Neuroscientists are tapping the power of virtual reality to improve recovery from a stroke.
When you strap on a virtual reality headset, your
brain is instantly convinced that it’s in a real environment. The
immersion is so complete that during tests at the Virtual Human
Interaction Lab at Stanford University, participants refused to step off
a VR bridge even though they knew that the drop was 100-percent
digital.
VR clearly messes with your mind, but can it also be
used to heal it? A Swiss company called MindMaze recently won FDA
approval to introduce a VR-based therapy in the United States that uses
virtual avatars and gamification to trick a stroke patient’s brain into
recovering faster.
Nearly 800,000 Americans a year suffer a stroke,
which is caused by a blocked artery cutting off oxygen to parts of the
brain. Without oxygen, brain cells in the affected region will die,
often resulting in partial or full paralysis of one side of the body.
Damage in the right hemisphere of the brain results in loss of movement
on the left side, and vice versa.
If post-stroke rehabilitation is initiated quickly
and effectively, some patients can recover movement in paralyzed limbs
and facial muscles by rerouting neural pathways to undamaged parts of
the brain. The best hope is to activate brain cells in the penumbra, the
area directly surrounding the damaged cells. But how do you stimulate
new brain activity if the corresponding limb is paralyzed?
One classic rehab method is called mirror therapy.
Holding a mirror down the center of a patient’s body, the patient is
prompted to move their healthy arm or leg, making it appear like the
opposite limb is moving. When neurologists track the brain activity of
healthy subjects, it’s clear that the mirror trick triggers brain
activity in the opposite hemisphere. The hope is that it can also spark
new brain connections in stroke victims.
Now MindMaze has developed a new rehab device that
brings the mirror method into the VR age. The machine, called
the MindMotion Pro, is like a hospital-grade Wii. Equipped with a 3D
motion-tracking camera, the MindMotion Pro captures a stroke patient’s
movements and displays them on a realistic virtual avatar. The device
takes advantage of the unique mind-bending power of VR, coupled with
game-like exercises, to deliver recovering times that are 35 percent
faster on average than conventional therapy.
Tej Tadi, CEO of MindMaze, said his decade-old
company has always seen virtual reality and augmented reality as
gateways to neuroscience, because they are such powerful catalysts of
brain activity.
“You’re able to present stimuli in a way that’s
ecologically valuable,” said Tadi. “It’s the difference between a
physical therapist asking you to imagine a cursor on the screen as your
hand, versus actually seeing a virtual hand that really moves like your
hand. Your brain says, ‘Listen, that’s my hand.’”
This is particularly true with the mirror therapy
exercise. In the MindMotion Pro version, there’s no actual mirror, just
the patient’s avatar on a flatscreen display in front of them. The game,
let's say for a patient with a paralyzed left arm, is to reach out and
touch a glowing green circle in the center of the screen. He reaches for
the ring with his right arm, but it’s the avatar’s left arm that moves.
The action is so simultaneous and convincing that the brain doesn’t
have time to realize it’s being tricked into action.
The virtual mirror therapy can be repeated across
many different types of actions — reaching, pointing, grabbing,
squeezing — each prompted by a different game-like interface. Since the
device can be rolled up to a patient’s bed or wheelchair, treatments can
begin just four days post-stroke.
“The neuroscience is in the content,” said Tadi,
referring to the gamified therapy exercises developed by an in-house
team. “There are so many ways to trigger those neural pathways, but the
exercises must be tailored to the patient.”
The MindMotion Pro was first introduced in Europe in
2013 and is now being used in three dozen hospitals and clinics across
the continent. Tadi said the device is popular with physical therapists
because it provides a level of quantitative feedback that’s missing from
conventional post-stroke therapy.
Therapists can access detailed performance data
measuring both time and accuracy of exercises. Also, by equipping
patients with small, motion-capture sensors, therapists can isolate and
track specific movements like the range of motion of a wrist or the bend
of an elbow.
A hospital in Lausanne, Switzerland conducted a
small study in 2015 to gauge the efficacy of the MindMotion Pro and came
back with some interesting results. Over several days of therapy,
patients made modest gains in range of motion and reported decreased
pain, but the biggest impact was on motivation. The gamification of
post-stroke therapy, reported the study, resulted in 90 percent of
patients reporting a greater desire to do their therapy, and full 100
percent saying that they “forgot they were in a hospital.”
Stroke survivors want to do more than reach out and touch an object. This was a good place to start 5 years ago, but the absence of useful goals means virtual reality continues to disappoint.
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