Postpolio Syndrome Accepted criteria for diagnosis of postpolio syndrome (PPS) are a prior history of poliomyelitis, a stable period after recovery, a residual deficit of the initial polio, new muscle weakness, and, sometimes, new muscle atrophy. Fatigue and muscle pain need not be present to meet the criteria for the syndrome.
One possible cause of PPS is decompensation of a chronic denervation and reinnervation process to the extent that the remaining healthy motor neurons can no longer maintain new sprouts; thus, denervation exceeds reinnervation.
A second possible mechanism for PPS is motor neuronal loss due to reactivation of a persistent latent virus. In addition to muscle atrophy and denervation, foci of perivascular and interstitial inflammatory cells have been found on 50% of biopsies of patients with PPS. Activated T cells and immunoglobulin M and immunoglobulin G antibodies specific for gangliosides also have been found.
Another possibility is an infection of the polio survivor's motor neurons by an enterovirus that is different from the one responsible for the patient's polio. Others sources hypothesize that PPS is merely the loss of strength due to the usual stresses of aging and weight gain. In patients with PPS, these processes occur in muscles that already are weak, so the consequences are more noticeable compared with those of patients who have not had polio.
For more information, please see http://www.emedicine.com/PMR/topic110.htm
Postpolio Syndrome – – Post-Polio Health International – http://www.post-polio.org/