Movement Disorders: Focal Dystonia
Guest: Dr. Vanessa Hinson - Neurology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. Today, I’m interviewing Dr. Vanessa Hinson who is Assistant Professor of Neurology and Director of the Movement Disorders Program here at the Medical University of South Carolina. Dr. Hinson, let’s talk, now, about focal dystonia. We talked earlier about generalized dystonia and you’d explained that a focal dystonia is just one portion of the anatomy. Can you give us, again, some examples of focal dystonia?
Dr. Vanessa Hinson: Focal dystonia most commonly affects the neck, and we call this cervical dystonia or spasmodic torticollis. It usually starts with something as generic as neck pain but then the patient, later, notices some excessive pulling of the neck muscles, maybe to one side, maybe their shoulder is pulling up towards their ear, and their movement in the neck might be restricted. Another symptom of cervical dystonia can be a head tremor, because if the neck muscles pull one way or the other, left and right, one can imagine that a shaking or a tremor can be produced by the musculature. So, basically, these patients present to me with persistent abnormal muscle contractions in their neck that lead to pain and painful postures.
Another example would be writer’s cramp which is an abnormal muscle contraction in the hand muscles that only occurs with writing, interestingly. So, with other hand functions, the hand function is completely normal, but once a patient takes a pen in their hand and attempts to write, the index finger, for example, or the thumb, might slide off the pen or they might just get a very tight sensation in the hand. They’re unable to complete the writing that they want to do. They might also just be shaky or tremulous. But the clue here is, it’s somewhat painful and it only occurs with writing.
And then another very important example, because it’s common, is blepharospasm. blepharospasm is a dystonia of the eye muscles. Patients that are affected by blepharospasms get excessive eye blinking. The eyes might be completely shut when they want to read a book or watch TV, and this is exacerbated by bright sun light. A lot of my patients actually wear sunglasses all the time to get some protection from that. This is a very common form of focal dystonia.
Dr. Linda Austin: What are some of the causes of focal dystonia?
Dr. Vanessa Hinson: We don’t exactly know, in most cases, what causes a focal dystonia. Very rarely we find a genetic family trait of focal dystonias. Most patients are what we call idiopathic, where something like a blepharospasm or a neck dystonia just happens to them and we don’t really know why. Another minority of patients develops a dystonia after a trauma. So, for example, if somebody is in a car accident and their neck gets hurt, it is possible that the patient, several months later, develops a neck dystonia.
And then the question is why people develop this writer’s cramp. There is a theory that says maybe there’s overuse of the hand. So, people who do a lot of handwriting on their job, for example, are more prone to develop a writer’s cramp than somebody else.
Dr. Linda Austin: Is a writer’s cramp always in the hand that’s used for writing?
Dr. Vanessa Hinson: It can, interestingly, also affect the other hand. So, somebody who’s right-handed and gets the cramping with writing with the right hand, after years of that might also develop writer’s cramp with the left hand, even though they’ve never used their left hand for writing. And that shows you that it’s really a brain disorder and not a disorder of the peripheral hand musculature. So, a body part that has never been used can still be affected by the dystonia.
Dr. Linda Austin: But does it always start in the dominant hand?
Dr. Vanessa Hinson: I’ve never seen it start in the non-dominant hand. That’s correct. I guess somebody wouldn’t notice it because they wouldn’t write with their non-dominant hand necessarily.
Dr. Linda Austin: But they might do other things.
Dr. Vanessa Hinson: Right, but it’s specific to the writing task.
Dr. Linda Austin: This sounds like an odd question, I’m sure, but do animals get focal dystonias?
Dr. Vanessa Hinson: We don’t know that. They don’t complain enough.
Dr. Linda Austin: (laughter) I’m just curious as a psychiatrist, wondering if there are any psychological components to it. I mean, you would think that they might be prone to, say, a torticollis.
Dr. Vanessa Hinson: It has not been observed in the animal world and we don’t even have a good animal model for focal dystonias. What is interesting to mention here is that musicians develop focal dystonias. For example, some people have what we call embouchure dystonia, which is a dystonia of the mouth muscles that play the trumpet professionally. Their lip muscles get into dystonic spasms and they can no longer play the instrument. There are famous piano players who have developed hand dystonia only while playing the piano. They have not problems writing. They can cut up their food, button their shirt, but they cannot play the piano.
Dr. Linda Austin: Then, I can’t resist, as a psychiatrist, asking this question. Do you think there is any psychological component to this?
Dr. Vanessa Hinson: I think this is clearly organic. It is worsened by stress, but many disorders are. I don’t think this is a psychosomatic problem. When you record the EMG, which is an electrical test of the musculature, you can see abnormal discharges that could not possibly be produced just by a psychological or emotional origin. Basically what we’re seeing in dystonic muscle contractions are simultaneous contractions of agonist and antagonist muscles, which are muscles that are pulling in opposite directions. A healthy brain cannot activate these muscles at the same time. Only the dystonic brain is able to actually activate the antagonist and agonist muscles at the same time.
Dr. Linda Austin: And yet it’s somehow connected to pathways that are used a lot. It sounds like it.
Dr. Vanessa Hinson: In some cases.
Dr. Linda Austin: Certainly not in all cases. That’s right.
Dr. Vanessa Hinson: In most cases, there’s absolutely nothing that triggers the dystonia. It just happens and nobody knows why.
Dr. Linda Austin: It must be so frustrating for the people who have it.
Dr. Vanessa Hinson: It’s very frustrating. The good news, though, for patients with focal dystonia is that there are very effective treatments, in most cases, especially for cervical dystonia and blepharospasm. The preferred treatment right now, and this is available at MUSC, are injections with botulinum toxin. There are two products on the market, two forms of botulinum toxin. One is very famously known as Botox, and the other one is Myobloc. These injections were developed for the treatment of focal dystonias.
We have a botulinum toxin specialty clinic at MUSC that offers this form of treatment. It’s very easy to administer. We inject the patient about every three to four months or three times a year. The toxin treatment is effective for three to four months, so patients don’t need to swallow a pill everyday. They just come to us about three to four times a year and get very significant relief. I usually have them fill out surveys. They answer how they respond to treatment, and usually that’s in the range of 70 to 90 percent improvement.
Dr. Linda Austin: But I wouldn’t think you could do that for writer’s cramp, could you?
Dr. Vanessa Hinson: You can. It is more difficult and we’re usually not quite as successful. We get responses in the range of 30 to 40 percent. The risk, if you inject somebody’s hand muscles with botulinum toxin, is that it weakens the hand muscles. So, if the hand gets excessively weak, it would obviously not be functional. The trick here is to find the muscle that is responsible for the dystonic movement with an EMG, which is a machine the records the muscle activity, isolate that muscle and only put the Botox in that muscle and nowhere else.
Dr. Linda Austin: It sounds as if it’s often, though certainly not always, associated with what one might think of as maybe an overuse situation or at least unnatural use. I mean, animals, for example, don’t practice the piano for hours a day. They don’t do repetitive things. Am I correct about that, that sometimes, at least, it’s where there’s been a lot of repetitive movement or use of a particular muscle?
Dr. Vanessa Hinson: Yes. Dystonias sometimes occur in instances where there’s repetitive use of a muscle, for example, in musicians who develop dystonia or, as we discussed, the writer’s cramp. In most patients though, we can find that out. Most of our patients have the cervical dystonia, and we all turn our head left and right, but it’s hard to define what would be an overuse of the neck musculature, unless there was trauma.
Dr. Linda Austin: Dr. Hinson, thanks so much for talking with us.
Dr. Vanessa Hinson: Thank you.
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