NIUSCULAR DYSTROPHY In this group we include, after Erb, Raymond and most neurol ogists, a number of muscular atrophies which were described by their first observers as special types of myopathies and accordingly regarded as so many different diseases of the muscular system. Depending on the time of appearance, the localization of the first symptoms, the character of the course, and the predominance of atrophic or pseudo hypertrophic changes in the muscles, a number of different forms were distinguished, which are described in the literature as the juvenile form of Erb; the Landouzy-D6jerine infantile type (facio-scapulo-humeral); the ltereditary form of I.eyden and Mobius, and pseudohypertrophy. The characteristic feature of muscular dystrophy is that the spinal cord escapes; although transitional forms between simple muscular dystrophy and spinal muscular atrophy have also been described.
The cffisease is usually transmitted by the mother. Boys are af fected somewhat more frequently than girls. Members of the same family usually present the sante type of dystrophy. With the exception of family predisposition. all other etiologic factors that have been advanced, such as exposure to cold, traumatism and infectious diseases have not even the dignity of an occasional cause. Babinski and Onanoff made the interesting observation that the disease simultaneously attacks those muscle groups which develop at the same time in the embryonal structure.
The onset of muscular dystrophy usually occurs in childhood, ex ceptionally during the adolescent period. Occasionally it is learned that the children have always been awkward. and have learned to walk with difficulty. The progress of all the different forms of dystrophy is exceedingly slow, slower than that of the spinal muscular diseases. The patients may live for years and even decades, but they spend most of their dreary existence in bed. Death ensues from intercurrent diseases, particularly tuberculosis.
The muscular affection in dystrophy presents the following pecu liarities: (1) The disease manifests itself in atrophy, temporary hyper trophy and pseutlohypertrophy (increase in the volume of the muscle from proliferation of the connective tissue attended by atrophy of the muscular eleinents). (2) The individual muscles are not affected uni formly; the morbid process presents a dissenthiated character and not until later extends to the entire muscle. (3) Fibrillary muscular tremors are usually wanting. (1) While the electric irritability of the muscles is often diminished so that they sometimes respond sluggishly, the usual law of reaction is not reverser' nor is electric irritability abolished except dining the terminal conditions. (5) The paralysis is usually flaccid; but, in contradistinction to a spinal palsy, the muscular tone is often present. Contractures sometimes develop. especially in the foot. (6) The tendon reflexes are preserved for a long time and are diminished only in palsies of long standing. (7) The muscle fibres exhibit atrophy and hypertrophy, as well as increase of the muscle nuclei and fatty degeneration of the individual muscle fibres. Macroscopically the muscles present a peculiar pale red or yellowish color.
Degeneration of the cells of the spinal cord and of the anterior roots has been observed particularly- in eases of long standing, but it is not improbable that these changes may be secondary. Nevertheless, this degeneration, and the fact that cases of spinal atrophy combined with psetidohypertrophy of the muscles occur, indicate that the distinction between the myelopathic and myopathic muscular diseases cannot be sharply drawn.
The individual types of dystrophy present the following features: (1) In the juvenile form of Erb, which preferably occurs during late childhood and tilf' years of puberty, the atrophy begins in tbe shoulder girdle; the arm ancl the hands escape. Later in the course of the disease the muscles of the pelvic girdle, of the back and of the thigh, rarely the abdominal muscles are affected. True and false hypertrophy is observed
both at the beginning, and during the later course of the clisease. (2) The infantile ov Tarim-scapula-humeral form (Lanclouzy-Dejerine) mani fests itself first in the face, in thc sphincter muscles of the eye and mouth, and in the masseter. The face assumes a mask-like appearance, the play of features is lost, and there is inability to close the eyes and round the lips. Pseudohypertrophy sometimes develops in the muscles of the face, affecting particularly the lips, which become thickened and unsightly (tapir lips). Later the muscles of the shoulder and arms are attacked. (3) The so-called hereditary form first shows itself in weakness of the muscles of the back, lordosis, and difficulty in walking, without pseudohypertrophy. This form of dystrophy preferably attacks children from eight to ten years of age. (4 Pseudohypertrophy, the most frequent and best known form of dystrophy, first attacks the long muscles of the back, the calf muscles and the extensor muscles of the thighs. Pseudo hypertmphy develops early in the calf muscles and soon afterwards in the di,eased muscles of the thigh, causing a very striking and char acteristic appearance which can not Ntiell be mistaken. I.ater in the course of the disease the muscles of the shoulder, arm and lumbar region are affected, the deltoid and supraspinat us and infraspinatus muscles show ing a tendency to pseuclohyper trophy. The forearm and hand escape. Pes equinus and con tractures in the calf muscles are not rare. These palsies first produce a peculiar waddling or rocking gait and there is marked lordosis of the sacral region. The children are unable to raise the trunk quickly from the stoop ing or recumbent position and help themselves by bracing their hands against their 01,V11 legs " they climb up on themselves" (see Plate WO. In the beginning of the disease they are sometimes able to raise themselves by a sudden jerk. The difficulty in walking shows itself particularly in going upstairs, in grea t 1 y diminished resistance to fatigue, and in a tendency to fall over. The weakness of the shoulder musclesis recognized by- defective fixation of the shoulders when one tries to raise the child with its arms pressed against its sides. When the child tries to raise the arm, an effort to find support along the back of the neck and head is also noted. (The hands climb up along the head.) Partial paralysis of the abdominal muscles causes arching of the abdomen and interferes with abdominal pressure. The abdominal reflex is absent in these cases. If the legs, the shoulder girdle, the muscles of the back and the pelvic girdle are paralyzed, the patients become absolutely helpless, and their condition offers a strange contrast to the athletic development of the body which may be simulated by the pseudohypertrophy. The muscles of the face almost always escape in pseudohypertrophy. Involvement of the eye movements is very rare. The sphineters in these, as in all other forms of dystrophy, remain intact. In advanced cases the intelligence sometimes suffers and speech is disturbed.
Differential diagnosis.—Muscular dystrophy must be differentiated front the spinal form of muscular atrophy- and from the neurotic form.
Characteristic features of muscular dystrophy are thc failure to involve the hands and forearm, the absence of fibrillary twitching, the preser vation of the patellar reflexes which are usually normal, and the presence of pseuclohypertrophy. From syringomyelia, a disease which rarely needs to be considered in children, muscular dystrophy is distinguished by the fact that the hands escape and by the absence of severe sensory disturbances. Rachitic disturbances of the gait, congenital dislocation of the hip, beOnning spondylitis, and spinal meningitis may be con founded with dystrophy. But the simple precaution of healing these things in mind mill enable one to arrive at the correct diagnosis after some observation of the case.