CONGENITAL ABSENCE OF MUSCLES It is a matter of surprise that the reported cases of congenital absence of muscles have to deal much less with children than with half grown or adult individuals. The reason probably is that the anomaly does not cause any marked symptoms and therefore does not become apparent until the muscles of the body are fully developed or some secondary phenomenon (such as an underdeveloped breast in absence of the pectoral muscle) calls attention to the condition. Moreover, other wise healthy individuals do not, as a rule, undergo medical examination until they are drafted for the army or apply for life insurance. Now that school inspection is becoming general, it is probable that congenital absence of muscles will be reported among school children.
Absence of the pectoral muscles is the most frequent anomaly; deficiency of the trapezius, serratus magnus, quadriceps femoris and other muscles is not so common (see Bing's statistics). With reference to congenital absence of the ocular niuscles see infantile nuclear atrophy.
The defect may be complete or partial, a point to be decided by post-mortem examination, which reveals various grades from complete absence of the muscle to the presence of numerous rudimentary muscle fibres. That in a number of ca.ses at least the condition is due to a con genital aplasia and not to disease acquired during intra-uterinc life is shown by- a case of absence of the pectoral muscle in a child five days old examined by R kert and in which not the slightest trace of inflammation could be found in the remaining muscle fibres.
The most typical picture is seen in congenital absence of the pec toral muscles. The normal fulness of the anterior chest wall is replaced by a depression, and no muscular tissue can be felt. Quite often other pathologic conditions are associatecl with this defect, such as abnormali ties of the thorax, absence of one or two ribs, imperfect development and webbing of the fingers of the hand of the same side, atrophy of the skin, deficiency in pigmentation around the nipple, which is higher than on the other side, and imperfect development of the breast. Steche
recently attempted to establish a special type of muscular deficiency in the coincidence of all these symptoms. Congenital upward displace ment of the shoulder (Sprengel) is another condition that often accom panies atrophy of the pectoral muscles.
The appearances in cases of absence of other muscles are less pro nounced and are practically the same as in acquired paralysis of the same muscles.
Although the function of the muscle in congenital aplasia is ob viously lost, the actual disability, so far as the patients are concerned, is relatively slight. They learn early in life to make as much use as pos sible of other, sound museles. Thus, even in the absence of the pectoral muscles, the boy often learns to do gymnastics, to swim, etc., without any trouble. Complicated movements of the arms, however, are per formed awkwardly and without the proper degree of strength, so that a man with absence of the pectoral muscles is regarded as unfit for military serviec.
Several muscles may be absent in the same individual, but the defects are never symmetrical on the two sides. This is an important point in the differential diagnosis between congenital absence and ac quired muscular atrophy, which also differs from the former by the mode of onset and the progress of the disease.
Muscular defects are permanent and no treatment is possible. If the disability is marked, surgical relief by transplantation of tendons or muscles may be considered.