Psychosocial factors and adjustment to pain in individuals with postpolio syndrome.

Postpoliomyelitis syndrome (PPS) is a disorder that is characterized by a collection of neurologic and non-neurologic symptoms that manifests many years after recovery from the initial poliovirus infection. Diagnostic criteria, as set forth by the Post-Polio Task Force, include (1) a previous episode of paralytic poliomyelitis with residual motor neuron loss, which can be confirmed through patient history, a neurologic examination, and, if needed, an electrodiagnostic examination; (2) a period of neurologic recovery followed by an interval (usually 15 yrs or more) of neurologic and functional stability; (3) a gradual or abrupt onset of new weakness or abnormal muscle fatigability (decreased endurance) or both, with or without generalized fatigue, muscle atrophy, or pain; and (4) exclusion of medical, orthopedic, or neurologic conditions that may be causing the symptoms noted earlier.1,2 Attrition of motor neurons, immunologic processes, muscle overuse and disuse, and normal aging have been implicated in the development of PPS.2 Estimates of the occurrence of PPS in polio survivors range from 29% to 64%, and up to 640,000 residents of the United States may be experiencing related symptoms.3 Pain is common in individuals with PPS. Prevalence rates range from 42% to 80% for joint pain and 38%–86% for muscle pain.2 The results from a recent study by our group found that 91% of participants who responded to a community-based survey reported experiencing pain currently or within the past 3mos.4 Evidence indicating that individuals with PPS can have significant pain problems also comes from research showing that persons with PPS report higher levels of pain severity than comparison samples of healthy individuals5 as well as those diagnosed with other potentially disabling conditions such as multiple sclerosis6 and other forms of neuromuscular disease.7 The sites and causes of pain in PPS vary and can include joint pain resulting from abnormal biomechanics secondary to muscle imbalance.1 In addition, individuals with PPS can experience significant muscle pain and cramping because of overuse as well as fasciculations presumably because of motor neuron irritability.1 Biopsychosocial conceptualizations of chronic pain have received increasing support in the broader pain literature. Biopsychosocial models acknowledge the biological bases that underlie most pain conditions but also note that psychosocial factors may contribute to the experience and impact of pain. In support of these models in populations of individuals with disabilities, factors such as pain-related cognitions or attributions, coping, and social support have been shown to be associated with pain and functioning in individuals with multiple sclerosis,8 spinal cord injury,9 acquired limb loss,10 and muscular dystrophy.11 However, as Ehde et al.12 noted, these psychosocial factors have received little empirical attention in the context of pain in persons with PPS. A few studies have examined the general quality of life among persons with PPS. For example, in an early study, Conrady et al.13 found high levels of “psychological distress” in a sample recruited from a PPS clinic and support group. More recently, Vasiliadis et al.14 found that mental health variables assessed by the MOS 36-item Short-Form Health Survey (SF-36) were associated with pain in a sample of 126 individuals with PPS. In a study with a relatively small sample (n = 32), Willen and Grimby15 also found pain to be significantly correlated with a broad psychological measure, the Emotional Reaction Scale of the Nottingham Health Profile.16 However, we are not aware of any research that has examined the influence of specific psychosocial variables (e.g., pain beliefs) on the severity and impact of pain in PPS. This is an important avenue of research because increased understanding of these relationships is likely to have important treatment implications that could potentially improve the quality of life of persons living with this condition. The purpose of the current study was to examine the associations among measures of psychosocial factors, pain, and adjustment in a sample of individuals with PPS. We hypothesized that a set of psychosocial variables—specifically, pain catastrophizing, pain beliefs, pain coping strategies, and social support—would be significantly and uniquely related to pain intensity, pain interference, and general psychological functioning in a sample of individuals with PPS, even after controlling for relevant demographic and clinical variables.