People who have a stroke seem to recover faster when they use a mirror to create the illusion that their paralyzed limb is moving alongside a healthy one, a Japanese researcher said Friday.

"The mental aspect of rehabilitation has far greater importance than previously understood and should be paid far more attention," Kazu Amimoto of Tokyo Metropolitan University said in a statement.

Amimota presented his findings on the therapy at the World Stroke Conference in Vienna.

A stroke is a brain injury caused by a lack of blood that deprives the brain of oxygen and glucose. People who have had a stroke often develop hemiplegia — paralysis of one side of the body.

Traditionally, stroke patients take therapy to stimulate and exercise the paralyzed half of their body.

In the mirror approach, a mirror is placed on the middle of the patient's body so that movements from the healthy limb appear to be mimicked by the paralyzed arms and legs.

The optical illusion seems to stimulate the brain and improve motor function in paralyzed areas, Amimoto said.

Research using functional magnetic resonance imaging and stimulation of the cortex also point to the importance of integrating motor and sensory aspects for limb movement.

In Amimoto's study, 14 stroke patients worked on bending their foot joint while researchers measured the degree it bent and how long it took.

When subjects used a mirror, there was a 0.9 degree improvement in the angle of bending and a 12 per cent acceleration in movement, compared with the conventional approach, Amimota told the conference.

The warning signs of a stroke include:

• Sudden numbness or weakness in the face, arm or leg, especially on one side of the body.
• Sudden confusion, trouble speaking or understanding.
• Sudden difficulty seeing.
• Sudden trouble walking; dizziness, loss of balance or co-ordination.
• Sudden, severe headache with no known cause.

Strokes afflict 50,000 Canadians each year.