Biofeedback in headache: An overview of approaches and evidence
ABSTRACT
Biofeedback-related approaches to headache therapy fall into two broad categories: general biofeedback techniques (often augmented by relaxation-based strategies) and methods linked more directly to the pathophysiology underlying headache. The use of general biofeedback-assisted relaxation techniques for headache has been evaluated extensively by expert panels and meta-analyses. Taken together, these reviews indicate that (1) various forms of biofeedback are effective for migraine and tension-type headache; (2) outcomes with biofeedback rival outcomes with medication therapy; (3) combining biofeedback with medication can enhance outcomes; and (4) despite efficacy in many patients, biofeedback fails to bring significant relief to a sizeable number of headache patients. Biofeedback methods that more directly target headache pathophysiology have focused chiefly on migraine. These headache-specific approaches include blood volume pulse biofeedback, which has considerable supportive evidence, and electroencephalographic feedback.
EEG-based methods
The next most investigated approach involves electroencephalographic (EEG) biofeedback, of which there are two types. The first derives from research investigating links between certain EEG frequency bands and the experience of pain.19 This research suggests that the experience of pain is associated with lower amplitudes of slow brain wave activity (delta, theta, and alpha) and higher amplitudes of faster brain wave activity (beta). Several uncontrolled series suggest that EEG biofeedback may be of value, but more well-controlled investigations are needed before further statements can be made.
The second line of EEG research takes a different approach, focusing on the contingent negative variation response (CNV). The CNV is a slow cortical event-related potential that examines EEG activity occurring between presentation of a warning stimulus and an imperative stimulus (in this case 3 seconds later), a stimulus requiring a response by the individual. This potential is related to the level of excitability upon activation in the striatothalamocortical loop, reflecting different stages of information processing.20 Studies in child and adult migraineurs reveal that these patients have a heightened response to novel stimuli and do not habituate as readily over repeated trials as do non-migraineur controls.21 The CNV is believed to reflect anticipation of a migraine attack because its amplitude and habituation patterns change during the headache-free interval. Abnormalities gradually increase in the days before a migraine attack, with the most pronounced changes occurring just prior to the attack.22
On the basis of these etiopathologic findings, Siniatchkin et al conducted an initial test to determine whether child migraineurs could learn, via biofeedback, to change their CNV activity and whether such learning would alter the subsequent course of migraine attacks.23 Ten child migraineurs without aura each received 10 sessions of CNV biofeedback. They were taught how to increase and decrease EEG negativity (as bidirectional control of a physiologic response is assumed to reflect a greater level of self-regulation). By the end of training, the children could indeed regulate their CNV activity when feedback was provided, but they were unable to do so when the feedback was removed.
The number of training sessions administered was low, as most treatment investigations using EEG biofeedback typically use 20 to 40 sessions. A greater number of sessions may have led to greater response generalization. Interestingly, baseline or tonic levels of EEG negativity changed over the course of treatment, so much so that the child migraineurs were no longer distinguishable from a matched sample of healthy controls, which suggests that the migraineurs’ level of cortical excitability may have diminished. CNV biofeedback led to improvements on most measures of headache activity relative to a second group of child migraineurs who comprised a waiting-list control group.23 These preliminary findings add to those briefly mentioned for other EEG biofeedback approaches, suggesting that further investigations are warranted.
