In perhaps one-fourth of all cases among children the onset is even more abrupt than as described. The child may be put to bed in apparent good health, sleep quietly or perhaps a little restlessly through the night, and is found the fol lowing morning bright, cheerful, and with a hearty appetite, but paralyzed in one limb, or, it may be, with a paraplegia, the affected limb hanging helpless and inert. Such cases were described in the older literature as West's morning paral ysis.
There is no sensory disturbance in poliomyelitis, or, if present at all, it amounts only to a slight tenderness on pressure or manipulation. The hyperces thesia of meningitis is extremely uncom mon, and suggests a complication. The bladder and rectum are not involved, the cranial nerves remain normal, nor is in telligence at all affected. Within two weeks usually, sometimes much earlier, the muscles paralyzed begin to atrophy. The wasting sometimes progresses rap idly. If the child is fat, this atrophy may not be apparent to the eye, but palpation will at once make it evident. Not only does the limb look wasted, but it usually presents a bluish, cyanosed appearance, and to the touch of the examiner it is dis tinctly colder than its fellow. The deep reflexes are lost, if affected at all. Care and familiarity with the subject are both needed to avoid misleading conclusions in eliciting this symptom. Simultane ously with the atrophy, or it may be a little later, an alteration both quantita tive and qualitative may be noted in the response to both the faradic and galvanic currents. To the faradic current the muscular response is at first simply di minished. It grows more and more feeble from day to day, and is eventually lost completely in severe cases. To the gal vanic current the nerves involved show at first beginning and later more or less complete reaction of degeneration. In making these electrical tests the corre sponding sound muscles in the unaffected limb should be examined and the re sponse compared with that obtained from the paralyzed muscles. Minor changes can only he determined in this way. Within a few months various deformities from contraction and unopposed mus cular antagonism may develop. Talipes varus and equinus and many other de formities are possible. Sometimes an arrest of development occurs, one limb after a few years being shorter than the other or one hand or foot smaller than the other. Chronic poliomyelitis is one of the forms of progressive muscular atrophy and, together with the subacute variety, differs chiefly in the mode of onset and rate of progress, but not in the essential nature of the established paral ysis.
Diagnosis.—Although less than 5 per cent. of the cases are correctly inter preted during the acute or febrile stage, the history of this stage is of importance in the differential diagnosis, especially in excluding cerebral meningitis and the cerebral palsies of childhood. In polio myelitis there are few irritative symptoms such as pain and spasm. One or two con vulsions may occur, but the habit is not established and the patient does not de velop epilepsy or mental enfeeblement. Epilepsy, on the other hand, is often a part of the symptom-picture in the cere bral palsies and mental impairment in some degree almost invariably present. The type of the paralysis in the two is exactly opposite. In poliomyelitis the paralysis is flaccid, the reflexes are lost, the muscles atrophy, the muscles affected are functionally associated, and a mono plegia is the rule as regards distribution. In the cerebral palsies the paralysis is spastic in type, with exaggerated reflexes; no wasting, although arrest of develop ment may result; the paralysis is of mus cles anatomically associated; the distribu tion is usually hemiplegic, monoplegias being rare. In cerebral palsies, too, the cranial nerves, particularly the facial, are often affected and the mind is almost in variably impaired, which is never true of infantile spinal paralysis. Finally, there are no electrical changes characteristic of the cerebral palsies. From other forms of myelitis infantile spinal paralysis is to be distinguished chiefly by the ab sence in the latter affection of sensory symptoms, of sphincter involvement, of bed-sores, of spastic or semispastic phe nomena. Palsies from peripheral neu ritis due to trauma, including so-called birth-palsies caused by obstetrical forceps or injury in delivery, are often difficult to distinguish from poliomyelitis. The history of injury to the arm or shoulder and the anatomical distribution of the paralysis are points of differential value. In neuritis of this type sensory disturb ances are not conspicuous, as a rule, but may be present. The history as to mode of onset and progress serves to distin guish poliomyelitis anterior acuta from the pure muscular atrophies.