Chap. 4. If the muscle contraction is frequent and prolonged, it is accompanied by an aching pain that may mistakenly be blamed for the spasm and the involved muscles may gradually undergo hypertrophy. Worsening under conditions of excitement and stress and improvement during quiet and relaxation are typical of this group of disorders and contributed in the past to the mistaken notion that the spasms had a psychogenic origin.
The most frequent and familiar type is torticollis, wherein an adult, more often a woman, becomes aware of a turning of the head to one side while walking. Usually this condition worsens gradually to a point where it may be more or less continuous, but in some patients it remains mild or intermittent for years on end. When followed over the years, the condition is observed to remain limited to the same muscles (mainly the scalene, sternocleidomastoid, and upper trapezius). Rarely, the torticollis is combined with dystonia of the shoulder, arm, and trunk; tremor; facial spasms; or dystonic writer’s cramp.
Other restricted dyskinesias involve the neck in combination with facial muscles, the orbicularis oculi (blepharospasm and blepharoclonus), the throat and respiratory muscles (spastic dysphonia, orofacial dyskinesia, and respiratory and phonatory spasms), the hand in writer’s cramp (graphospasm) or musician and other performing artist’s dystonia, and proximal leg and pelvic-girdle muscles, where dyskinesia is elicited by walking. All these conditions and their treatments are discussed fully in Chap. 4.
Other Forms of Hereditary Dystonia
Several familial movement-induced (kinesogenic) dystonic syndromes and a type that is not kinesogenic and arises suddenly in adolescence, at times with parkinsonian features, have been described. There are other degenerative diseases that combine hereditary dystonia with neural deafness and intellectual impairment (Scribanu and Kennedy) and with amyotrophy in a paraplegic distribution (Gilman and Romanul). These are discussed in greater detail in Chap. 4 and have assignments using the DYT nomenclature. The mutations causing the dystonias are distributed throughout the genome and have both dominant and fewer, recessive or X-linked, patterns of inheritance.
Other important symptomatic dystonias that fall into the category of hereditary dystonia were described in Chap. 36. These are PKAN and calcification of the basal ganglia; of course, Wilson disease may also have dystonia as a central feature. Many extrapyramidal diseases, including idiopathic Parkinson disease and progressive supranuclear palsy, may include fragmentary dystonias of the hand, foot, face, or periorbital muscles.
Wilson wrote that “the group of degenerative conditions strung together by the common feature of ataxia is one for which no very suitable classification has yet been devised,” a statement that is not as appropriate today as when it was written 80 years ago. This topic was introduced in Chap. 5 and some of the congenital and acute acquired varieties are mentioned there. Here we consider the chronic, progressive forms of cerebellar disease. Although most of these are familial and are more or less confined to this part of the nervous system, a number of other systems may be involved to varying degrees. Most of the chronic progressive cerebellar diseases are subsumed under the “system atrophies,” but no one classification designed to bring order to this category of diseases has proved satisfactory and a preferable genetic classification is emerging.