V31. Learned control over spinal nociception in chronic back pain patients. Issue 8 (August 2015)

• Record Type: Journal Article
• Authors: Krafft, S.; Göhmann, H.-D.; Sommer, J.; Straube, A.; Ruscheweyh, R.
• Is Part Of: Clinical neurophysiology. Volume 126:Issue 8(2015:Aug.)
• Page Start: e82
• Page End: 380
• Publication Date: 2015-08
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2015.04.109
• Languages: English
• ISSNs: 1388-2457

Abstract

<abstract xml:lang="en" abstract-type="author" id="ab005"> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title id="st005">Question</title> <p id="sp005">The descending pain inhibition is a top-down system exerting powerful endogenous pain inhibition. It originates in the brainstem and sends serotonergic and noradrenergic pathways to the spinal dorsal horn, where they inhibit spinal nociceptive transmission and therefore reduce nociceptive input to the brain. The brainstem centers at the origin of descending inhibition are targeted by cortical regions like the prefrontal cortex and the anterior cingulate cortex, and are susceptible to cognitive-emotional modulation (<xref id="c0005" rid="b0005">Bingel and Tracey, 2008</xref>). A method to measure spinal nociceptive transmission and quantify the effects of the descending pain inhibition is the spinal withdrawal (RIII) reflex. Young healthy subjects can learn to use cognitive-emotional processes to suppress their spinal nociception to 66% when receiving feedback on the size of their RIII reflex, likely by learning to deliberately activate their descending pain inhibition (<italic>n</italic> = 15; <xref id="c0010" rid="b0010">Ruscheweyh et al., in press</xref>). Here, we investigated if chronic pain patients are also able to learn using cognitive-emotional strategies to suppress their spinal nociception under feedback of the RIII reflex. If this is the case, this approach may be used to improve descending pain inhibition in chronic pain patients.</p> </sec> <sec> <title id="st010">Methods</title> <p id="sp010">The RIII reflex was evoked by painful electrical stimulation of the sural nerve at the ankle and recorded from the biceps femoris muscle. Subjects were in one of three groups: (1) chronic back pain patients receiving true feedback of their RIII, (2) chronic back pain patients receiving sham feedback of their RIII and (3) healthy control subjects receiving true feedback of their RIII. Subjects were trained in three sessions. The RIII reflex was recorded every 8–12 s, and subjects received immediate true and sham feedback, respectively, on their RIII reflex size. During a defined time window, subjects had the task to use cognitive-emotional strategies to reduce the RIII reflex size. Additionally, we documented the subjective pain sensation. To date, 10 patients with true feedback, 5 patients with sham feedback and 4 healthy controls with feedback have been trained to reduce their RIII reflex.</p> </sec> <sec> <title id="st015">Results</title> <p id="sp015">In three sessions, the patients with true feedback achieved a significant (<italic>p</italic> < 0.01) average RIII-suppression to 84 ± 17% (<italic>n</italic> = 10), patients with sham feedback reached a suppression to 93 ± 8% (<italic>n</italic> = 5) and controls to 47 ± 33% (<italic>n</italic> = 4). Simultaneously, the pain perception was significantly reduced to 83 ± 8% in patients with sham feedback (<italic>p</italic> < 0, 01), to 91 ± 13% in patients with feedback and to 79 ± 16% in controls. Hence, these preliminary data suggest that chronic pain patients are able to learn control over their spinal nociception under feedback of the RIII reflex, but the extent of reflex reduction achieved may be smaller than in healthy subjects.</p> </sec> <sec> <title id="st020">Discussion</title> <p id="sp020">Consequently, this feedback training might be a useful approach to enhance endogenous pain inhibition in chronic pain patients. It remains to be determined if the feedback training has an effect on the patients' clinical pain and on supraspinal measures of nociception (somatosensory evoked potentials).</p> </sec> </abstract>