Post-Polio Syndrome

Post-polio syndrome (PPS) is a late neurological syndrome in a person with a documented history of paralytic poliomyelitis. The characteristic pattern is a period of at least 15 years of neurological stability followed by new, gradually developing muscle weakness, fatigue, pain, or muscle atrophy that is not better explained by another condition. A remote history of polio alone does not establish PPS, and PPS is not a recurrence of acute poliovirus infection. The mechanism explains the delayed presentation. The original infection damaged motor neurons. Surviving neurons compensated by sprouting branches to activate muscle fibres that had lost their nerve supply. These enlarged motor units could maintain movement for decades, but they carry an unusually large workload. With time, their reserve may fail, producing renewed denervation and loss of strength. Inefficient movement also increases the energy cost of walking, transfers, and other tasks, which helps explain why fatigue and pain can become prominent even when the neurological examination changes gradually. PPS should not be used as a catch-all explanation for every new symptom in someone who had polio. A new problem...