration in their ability to perform ADLs, reducing their quality of life.

Although new drugs aimed at modifying the course of the disease have appeared in recent years, there is currently no curative treatment for MS. For this reason, pharmacological therapy is complemented by rehabilitative treatment in order to maintain functional capacity and favor adaptation to the changes produced by the evolution of the disease itself. However, conventional rehabilitation treatment of people with MS is sometimes referred to as systematic, so that patients may lose motivation and adherence to it. This is why in recent years new intervention strategies have been introduced, such as VR, which encourage patient motivation through the practice of functional tasks in virtual environments that provide feedback on the results obtained and the possibility of increasing repetitions and work intensity through simulated ADL training.

The development of these technologies has offered professionals working in the field of neurological rehabilitation to extend the care of MS patients as a complement to their conventional rehabilitation program, reaching a higher intensity of treatment and sometimes at a sustainable cost. However, studies on the effects of VR on manipulative skills in people with MS are still scarce and, to our knowledge, quality studies proposing the use of mixed reality as a tool for the treatment of MMSS impairments in people with MS are nonexistent.

For the reasons described above, an RCT is justified to investigate the effects of the application of a treatment protocol through mixed reality environments that simulate the re-training of activities in the locations of a house (from the Latin, "domus") and, therefore, facilitate its transfer from learning to the real world, on manipulative skills, functionality and quality of life in people with MS (VIRTUAL-DOMUS), following international recommendations on the design of virtual environments for therapeutic purposes in neurorehabilitation.

Inclusion Criteria:

->18 years of age.

• Diagnosis of MS according to McDonald criteria (53) with a time of evolution longer than two years.
• Assessment on the Kurtzke Multiple Sclerosis Disability Status Scale (EDSS) with a score between 2. 0 (minimal disability in one section of the FS (at least one with a score of 2).) to 7.0 (unable to walk more than a few steps, even with assistance, basically confined to wheelchair and able to transfer from wheelchair to another place, or can manage to go to the toilet for 12 hours a day) .
• Stable medical treatment for at least six months prior to surgery.
• Upper extremity muscle tone no greater than 2 points (moderate hypertonia, increased muscle tone during most of the arc of motion, but can passively move the affected part with ease) on the modified Ashworth Scale.
• Muscle balance equal to or greater than 3 in the upper extremity.
• Score less than or equal to 4 points on the "Pyramidal Function" section of the EDSS functional scale.
• Absence of cognitive impairment, with ability to understand instructions and score equal to or greater than 24 on the Minimental Test.

A- score equal to or less than 2 points on the "Mental Functions" section of the EDSS.

Exclusion Criteria:

• Diagnosis of a neurological disease or musculoskeletal disorder other than MS.
• Diagnosis of a cardiovascular, respiratory or metabolic disease or other conditions that may interfere with this study.
• Having suffered an exacerbation or hospitalization in the last 3 months before starting the assessment protocol, or during the therapeutic intervention process.
• Having received a course of steroids, intravenous or oral, 6 months prior to the start of the assessment protocol and within the intervention period of the study duration.
• Having received treatment with botulinum toxin in the 6 months prior to the start of the study.
• A score higher than 2 points on the modified Ashworth scale.
• Cognitive or language impairment that prevents adequate communication or comprehension.
• The presence of visual disturbances not corrected by ocular devices; or a history of photosensitive epilepsy.

The investigator who will randomize the sample will be external to any intervention. The evaluators will be external to any intervention.