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Research Shows How a Stroke Affects Hand Function

Focus: Stroke

Research Shows How a Stroke Affects Hand Function

15/06/2009

Gripping the keys is often difficult
after a stroke © SXC

A person whose hand function has been affected by a stroke can release an object more quickly when the affected arm is supported on a platform, but the support does not make it easier to grip the object, according to a new study.

The study also found that active muscle-stretching exercises improved how quickly the stroke survivor could grip an object, but made release of the object more difficult. These findings show how a stroke affects hand function, and provide a roadmap for rehabilitation.

Stroke is a leading cause of long-term disability among American adults. People who have suffered strokes often experience hand impairment, including significant delays in how long it takes to grip and release objects.

The study included 10 people with severe hand impairment because of a stroke. The study also included five healthy people as controls. The study participants sat in front of a cylinder that they gripped as quickly and as strongly as they could when they heard an auditory signal. The researchers instructed them to release the cylinder as quickly as they could when the signal stopped. The researchers recorded grip initiation and release by using an electromyogram, which detects muscle activity.

The study found that the speed of grip and release was impaired in both hands for those who suffered a stroke, even though only one hemisphere of the brain had been injured. They found that stroke survivors could grip the cylinder much more quickly than they could release it.

The researchers also looked at grip initiation and grip termination when the stroke survivors used a device that supported the arm on a platform, leaving the hand free. They found that the device helped stroke survivors release the cylinder more quickly. With the device, they were able to reduce the delay in grip termination by 37%. The device made no significant difference in the time needed to initiate the grip.

The assistive device compensates for gravitational forces, thereby supporting the weight of the arm and permitting relaxation of the muscles of the arm and shoulder. This allows the stroke survivor to more easily control the muscles of the fingers, wrist and hand, Dr. Seo said. She also noted that a special device may not be necessary. Supporting the paretic arm with the non-paretic arm, or using a table to support the arm, may do just as well.

REHACARE.de; Source: Journal of Neurophysiology

- More about the Journal of Neurophysiology at: http://jn.physiology.org