Impaired sensory and functional balance ability following strokes often has negative impacts on patients, their family, and society. 
About 50% of stroke patients experience sensory impairment. Occasionally, this impairment may be accompanied by neurological disorders, including hemianopsia, aphasia, or hemispatial neglect. In >50% of cases, sensory disorders include the face, arm, trunk, and leg of the affected side. Sixty-five percent of stroke patients experience impaired tactile and protective responses, including proprioceptive sensations. As a result, stroke patients are less able to transmit information to the brain and spinal cord regarding muscle strength, pressure, joint position, and muscle length, which are required to maintain posture and can be detected in various joints on the paralyzed side. 
Stroke survivors typically have decelerated and impaired balance reactions, poorer body weight support on the affected limb, and excessive postural sway. Balance impairment ranks first among stroke disorders. Reduced muscle force and range of motion, impaired motor coordination, and sensory organization issues emerging after a stroke impair the maintenance of balance. Impaired balance not only increases the risk of falls and social isolation, but also negatively affects physical activity.
In general, repetitive sensory stimulation and mass motor or task practice facilitate neuroplasticity and brain reorganization in stroke patients, resulting in enhanced motor and functional recovery after stroke. These rehabilitative programs can be categorized into the following two main groups according to theoretical backgrounds of clinical trials: conventional and advanced rehabilitation programs. Conventional rehabilitation programs address the effectiveness of treatment approaches based on neurophysiological, motor control and learning, or strengthening and functional principles. 
Conventional rehabilitation programs include the Bobath (also called Neurodevelopmental Treatment), Brunnstrom, proprioceptive neuromuscular facilitation (PNF), and functional strengthening approaches, as regular therapies apply sensory input with visual, verbal, tactile, cutaneous, proprioceptive, and auditory assistance in clinical stroke rehabilitation. Advanced rehabilitation programs include electrical stimulation, Robotic therapy, virtual reality, etc. to input proprioceptive, tactile, visual, and auditory help, and emphasize the effectiveness of specific interventions based on neuro-scientific evidence. Previous researchers have recommended trunk-targeted training on a vibration board and reactive balance training through perturbation, which are types of sensorimotor training, as described by Janda. Sensorimotor training includes passive and active facilitation of afferents that have a strong impact on posture control and equilibrium, which is effective for facilitation of the muscle spindle.
Recently, according to the patient’s mobility status and recovery phase, the appropriate advanced rehabilitation therapy combined with conventional rehabilitation treatment comprise of sensorimotor training. This combined sensorimotor training may provide multiple sensory inputs for therapists to maximize the recovery of stroke patients. However, to our knowledge, it is rare that previous studies have targeted multi-sensory input training in stroke patients. 
Thus, the purpose of the current study was to examine the effect of multi-sensory input training on proprioception and balance in stroke patients.

 Supportive Care

Thirty subjects who experienced stroke participated in this study and were randomly assigned into two groups: the multi-sensorimotor training group (n=21) and the treadmill training group (n=21). Both groups first performed conventional physical therapy for 30 min, after which the multi-sensorimotor training group performed multi-sensorimotor training for 30 min, and the treadmill training group performed treadmill gait training for 30 min. Both groups performed the therapeutic interventions 5 days per week for 8 weeks.

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The treadmill group underwent treadmill gait training with a Placebo TENS for 30 min in the paralyzed medial and lateral bellies of the gastrocnemius muscle. Subjects participated 5 days per week for 8 weeks. Training started with 10-20 min at low intensity (40-50% heart rate reserve [HRR]). The duration progressed 5 min every 2 weeks and the intensity progressed 5 percent HRR every 2 weeks, with a goal of 30 min at 60-70% HRR.

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The multi-sensorimotor training program included the Stabilize-T and Reha-Bar (Pedalo®) exercises with TENS. The electrical stimulation (bipolar-balanced stimuli, pulse width of 200 μs, frequency of 100 Hz) was delivered by a dual-channel commercial TENS unit (TENS 7000TM, Koalaty Products Inc, USA) and adhesive TENS electrodes (5 cm2) were fastened to the skin overlying the paralyzed medial and lateral bellies of the gastrocnemius muscles. In conditions involving stimulation, the TENS amplitude was adjusted before the start of measurements in increments of 0.01 mA and set at the sensory detection threshold of each subject. Stabilizer T is a piece of equipment that trains an individual to improve sensory (proprioceptive and tactile) control of their posture and movements as well as the reaction and stabilization of their locomotor system. The platform can either be mounted on springs (three-dimensional effect) or suspended from ropes (two-dimensional effect). 
Exercise methods: (i) Subjects looked straight ahead while standing with their knee slightly bent on the Stabilize-T. They closed their eyes for 15 s, subsequently opened their eyes for 10 s, then maintained balance for 30 s. After subjects stood on the Reha-bar, they pedaled up and down and rotated the wheels to move forward while holding the safety bar with both hands with the therapist’s assistance. (ii) Subjects looked straight ahead while standing with their knee slightly bent on the Stabilize-T. They abducted their arms and slowly rotated their neck to the left, center, and right for 30 s each, and maintained balance for 30 s. After subjects stood on the Reha-bar, they pedaled up and down and rotated the wheels to move forward while holding the safety bar with both hands without assistance by the therapist. (ii) Subjects looked straight ahead while standing with their knee slightly bent on the Stabilize-T. They abducted their arms and extended their neck for 10 s. Subjects repeated the neck extension 3 times and afterward they maintained balance for 30 s. After subjects stood on the Reha-bar, they pedaled up and down and rotated the wheels to move forward and backward with holding the safety bar with both hands without assistance by the therapist. Number one was the easiest and number three was the hardest. We applied one of these methods to the patients considering their ability. These exercise methods were provided by a previous study.

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Description

Subjects who were diagnosed with first onset of unilateral hemisphere stroke ≥6 months previously, could walk for ≥30 s (regardless of using an assistive device), and had a mini-mental state examination Korean version (MMSE-K) score of ≥24 were enrolled.

Exclusion criteria consisted of the presence of a cognitive disorder, visual disorder, cardiorespiratory disorder (with cardiac pacemaker), orthopedic intervention, and those receiving botulinum toxin injections within the past year.

Balance test

pretest-posttest

Proprioception test

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gait ability

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fall risk

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This study provides evidence that combined rehabilitation methods significantly enhance the proprioception and balance ability during the chronic phase of recovery from stroke. Therapists play an important role in achieving the maximum benefit through an entire rehabilitation process, from acute to subacute and to the chronic status of stroke. They have systematically evaluated the optimal intensity and duration of specific interventions. Therefore, combining valuable trainings to input multiple senses is believed to be a good method to facilitate the restoration of proprioception and balance ability.