The essential myoclonias have had a more than usually difficult pathway to their full recognition as morbid states since the first description of paramyoclonus multiplex by Friedrichs in 1881. There are those who still claim that myoclonias have not passed beyond symptom complexes, parts of the hysterias, or the epilepsies, and as an accompaniment of those more frankly established organic diseases of paralytic encephalopathies, hemiplegias, and the residual irritative scleroses and softenings of the latter group. To prove that the myoclonias are but syndromes, their occurrence even in organic spinal affections such as myelitis and poliomyelitis is cited. However this may be for types of pseudomyoclonia, the pathogenesis of essential myoclonus is now known, in the majority of cases, to develop on a basis of neuropathy from which many other types of the spasmophilia may coincidentally also take their origin, either in the myoclonic's own family or in collateral branches