Does Constraint Induced Movement Therapy Improve Arm Recovery?

Hemiplegia (weakness on one side of the body) can be a huge cause of disability following a stroke.  This can make activities such as grasping, reaching, and manipulating objects difficult, if not impossible. Constraint Induced Movement Therapy has been well documented to have a positive impact on the quality of arm movement. On the other hand, there is much less convincing evidence that it improves overall disability or burden of care.

All that being said, it is still an extremely valuable treatment strategy with several studies reporting positive brain changes.  Therefore, CIMT is definitely one of many tools that should be explored as a potential option as part of stroke rehabilitation program.

What is Constraint-Induced Movement Therapy?

CIMT includes a combination of restraining the uninvolved arm and “forcing” intensive use of the involved (or affected limb).  Types of restraints include a standard arm sling, a splint combined with a resting hand splint, or a glove.

History of Constraint-Induced Movement Therapy (CIMT)

The concept that lay the foundation for CIMT was first documented by a German Scientist Munk in 1908.  Munk reported that non-human primates would use an impaired arm if forced to do so for a purposeful or meaningful activity. 

Several years later, (mid 1960s) this information was utilized to conduct studies with monkeys who had an injury to one hemisphere of the brain. In these later studies the animal’s “better arm” was constrained.  As a result, they showed that under these conditions the monkeys would use the impaired arm.

And again in the 1980s this idea re-emerged with the work of Edward Taub, PhD, a behavioral neuroscientist, and his associates.  Taub and his associates reported that constraining the involved limb could reverse the effects of “learned non-use”.  

What is a standard CIMT protocol?

1. Intensive graded practice with the involved arm with activities aimed at task-specific use for up to six hours a day for two weeks.

2. Immobilizing the uninvolved arm during 90% of the waking hours.

Unfortunately, there are several reasons this protocol is not practical.  First, due to insurance limitations and financial constraints, six hours of therapy per day is no possible.  Second, asking patients to adhere to a protocol for 90% of their waking hours makes patient compliance (adhering to the protocol outside of therapy) a problem.  And, finally, there is some concern for safety. For example, a few studies have reported arm burns caused by an iron.

Due to these factors, a modified CIMT protocol was created and has some moderately convincing evidence that it is equally effective as the traditional CIMT

What is a modified CIMT protocol?

1. Patients attend therapy three days per week for ten weeks where they perform goal-directed activities

2. Patients are asked to wear a mitt on the uninvolved hand for five hours per day (Monday through Friday) for the same ten week period

Compared to traditional CIMT, this protocol is less costly and is easier to implement. However, I have my doubts that the outcome is the same as a the traditional protocol. First, I think the non-compliance is far greater with this protocol.  In addition to compliance issues, the dramatic decrease in therapy time make me doubt the claims that his protocol is equally effective. 

Why does CIMT work?

Two main reasons why CIMT works.

Neuroplasticity

Neuroplasticity is the brain’s ability to reorganize after injury. One critical component of “brain rewiring” is repetitive practice.  Clearly, with the number of hours spent “training” with a (traditional) CIMT protocol, the numbers would speak for themself. In other words, more time practicing will yield more learning. This would be very similar to elite athletes, who also play a “numbers game”.  The “Michaels Jordans” and “Kobe Bryants” put in more numbers perfecting their craft to achieve their level of success.

Similarly, CIMT, when compared to “traditional” physical therapy, involves more time “training” each week.  Therefore more “learning” and positive brain changes are possible.

Learned Non use

A stroke survivor recognizes early on that it is “too difficult” to use the involved arm and therefore learns ways around that.  We call this compensation. Once the brain establishes that there is an easier way, it will take the path of least resistance.  This is a form of learned nonuse. And actually you do get neuroplastic changes. Unfortunately the neuroplasticity (rewiring) that occurs actually occurs on the undamaged side of the brain.

Studies of CIMT, if started early, claim that you prevent learned non-use.  As learned nonuse becomes more “engrained” into the “hard drive” of the brain, they actually see that the damaged side of the brain is further suppressed. It is important to note that this is different and separate from damage caused by the stroke. These negative changes are seen much later in recovery and therefore are (partially) preventable.