Repetitive peripheral magnetic stimulation for impairment and disability in people after stroke

What is repetitive peripheral magnetic stimulation (rPMS)?
Repetitive peripheral magnetic stimulation is done with a stimulation coil that generates a magnetic field. In people who experience stroke, it is placed over the paralysed muscles so that the magnetic field directs an electrical current into the neurons. Once the current achieves a certain value, an action potential is induced, causing the neuron to depolarise and the muscles to eventually contract. Stimulation with a magnetic field penetrates to deep structures and promotes brain plasticity in damaged circuits, facilitating motor movement. Intervention with rPMS allows painless stimulation of deep muscle structures, generating a proprioceptive feedback (kinaesthetic or awareness of position, motion, and equilibrium). It is contraindicated in patients with implanted medical devices, such as pacemakers or deep brain simulators, due to magnetic-field stimulation.
Why it is important for stroke?
Every year, around 23 million people experience stroke for the first time throughout the world, making stroke the third most common cause of disability‐adjusted life years (46.6 million people), affecting 87% of people with motor impairment of arm and leg. It is predicted that by 2030, 70 million stroke survivors will need long-term rehabilitation to attain maximum physical, mental, social, and vocational independence and participation in quality life. Although functional recovery remains the priority in healthcare, 76% of stroke survivors remain at home after one year due to disability. 

What does this review talk about?
This is an update of the Cochrane systematic review published in 2017, since the effectiveness and safety of rPMS intervention in stroke were non-conclusive. It aimed to assess the effects of rPMS in improving the activities of daily living and functional ability in people after stroke. It included 4 randomised controlled trials comparing rPMS with placebo-(sham)-stimulation or sham-stimulation plus rehabilitation, involving 139 participants. Outcomes measured were activities of daily living, upper-limb function, lower-limb function, spasticity, muscle-strength, and death. 

Key results
The author concludes that evidence is still insufficient to allow generalization about the effectiveness of rPMS for people with stroke. None of the studies provided information on lower limb function or adverse events (including death). So the routine use of rPMS for stroke cannot be supported by the results. 
Future studies need to verify the efficacy of rPMS involving large-scale RCTs, and larger numbers of participants (bigger sample sizes). In addition, the most optimal rPMS protocol (eligible participants, intensity, duration, and frequency) and long-term effects should be investigated for each outcome parameter. 

Who will be interested in this review?
People who have experienced stroke, family/caregivers of the patients, health professionals dealing with stroke and rehabilitation, general practitioners, and policymakers. 

Comment by Sunita Gudwani