Pain Catastrophizing and EEG-α Asymmetry.

OBJECTIVES: Pain catastrophizing is thought to play a causal role in the development and maintenance of chronic pain and its negative impact on functioning. However, few studies have examined the factors that might contribute to the development and maintenance of catastrophizing. The Anterior Asymmetry and Emotion (AAE) model hypothesizes that more activity in left anterior brain regions is associated with a tendency to engage in approach responses (often, but not always, associated with positive valance), and that more right anterior activity is associated with a tendency to engage in more withdrawal responses (often associated with negative valance). Given the consistent associations found between catastrophizing and both (1) approach versus avoidance pain coping style; and (2) affective responses to pain, the AAE model would predict that more left (vs. right) anterior brain activity would prospectively predict future catastrophizing. METHODS: Anterior asymmetry measures computed using electroencephalogram data from 30 individuals with spinal cord injury were correlated with catastrophizing scores obtained 2 years after the electroencephalograph recording. RESULTS: Consistent with the AAE model, anterior asymmetry scores reflecting greater left than right anterior activity were negatively associated with subsequent catastrophizing. CONCLUSIONS: The study findings identify a biological factor that may be associated with greater vulnerability to pain-related catastrophizing. If replicated in future research, the findings suggest new possibilities for treating catastrophizing, which may then contribute to improved pain treatment outcomes.

Baseline brain activity predicts response to neuromodulatory pain treatment.

OBJECTIVES: The objective of this study was to examine the associations between baseline electroencephalogram (EEG)-assessed brain oscillations and subsequent response to four neuromodulatory treatments. Based on available research, we hypothesized that baseline theta oscillations would prospectively predict response to hypnotic analgesia. Analyses involving other oscillations and the other treatments (meditation, neurofeedback, and both active and sham transcranial direct current stimulation) were viewed as exploratory, given the lack of previous research examining brain oscillations as predictors of response to these other treatments. DESIGN: Randomized controlled study of single sessions of four neuromodulatory pain treatments and a control procedure. METHODS: Thirty individuals with spinal cord injury and chronic pain had their EEG recorded before each session of four active treatments (hypnosis, meditation, EEG biofeedback, transcranial direct current stimulation) and a control procedure (sham transcranial direct stimulation). RESULTS: As hypothesized, more presession theta power was associated with greater response to hypnotic analgesia. In exploratory analyses, we found that less baseline alpha power predicted pain reduction with meditation. CONCLUSIONS: The findings support the idea that different patients respond to different pain treatments and that between-person treatment response differences are related to brain states as measured by EEG. The results have implications for the possibility of enhancing pain treatment response by either 1) better patient/treatment matching or 2) influencing brain activity before treatment is initiated in order to prepare patients to respond. Research is needed to replicate and confirm the findings in additional samples of individuals with chronic pain.

Effects of non-pharmacological pain treatments on brain states.

OBJECTIVE: To (1) evaluate the effects of a single session of four non-pharmacological pain interventions, relative to a sham tDCS procedure, on pain and electroencephalogram- (EEG-) assessed brain oscillations, and (2) determine the extent to which procedure-related changes in pain intensity are associated with changes in brain oscillations. METHODS: 30 individuals with spinal cord injury and chronic pain were given an EEG and administered measures of pain before and after five procedures (hypnosis, meditation, transcranial direct current stimulation [tDCS], neurofeedback, and a control sham tDCS procedure). RESULTS: Each procedure was associated with a different pattern of changes in brain activity, and all active procedures were significantly different from the control procedure in at least three bandwidths. Very weak and mostly non-significant associations were found between changes in EEG-assessed brain activity and pain. CONCLUSIONS: Different non-pharmacological pain treatments have distinctive effects on brain oscillation patterns. However, changes in EEG-assessed brain oscillations are not significantly associated with changes in pain, and therefore such changes do not appear useful for explaining the benefits of these treatments. SIGNIFICANCE: The results provide new findings regarding the unique effects of four non-pharmacological treatments on pain and brain activity.

Steps toward developing an EEG biofeedback treatment for chronic pain.

Chronic pain, usually refractory to analgesics, is a significant problem for many individuals with spinal cord injury (SCI). Preliminary studies suggest that electroencephalography (EEG) biofeedback (also known as neurofeedback, NF) has the potential to help patients with otherwise refractory chronic pain. However, there remain many unanswered questions about the effects and mechanisms of this treatment. We studied 13 individuals with SCI and chronic pain with NF. Ten of the 13 individuals completed 4 sessions each of three different neurofeedback protocols assigned in random order for a total of 12 NF sessions. All three protocols had similar immediate effects on pain intensity. In addition, the participants reported modest pre- to post-treatment decreases in worst pain and pain unpleasantness following completion of the 12 NF sessions. These improvements were maintained at 3-month follow-up. The majority of the participants felt they benefited from and were satisfied with the treatment. No significant effects on measures of other outcome domains (sleep quality, pain interference and fatigue) were observed, although there was a non-significant trend for an increase in fatigue. Finally, pre- to post-treatment changes in EEG bandwidth activity, consistent with the training protocols, were observed in θ and α but not ß frequencies. The findings provide preliminary support for the potential efficacy of NF for the treatment of SCI-related pain, and suggest that further clinical studies are warranted.