Many people survive a stroke but continue to struggle with an arm or hand that does not work as it once did.
A new rehabilitation system developed by researchers at the Medical University of Vienna and ETH Zurich may offer another way to help. It combines virtual reality exercises with gentle electrical stimulation of nerves in the skin.
The technology, called MultiSensy, was tested in a small randomized clinical study involving people who had experienced a stroke more than three months earlier. The results were published in the journal Nature Medicine. Participants using the system showed improvements in movement, touch and awareness of their affected arm.
A stroke happens when blood flow to part of the brain is blocked or when a blood vessel in the brain bursts. Brain cells can then become damaged because they are deprived of oxygen and nutrients. The effects depend on which part of the brain is injured and how severe the damage is.
Problems with an arm or hand are common after stroke. A person may have weakness, poor coordination or difficulty performing simple tasks such as reaching for a cup, holding a fork or fastening clothing. Some people also lose part of their ability to feel touch or accurately sense where their arm is positioned.
Rehabilitation can help the brain relearn skills by repeatedly practicing movements. Physiotherapists and occupational therapists commonly work with stroke survivors to improve strength, movement and independence. However, recovery can slow over time, and some people are left with long-lasting disability despite months of therapy.
The researchers designed MultiSensy to train more than movement alone. Patients wear virtual reality goggles and see interactive activities in a digital environment. The exercises involve actions such as reaching, grasping, pinching and turning the forearm.
At the same time, electrodes placed on the skin deliver carefully controlled electrical signals to sensory nerves. These signals are timed with what happens in the virtual world. When a patient touches a virtual object, for example, the stimulation can create a sensation that helps make the digital interaction feel more physical.
The goal is to reconnect three important parts of recovery: movement, sensation and awareness of the body. After a stroke, these abilities can become disconnected because the brain networks that once handled them have been damaged. Training them together may give the brain stronger information to use while it adapts after injury.
The system can also be adjusted to match each person’s abilities. Someone with severe weakness can receive different tasks from someone who already has better control of the hand. This personalized approach may help keep exercises challenging without making them impossible or discouraging.
The study included 34 stroke survivors. Some participants trained with MultiSensy, while others received conventional rehabilitation that included physiotherapy and occupational therapy. Both groups completed 12 sessions over three weeks.
Researchers used established clinical tests to measure changes in arm and hand ability. On one widely used test of upper-limb movement after stroke, the people using MultiSensy improved by nearly twice as much as those receiving conventional rehabilitation.
Another test of practical arm and hand tasks also showed greater improvement in the MultiSensy group.
The benefits were not limited to movement. Some stroke survivors have difficulty feeling touch in the affected hand, while others may feel that their arm has an unusual size, shape or position. Participants receiving the new treatment also showed improvements in touch and in how they perceived their affected arm.
MultiSensy has another possible advantage because it records movement during every training session. This gives therapists objective information about how a patient is performing rather than relying only on occasional clinical tests. In the future, such data could help therapists adjust exercises as a person’s abilities change.
The researchers believe this type of system could eventually make rehabilitation more personalized and perhaps easier to provide outside specialist clinics. A home-based version could be especially useful for people who need long periods of therapy but have difficulty traveling frequently to rehabilitation centers.
The findings are encouraging, particularly because the participants were already months beyond their strokes. They suggest that the brain and body may still respond to carefully designed rehabilitation well after the early recovery period. Combining meaningful movement with sensory feedback may be one way to support that continuing recovery.
However, the study was designed mainly to test whether the approach was practical and showed enough promise for further research.
With only 34 participants and three weeks of treatment, it cannot yet establish how well the system would work for the wider stroke population or whether improvements last for months or years. Larger clinical trials will be needed before MultiSensy could become a routine treatment.
Even so, the research offers an interesting direction for stroke rehabilitation. Instead of training an affected arm only to move, future therapy may help patients move, feel and recognize their limb at the same time.
That more complete approach could ultimately help some stroke survivors regain abilities that conventional rehabilitation has been unable to fully restore.
Source: Medical University of Vienna and ETH Zurich.
