Abstract
1. The results of a three-year study of recovery in 3,033 lower limb muscles and 1,905 upper limb muscles in 142 patients are presented.
2. The rate of recovery of partly paralysed muscles is the same in all muscles and muscle groups in the lower or upper limb. Clinical differences in the ability of individual muscles to recover depend upon the proportions of their number that remain permanently paralysed.
3. The rate of recovery is slowest in adults and most rapid in young children.
4. The amount of further recovery to be expected in a muscle can be predicted from a knowledge of its grade at any time after one month from the onset of the paralysis. Fourteen-fifteenths of the total amount of recovery takes place by the beginning of the twelfth month; with rare exceptions individual muscle recovery is complete after twenty-four months.
5. Ninety per cent of muscles that are still completely paralysed after six months remain permanently paralysed.
6. The prognosis of a completely paralysed muscle is related to the level of paralysis in muscles supplied by the same spinal segments.
7. Deterioration in power in a muscle is uncommon and, when it occurs, is associated with the presence of the strong opposing force of antagonist muscles or of gravity.
8. The application of these findings to the management of cases of paralytic acute anterior poliomyelitis is discussed.
