Definition.—A disease of the muscles, first described by Friedreich, in which there is clonic contractions, principally of the extremities, and occurring constantly or paroxysmally.
Etiology.—The etiology of this rare disease is unknown. It occurs more frequently in males than in the opposite sex. Heredity may bear some part as a predisposing factor, since the disease is found more frequently in those of a nervous temperament.
Traumatism, overwork, exposure to cold, fear, and great mental disturbances have been considered as exciting causes.
Pathology.—The pathology is unknown, no characteristic lesion having been as yet discovered. It is supposed to be closely allied to convulsive tic, and possibly there may be some disturbance in the motor cells in the cortex and cord.
Symptoms.—The most characteristic symptoms are sudden paroxysmal contractions, of a clonic character, of a group of muscles. The contractions vary from fifty to one hundred and fifty per minute, and are usually bilateral. They are the most pronounced in the muscles of the trunk and hips, though those of the arms, legs, and face, are sometimes affected.
The contractions are so severe in some cases as to throw the patient from the chair or bed, and in rare cases are tonic in character. The tendon reflexes are increased, and any irritation of the skin or an electric shock brings on an attack.
Diagnosis.—The sudden,, lightning-like contraction of the muscles is the chief diagnostic sign.
Prognosis.—This is favorable in most cases, a spontaneous cure not infrequently resulting.
Treatment.—The disease has thus far been unaffected by treatment.