Dystonia: The Syndrome, Its Term, Concept and Their Evolution

Abstract

At the end of the 1970s, dystonia was seen as something peculiar, balancing on the edge between organic disorder and psychiatric condition. The everlasting enigma of dystonia has been breeched for the first time by David Marsden, who attributed the clinical syndrome to a disorder of basal ganglia functioning. As he postulated in the seminal work regarding the natural history and clinical presentation of dystonia, dystonia is a syndrome of sustained involuntary muscle contraction, frequently causing twisting or repetitive movements or abnormal postures. Although a new definition of dystonia has been recently adopted, Marsden’s concept is still a cornerstone of it. One can undoubtedly characterise the dystonic movement as a result of volitional (albeit unconscious) motor action. There is enough evidence that dystonia is the “normal” motor action abnormally accompanied by the action of antagonists, or by the co-contractions of inappropriate muscles, and by the defective reciprocal inhibition of other muscles. As a result, there is a dystonic movement or dystonic posture appearing as final vector of that deviant muscle activity. Dystonia does not look like a chaotic medley of contractions and muscle relaxation, as do a majority of other hyperkinetic movement disorders. Dystonia rather looks like a highly (albeit aberrantly) organised motor performance. The motor action seen in patients with dystonia is apparently not a result of several abnormal contractions or muscle jerks. It is complex dyskinesia, which only sometimes changes character over time. Named “a shadow of movement” by Rondot more than 20 years ago, dystonia was proposed as a primitive “kind of movement”, similar to that which can still be seen in other primates. The motor action itself was seen as a “dystonic way back” in the phylogenetic history of motor action. In Rondot’s view, dystonia is something that is constantly present in the mature human motor system, but which can only be seen in particular circumstances, for instance in the case of basal ganglia lesion (or other basal ganglia involvement, as in the case of idiopathic dystonia). Nevertheless, all recent and current physiological indices are only pieces of a puzzle. We believe that once completed, this jigsaw will show idiopathic dystonia in the frame of defective programming and organisation of motor action due to defective somatosensory flow consequent to defective sensorimotor integration or brain plasticity, in which the movement itself is perfectly performed.