Aside from this form of postinfectious poliomyelitis, there is no doubt, however, that the disease in the great majority of cases occurs spontaneously and presents the character of a non-contagious infectious disease. This is shown by the massing of eases of acute myelitis during the summer months (July and August) (Barlow, Sinkler, Sachs, Zappert and Baumann), which is absolutely typical, and by the epidemic ap pearance of the disease which has been reported from various locali ties—Atnerica, Sv-eden, Norway, Switzerland, France, Italy, Germany and Austria. The Stockholm epidemic described by von Mediu is particularly instructive from the fact that cerebral spinal and peripheral disturbances were observed at the same time.
Poliomyelitis is a disease of earliest childhood, most of the cases occurring in children who have not yet completed the second year. In half-grown individuals and adults the disease is much more rare and also exhibits certain differences in its course.
Poliomyelitis shows a preference for children who have previously been healthy. The initial symptoms are very variable. While it is true that prodromal symptoms, such as lassitude, anorexia and a low degree of fever are often overlooked, the onset of poliomyelitis is often so imperceptible that the children go to bed well the evening before, and wake up in the morning with signs of paralysis. More frequently the disease is ushered in by several days of fever of an uncertain type or by severe meningitic febrile states ithe latter also when the disease is localized in the lumbar portion of the cord). The paralysis attains its maximum extent at the very beginning of the disease; gradual develop ment of the paralysis by successful stages is the exception (Neurath ancl others). As soon as the initial maximum extent has been attained the paralysis in the extremities begins to diminish and ultimately is confined to a definite muscular region. This condition is permanent and is regarded as the recovery from the disease.
The characteristic sign of poliomyelitis is a flaccid, atonic muscular paralysis, accompanied by atrophy and loss of electric irritability. The paralysis is pronounced from the very onset, while atrophy and loss of electric irritability- make their appearance within a few days. The muscles, shortly after the onset of the disease, exhibit loss of function but retain irritability wholly or in part and may be expected to recover.
Various portions of the body are particularly liable to be attacked by the paralysis, a point on which there exist numerous statistics. The most frequent distribution is the two legs; next in frequency one leg, one arm, an arm and leg, either on the same or on opposite sides, and finally the muscles of the trunk and both arms.
In the extremities the disease exhibits a remarkablkk predilection for certain muscles. In the arm, the deltoid, next the biceps, brachialis anticus, sttpinator longus (also the muscles of the upper plexus-type and the other shoulder inuscles are chiefly attacked: paralysis of the triceps, of the muscles of the hand and complete paralysis of all the muscles of the arm are more rare. To sunk up, therefore, the paralysis of poliomyelitis generally attacks the proximal portions of the ann. In the lower extremities the perinea] muscles are very frequently af fected. Next to these the tibialis anticus, the quadrieeps, the gluteal muscles, the tibialis posticus and less frequently the muscles of the calf of the leg become paralyzed; tlte sartorius is never affected. Wide spread flaccid paralysis of one or both legs is seen more frequently than the, same condition in the arms. Paralysis of the nntscles of the back with lordosis and disturbance of the gait, paralysis of the muscles of the neck causing dropping of the head, and paralysis of the abdominal muscles with unilateral or bilateral protrusion of the abdomen (Ibrahim) are rare, although I have personally seen all these forms. Associated paralysis of the muscles innervated by the cranial IlerVe6 (facial, hypo glossus and eye muscles) has also been observed a few times. The palsies may be combined in a -variety of ways. Associated paralysis of several extremities (also in the form of spinal herniplegia) often se(kn in recent eases. As a rule, when different groups of muslces are affected, the paralysis subsides in one or more groups and the disease ultimately is confined to a much smaller territory than that of the original affection. Why certain muscle groups are affected more than others we do not know (Baumann); possibly the distribution depends on certain ana tomical conditions such as the vascular supply of the individual muscle nuclei in the spinal cord.