Investigation of the Effects of Motor Imagery and Sensorimotor Training on Neuropathic Pain, Proprioception, Balance, and Reaction Time in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating, progressive neurological disease that affects the Central Nervous System (CNS). Among the most common problems in MS are neuropathic pain, loss of proprioception, and balance issues. Many types of pain can be observed in MS, and neuropathic pain is one of the most common types. Neuropathic pain is directly related to the disease's demyelination process and is associated with dysesthetic pain, allodynia, and hyperalgesia. For neuropathic pain in MS, there are numerous physical therapy and rehabilitation interventions focused on proprioception, balance, and reaction time management. Loss of proprioception is commonly observed in MS, and this loss results from the demyelination of the central somatosensory pathways. Loss of proprioception negatively affects the patient's independence in activities of daily living. Proprioception-the ability to perceive the position of the body and limbs relative to the environment-is also related to balance performance. Balance problems are observed in 50-80% of people with MS. Balance problems emerge throughout the course of MS and, while they may worsen with recurrent relapses, they can also occur between relapses. Balance problems can be detected in the early stages of the disease, even in the absence of any disability. Another effect of MS is observed in reaction time. In MS, which is characterized in particular by demyelination and axonal damage, a slowing of nerve conduction velocity leads to a decrease in information processing speed, resulting in prolonged reaction time. Studies have shown that reaction time is significantly longer in people with MS compared to healthy individuals. Neuromuscular training models designed to train the CNS can be used to treat these conditions. Motor Imagery (MI) is one such neuromuscular training model.

Imagery can be defined as the use of all the senses to create a mental image of an activity. MI is referred to as a brain training method and utilizes the neuromatrix theory to inhibit pain. MI training aims to retrain the neural networks that activate the neuromatrix so that they become less sensitive to stimuli that would not normally cause pain. Lateralization is a method used in conjunction with MI to distinguish between the right and left sides of the painful area. The imagery phase is defined as visualizing the positions and movements of the painful areas. A study examining the effects of telerehabilitation-based MI training on pain and related factors in individuals with MS included 32 participants with MS. Two groups were formed-a treatment group and a control group-and the treatment group received MI training via telerehabilitation for 8 weeks. The outcome measures included pain, motor imagery ability, cognitive functions, fatigue, quality of life, sleep quality, daytime sleepiness, and levels of depression and anxiety. The results of the study showed a significant reduction in the treatment group in overall pain intensity over the last two and seven days, in pain intensity in areas other than the elbow region over the last seven days, and in fatigue and depression levels, while there was an increase in MI ability, quality of life, and scores for processing speed and visual memory in cognitive functions. Another study examined the physical, cognitive, and psychosocial effects of telerehabilitation-based MI training in individuals with MS. A group of MS patients and a healthy control group were formed, and the MS patients underwent 8 weeks of MI training. The results of the study showed significant improvements in the intervention group in dynamic balance during walking, walking speed, perceived walking ability, balance confidence, most cognitive functions, fatigue, anxiety, depression, and quality of life. When these two studies are examined, it is possible to conclude that MI has a positive effect on individuals with MS across multiple parameters. MI is a neuromuscular training model, and another neuromuscular training method is Sensorimotor (SM) training.It is known that SM, which applies repetitive sensorimotor stimulation, passively enhances sensorimotor performance. Known as perceptual learning, this approach involves simple exposure to SM stimulation for several hours. While the term "perceptual" encompasses various senses, including sight and hearing, the term "sensorimotor training" is used here specifically to refer to methods focused on SM stimulation. SM training typically does not require participants to actively focus on external stimuli, making it easily applicable in neuro-rehabilitation settings. It does not focus solely on increasing muscle strength in a specific region but aims to improve movement quality and patterns by training CNS. This training model, which emphasizes the importance of sensation in developing motor skills, plays an effective role in improving balance, enhancing functionality, and reducing pain. Studies demonstrating the effectiveness of SM interventions in MS are available. A randomized controlled trial conducted with MS patients, a robot-assisted intervention and an SM training intervention were applied to improve upper extremity motor function. Forty-two MS patients were divided into two groups and received treatment twice a week for four weeks. The study found that the SM intervention was effective in improving upper extremity motor function. In another study, the effects of SM balance training on balance disorders, perceived balance confidence, quality of life, fatigue, fall frequency, and sensory integration processing were compared with those of traditional rehabilitation in 80 patients with MS. Patients were assessed by a blind evaluator before treatment, after treatment, and one month after treatment using the Berg Balance Scale (BBS), the Activity-Specific Balance Confidence Scale (ABC), the Multiple Sclerosis Quality of Life-54, the Fatigue Severity Scale (FSS), the number of falls, and the Sensory Organization Test (SOT). The study found that SM is effective in improving balance disorders in patients with MS. The literature shows that both MI and SM have effects on neuropathic pain, proprioception, balance, and reaction time in individuals with MS. These two methods involve different neurophysiological mechanisms. For example, MI sends a "top-down" message to the brain. It first uses laterality (right/left distinction), then imagery, and prepares the brain for movement. SM, however, sends a "bottom-up" message to the brain. It focuses primarily on sensory input. Furthermore, while MI is an approach that aims to activate central motor networks without peripheral afferent input, SM supports central motor control processes by enhancing peripheral sensory input.There are only a few studies comparing these two methods. In a study conducted on individuals with knee osteoarthritis, three groups were identified: one group received SM, one group received MI, and the other group received conventional treatment. As a result of the intervention, which was administered twice a week for a total of 6 weeks, it was concluded that MI and SM exercises significantly improved static and dynamic balance, thereby reducing the risk of falls, and-particularly during early rehabilitation-promoted proprioceptive development at small angles (20°). No studies have been found in the literature that compare these two methods in patients with MS and examine their effects.

The aim of our study is to examine the effects of MI and SM training in individuals with MS. Motor control in patients with MS is a process resulting from the interaction of central and peripheral mechanisms. For this reason, it is believed that comparing the relative effects of central-focused (MI) and peripheral-focused (SM) approaches could contribute to the development of rehabilitation interventions.