Myotonia.

Synonym.—Thompson's Disease.

Definition.—A hereditary disease of the muscles characterized by prolonged contraction of the muscles whenever voluntary motion is attempted, contraction and relaxation being slow and the muscles stiff.

Etiology.—Heredity is an important factor in the causation of the disease, Thompson, who first described the disease, having traced the affection in his family for five generations. It occurs more frequently in men than women, and usually in those whose families are characterized by neuropathic tendencies. Prolonged, severe exertion has been followed by the disease where no history of the affection could be traced in the family. It has also been attributed to cold and fright, where the patient has been of a neurotic temperament.

Pathology.—The muscle fibers are hypertrophied, especially in their transverse diameter.

Symptoms.—The most characteristic symptom of this rare disease is that, upon voluntary movement, the contraction of the group of muscles which the patient desires to move is slower than normal, and when once contracted they remain so for several seconds. The muscles of the hand and leg are the most commonly affected. If of the hand, the patient readily grasps the object desired, but for some seconds is unable to let it go, and, even when relaxed sufficiently to permit the object to be released, the fingers remain, for a few seconds, partially contracted.

If of the leg, and the patient attempts to walk, he is unable to take a second step for several seconds owing to the tonic contraction and stiffness of the muscles; the first few steps are therefore a halting gait; with each step, however, the contraction becomes less marked till the normal gait is assumed and the patient may walk indefinitely in a natural manner, provided he does not rest for a considerable period. It is only after a period of rest that the contraction occurs.

All the voluntary muscles may be involved, though the muscles of the face are usually exempt. The muscles of deglutition and the sphincters are never involved.

The reflexes are not constant, being sometimes exaggerated, diminished, normal, or even absent. There is generally an absence of pain.

The mental disturbance is only such as would be, natural to one of his condition, his anxiety causing more or less irritability.

Diagnosis.—This is readily made by carefully observing the tonic contraction of the muscles, which grow less. with each muscular movement, till normal action is restored, to become rigid again after a rest.

Prognosis.—This is unfavorable, for though in rare cases there is a temporary arrest of the disease, its return is certain. It does not necessarily shorten life, though accidents are more common to those with this affection.

Treatment.—No treatment has as yet proven of much benefit. Massage and electricity have been used with doubtful benefit. Exposure to cold, and mental worry, aggravate the disease, hence should be avoided as far as possible.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.