Intention tremor, and a possible neuroplastic treatment

In stroke intention tremor is caused by damage to the cerebellum. 

The cerebellum is important in fine coordination. If the stroke damages the cerebellum fine motor coordination suffers. 

(Note: Intention tremor is different from essential tremor, often found in Parkinson's) 

It is called intention tremor because the tremor happens when somebody moves intentionally. So let's say the intended movement is touching your nose with a fingertip. If someone has intention tremor the trajectory toward the nose is good but when they get close to the nose (closer to the intended target) the tremor begins. As the New York Times put it:

Intention (or kinetic) tremors: These tremors occur at the end of a purposeful (intended) movement, such as writing, pressing a button, or reaching for an object. The tremor will often disappear while the affected body part is at rest.

Outside of stroke it is often seen long-term alcoholics. So here's my first suggestion: If you have intention tremors, don't drink. Other drugs can cause tremors as well. So, the "Brown Bag Medication Review" may help in reducing tremors.

How has intention tremor typically been treated? 

Intention tremor is notoriously difficult to treat. There are several drugs that are used for treatment, but they all work for some of the people some of the time. (Here's an example of an herbal "remedy.")

Other things that had been tried:

Physical therapy: In some people it works great to temporarily reduce tremors. It's not cure.
 

Meditation, yoga, deep breathing exercises, biofeedback have all been used with varying levels of success.

The neuroplastic model
So what is the neuroplastic model for overcoming intention tremor? I guess the first question is: Is there a neuroplastic model? Is there anything that can be done to rewire the brain "around" this movement disorder?

We will wait for neuroscience to catch up to that question. It could take decades, it could take centuries. On the other hand, somebody could come up with a really good way of applying the brain's inherent plasticity tomorrow. So you never know.

Having said all that, I still have some suggestions that may very well rewire the brain to help overcome this issue. Here are my suggestions:

Mirror therapy. This is the way that mirror therapy would be applied:

Just like in mirror therapy for movement recovery, you look only at the "good" side. That is, you only see the flawless movement of the unaffected side.

Bimanual training. This option involves having the "good" train the "bad." It's a simple enough concept; whatever the good hand does, the bad hand attempts to copy.

Recovery with a Beat

With the lower extremity "function" is inherently bilateral. That is, because the primary function of the lower extremities is ambulation, bilaterality is inherent. 

(By "advantage" I do not suggest that I buy into the concept that the lower extremities come back before the upper extremities post-stroke. This is common wisdom in rehab, but it may be incorrect. The only way to prove the lower extremity comes back before the upper extremity would be to measure the most distal element of both: the fingers and toes. Measuring toe extension in comparison to finger extension has, to my knowledge, never been done.)

Beyond bilaterality, ambulation is also inherently rhythmic. The rhythm after stroke is disrupted and made unequal. And rhythm is what bilateral leg training with rhythmic auditory cueing attempts to re-establish in the lower extremity.

That is, if you re-establish the rhythm of gait, you will go a long way to re-establish symmetry of both step length and step timing.

There are commercial systems that use a heel switch so that the moment of heel strike is radio-delivered to headphones. The patient hears their own heel strike through the headphones, as well as a beat that they have to match with each heel strike.

But as is true with many technologies purported to help stroke survivors relearn movement, no special system is really needed to bring the idea of rhythmicity into gait.

A simple metronome either heard through headphones or carried by the therapist next to the stroke survivor can be used to promote the re-establishment of rhythmicity of gait. Plugging the ears using standard noise-reducing plugs can boost the volume of footfall to make that obvious to the survivor. The trick is then to match the footfall to the beat. 

Details are the devil

Because it involves the brain, stroke recovery is complicated. The brain is complicated, so anything that involves the brain is complicated as well.

Except that's not true. And it's more than not true. Complexity, when it comes to stroke recovery, is evil. 

Of course, complexity is out there if you want it. There are "treatment options" that force therapists to spend thousands of dollars and weeks of their life getting trained in the devil in the details. Some of these treatment options have been around for 40 years, but new ones are invented every year. Do these therapies work? They generally fall into two categories; 1. Been around forever, the data doesn't look good. 2. They're completely untested.

Anyhoo... with regard to stroke, complexity is evil. Complexity separates the survivor from recovery. Why? It turns out that no matter what any clinician is telling you, only you can make you better. Remember the old-fashioned way of saying "teach me?" It was "learn me." Learn me to do math. No one can you learn you stuff. You have to learn it. That seems rational to just about everyone when it comes to learning that involves the brain; things like learning math and chemistry and French. But for some reasons when we talking about movement, its not considered learning. But it is.

• Learning math involves changes in the structure and function of neurons in the brain. So does learning how to move.
• Learning math involves neurons in the cortex (the outer shell of the brain). So does learning how to move.
• Learning math involves repeated attempts towards the correct outcome. So does learning how to move.
• Learning math increasing complexity. So does learning how to move.

How complexity kills recovery.

• If instructions from a clinician are complicated ("Move your arm up but keep you shoulder down now turn your hand blah blah blah") movement performance gets worse.
• If the pieces that go into recovery are complicated the survivor will not be able to drive their nervous system towards recovery. Complexity make it impossible for survivors to work towards recovery on their own.
• Learning complicated treatment options ties up clinician's scarce education resources (time and money).

In every sense of the word, regaining the ability to move after stroke is learning. People, especially clinicians, want to talk about muscle weakness. "These exercise will help you move better." No they won't. What helps you relearn how to move after stroke is moving, not exercise. Of course, there's a fine line between the exercise and movement needed to relearn movement. But the emphasis on trying to build muscle is as mistaken as changing the oil in a car with no gas: Its a good thing, but hardly the main issue.

Try: to attempt to do or accomplish

Here is clarification of a paragraph in the previous post:

Of course, there's a fine line between the exercise and movement needed to relearn movement. But the emphasis on trying to build muscle is as mistaken as changing the oil in a car with no gas: Its a good thing, but hardly the main issue.

This difference between exercise and repetitive practice (movement needed to relearn movement) may seem like a distinction without a difference. In fact, both build muscle and both drive plastic changes in the brain. The distinction is in the focus. Repetitive practice paradigms focus on driving changes in the motor and sensory cortices of the brain, not specifically in changes in muscle strength. Sure, muscles will build. But focusing on strengthening is like climbing a ladder to the top only to find the ladder is leaning against the wrong building. Stroke is brain damage. And, unlike most other forms of acquired brain injury, stroke involves just one part of the brain. So if a survivor is, say, 2 years post-stroke and they can’t open their hand and then, later they can, that is not a reflection of muscular strength. It is a clear indication of a change in the brain. The muscles have been there all along. Muscle strengthening is the easy part. 

Clinicians often sweat the fact that survivors have limited energy for therapy. But does it need to be very strenuous to be beneficial? No! The ability to open the hand (or lift the foot or straighten the elbow or move the mouth) can be done while sitting in a comfy chair. Each attempt should be focused and deliberate. The very ends of the movement should be the point of focus. Each attest is measured as a success if it is just beyond the previous attempt.

Exercise helps recovery because it strengthens what?

Interesting video, below, by one of my favorite neuroscientists, Dale Corbett.  For the record: There is no one I know up doing a better job of translating what neuroscientists have to offer to stroke recovery. Have a watch. The insights really start at 1:40 in. I'll post my critique below the video.  

The overall message is important. Exercise is essential. It is unfortunate that the message is sort of convoluted in this video. They're talking first about TIA, and how if you have a TIA you should use exercise as a way to lessen the chance of a full-blown stroke. Then the discussion takes an obtuse tangent into how exercise is important to recovery, and then with no real explanation doubles back to talking about TIA again. Still, while maybe the messages should have been separated, both are important. 

1:50 Another person, besides Corbett, whose interviewed in this video is William Mcillroy, who like Corbett is a PhD. I quibble a bit with Mcillroy's statement that exercise can be started "...as short as two weeks after stroke." Charitably, this is highly debatable. Once a patient is medically stable, intensity should be increased to tolerance. There is no one-size-fits-all timeline for every survivor that is rigid enough to predict that someone can start exercise "as short as two weeks after stroke." In fact, it could be much shorter. For instance, in a survivor who is medically stable day 4, waiting another 10 days to start a progressively rigorous exercise program would allow learned nonuse to take hold. 

2:20 Both PhD's talk about how exercise is good for the brain. Corbett talks about how exercise helps cognition, and points out exercise also helps sensory motor recovery. I would remind anyone who is willing to listen: sensation and motor behavior are cognitive. We learn sensation and movement the same way we learn French, or trumpet, or algebra. That is, changes in motor and sensory behavior happen involve the same brain processes as any other kind of learning.

2:50 I'm not sure that there should be such an unequivocal endorsement of balance retraining using biofeedback. Certainly the research is not there yet. 

Having said all that, I think this is a really great video with some really essential points. Interviews can be misrepresented because the person being interviewed is not doing the editing. The points these guys were making may have been a ton more cogent in the original interviews. 

The best line is by Dr. Corbett: 

 "It's still early days and you know we're nowhere near to the level that I think we can get to. And if we can understand what the mechanisms are then we might be able to optimally better design exercise programs to improve stroke recovery." 

"Until then, anyone trying to sell you certainty is after your wallet," he didn't add.