Hereditary predisposition is usually very marked. Alen are attacked more frequently than women. The tendency of the disease to occur in different members of the same family is shown in the accompanying diagram taken from Erb. The preponderance of the male sex, however, does not appear from the diagram.
When the disease is fully developed, any rapid movement, setting in motion muscles that have been at rest, is accompanied by a sudden stiffness, -which forces the patient to persist in the spastic position. Mien the patient shakes hancls lie is unable to let go; when he suddenly takes a step forward the feet remain rooted to the ground; when lie opens his mouth to masti cate his food, the jaws are arrested in a half open position. Even in beginning to speak and read the sluggishness of the muscles of the tongue and eye becomes apparent. After an interval, varying from several seconds to a half minute during which the muscles remain rigid and the patient makes awkward movements to overcome the rigidity, the muscles relax and the desired movement can be executed without further trouble; even such sustained muscular movements as dancing can be performed without difficulty. Cold, excitement, and the sense of being observed appear to favor the occur ence of the muscular tension. Passive movements are not, as a rule interferred with. The muscles themselves are usually well developed and the patient may even be quite athletic. When the muscles are examined by percussion, a peculiar state of affairs is discovered. The tapping brings out a localized swelling, sometimes \\id] ft central de pression, which persists a few seconds and then gradually disappears (Erb's myotonie reaction). Mild faradic irritation induces clonic spasm of the muscles which persists for some time after the current is turned off. Galvanic irritation is followed by sluggish contraction and some
times the contraction is reversed (reaction of degeneration). Strong currents may induce undulation of the muscles. There are no other symptoms. Association of the disease with psychic affections, epilepsy-, and muscular atrophy has been observed.
This very characteristic clinical picture is observed in children and even in infants at the breast. In the latter Friis, whose attention was called to the disease in infants by its presence in other meMbers of the fantily, observed frequent, sighing respiration, inability to open the eyes, immobility of the face when the child began to cry, and interference with the movements of the legs and fingers. Inability to nurse tit the breast is also nientioned as an early symptom of the disease. Eriis' ease did not show the myotonie reaction, although the muscles of the legs were hypertrophic.
The prognosis of myotonia is unfavorable as regards recovery, although periods of remission and improvement may. be observed. especially in advanced age. The disease causes great disability in the choice of an occupation, and the subjects of myotonia are more exposed to accident because of their inability to make a sudden movement to save themselves at the right time. Examination of excised pieces of muscle shows a somewhat doubtful hypertrophy of the rousele fibrils and the presence of granules in the sarcoplasin (Schiefferdecker). In one case that was examined post 1nm-tem no pathologic changes were found in the nervous system. The treatment is hopeless. Internal medication, particularly with organotherapeutic products, has so far proved of no avail. Gymnastic exercises. massage, and warm baths have been employed with doubtful success.