This study aims to determine whether peripheral magnetic stimulation (PMS) during balance training in patients with diabetic polyneuropathy reduces fall risk, as measured by balance tests, and lessens disease severity compared to balance training with sham stimulation.
This proof-of-concept study will utilize the Magnetic and Balance Training Activator (MAGBATA), a platform mounted with a magnetic stimulation coil that delivers electromagnetic pulses directly to the plantar surfaces of the feet while patients stand. A racetrack coil (RT-120), connected to the MagPro X100 magnetic stimulator with MagOption (MagVenture, Farum, Denmark), will be used. Parameters for the repetitive peripheral magnetic stimulation (rPMS) protocol will be configured to facilitate sensory input, enhance brain plasticity, and promote axonal regeneration.
Diabetes mellitus type 2 with any symptoms of distal polyneuropathy, including numbness, paresthesia, dysesthesia, or lower leg weakness.
Abnormal 10g monofilament test.
Abnormal one-leg stance test (OLST) with eyes open.
Chronic foot ulceration.
Severe leg or foot pain not controllable with medications or other interventions.
Significant foot deformity, including severe pes cavus, severe claw toe, or toe amputation.
Body mass index (BMI) over 35 kg/m².
Parallel
Peripheral magnetic stimulation
DeviceDuring the warm-up exercise, 10-Hz rPMS will be applied to the tibialis anterior with an on-time of 4 seconds (40 pulses per train), followed by an off-time (inter-train interval) of 8 seconds, for a total of 25 trains for each leg. During the one-leg stance exercise, 20-Hz rPMS will be applied to the plantar surface of the standing foot for 3 seconds of on-time (60 pulses per train), followed by 12 seconds of off-time, for a total of 20 trains for each foot. Stimulation intensity will be set at 110% of MCT for the warm-up exercise and 120% of MCT for the treatment during the one-leg stance exercise.
Balance training
BehavioralThe warm-up exercise consists of 25 repetitions of 4-second active contractions of the tibialis anterior muscle in each leg while seated. Following the warm-up, participants will stand on the MAGBATA platform and perform 20 cycles of one-leg stance exercises under the supervision of a physiotherapist. Each cycle lasts 20 seconds, consisting of 3 seconds of one-leg stance while the other leg is raised about 10 centimeters above the ground, followed by 12 seconds of rest during which the participant stands on both legs, keeping their arms close to their body and hands free. The same sequence will then be repeated for the other leg. To prevent falling, participants will wear a safety belt around the waist, allowing the physiotherapist to assist if they lose balance. Participants will also be allowed to grab the walker positioned in front of them to prevent falling.
Sham stimulation
Other interventionDuring the warm-up exercise, the stimulation coil will be placed perpendicular to the participants' shin. The same parameter settings will be used, except for the intensity, which will be set at 30% of the maximum stimulator output (MSO). Sham stimulation during the one-leg stance exercise is achieved by disconnecting the coil mounted in MAGBATA and placing an alternate coil, connected to the magnetic stimulator placed behind the participants so they can hear a clicking pattern similar to that of the rPMS-BT arm.
One-leg standing balance test (OLST)
Participants stand on the floor with their eyes open and arms relaxed at the sides of the body. They are instructed to lift the opposite foot off the floor, flex the knee to 90 degrees, and position the lifted foot behind the body, maintaining balance on the tested leg for as long as possible. The assessor begins timing when the participant's foot leaves the floor and stops timing if the participant sways, extends either arm to maintain balance, or successfully holds the position for 30 seconds. The test is then repeated on the opposite leg. The durations from each legs are reported in seconds.
Timed up and go test (TUGT)
Participants sit on a chair with a seat height between 44 and 47 cm, with their back resting against the backrest. The assessor instructs them to walk to a marked point 3 meters straight ahead and then return to sit on the chair. Timing begins when the participant's back leaves the backrest and stops when they return to the chair and their back touches the backrest. The test is performed twice, and the best performance with shorter duration in seconds, will be recorded.
Short physical performance battery (SPPB)
The Short Physical Performance Battery (SPPB) includes three subtests: gait speed, chair stand, and balance. Each test scored from 0 to 4and are summed up to give a total score ranging from 0 to 12. Gait speed: Participants are instructed to walk at their normal pace over a distance of 4 meters. The assessor times each trial from the start of walking until the participant reaches the end. Chair stand test: Participants are instructed to rise from a seated position to standing five times, keeping their arms crossed at chest level. The assessor starts timing when the participant's buttocks leave the chair and stops when they return to the seat after the fifth stand. Balance test on both feet: Participants first stand with feet together for 10 seconds to earn 1 point, then in semi-tandem with the heel beside the mid-foot for 10 seconds to earn another point, and finally in full tandem for 10 seconds to earn 2 points.
Nerve conduction study
Nerve conduction study will be performed using the electrodiagnostic unit, Sierra Summit (Cadwell, Kennewick, WA, USA). Bilateral sural and tibial nerves will be tested, measuring parameters including sensory nerve action potential (SNAP) amplitude of the sural nerves, compound motor action potential (CMAP) amplitudes of the tibial nerves, F-wave latency of the tibial nerves. The parameters of each legs are reported separately.
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Queen Savang Vadhana Memorial Hospital, Thailand
Lead sponsor
Chulalongkorn University
Collaborator
