"There is a peculiar form of progressive muscular atrophy which is characterized by a definite location, definite course, definite behavior of affected muscles, and definite alteration in them, but without alterations in the spinal cord—the condition named by me the juvenile form. It begins in youth or childhood.
"This form agrees in its symptomatology—especially in its localization in the upper half of the body, partly also in the lower—entirely with the so-called pseudo-hypertrophy of muscles, only that in the former a decided lipomatosis leading to an increase in volume is wanting; on the other hand, true muscular hypertrophy is not infrequent in both forms of the disease.
"If this juvenile form occurs in the earliest childhood, it may in all its details be identical with pseudo-hypertrophy, except that the lipomatosis is wanting.
"The anatomico-histological alterations of the muscles are exactly the same in the juvenile form as in pseudo-hypertrophy.
"The juvenile form not infrequently occurs in entire groups in one family, producing the so-called hereditary—better named family-muscular—atrophy.
"If this juvenile-hereditary form occurs after puberty, it affects most frequently, although not exclusively, the upper half of the body. If it sets in, on the other hand, in earliest childhood, it affects preferably the lower extremities and the pelvis. Transitional forms, however, occur also in family groups.
"In the latter form, that occurring in earliest life, we have that which Leyden has proposed to designate as hereditary muscular atrophy.
"Thus, hereditary muscular atrophy is in all essential points identical with pseudo-hypertrophy, and is distinguished from it only in the slighter degree of lipomatosis of the muscles.
"All of these forms have probably nothing to do with spinal progressive muscular atrophy; they differ from it in localization and course, anatomical changes and clinical phenomena in the muscles, and alterations in the spinal cord."