TP Straube/Ruscheweyh: Can patients with chronic back pain learn control over spinal nociception?
PhD Student Stefanie Krafft:
"Descending pain inhibition is a powerful endogenous pain control system that originates in the brainstem and descends to the dorsal horn of the spinal cord. There, it inhibits spinal nociception by releasing serotonin and noradrenalin and hence reduces nociceptive input to the brain, which in turn leads to reduced pain sensation. Cognitive and emotional processes modulate the activity of descending pain inhibition, and thus also pain sensation.
Patients with chronic pain exhibit impaired descending pain inhibition, which might be one reason for the persistence of pain. Improving descending pain inhibition in patients with chronic pain is therefore a promising target for pain therapy.
We previously developed a feedback training in which healthy subjects learned control over their spinal nociception, by using cognitive-emotional strategies and receiving visual feedback about their nociceptive flexor reflex (RIII reflex), a measure of spinal nociception. Likely, this spinal nociception control was achieved by activation of the descending pain inhibitory system.
In my study, I investigate if also chronic back pain patients can learn to control their spinal nociception under feedback about their RIII reflex, by activating their descending pain inhibition. Also, I explore the effect of the feedback training on clinical outcomes.
In the context of my project I employ
- electrophysiology: EMG, SEP
- conditioned pain modulation (CPM)."
„The experimental setup used for the RIII feedback training is illustrated. The nociceptive RIII reflex is evoked by electrical stimulation over the sural nerve (every 8-12 s) and recorded from the thigh. Somatosensory evoked potentials are recorded from the vertex. The RIII reflex size is displayed in form of bars on a separate screen. During the task phase, marked by green bars, the subjects uses cognitive/emotional strategies to activate her descending inhibition and achieve a voluntary decrease of her RIII reflex size.”