PAIN IN POST-POLIO SYNDROME: A SEPARATE PAIN ENTITY?

Background Most patients with polio recover from the initial infection, but develop muscle weakness, pain and fatigue after 15–40 years, a condition called post-polio syndrome. Although poliovirus has been almost eliminated, 12–20 million people worldwide still have polio sequelae. The pain is described mainly as nociceptive, but some patients experience neuropathic pain. The aim of this study was to further characterize post-polio pain. Patients and methods A total of 20 patients with post-polio syndrome participated in the study. Physical examination was performed, and questionnaires containing pain drawing and visual analogue scales (VAS) for pain intensity during rest and motion and VAS for fatigue were completed. A walk test was performed to evaluate physical performance. Results Pain intensity was high (42/100 on the VAS at rest and 62/100 while moving). The pain was localized in both joints and muscles. Pain in the muscles was of “deep aching” character, included “muscle cramps” and was located mainly in polio-weakened limbs. Conclusion Muscle pain in patients with post-polio syndrome does not fulfil the criteria for either nociceptive or neuropathic pain; thus, it is suggested that the pain is termed “post-polio muscular pain”. The intensity of post-polio muscular pain is higher while moving, but does not influence physical function, and is separate from fatigue. LAY ABSTRACT Most polio patients recover from the initial infection, but develop muscle weakness, pain and fatigue after 15–40 years, a condition called Post-Polio Syndrome. Though the poliovirus has almost been eliminated, 12-20 million people worldwide still have polio-sequelae. The pain is mainly described as nociceptive, but some patients experience neuropathic pain. This study was undertaken to further characterize post-polio pain. We examined 20 Post-polio patients and found that the pain was localised in both joints and muscles. The pain in the muscles was of ‘deep aching’ character, included ‘muscle cramps’ and was mainly located in polio-weakened limbs. The intensity of the pain is higher while moving but does not influence the physical function. To know more about the characteristics of the pain perceived gives better possibilities for treatment and rehabilitation