From the Editor
There are a lot of reports on the Internet of people with dystonia who have managed to reduce their spasms or change the pattern of their spasms through one form or another of corrective exercises. Some are able to correct deviations of the head, for example, by concentrating on a good body posture at all time. Others have gone through intensive physiotherapy and found that they are able to regain a certain control over their affected muscles. Others still, using biofeedback or visualization techniques are now able to do things they were not able to do before, such as moving their head in all directions with ease or walking without it being an unpleasant experience. One of our group member, working with his neurologist, tried various methods to immobilize the neck for a prolonged period of time, with the result that the spasms have decreased slightly and some of the twitches have disappeared completely.
We are told that this has to do with the "plasticity" of the brain – some parts of the brain that are affected by dystonia can somehow be remolded or remapped. So we have asked Rosalie Labelle, who has a Master's degree in Neuroscience and has recently joined our group of volunteers, to look into this and tell us what science has to say on this matter. As you can see in this article she wrote for us, it turns out that recent findings regarding brain plasticity and dystonia shed a new light on our movement disorder and point to encouraging prospects for future therapies that may help improve, if not cure some forms of dystonia.
Of course this is simply part of our ongoing effort to try to understand dystonia better and support our members in their attempts to improve their situation when everything else fails. For the time being, Botox and medications remain the most effective treatments for dystonia, but many are looking at other ways to decrease their spasms. For some, Botox no longer works and for others medications have become too difficult to live with.
On behalf of the group I would like to thank Rosalie for this excellent report.
Yvon
Dystonia and Brain Plasticity
by Rosalie Labelle
(for the Newsletter of the Ottawa Area Dystonia Support Group)The brain is plastic. Connections in the brain can organize and reorganize in response to experience or sensory stimulation (Kolb and Whishaw, 1998). While the brains' plastic nature is positive and adaptive, it can also be maladaptive. The ability of the brain to remap itself is of interest to researchers studying dystonia.
The somatosensory cortex of the brain receives information regarding bodily sensation such as touch. The inputs from different body parts are laid out in an orderly arrangement that segregates information from adjacent areas (ie the hand and wrist) in adjacent parts of the cortex (Holmes, 1999). A similar topography exists in the motor cortex, where nearby brain areas control neighbouring muscle groups (Holmes, 1999).
Researchers believe that there is a disorder of sensory function in dystonia (Hallett, 2000, and Byl et. al., 2000). A role of the sensory system is to drive the motor system; hence disordered sensation can lead to disordered movement (Hallett , 2000). Byl et. al. (2000) report degradation in hand representation (ie disorganized electrical activity) in the somatosensory cortex of a flutist with focal hand dystonia when compared to the hand representation of a healthy flutist. Other studies in humans support these findings (Elbert et. al., 1998 and Bara-Jimenez et. al. 2000).
Studies on monkeys indicate that brain changes can be pathological and lead to motor dysfunction. Monkeys developed movement control disorders following completion of training that required them to carry out rapid, repetitive, highly stereotypic hand movements (Byl et. al., 1996). Degraded hand representations were found in the somatosensory cortex of the monkeys (enlarged, overlapping receptive fields). This study showed that the brain is constantly refining maps and may confuse the information when repeated rapid movements happen simultaneously, leading to diminished control over hand movements. Merzenich and colleagues found rewiring in the brain's sensory body map in monkeys following training that required them to use their hands repetitively. After training it was found that the usually precise map in the sensory cortex had blurred so that a single neuron might respond no matter which finger they touched, indicating that the brain had rewired and lost resolution (Holmes, 1999).
Maladaptive brain changes have been reported by Nudo et. al. (1996 ) in the motor cortex of monkeys following rapid, stereotyped, learned hand movement. The muscles the monkeys used responded to stimulation over a larger patch of the motor cortex. Before training each spot on the cortex had controlled just one muscle. After training some spots controlled two or more muscles that the monkeys had used to simultaneously perform the task that they were trained to do. The cortex now treated the compound muscle movements as a single stereotyped action, displaying overlapping regions that now controlled muscles of the wrist and fingers (Holmes, 1999). The muscles were no longer able to act with precision and movement control disturbances resulted.
Byl et. al. (1996) proposed that human focal hand dystonias could be treated by making use of the brain's ability to make positive, adaptive changes. According to Byl in order to change the nervous system a task has to be highly attended and repetitive. While tasks that are highly attended, very ritualistic, repetitive and near simultaneous will lead to degradation, tasks that are highly attended, repetitive and variable lead to improved performance (Ryl, 1999). Byl's training exercises (ie to play dominoes by feel) forced patients to make more delicate discriminations with their fingers in order to help them to relearn fine distinctions between neighbouring finger representations in the cortex. Following their training patients displayed lasting improvements in function. Brain scans of one patient before and after therapy showed that the sensory map was moving towards a more normal arrangement (Holmes, 1999). Recent reports support Byl's findings. Zeuner et. al. (2002) reported that 60% of patients with focal hand dystonias, who were trained in Braille reading, required shortened times to write a standard paragraph.
Byl's results are promising and suggest that traditional treatments for focal hand dystonia should be reassessed. Byl's retraining requires high levels of repetition, and thus it may not be the type of task that all patients are willing to perform (Rayl, 1999). Some authors believe immobilization and rehabilitation might boost each other, leading to improved therapy (Priori et al., 2001). Priori and colleagues (2001) state that limb immobilization for the treatment of severe dystonia of the hand and forearm, probably acts by prompting inactivity dependent plastic changes, reversing the functional abnormalities present at the cortical level. In nondystonic subjects prolonged limb immobilization causes the motor cortical representation of the immobilized limb to shrink. Priori believes that prolonged immobilization would normalize the abnormally enlarged cortical representation of dystonic muscles. Priori et al state that their observations fit with the hypothesis of activity dependent neuroplasticity. In their protocol inactivity dependent neuroplasticity (a sort of detraining) would be beneficial to focal dystonia sufferers because prolonged immobilization would normalize the abnormally enlarged cortical representation of dystonic muscles.
Retraining experiments have focused on focal hand dystonia, thus the consideration of the application of Byl's principals for the treatment of other forms of dystonia would be of interest. Retraining methods have been used in the treatment of spasmodic torticollis. De Benedittis (1996) found that hypnosis and biofeedback could be used successfully to retrain neck muscles to reduce symptoms in four patients with spasmodic torticollis.
Retraining studies that make use of the brains’ plastic nature have been successful at reducing the symptomology of focal hand dystonias in humans. These studies indicate that traditional methods for the treatment of focal hand dystonias require re- evaluation in light of new findings.
Literature Cited
Bara-Jimenez, W., Shelton, P. and Hallett, M. 2000.Neurology. Spatial discrimination is abnormal in focal hand dystonia. V. 55 (12) pp 1869-1873.Byl, N.N., McKenzie, A. and Nagarajan, S.S. 2000. Journal of Hand Therapy. Differences in somatosensory hand organization in a healthy flutist and a flutist with focal hand dystonia: a case report. V. 13 (4) p 302-309.
Byl, N.N., Merzenich, M.M. and Jenkins, W.M. 1996. Neurology. A primate genesis model of focal dystonia and repetitive strain injury: I. Learning induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys .V. 47 (2) pp 508-520.
De Benedittis, G. 1996. International Journal of Clinical and Experimental Hypnosis. Hypnosis and spasmodic torticollis--report of four cases: a brief communication. V. 44 (4) pp 292-306.
Elbert, T., Candia, V., Altenmuller, E., Rau, H., Sterr, A., Rockstroh, B., Pantev C. and Taub, E. 1998. Neuroreport. Alteration of digital representation in somatosensory cortex in focal hand dystonia. V. 9 (16) pp 3571-3575.
Groves, P.M. and Rebec, G.V. 1988. Introduction to Biological Psychology. Wm. C. Brown Publishers. USA.
Hallett, M. 2000. Brain. Disorder of movement preparation in dystonia. Vol. 123, No. 9. pp 1765-1766.
Holmes, B. 1999. New Scientist. The strain is in the brain. V. 162, issue 2181. p26.
Kolb, B. and Whishaw, I.Q. 1998. Annual Review of Psychology. Brain plasticity and behavior. V. 49 pp 43-64
Nudo, R.J.et. al. 1996. Journal of Neuroscience. Use dependent alterations of movement representation in the primary motor cortex of adult squirrel monkeys. V. 16. pp 785-807.
Priori, A., Pesenti, A., Cappellari, A., Scarlato, G. and Barbieri, S. 2001. Neurology. Limb immobilization for the treatment of focal occupational dystonia. V. 57 (1 of 2) pp 405-409.
Rayl, A.J.S. 1999. The Scientist. Research: Recent Findings Lead to New Understanding of Dystonia. V. 13 (3): 14.
Zeuner, K.E., Bara-Jimenez, W., Noguchi, P.S., Goldstein, S.R., Dambrosia, J.M. and Hallett, M. 2002. Annals of Neurology. Sensory training for patients with focal hand dystonia. V. 51 (5): 593-598.
* Rosalie Labelle is a volunteer with the Ottawa Area Dystonia Support Group and has a Master's Degree in Neuroscience.
For information: Yvon Breton, Hull, Quebec