ENDOGENOUS DISEASES OF THE CENTRAL NERVOUS SYSTEM The group of diseases collected under this. head contains a number of very different morbid conditions. Their common feature is the occurrence in children, who are healthy at birth, of disturbances in the nervous and muscular systems after the lapse of months, years or decades. The mode of origin of these conditions is generally believed to be that certain portions of the nervous system are endowed with abnormally low resisting power and wear out after a short period of normal functional activity. Cowers describes this condition as abiotic atrophy of the central nervous system. The group is also called endog enous, i.e., due to internal predisposition, in contradistinction to exogenous diseases or such as are due to external causes.
The remote causes of this congenital weakness of certain portions of the nervous and muscular apparatus are not known. Consanguinity of the parents, alcoholism and syphilis or more exactly the so-called parasyphilitic diseases are regarded as exciting causes; for hereditary syphilis which is due to exogenous causes even though operative in utero, does not belong to this group. In many of these endogenous diseases there are very distinct racial factors.
An important feature of the diseases here under discussion is hered ity, or the tendency to occur in different members of the same family. All endogenous diseases are encountered either in several generations of the same family or in various members of the same generation (brothers and sisters and cousins). This peculiarity is an extremely valuable symptom, although its absence in an individual case by no means ex cludes it from the category, since in any hereditary disease some individ ual must be the first to exhibit the pathological symptoms.
The proof that these conditions deserve to be placed in a special class is furnished by the pathologic findings, which consist in various grades of atrophy degeneration and aplasia; but never, at least in recent cases, acute or chronic inflammations or neoplastic changes.
The number of cases that have been described and classified under this head is practically unlimited. Strictly- speaking the group includes not only diseases caused by functional inactivity of the central nervous system, but also diseases in which the muscles, connective tissue, skin. etc., spontaneously undergo morbid changes after a variable period of normal vital activity. Acconling to the special part of the nervous system or muscular apparatus affected and the grouping of the symp-, toms with relation to one another we have an enormous number of different types, which their observers have attempted to bring into reltttion with known diseases, as far as possible. under the impression that in finding points of similarity between these apparently inexplic able diseases and tabes or multiple sclerosis an explanation of their pathogenesis would be found at the same time. This attempt to classify the hereditary diseases among exogenous conditions has now been given up. We believe with Jendrassick that the fact that a combination
of symptoms cannot be classified according to our conception of the clinical manifestations of cerebrospinal diseases points to the assump tion of sonm endogenous condition. The endeavor to subdivide these diseases into different groups by sharp dividing lines has also been abandoned. It is true that we are sometimes surprised to find that among the endogenous conditions there are certain very characteristic diseases which show a constant and complete similarity to one another; but it is extremely common to find deviations from a type of an otherwise very well known condition, and there are also observed innumerable mixed and transitional forms, which combine the symptoms of one large group of diseases with symptoms of another.
That such a family or hereditary predisposition to some morbid development of a nervous system or parts of a nervous system is con ceivable was shown by the investigations of Karpluss on normal brains. He repeatedly observed in various members of the same family peculiar characteristic fissures in the brain, proving that in non-pathologic cases anatomical peculiarities. of the nervous system are unquestionably inherited. It is a very obvious conclusion, therefore, that congenitally deformed or niorbidly developed portions of the llerVOUS system and consequently also functional disturbances may be inherited in a similar manner.
Why it. is that, in spite of the givat variety of the endogenous diseases, pertain symptoms such as spasticity of the legs, difficult articu lation, ocular disturbances, muscular atrophy rind the like recur again and again and in similar combinations still remains a mystery. Edinger proposed an ingenious theory of substitution to explain this group of diseases. He assumed that certain portions of the nervous system in these cases lack the power to renew the nerve substances used up in carrying on the functions as is the case in normal conditions.
The following discussion will be limited to the most frequent and well-known combinations of endogenous symptom-complexes, retaining those groups of diseases which formerly were usually described sepa rately. In doing so. however, let it be emphasized once more, that transitional cases between most of these groups also occur.
We offer the following as a provisional classification of endogenous diseases: A. Spastic Family A fjections.
1. Spinal.
2. Cerebrospinal symptom-complexes.
B. Hereditary Ataxia (Friedreich's Disease) (Marie's Heredoataxie c6re-belleuse).
C. Muscu/ar Atrophies.
1. Spinal muscular atrophies.
(a) Cases in adults not occurring in families (includ ing amyotrophic lateral sclerosis).
(b) Infantile spinal muscular atrophy.
2. Neural form of progressive muscular atrophy.
3. Dystrophy of the muscle.s.
D. Bulbar Diseases. Progressive bulbar paralysis. Appendix.
(a) My-asthenia.
(b) Amaurotic family idiocy.
(c) Thomsen's myotonia.
(d) Periodic paralysis of the extremities