Post-polio syndrome

Post-polio syndrome (PPS) is a condition that affects polio survivors years or decades after they have recovered from the original poliomyelitis infection. Polio — a neurological disease caused by the poliovirus — was largely eradicated through systematic vaccination campaigns beginning in the 1960s. However, the estimated 15–20 million survivors worldwide may develop PPS in later life.

During the original polio infection, the poliovirus destroys motor neurons in the spinal cord and brainstem. Survivors recover function because remaining neurons sprout new branches (axonal sprouting) to reinnervate orphaned muscle fibres and compensate for the lost neurons. This compensation works for decades, but the overworked surviving neurons eventually begin to fail — producing the new weakness and fatigue of PPS.

**Who is at risk:** PPS occurs in an estimated 25–40% of polio survivors. Risk is higher in those who had more severe original paralysis, who recovered significant function after polio, and who are now older. Time since infection is also a factor — PPS typically appears 15 to 40 years after acute polio.

**Symptoms** of post-polio syndrome include: - New muscle weakness in previously affected or apparently unaffected muscles - Severe fatigue — physical and mental — disproportionate to activity levels - Muscle and joint pain - Atrophy of previously affected muscles - Breathing or swallowing difficulties (if original polio affected the bulbar muscles) - Sleep-related breathing problems - Intolerance to cold - Functional decline: difficulty with previously manageable tasks such as walking, climbing stairs, or using the hands

**Associated complications** seen in long-standing polio survivors include scoliosis, osteoporosis and fractures, peripheral nerve entrapments (from chronic use of walking aids or wheelchairs), and respiratory failure.

**Diagnosis** is clinical — based on a history of paralytic polio, a period of functional recovery or stability, and new onset of the symptoms above, with no other medical explanation. Electromyography (EMG) can confirm chronic denervation and reinnervation patterns consistent with old polio.

Since PPS cannot be cured, management focuses on conserving energy, protecting joints, preventing overuse, and maintaining the best possible function. An interdisciplinary team including neurology, physiotherapy, occupational therapy, respiratory medicine, and orthopaedics provides the most comprehensive care. Fatigue management — including pacing, energy conservation techniques, and appropriate rest — is a cornerstone of treatment.