When the muscles of the thigh are permanently weakened, there is no contraction about the knee unless the child attempt to aid himself by the use of crutches. Children in whom there is partial paralysis of the quad riceps femoris walk, says Volkmann, exactly like a person who wears an artificial leg. To get such a leg to support the weight of the body with out bending the knee, the weight must be thrown in front of and not be hind the joint. Every time that the body rests upon the weakened limb, the weight is thrown forwards, so that the knee is in a state of complete exten sion, and the posterior ligaments are put upon the stretch. These after a time relax, and the knee is over-extended so as to produce a genu recurvatum.
In the arm, the elbow-joint is little affected. It remains quite free, and no contractions occur unless the arm is kept permanently in the bent posi-' tion, as when worn constantly in a sling. When the paralysis is so marked that the hand is useless, the power of supination of the arm is soon lost, for the child, having no occasion for the movement, soon ceases to employ it. The wrist becomes slightly flexed, and the fingers, completely clenched upon the palm, undergo contraction in that position. This is the position the fingers assume when left to themselves ; and if the flexors are not used, or are not passively stretchal,.they become contracted. The shoulder is flattened, and if the muscles proceeding from the thorax to the arm are ex tremely weakened, the capsule is pulled upon by the dead weight of the arm and becomes permanently stretched, so that a distinct interval is felt between the head of the bone and the socket. In this case the affected arm, by measurement from the acromion, may seem longer than the sound one.
From what has gone before it will be noticed that cases of infantile spinal paralysis fall naturally into two classes : those in which complete recovery takes place in all the muscles affected, after the lapse of weeks or months ; and those in which power is completely restored in some muscles, while others remain permanently useless, and the disease ends in atrophy and deformity. In the muscles in which the paralysis is likely to be last-. ing, faradic contractility disappears at a very early date—usually before the end .f the first week, or in the course of the second. to the elder Duchenne, muscles which retain some degree of faradic contractility on the seventh or eighth day may be expected to recover their power, and this the more rapidly the less their faradic irritability has been weakened.
Diagnosis.—In a case which is seen at an early period of the disease the symptoms are so characteristic that it is difficult to mistake this form of illness for any other lesion of the nervous system. But every case of paralysis with atrophy is not a case of infantile spinal paralysis. To iden tify the disease with accuracy we must require all the essential phenomena of the affection, viz., complete motor paralysis without alteration of sensibil ity or pain in the back or elsewhere ; rapid loss of faradic excitability ; a normal temperature ; absence of paralysis of the face or of the sphincters ; complete flaccidity of the limb, without stiffness or contraction of the joints ; marked coldness of the affected parts, and no tendency to the for mation of sores upon the skin.
In acute generalised myelitis, where the whole of the gray matter is in volved and a large part of the white columns, there is lessened cutaneous sensibility ; there is paralysis of the sphincters, so that the child can no longer control the bladder or the bowel ; there is an increase of reflex ex citability ; sores form readily on the parts exposed to pressure ; the urine is alkaline, purulent, and offensive, and, as a rule, atrophy in the affected muscles does not occur.
Ilmmorrhage into the cord produces a sudden paralysis, which is fol lowed by atrophy of the affected muscles and loss of reflex excitability ; but here also there is diminution of cutaneous sensibility, the sphinc ters are paralysed, and bed-sores form early.
Paralysis of cerebral origin may be distinguished by the affection of the cerebral nerves, such as squinting, facial paralysis, etc. ; by the palsy being accompanied by tension of the muscles and spasmodic contract ures ; by the preservation of electrical irritability ; by the stiffness and extension of the joints ; by increased excitability of tendons, and by the absence of atrophy.
In spasmodic spinal paralysis the loss of power is incomplete, and occurs slowly and insidiously ; muscular tension and contractions are present ; there is increased irritability of the tendons, and the affected muscles do not atrophy.