Dyssynergia

DYSSYNERGIA, dyssynergia (from the Greek dys- prefix, meaning qualitative disorder, syn- together, and ergon-work), disorder of movement coordination in the sense of violation of the correct sequence and combination of actions; most often of cerebellar origin. The cerebellum is the highest regulator and controller of movement coordination, and the loss of its influence leads to a disorder of coordination, expressed by a series of so-called cerebellar symptoms—cerebellar ataxia, intention tremor, dysmetria, adiadochokinesia, nystagmus, scanning speech, etc. (see Cerebellum). In connection with the combination of these cerebellar symptoms with myoclonus and epilepsy, a special form has been identified—dyssynergia cerebellaris myoclonica, or Hunt's disease (Hunt; 1921), which is characterized by a certain clinical picture of progressive cerebellar disease in combination with myoclonus and epilepsy. The disease occurs in childhood or adolescence (from 7 years to 17 years) among complete health, occasionally among members of the same family; direct heredity is not noted; besides this, nothing reliable is known about the cause and origin of the disease. Pathological-anatomical changes amount to primary degeneration of the nuclei dentati of the cerebellum and the cerebellar peduncles (brachium conjunctivum) emerging from them, as a result of which the regulating influence of the cerebellum is lost. The disease usually begins with myoclonus or epileptic seizures, to which gradually, sometimes after several years, cerebellar phenomena are added—intention tremor, scanning speech, adiadochokinesia, dysmetria, hypotonia, etc. Gradually all symptoms worsen. The course is prolonged; death usually occurs from accidental diseases. A combination of dyssynergia cerebellaris myoclonica with Friedreich's ataxia has been described. The prognosis in terms of cure is hopeless. Therapy is ineffective.