Assessment of physical activity of patients with chronic pain.

OBJECTIVES: To define the key terms and concepts relating physical activity to chronic pain; to provide a brief overview of the various methods of assessment of physical activity; to review the current literature about physical activity and chronic pain; and to identify needs for future research. MATERIALS AND METHODS: A narrative review based on results of a PubMed search (to May 2011) and the references of recent systematic reviews. RESULTS: Many methods exist for measuring physical activity. Movement sensors, such as accelerometers, offer objective assessment of physical activity of patients with chronic pain. It is often assumed that patients who feel disabled and report daily life restrictions due to chronic pain also will be less physically active. Studies that have compared the activity of patients with chronic back pain with that of healthy individuals consistently showed that the relationship of physical activity and severity of pain, as well as the change in activity following interventions, was variable and complex. CONCLUSIONS: It is important to understand the relationship between physical activity and chronic pain. Future studies should objectively assess not only the pattern and complexity of that relationship but also the interaction with the patient's mood and ability to cope with the pain.

Assessment of patient preference for constant voltage and constant current spinal cord stimulation.

OBJECTIVES: Spinal cord stimulation devices control energy by generating either constant voltage (CV) pulses or constant current (CC) pulses. This study aimed to investigate: 1) whether patients feel differences between CV and CC stimulation; 2) if patients prefer CV or CC stimulation. METHODS: Fourteen patients blinded to the type of pulse generation received 20 randomized pairs of 15-sec pulse trains (CC-CV, CV-CC, CV-CV, or CC-CC). Patients identified whether the pairs were the same or different, and if they preferred the first or second train. RESULTS: There was no difference in charge-per-pulse input between CV and CC modes. Patients performed at chance level in identifying identical pairs (55.7 ± 24.1% correct, 10 trials), and slightly better in identifying different pairs (67.1 ± 25.2% correct, 10 trials). No patients correctly identified all pairs. Patients were categorized based on their performance in this task. Only three patients fell into a category where preference could be established with some confidence with respect to the group averages. Two of these patients preferred CV, while one patient preferred CC. CONCLUSION: The lack of patient ability to discriminate in this preliminary investigation suggests that patient preference for a stimulation type should not be the key determining factor in choosing a spinal cord stimulation system.